# FINAL REPORT
Zeolite Coating System for Corrosion Control to Eliminate Hexavalent Chromium from DoD Applications



## SERDP Project WP-1342

AUGUST 2009

Yushan Yan University of California, Riverside, CAThis report was prepared under contract to the Department of Defense Strategic Environmental Research and Development Pr ogram (SERDP). The publication of this report does not indicate endorsement by the Department of Defense, nor should the
contents be construed as refl ecting the official policy or pos ition of the Department of Defense. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or othe rwise, does not necessa rily constitute or imply its endorsement, recommendation, or favoring by the Department of Defense.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 2 

## Contents

1. PERFORMING ORGANIZATIONS

.................................................................... 3

2. PROJECT BACKGROUND

............................................................................... 4

3. OBJECTIVES

.................................................................................................. 8

4. TECHNICAL APPROACH

................................................................................. 9

5. PROJECT ACCOMPLISHMENTS

.................................................................... 15

T ASK 

### 1

‐ 1: E XTENSION OF 

### ZSM

‐ 5 COATING TO OTHER 

### D O 

### D ALLOYS



### ................................... 16

T ASK 

### 1

‐ 2: S CALE UP THE DEPOSITION PROCESS TO 

### 3 X 

### 6” PANELS FROM 

### 2 X 

### 3 CM COUPONS



### ....... 18

T ASK 

### 1

‐ 3 & 1

‐ 4: A LTERNATIVE ZEOLITE AND DEPOSITION PROCESS



### ..................................... 21

T ASK 

### 2. Z EOLITE 

### / TOPCOAT SYSTEMS



### ........................................................................... 33

T ASK 

### 3.1: L ASER 

### S CANNING 

### C ONFOCAL 

### M ICROSCOPY 

### (LSCM) CHARACTERIZATION OF COATING

SURFACES



### ............................................................................................................... 35

T ASK 

### 3.2: I NSTRUMENTAL ANALYSIS OF COATING DEGRADATION



### ........................................ 39

T ASK 

### 3

‐ 3: Q UANTITATIVE 

### / QUALITATIVE ADHESION TESTING OF COATING TO 

### A L 

### & STEEL

SUBSTRATES



### ............................................................................................................ 42

T ASK 

### 3

‐ 4: C ONDUCT ACCELERATED SERVICE SIMULATION TESTING



### ...................................... 48

T ASK 

### 3

‐ 5: E XAMINE SUBSTRATE DEGRADATION AND CORROSION INHIBITION



### – EIS TEST



### .......... 66

T ASK 

### 3

‐ 6: M ARINE ATMOSPHERE TEST 

### / COATING DEGRADATION STUDIES



### ............................. 68

T ASK 

### 4: T ECHNOLOGY 

### T RANSITION



### .............................................................................. 82

APPENDIX

......................................................................................................... 83

REFERENCE

....................................................................................................... 86

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 3 

### 1. Performing Organizations

Dr. Y. Yan

Dr. P. Zarras Mr. S. Smith Dr. M. Tsapatsis Dr. Y. Yan

Mr. D. Beving Dr. Y. Kim Dr. R. Cai
Mr. R. Munoz Mr. C. O’Neill Ms. N. Anderson Ms. C. Webber Dr. A. Guenthner Mr. M. Fleszar Ms. Aisha Bishop Dr. Gay Kendall Dr. Z. P. Lai Dr. S. Ghosh Mr. M. Boretz Ms. L. Arth Ms. C. Howard

Zeolite coating In-situ crystallization Basic and standard characterization Standard (Mil-spec) characterization Polymer coating Formulation/deposition Basic coa ting characterization Standard (Mil-Spec) characterization Zeolite coating Alternative deposition Basic coa ting characterization

Materials engineering/Chemical engineering /Inorganic chemistry/Polymer chemistry/Polymer physics/Physics Mr. D. Harmston, NADEP

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 4 

### 2. Project Background

Corrosion control coa ting systems for DoD applications. Corrosion costs associated with corrosion prevention and correction of corrosion- generated failures account for approximately 25% of the armed services’ annual maintena nce budgets, or more than $1 billion a year 1 . A majority of these costs is associated with compliance with new environmental regulations regarding worker safety and hazardous waste dis posal. These costs have risen dramatically over the past several years – as high as 20% in some DoD facilities. This increase is responsible for a significant portion of noncompliance with new e nvironmental regulations, systems downtime, and failure of mission readiness.

Current effective corrosion contro l coating systems for alloys and especially aluminum alloys used in DoD applications rely on exte nsive use of hexavalent chromium (Cr +6 ) in conversion coatings and primers. Table 2-1 shows several current military coating systems used for corrosion inhibition on aluminum alloys. All co atings contain hexavalent chromium. As a surface pretreatment, chromium conversion coa tings (CCC) were firs t introduced during the
1950s 2-5 . Since this time, they have found widespread use in both military and commercial applications. Within the DoD community, the CCC process is extensively used to enhance paint adhesion and corrosion inhi bition. CCC has been used to effec tively treat numerous metals such as aluminum, copper, cadmium, manganese and zinc . Hexavalent chromium is also widely used in the primers for corrosion control ( Table 2-1). Unfortunately, Cr +6 is toxic and carcinogenic 6

. Therefore, regulations regarding its use and dis posal have become increasingly stringent. The current Permissible Exposure Limits (PEL) (50 μ g/m 3 ) of Cr +6 have been recommended to be
reduced to 1.0 μ g/m 3 by OSHA in order to meet the required low level of risk. Additionally, painting and depainting operations c ontinue to be a significant s ource of hazardous waste for the
DoD 7 . Hazardous waste generation and disposal from such operations are a significant source of painting operation costs. The National Emission Standards for Hazardous Air Pollutant (NESHAP)/Environmental Protection Agency (EPA) regulations are implementing new regulations for reducing chromate exposure for wo rkers and will eventua lly eliminate its use altogether in the near future. Therefore, a new chromium-free coating syst em is critically needed to meet corrosion protection performance re quirements in all DoD applications.

Table 2-1 Military coatings specifications (All coatings systems listed below contain chromates)

MIL-Spec Description

TT-2756 solvent-based polyurethane self-priming topcoat

TT-P-2760 solvent-based polyurethane flexible primer

MIL-P-53022 solvent-based epoxy primer

MIL-P-53030 water-reducible epoxy primer

MIL-PRF-85582 water-reducible epoxy primer

MIL-PRF-23377 solvent-based epoxy primer

DOD-P-15328 wash pretreatment (primer)

DOD-P-5541 chromate conversion coating

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 5 Corrosion resistant zeolite coatings . Zeolites are crystalline inor ganic polymers with a reduced molecular formula mSiO 2 -AlO 3 (1 ≤ m ≤∞ ) 8

. At the atomic level, zeoli tes are constructed from
TO 4 tetrahedra (T = tetrahedral atom, e.g., Si, Al); each apical oxygen atom is shared between two adjacent tetrahedra. Aluminum atoms usually are uniformly distributed within the polymer structure. According to Si/Al ra tio, zeolite can be classified in to two groups – high-silica (i.e., high Si/Al) and low-silica (i.e., lo w Si/Al). Zeolites, and especial ly high-silica ze olites are known for their thermal stability. Many ze olites are stable to 900 °C a nd some high-silica zeolites are stable up to 1400 °C without losi ng their crystalline structure 9 . All zeolites are st able to organic solvents and high-silica zeolites ar e stable to most mineral acids and react only w ith hydrofluoric acids 10 . Zeolites are inexpensiv e. Zeolites are non-toxic. Although not a high-volume application, zeolites are used in personal hygiene products such as odor removal gels and baby diapers. Very recently FDA has approved a medical application, which involves using zeolites as an oral contrast agent for magnetic resonance imaging 11

.

Thus far, zeolite materials are most commonly used in particle form as catalysts (e.g., catalytic cracking for petroleum refining) and gas separa tion media (e.g., air separation into nitrogen and oxygen). Recently zeolite films have been prepar ed as membranes for separation applications 12

. All of these applications take advantage of the uniform microporosity of zeolites (3-13Å). In other words, zeolites are used in these applica tions as molecular sieves – sieving molecules according to their size with precision of a fraction of an angstrom. UCR has recently demonstrated for the first time that as-synthesi zed high-silica zeolite ZSM-5 coatings can be extremely corrosion resistant ( Figure 2-1, Figure 2-2) 13, 14 . Syntheses of high-silica zeolites usually involve using an organic te mplate (or structure-directing-ag ent) to crystallize the desired structure. These template molecules (e.g., te trapropylammonium) are bulky and eventually trapped inside the zeolite structure. To free up the pore spaces for catalysis and separation applications, these trapped molecules are usuall y burned-out by high temperature calcinations (e.g., 500 oC) in air or oxygen overnight. Therefore, as-synthesized zeo lite coatings (without going through calcinations ) can be non-porous ( Figure 2-1c).
High-silica zeolite ZSM-5 coa tings on aluminum alloy 2024-T3 (AA-2024-T3) have been shown to offer remarkably better corrosion resistance than chromate conversion coating and anodization coating in strong acids (Figure 2-2 a&b), bases (0.5 M NaOH, not shown), and pitting aggressive environments ( Figure 2-2 c&d) 13, 14 . For example, there is no decrease of corrosion resistance after the zeolite coated AA-2024-T3 sample is immersed in 0.5 M H 2 SO 4 for 10 days ( Figure 2-2 b). The zeolite coating is chemically bonded to the aluminum alloys or other metals through condensation of surface hydroxyl groups 12 . Zeolite coating also has good thermal stability (e.g., 240 oC) and thermal shock stability (e.g., fast th ermal cycling between 240 oC and – 70 oC) and good adhesion under mechanical stresses (cutting, impact, and bendi ng). Preliminary results have shown that the zeolite coatings have good paint compatibility and is compatible to polyurethane type paints 13

. They also have better ab rasion resistance than anodiza tion coatings. The coating thickness can be readily c ontrolled between 0.5 to 50 μ m according to specific needs.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 6

Figure 2-1 Scanning electron microscope (SEM) micrographs of an as-synthesized zeolite coating on

Al-2024-T3, (a) top view and (b) cross

- sectional view, (c) schematic of ZSM-5 pore system andlocation of the trapped template – tetrapropylammonium (TPA) molecule. Open circle for nitrogen atom and solid circle for carbon atom, and hydrogen atoms were not shown. Ref. 13

. Figure 2-2 DC polarization curves of several coatings in different corrosive media. (1) zeolite coating on Al-2024-T3, (2) anodization coating on Al-5005 (sulfuric acid anodized and sealed by hot water, 18 μ m thick, provided by SouthernAluminum Finishing, Atlanta, GA), (3) bare Al2024-T3, (4) chromate conversion coating on Al2024-T3 (submicron thick provided by Triple AAA

plating, Inc. Bells, Texas); (a) 0.5 mol/L H 2 SO 4 after immersion for 2 hours, (b) 0.5 mol/L H 2 SO 4 after immersion for 10 days, (c) 0.5 mol/L NaCl/HCl (pH=1) after immersion for 2 hours, (d) 0.5 mol/L NaCl + 0.26 g/L CuCl 2 + HAc (pH=3) after immersion for 1 day. All tests at 25 °C with sweep rate of 1 mV/s, saturated calomel electrode and Solartron 1287 potentiostat. . Ref. 13

. Zeolite coating (line 1) provides better corrosion protection than chromate conversion coating and

anodization coating in strong acid (a) and (b), strong base (0.5 M NaOH, not shown), and pitting aggressive solutions (c and d).

Zeolite coating by in-situ crystallization

. The high-silica ZSM-5 coatings discussed above were prepared by in-situ crystallization process. In-situ crystallization here refe rs to a coating process in which the zeolite crystals making up the even tual polycrystalline coating are crystallized directly at the solid-liquid in terface from a synthesis solution during the coating formation

process (Figure 2-4) 12 . The synthesis solution used is a clear, dilute aqueous solution containing primarily molecular species of silicon and aluminum. The term “ in-situ crystallization” originates from the fact that there are no preforme d zeolite particles in th e synthesis solution. TheUnivers i in-situ c r 180 oC) h does no t immerse d during c r very lo w sight sp a confined time is a heating 1 5 crystalli z heating g reaction t

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## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 8 

### 3. Objectives

The overall objective of the proposed project is to develop a new environmentally friendly zeolite coating system for corrosion control to eliminate hexavalent chromium in DoD applications without sacrificing performance. The specific goals of the project are as follows.

1) Development of zeolite coati ngs (see Tasks for details). 2) Demonstrate compatibility with current Milita ry water-dispersible po lyurethane topcoats. 3) Basic characterization and standard testing of zeolite and zeolite /topcoat systems and provide performance benchmarking with current chromium-containing DoD coating systems. 4) Fast technology transition.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 9 

### 4. Technical approach

This SERDP project will have four major thrust s: (1) development of zeolite coatings on DoD relevant alloys; (2) demonstrate compatibility ofzeolite coatings with current Military waterdispersible polyurethane topcoa ts; (3) basic characterization and standard testing of zeolite/topcoat systems with benchmarking obtai ned from performance of current chromiumcoating coating systems; (4) technology tran sition. Specifically, the following tasks will be carried out by the research team consisting of UCR, UMN, NAWCWD (China Lake), Army Benet Labs, and NADEP (North Island).

Task 1: Zeolite coatings
Task 1-1: Extension of in-situ crystallizatio n coating deposition process from AA-2024-T3 to other DOD relevant alloys such as AA-6061- T6, and AA-7075-T6, and steels (S1008, S4130, SS304)
With support from US EPA, UCR has so far focused on 2x3 cm coupons to demonstrate that high-silica-zeolite (PSZ) coatings can be successfully deposited on AA-2024-T3, and the assynthesized coatings are corrosion-resistant in strong acid, base, and pitting aggressive environments, and have good thermal and th ermal shock stability, and good adhesion under mechanical stresses (cut, bending, and impact). Fo r the proposed effort, it is important to show that the in-situ crystallization coating process can be exte nded to other DoD re levant alloys such as AA-6061-T6, AA-7075-T6, and cold rolled steel S-1008.

Task 1-2: Scale-up in-situ cr ystallization coatin g deposition process from current 2x3 cm coupons to larger panels such as 3x6 inches
With US EPA support, UCR’s effort up to to day has focused on 2x3 cm coupons because they are convenient to produce and adeq uate for the current research needs. By using small coupons, the amount of chemicals used can also be mini mized. In the proposed effort, it is critical to demonstrate that the process can be scaled up . Large 3x6 inch panels are also needed for standard tests (e.g., ASTM and Mil- Spec as described in Task 4).

Task 1-3&1-4: Develop alternative c oating and coating deposition method
The goal of this task is to develop alternativ e zeolite coatings (i.e., other than ZSM-5) and deposition process. The central requirements ar e ambient pressure, low temperature, and short deposition time. The process should also be conve nient for repair should the original coating damaged. Two different deposition methods are being developed. The fi rst one is a layer-bylayer deposition process using MCM-22 developed by UMN. The precursor of zeolite MCM-22, namely MCM-22(P), is a layered aluminosilicate. Layers in th e as-synthesized MCM-22-(P) are weakly linked together with organic structure directing agents, Hexamethyuleneimine (HMI), along the [001] direction. Two-dimensional large channels are running in-plane of the MCM-22- (P) layers. However, the limiting apertures for tran sport perpendicular to the layers (along [001] direction) are 6MR’s, i.e. de fined by six interconnected SiO 4 tetrahedra. Thus, molecules like water and O 2 cannot penetrate along the c-axis. Upon calcination, MCM-22(P) condenses to MCM-22. On the other hand, layers in MCM-22(P) can be delaminated. After calcination, it

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 10 forms another material called ITQ-2. Either MC M-22(P) or MCM-22 part icles are plate-like. Delaminated layers will be even thinner. We use these materials as building blocks to assemble a thin film by a chemical interaction based Layer-by-Layer method for corrosion protection. The second one is microwave-assisted ambient pres sure ionothermal synthe sis method using SAPO11. In this method, ionic liquid was used instead of water, making it possible for zeolite synthesis at ambient pressure even at temperatures higher than 100 o C since ionic liquid has negligible vapor pressure. Microwave radiation can accelerate the deposition process to fulfill the requirement of short deposition time.

Task 2: Application of primer/topc oat or topcoat to zeolite coatings
The U.S. Army has developed a water disper sible polyurethane (U. S. Patent #5,691,410), which is currently being used by DoD for tactical and related support equipment. The water-dispersible (WD) chemical agent resistant coating (C ARC) utilizes hydroxyl-functional polyurethane dispersions and water dispersible polyisocyanates. The U.S. Air Force has similarly developed a water dispersible polyurethane t opcoat. Both Army and Air Force polyurethane topcoats will be applied to the zeolite coated alloys to demonstrate compa tibility with these systems.
Primers and primer/topcoat systems currently in us e by the military will al so be applied to the zeolite coatings to demonstrate compatibility of the zeolite coating with existing systems. The different primers and topcoa ts and combinations to be tested are shown below.

Primer Topcoat
Mil-P-23377 I (chromated) Mil-PRF-85285
Mil-P-23377 I (non-chro mated) Mil-PRF-85285
Mil-P-85582 (non-chromated) Mil-PRF-85285

Mil-P-23377 I (chromated) none
Mil-P-23377 I (non-chromated) none
Mil-P-85582 (non-chromated) none
TT-P-2756 A (self-priming topcoat) none

Task 3: Laboratory characterization and standard tests
Task 3-1: Characterization of coating surfaces

. Quantitative surface characterization will be performed by Laser Scanning Confocal Micros copy (LSCM) and Atomic Force Microscopy (AFM). These methods provide non-destructi ve 2- and 3-dimensional imaging with no a priori surface preparation. Surface character ization of individual proposed layers will provide insights to total coating system perfor mance (e.g., enhanced adhesion of topcoat to ze olite due to significant surface area available for bonding). LSCM and AFM will be used to obtain a quantitative measure of surface area, complex ity (roughness, fractal dimension), and quality

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 11 (frequency/size of defects) of the following systems, having b een applied to Al and steel substrates: (i) zeolite coating, (ii) zeolite/polyurethane topcoat system.
Surface characterization by LSCM and AFM will be repeated following sequential accelerated weathering exposures (see Task 3-4) of systems (ii) to quantitati vely describe coating system degradation. Results will be benchmarked with current Army & Air Force pretreatment/primer/topcoat systems.

Task 3-2: Instrumental analyses of coating degradation. Several analytical techniques will be used to examine the degradation due to accelerat ed environmental weathering of zeolite/topcoat systems on aluminum alloy and steel substrates. These tests include thermal gravimetric analysis (TGA), Fourier transform infrared spectrometry (FTIR), thermal mechanical analysis (TMA), scratch tests and wear tests. In all cases, these tests will be conducted before, during and after accelerated service simulation testing. TGA is a technique which measures the weight of a sample as a function of temperature. TGA can effectively measure moisture, solvent, additive or plasticizer loss and the rate of thermal decomposition. FTIR can provide valuable information regarding the chemical nature and molecular st ructure of the material. This technique can provide information regarding the effects of drying and weathering on paints. TMA techniques can measure the coefficient of thermal expansi on, stress relaxation, pene tration, softening and glass transition temperature of thin films such as paint coatings, which will provide degradation profiles.

Task 3-3: Quantitative/qualitative adhesion testing of coatings to substrates. Current standard techniques for adhesion testing wi ll be performed using ASTM qua litative adhesi on testing such as the wet tape adhesion (FED-STD –141 met hod 6301) and dry tape adhesion (ASTM D3359). Benet Laboratories will apply semi-quantitative assessments of coating adhesion. They will use several techniques pioneered in their laboratories 16

. Adhesion Peel Testing (APT) and Dynamic Mechanical Analysis (DMA) will be utilized to evaluate the effects of surface pretreatments and coating process parameters on interfacial a dhesion. Tests will be performed on zeolite and zeolite/topcoat systems.

Task 3-4: Conduct accelerated service simulation testing

. Accelerated testing of all panels using novel zeolite and zeolite/topcoat systems and cu rrent military coatings as controls will be carried out using an Accelerated Corrosion Test Chamber. This chamber will provide precision testing such as 2000-hour salt-fog (ASTM B117) te sts. If test panels meet this initial requirement, further testing will include acetic acid/salt spray (ASTM B287), copper accelerated salt spray (ASTM B368), corrodkote (ASTM B380), sulfur dioxide (ASTM B605) and GM 9540 tests. UV exposure tests will be performed on coated coupons following ASTM test 53-96 guidelines for 32 weeks.

Task 3-5: Examine substrate degradation and corrosion inhibition . The evaluation of the substrate corrosion, pitting, etc., will be evaluated using such techniques as eddy current, electrochemical impedance spectroscopy (EIS) and DC Polarization. Nondestructive eddy

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 12 current techniques will be used to measure electrical resistivity of the component structure to determine if corrosion has occurred. Eddy currents have been extensively used to measure the electrical resistivity of metals and have been very successf ul at determining cracks and corrosion 17

. EIS is a very sensitive technique to meas ure the corrosion barrier performance of a coating by measuring its electrical impedance. The charge transfer resistance obtained from this experiment provides an excellent indicator of the integrity of the coating and successfully predicts long-term corrosion beha vior. This technique can effec tively measure coating defects, water uptake, coating degradation and substrat e corrosion. The technique measures various degradation processes in the coating, which causes absorption of electrical energy at different frequencies. This causes a time lag between th e time-dependent excitation and response signals. These processes can be simulated by equivalent electrical networks. Th e frequency response generated from the EIS test is analyzed using a Bode plot, which can discriminate between different electrochemical processes. These plot s provide detailed info rmation about coating stability and degradation. They do not require any accelerating factors for testing and can be conducted in-situ

.

Task 3-6: Marine atmosphere tests. Zeolite and zeolite/topcoat systems will be field-tested in marine environment, and subsequently evaluate d by all the relevant laboratory tests listed previously including adhesion. The coated coupons will be exposed to a marine environment both continuous and intermittent. The intermittent exposure tests will be performed at the NADEP located near coastal waters. If the panels pass this initial phase of testing, they will be subject to continuous e xposure mounted on a navy vessel. Both these tests will provide initial verification of the robustness of the proposed co atings systems. Further studies for extensive field-testing will be developed as part of the transition study (Task 4).

Task 3-7: Toxicology studies. Initial toxicology studies will focus on the Extraction Procedure (EP) Toxicity Test Method (EPTOX) (Method 1310A) and Toxicity Characteristic Leaching Procedure (TCLP) (Method 1311) for the analysis of potential byproducts from the zeoliteconductive polymer coatings. These tests are EPA approved to determine the leachates obtained from solid materials (Index to EPA Methods, ed. Peg Nelson, updated December 2001, SW-846 Manual, Chap 8.4-Methods for Determining Charac teristics, April 1998), such as any potential small molecules that can be leached out of the coating into the environment.

Task 4: Transition study of proposed technology
After successful completion of Task 3, a transitio n plan will be implemented. This plan will document all data from all laboratory tests. Once all technical data is assembled, it will provide a basis for a new MIL-spec for control of corrosion and elimination of hexavalent chromium. The cost-effectiveness data will also be documented and provided for fleet-wide study. This will allow an easy transition and dispersion of the data to other applications and maintenance sites for NAVAIR, AF and Army systems.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 13 Milestones and milestone owners The following milestones are built according to the federal fiscal year cycles. Milestone owners and the deadline are in parenthesis. In case of multi-institutions as milestone owners, the first one is the lead institution

. Task 1-1: Extension of in-situ crystallization from AA-2024-T3 to AA-6061-T6, AA-7075-T6,
S-1008 (1) Production of 2x3 cm ZSM-5 on AA-2024- T3, AA-6061-T6, AA-7075-T6, and S-1008. ( UCR 10/1/03) Æ COMPLETED

Task 1-2: Scale-up in-situ crys tallization from 1x3 coupons to 3x6 panels (2) Production of 3x6 ZSM-5 on AA-2024-T3 ( UCR 10/1/03) Æ COMPLETED (3) Production of 3x6 ZSM-5 on AA-5052-H 32, AA-6065-T6, AA-7075-T6 and S1008, ( UCR 10/1/04) Æ COMPLETED and expanded to include ZSM-5 on S4130 and SS304- 2b

Task 1-3 and 1-4: Develop alternative zeol ite and alternative deposition method (MCM-22) (4) Production of 2x3 cm MCM-22 on AA-2024-T3 ( UM 10/1/03) Æ COMPLETED (5) Production of 3x6 inches MCM-22 on AA-2024-T3 ( UM 10/1/05) Æ COMPLETED (6) Production of 2x3 cm SAPO-11 on AA-2024-T3 (UCR 1/31/08) Æ THIS WAS AN
ADDED TASK WITH SERDP PERMISSION AND COMPLETED

Task 2: Application of primer/topcoat or topcoat to zeolite coatings
(7) Production of 3x6” ZSM-5/CA RC Topcoat(Mil-PRF-64159) ( UCR, Benet, NAWCWD 10/1/05) Æ COMPLETED (8) Production of 3x6” ZSM-5/topc oat [VOC-free topcoat (Deft product #55W-002, Deft, Irvine CA) and Self-Priming topcoat (TT- P-2756A from Deft, Irvine, CA)] ( UCR, NAWCWD 10/1/05) Æ COMPLETED (9) Production of 3x6” ZSM-5/topcoa t and ZSM-5/primer/topcoat ( UCR, NAWCW D 10/1/06) Æ COMPLETED

Task 3-1: Characterization of coating surfaces. (10) Quantitative Surface Imaging by LSCM ( Benet 10/1/05) Æ COMPLETED (11) RMS Roughness ( Benet 10/1/05) Æ COMPLETED (12) Scaling Analysis & Optimized Filtering for LSCM Images ( Benet 10/1/05) Æ
COMPLETED

Task 3-2: Instrumental anal yses of coating degradation. (13) Dynamic mechanical analysis ( Benet 10/1/05) Æ COMPLETED (14) Quality Control testing method by DC Pola rization on 3x6 inch zeolite coatings on AAs(2024-T3, 5052-H32, 6061-T6, 7075-T6) and steels (SS304, S4130, S1008)( UCR 10/1/06) Æ COMPLETED (15) 3x6 ZSM-5 on AA-6061-T6, AA-7075-T6, and S-1008 ( Benet, NAWCWD, UCR 10/1/03 ) Æ COMPLETED (16) 2x3 cm MCM-22 on AA-2024-T3 ( UM, UCR 10/1/03 ) Æ COMPELTED (17) 3x6 MCM-22 on AA-2024-T3 ( UM, UCR 10/1/05) Æ DROPPED

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 14 (18) 3x6” ZSM-5/topcoat system on AA-2024-T3 ( Benet, NAWCWD, UCR 10/1/05 ) Æ
DELAYED BUT LATER COMPLETED

Task 3-3: Quantitative/qualitative adhesion testing of coatings to substrates (19) ASTM D3359-2 adhesion test of ZSM-5 on AAs (2024-T3, 5052-H32, 6061-T6, 7075- T6) ( UCR 10/1/04) Æ COMPLETED (20) Mechanical cutting test of ZSM-5 on AAs ( UCR 10/1/04) Æ COMPLETED (21) Mechanical hole punching of ZSM-5 on AA-2024-T3( UCR 10/1/04) Æ COMPLETED (22) ASTM D-2794-93 impact test ( UCR 10/1/05) Æ COMPLETED (23) ASTM D- 522-93a bending test ( UCR 10/1/05) Æ COMPLETED (24) ASTM G154-00a UV exposure ( UCR, Benet 10/1/06) Æ COMPLETED

Task 3-4: Conduct accelerated service simulation testing (25) ASTM B117 Salt-fog testing on bare zeolite coa ting (0.5 -2 um thick) on AA2024-T3 (3x6 inch) (NAWCWD, 4/1/04 ) Æ COMPLETED (26) ASTM B117 Salt-fog testing on 3x6” ZSM-5/CARC Topcoat(Mil-PRF-64159) ( NAWCWD 10/1/05) Æ COMPLETED (27) ASTM B117 Salt-fog testing on bare zeolite coating (7.5 um thick, no QC) on AA2024-T3 (3x6 inch) (NAWCWD, 4/1/05 ) Æ COMPLETED (28) ASTM B117 Salt-fog testing on bare zeolite coa ting (7.5 um thick, with QC) on AA2024-T3 (3x6 inch) (NAWCWD, 4/1/06 ) Æ COMPLETED (29) ASTM B117 Salt-fog testing on ZSM-5/t opcoat [VOC-free topcoat (Deft product #55W-002, Deft, Irvine CA) and Self-Priming topcoat (TT-P-2756A from Deft, Irvine, CA)] ( NAWCWD 10/1/05) Æ COMPLETED (30) ASTM B117 Salt-fog testing on machine scribed bare zeolite coating (7.5 um thick, with QC) on AA2024-T3 (3x6 inch) (NAWCWD, 4/1/06 ) Æ COMPLETED (31) ASTM B117 Salt-fog testing on ZSM-5/topc oat and ZSM-5/primer/topcoat ( NAWCWD 10/1/06) Æ COMPLETED (32) ASTM B117 Salt-fog testing on bare zeolite coati ng (4-5 um thick, with minimal QC) on 3x6 inch steels (SS304,S4130,S1008) (NAWCWD, 10/1/06 ) Æ COMPLETED (33) ASTM B117 Salt-fog testing on machine scri bed bare zeolite coating (4-5 μm thick, with minimal QC) on 3x6 inch steels (SS304 and S4130) (NAWCWD, 6/20/08 ) Æ
COMPLETED

Task 3-5: Examine substrate degr adation and corrosion inhibition

. (UCR, NAWCWD, 4/1/07) Æ COMPLETED

Task 3-6: Marine atmosphere tests/EIS meas urements/coating degradation studies. (UCR, NAWCWD, 4/1/07) Æ In progress

Task 3-7: Toxicology Studies (UCR, NAWCWD, 4/1/07) Æ DROPPED WITH PERMISSION FROM SERDP
Task 4: Transition Study of Proposed Technol ogy (NAWCWD, NADEP, Benet, UCR, 4/1/07) Æ Considered finished for the project but will still be pursued

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 15 

### 5. Project Accomplishments

This is a final report for a project with dura tion of 5/2003 – 7/1/2008. We will follow the order of tasks. We use a simplified section heading for each task in most cases to save space, and for the details of each milestone please see section 4.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 16 Task 1

­ 1: Extension of ZSM

­ 5 coating to other DoD alloys

UCR has successfully extended ZSM-5 coating from AA 2024-T3 to AA-6061-T6, AA7075-T6 and steel SS1008 using 2x3 cm coupons. A universal solution composition and a universal deposition procedure were developed that produce high quality coatings on all of the aluminum alloys tested (2000, 5000, 6000, and 7000 series). Universal solution and deposition procedures are important as this eliminates the need to adjust the solution composition and deposition procedure to suit an individual alloy, and this means significant cost savings. The molar composition of the synthesis solution is TPAOH/0.16 : NaOH/0.64 : TEOS/1 : H2O/92 : Al/0.0018. Here TPAOH is for tetrapropylammonium hydroxide and TEOS for tetraethylorthosilicate. This is a fairly dilute aqueous solution and the deposition process produces uniform coating on the substrate with little bulk crystallization. The deposition was carried out in convection
oven at 175 ° C for 12-16 hours.

Figure 5-1 shows the scanning electron micrographs of ZSM-5 coatings on AA-2024-T3, AA-5052-H32 (not require d by the project), AA-6061-T4, and AA-7075-T6. The coatings are pol ycrystalline, continuous, and well adhered to the substrate. Thickn ess varies from 7-10 um.

The corrosion resistance of the ZSM-5 coatings on these aluminum alloys are measured in acid, base and pitting aggressive media and th eir polarization curves are shown in Figure 5-2. Clearly, good corrosion resistance was obtained on all of these coatings and in all of the media tested. 20 um 

### a

b

10 um 

### d 10 um 

### c a 10 um



### b 10 um



### c 10 um



### d 10 um 20 um 20 um 

### a

b

10 um 

### d 10 um 

### c a 10 um



### b 10 um



### c 10 um



### d 10 um 20 um 

### a

b

10 um 

### d 10 um 

### c a 10 um



### b 10 um



### c 10 um



### d 10 um 20 um

Figure 5-1. SEM images of ZSM-5 coatings on aluminum alloys (a)AA-2024-T3, (b)AA-5052-H32, ( c ) AA-6061-T4

, and ( d ) AA-7075-T6.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 17

Figure 5-2 Polarization curves of ZSM-5 coati ngs on AA2024-T3, AA-5052-H32, AA-6061-T4, and AA-7075-T6 in acid (H 2 SO4), base (NaOH) and NaCl solutions. 

## DC Polarization Curves
and Corrosion Profiles

0.5M NaOH immersion 2 min 0.5M NaCl/HCl (pH=3) immersion 30 min 0.5M H 2 SO 4 immersion 30 min 

### 2024 - T3
5052 - H32
6061- T4
7075 - T6 Al Alloys

10 -12 10 -11 10 -10 10 -9 10 -8 10 -7 10 -6 10 -5 10 -4 10 -3 10 -2 10 -1 -2 -1 0 1 2

..

ZSM-5 coated alloys Bare alloysE (Volts)

I (Amps/cm 2 ) NaOH

10 -12 10 -11 10 -10 10 -9 10 -8 10 -7 10 -6 10 -5 10 -4 10 -3 10 -2 10 -1 -2 -1 0 1 2

..

ZSM-5 coated alloys Bare alloysE (Volts)

I (Amps/cm 2 ) NaOH

10 -12 10 -11 10 -10 10 -9 10 -8 10 -7 10 -6 10 -5 10 -4 10 -3 10 -2 10 -1 10 0 -1.0 -0.5 0.0 0.5 1.0 1.5

..

I (Amps/cm 2 )E (Volts) ZSM-5 coated alloys Bare alloys NaCl/HCl

10 -12 10 -11 10 -10 10 -9 10 -8 10 -7 10 -6 10 -5 10 -4 10 -3 10 -2 10 -1 10 0 -1.0 -0.5 0.0 0.5 1.0 1.5

..

I (Amps/cm 2 )E (Volts) ZSM-5 coated alloys Bare alloys

10 -12 10 -11 10 -10 10 -9 10 -8 10 -7 10 -6 10 -5 10 -4 10 -3 10 -2 10 -1 10 0 -1.0 -0.5 0.0 0.5 1.0 1.5

..

I (Amps/cm 2 )E (Volts) ZSM-5 coated alloys Bare alloys NaCl/HCl 10 -13 10 -12 10 -11 10 -10 10 -9 10 -8 10 -7 10 -6 10 -5 10 -4 10 -3 10 -2 -1.0 -0.5 0.0 0.5 1.0 1.5

..

Bare alloys ZSM-5 coated alloys

I (Amps/cm 2 )E (Volts) H 2 SO 4

10 -13 10 -12 10 -11 10 -10 10 -9 10 -8 10 -7 10 -6 10 -5 10 -4 10 -3 10 -2 -1.0 -0.5 0.0 0.5 1.0 1.5

..

Bare alloys ZSM-5 coated alloys

I (Amps/cm 2 )E (Volts) H 2 SO 4

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 18 Task 1

­ 2: Scale up the deposition process to 3x6” panels from 2x3 cm coupons

UCR successfully scaled up the coating process from 2x3cm coupons to 3x6" panels (ZSM-5 on AA-2024-T3) in October 2003. This allows the performance of many ASTM and Mil-spec testing. The same chemical solution (TPAOH/0.16 : NaOH/0.64 : TEOS/1 : H2O/92 : Al/0.0018) was used on the large 3x6” panels as for the small 2x3cm” coupons. And the deposition was also carried out in a convection oven at 175 ° C for 12-24 hours. The reactor used was a simple standard steel autoclave with a Teflon liner from Parr Instruments. The substrate was suspended from a Teflon bri dge at the top of the liner ( Figure 5-3a). The scale up had little impact on deposition chemistry. The coatings are extremely uniform ( Figure 5-3b) and have excellent adhesion. The coatin gs are very flexible.

Figure 5-3 (a) A commercial Parr autoclave was used as the reactor; with white Teflon liner, (b) Optical images of bare AA-2024-T3 (right) and ZSM-5 coated AA-2024-T3 (left).

We have gone through three evolutions of zeo lite coating syntheses on the 3” x 6” AA-2024-T3 coupons ( Figure 5-4). Each generation of zeolite co ating was salt fog te sted by ASTM B117 (results shown later in this report).

By adjusting the solution to surface area ratio an d crystallization time, we can produce uniformly coated 3x6”panels of variable but controlled th icknesses. We have i nvestigated the coating corrosion properties at several th icknesses (0.5, 2, 4.5, 7.5, 11, and 13 um thick). Salt fog tests (ASTM B117) were performed on zeolite coated AA-2024-T3 (0.5 um [Generation – 1] and 7.5 um thick [Generation - 2 & 3]) and on scribed coatings (7.5 um thick [Generation – 3]) (see testing results in later sections).

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 19 Figure 5-4 Evolution of zeolite coatings on metal alloys.
The scale up and application of Generation - 3 zeolite coatings was su ccessfully expanded to other DoD aluminum alloys (AA-5052-H32, AA- 6061-T6, and 7075-T6) and to several steels (SS304-2b, S4130, and C1008). These have all been tested by DC Polarization in 5 wt% NaCl, showing excellent corrosion resistance (results and details shown later in this report).

Figure 5-5 shows the scanning elec tron micrographs of Genera tion – 3 ZSM-5 coatings on S1008, S4130 and SS304-2b (S4130 and SS304-2b not required by the project). The coatings are polycrystalline, continuous, and we ll adhered to the substrate. Thic kness varies slightly from 4 -
5 um.

Five zeolite coated panels of each steel (SS 30-2b, S4130, and C1008) with zeolite thickness of about 5 um salt fog tested (ASTM B117) at China Lake (results and details shown later in this report).

Key features and milestones of zeolite coating technology :

• Simple alkaline detergent solution pr etreatment adequate for all metals

• Immerse metal in 3 grams Alconox® per 400 ml de-ionized H 2 O at 60 o C for 30 minutes

• Single zeolite chemical formulation adequate for all metals

• TPAOH/0.16 : NaOH/0.64 : TEOS/1 : H2O/92 : Al/0.0018



# Evolution of zeolite coatings on metal alloys

Evolution of zeolite coatings on AA-2024-T3 (and other AAs)

Generation – 1

–0.5 um thick (no optimization and no QC) –Poor salt-fog performance of bare zeolite on AA-2024-T3
–Actions •Developed protocols for producing coatings of various thickness (e.g., 0.5, 2.0, 4.5, 11, 13 um) •Decided to use 7.5 um as the new benchmark (Generation-2 and -3 coatings) Generation – 2

–7.5 um thick (no optimization) –Inconsistent salt-fog performance of bare zeolite on AA-2024-T3
–Actions •Optimize zeolite coating synthesis •Implement QC testing on zeolite coatings (DC Polarization in 5 wt% NaCl) Generation – 3

–7.5 um thick (limited optimization – aging time and DC Polarization in 5 wt% NaCl testing for QC) –Excellent DC Polarization performance in 5 wt% NaCl –Consistently excellent salt-fog performance of bare zeolite on AA-2024-T3 

### Evolution of zeolite coatings on steels (SS-304-2b, S4130, S1008) Generation – 3 (same synt hesis methods as Generation – 3 for zeolite on AAs)

–4-6 um thick (no optimization specific for zeolite on steels and no routine QC testing) –Excellent DC Polarization performance in 5 wt% NaCl –Good to excellent salt-fog perfor mance of bare zeolite on steels

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 20

Figure 5-5 SEM images of ZSM-5 coatings (4 - 5 um thick) on steels. SS304-2b (a, b); S1008 (c, d); S4130 (e, f)

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 21 Task 1

­ 3 & 1

­ 4: Alternative zeolite and deposition process

The central goal of this task is to develop a coat ing process that is low pressure, low temperature, and short deposition time.

Layer by layer deposition of MCM‐22 MCM-22 and its precursor MCM-22(P) are micr oporous aluminum silicates reported by Mobil researchers 18 . In MCM-22(P), the structure directing agent, hexamethyleneimine, is located between layers. By special treatments, MCM-22(P) can be delaminated leading to a new aluminosilicate, ITQ-2 19 . The delaminated material was re ported to be stable at high temperatures (in excess of 500 ° C). On the other hand, by calcinati on the silicate layers in MCM22(P) condense to form MCM-22 (structure code MWW). Based on their framework structures, the limiting apertures for transpor t perpendicular to the layers (a long [001] direction) are 6MR’s, i.e. defined by six interconnected SiO 4 tetrahedra. Molecules like water and O 2 cannot penetrate along the c-axis. Therefore, the primary idea of th is project is to prepare a dense c-oriented MCM-22 film which is practically impermeable a nd thus suitable for the corrosion protection

purpose.

Synthesis of MCM

­ 22(P) Layered MCM-22(P) precursor was prepared us ing hexamethylenimine (HMI, Aldrich), silica (Aerosil 200, Degussa), sodium aluminate (56% Al 2 O 3 , 37% Na 2 O Carlo Erba), sodium hydroxide (98% Prolabo) , and deionized water 18 . More specifically a sample with Si/Al = 50 was prepared as follows: 0.239g of sodium alum inate and 0.826g of NaOH were dissolved in 103.498g of H 2 O by magnetic stirring for few minutes, then 6.373g of HMI were added slowly leading to a yellowish solu tion, and finally 7.86g of SiO 2 were added very slowly under continuous stirring. After 30 minutes of vigorous stirring, the very viscou s final gel was poured into a 60-ml Teflon lined stainless-steel autoclav e and treated at 408K for 11 days, rotating at 60 rpm. After cooling down the autoclaves quickl y, the samples were centrifuged at 10,000 rpm and washed with water until pH < 9. Typical particle morphology of as-synthesized MCM-22(P) is
shown in Figure 5-6. Most particles are plate-lik e with dimensions of about 1 μ m in width and length and less than 100nm in thic kness. Some particles curl. Th e x-ray diffraction pattern on the right verifies that the synthe sized materials are MCM-22(P).

Figure 5-6 MCM-22(P) as made for 11 days at 135oC, before calcination or swelling.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 22 Condensation of MCM

­ 22(P) to MCM

­ 22 and avoidance of agglomeration To ensure good dispersion and to avoid agglom eration during calcinatio n, MCM-22(P) particles were first filtered and then calcined in a way analog to that reported in ref 20 . First, 5g of MCM22(P) wet cake was well-dispersed into 20ml DI water by stirring for one hour followed by ultrasonication for another one hour. The suspension was filtered by high-density polyethylene filter tips (POREX) with part icle retention size of 5 μ m, and then diluted to a total volume of 100ml. The solution was stirred at room temperature for another one hour before 10g of acrylamide (AM, Aldrich) and 0.1g of N, N’-m ethylenebisacrylamide (MBAM, Aldrich) were added inside. The mixture was further stirred fo r about 30 minutes until all the water-soluble organic monomers completely dissolved. Then 0.25g of (NH 4 ) 2 S 2 O 8 was added to the solution under stirring. Finally the solution was placed in an ultrasonicator for one hour. During sonication the solution will become warm and th e organic monomers will be polymerized to form a white hydrogel with the MCM-22(P) partic les trapping inside. The hydrogel was dried at
90 ° C overnight before it was carboni zed under nitrogen (150cc/min) at 540 ° C for 2 hours (heating rate 2 ° C /min) and then calcined at 540 ° C for 3 hours under air (150cc/min).

Figure 5-7 shows the SEM image and the x-ray diffraction pattern of particles after calcination. Most crystals have the plate-like shape withsimilar dimensions to the as-synthesized MCM22(P) crystals. The x-ray diffraction pattern confir ms that the MCM-22(P) crystals condensed to MCM-22 during calcination.

Figure 5-7 MCM-22 crystals. A) SEM image of particles after calcination at 540oC in air for 3 hours; B) X-ray diffraction pattern.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 23 Exfoliation of MCM

­ 22(P) to ITQ

­ 2 The exfoliation procedure involves two steps, that is, swelling under the interaction of surfactants followed by exfoliation provoked by ultrasonication. After compared the swelling procedures in ref. 21 and ref. 22 , we adopted the following procedure. First, 3.05g cetyltrimethylammonium bromid e (CTAB surfactant, Aldrich), 4.16g deionized water and 6.60g tetrapropylammonium hydroxide (TPAOH, 1M in water, Aldric h) were mixed together and stirred for 1 hour to form a slurry. Then 1.00g MCM-22(P) cake was adde d to the slurry under stirring. Swelling was processed by refluxing the mixture at 80 ° C for 20 hours. The excess surfactant was dissolved by adding about 10 drops of concentrated hydrochlor ic acid until the pH of the mixture was less than 2. The mixture was s tirred for another 1 hour before the remained powder was collected by filtration. Th e collected powder was dried at 90 ° C overnight. XRD pattern of the powder was taken at this point. Exfoliation of the dry powder was carried out by first re-disperse the powder (~1g) into 40g of deionized water. The solution was then ultrasonicated for 2 hours. Powder was collected from the solution by cent rifuging at the speed of 15000rpm.

XRD patterns of the MCM-22(P) powder before swelling, after swelling and after exfoliation are shown in Figure 5-8, respectively. As pointed out in ref. 22 , a successful swel ling can be roughly determined from changes in the XRD patterns according to the following criteria.

1) General hkl reflections shift to lower 2 θ angles or disappear altogether. 2) hk0 reflections remain invariant. 3) A prominent 001 peak emerges around 5.0- 5.5nm d-spacing, possibly accompanied by higher order peaks at appropriate positions.

As can be seen from Figure 5-8, the XRD pattern before swelling is the typical pattern for MCM22(P) 19 . After swelling, the [ 001] peak moves to a
lower 2 θ angle with d-spacing of about 4.5nm. The [002], [101] and [102] p eaks disappear, while the [100] peak remains. All of these changes roughly obey the rules as stated above, thus suggesting a successful swelling. After ultrasonication, all reflections disappear. C onsidering the exfoliation process is carried out in a chemi cally mild condition, we think the layers are exfoliated instead of completely destructed. If this is true, the exfoliate d layers will also be out of the detection limit of SEM. Other techniques, such as Small Angle X-ray Scattering, AFM or TEM, are necessary and going to be used in future studies. Figure 5-8 XRD patterns of MCM-22(P) powder before swelling, after swelling and after exfoliation.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 24 Layer

­ By

­ Layer deposition The deposition procedure is mainly based on a ch emical-interaction method which is originally developed by Ha and coworkers 23 . We extended this method in ou r previous work to make a boriented silicalite-1 seed monolayer on α -alumina supports and satisfactory results were obtained 23 . The procedure can be easily adapted he re for the purpose of depositing MCM-22 particles to aluminum alloy su rface for corrosion protection. In this method, first a mesoporous silica layer is coated on top of the support to provide a smooth and common functional surface. Then a silane coupling agent, 3-chloropropyltrim ethoxylsilane, was used to covalently link the plate-like MCM-22 particles to the silica surface . The silane coupling agent has two functional groups, i.e., chloro and methoxyl, w ith one reacting to the silica su rface and the ot her reacting to the MCM-22 particle surface. Extra MCM-22 particles can be removed by sonication, and therefore after each coating, an almost close-pa cked monolayer can be obtained. The procedure can be repeated to make the films with two laye rs, three layers and so on to increase coverage.

An image of the mesoporous silica layer is shown in Figure 5-9A, which shows that shallow dents in the original substrate surface can be le veled off by the mesoporous layer and the entire surface is much smoother than before. However, the corrosion results s howed this mesoporous silica layer was rather detrimental than benefi cial for corrosion prot ection. Since XPS results show that there is an oxide layer on the alum inum alloy surface which can also provide enough functional groups for deposition, therefore th is mesoporous layer can be eliminated.

Figure 5-9B shows a SEM image of the MCM-22 la yer after one depositi on. The deposit is almost a close-packed monolayer. Most crystals retain their plate-like sh ape without breakage or Figure 5-9 A) SEM image of the mesoporous layer; B) SEM image of the MCM-22 layer after one time deposition; C) SEM image of the MCM-22 film after three times deposition; D) Cross view of the MCM-22 film after three times deposition.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 25 curling, and attach to the substrat e surface with their flat surfaces and therefore the obtained film is c-oriented. After adopting the special treatmen t during calcination, the film is much smoother with few agglomerates bigger than 10 μ m. Figure 5-9C shows the MCM-22 film after 3 depositions and Figure 5-9D the corresponding cross view. F ilm coverage improves substantially without loss in orientation by repeating the depo sition process. The film is very smooth. From the cross view, the film thickness is less than 100 nm even after 3 depositions.

We have demonstrated our successful effort s on the synthesis of MCM-22(P) and MCM-22 particles with the desired plate-like shapes. The particle size is about 1 μ m in diameter and less than 100 nm in thickness. Significant progress wa s also made regarding the exfoliation of MCM22(P) to ITQ-2 and the elimination of big agglom erates during the calcination process. The film after one-time deposition is almost a close-packed and c-oriented monolayer. Without loss of the film orientation, the cove rage of the film increases substa ntially by repeating the deposition process. The thickness of the f ilm after three-time deposition is still less than 100nm. Therefore, the goal to make a thin, compact, and c-orient ed MCM-22 film is very close, although the compactness of the film and the reproducibility of the procedure still need to be improved.
To improve the compactness of the film, we will use uncalcined MCM-22(P) crystals or ITQ-2 crystals instead of MCM-22 crystals to make the film. The film will then be condensed by calcination to eliminate gaps between layers a nd thus to improve the compactness of the film.
Significant corrosion protecti on is demonstrated by coating a subs trate with alternating layers of zeolite particles and mesostructured surfactant- templated silica. The UMN team developed and optimized a coating process that involves deposit ion of plate-like partic les of zeolite MCM-22 on a substrate by chemical attachment under sonica tion. DC-Polarization test s, conducted in acid (H 2 SO 4 ) as well as in salt (NaCl) solution at UC Riverside, show consistent and reproducible results of polarization current density of th e level achieved by use of chromate conversion coatings. Figure 5-10 shows an overview of the layer- by layer deposition process and Figure
5-11 shows a typical MCM-22 film with silica aerosol coating.

The sequence of processes 19-24 to prepare the samples for DC pol arization test is described on the left side of Figure 5-11. MCM-22 particles were deposite d using chemical attachment under sonication 21, 22 on the polished aluminum plates fo llowing experimental protocol ( 1 ). The deposition of MCM-22 was followed by deposition of surfactant-silica composite by aerosol coating using the experimental protocol ( 2 ). Samples MN107, 108, prepar ed using these steps, were tested for corrosion protection. Other samples were subjected to additional coating cycles. The substrate was calcined at 300oC (experimental protocol ( 3 )) in order to generate enough hydroxyl groups for the reaction based deposition of MCM-22 particles. Another deposition of MCM-22 particles, this time w ithout sonication, was performed fo llowing experimental protocol ( 4 ), followed by coating with surfactant silica composite layer using procedure ( 2 ). At this stage samples MN 122, 123, 124, 125 were tested for corrosion protection. Other samples were calcined at 300 oC using procedure ( 3 ) for an additional deposition cycle yielding samples MN 126, 127, 128, 129.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 26 Figure 5-10 Overview of the Laye r-by-Layer deposition process.

Figure 5-11 MCM-22 film with silica aerosol coating
DC polarization test results performed in 0.5 M H 2 SO 4 are shown on the right side (top) of Figure 5-12. Sample MN 108 with one layer of MCM-22 and one layer of surfactant-silica composite shows corrosion protection action. Th e corrosion protection performance improved progressively with additional layer of MCM- 22 as observed in samples MN 122 and MN 124

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 27 (both with two coatings of MCM-22 and surf actant-silica composite) and samples MN 127 and MN 129 (both with three coatings). Our findings demonstrat e that as the number of deposited layers increases, the level of corrosion protection is enhanced considerably.

DC polarization tests in 0.1M NaCl solution were also performed for the samples prepared in the same manner as described above and shown in Figure 5-12 (right side – bottom). Samples MN 123 and MN 125 (with two MCM-22 layers and tw o aerosol coatings) show comparable or higher degree of corrosion protection as comp ared to the samples MN 126 and MN 128 which have an additional layer of MCM-22 and silica. Therefore, in contrast to the measurements in
H 2 SO 4 , it appears that for NaCl there is an op timum corrosion protection action exhibited by films with two layers of MCM-22.

Figure 5-12 Preparation procedure and DC-Polarization Tests in 0.5M H 2 SO 4 and 0.1M NaCl

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 28 Experimental Section Procedure (1) : Deposition of MCM-22 particles by chemical attachment under sonication

Prior to seed deposition the polished supports we re dried at 120 °C overn ight in a drying oven, apparatus required during the experi ments were dried at 80 °C at least overnight prior to the experiments. The substrate which was supported by a Teflon holder was loaded vertically into a specially designed glass reactor which was under continuous purge with argon. First, 30 mL of dry toluene and then 3 mL of 3-chloropropyltrimethoxysilane were quickly transferred to the reactor from argon-purged containers. The reactorwas then closed and connected to a watercooled condenser (15 °C). The solution was refluxed for 3 h at 110oC under a gentle argon stream. After this, the support wa s taken out, washed in fresh to luene and dried for about 15 min
at 120 °C.

In a separate step 20 mg of precalcined MCM-22 seeds and 50 mL of dr y toluene were charged into a dry reactor under argon flow. The suspension was sonicated for 1hour (seed dispersion) after which the functionalized s upport was then quickly introdu ced into this suspension under argon purge. The support was positioned vertically sandwiched between two cover glasses using a combed shaped Teflon holder. The reactor was then closed and placed in a sonicator (Branson 1210, 50/60 Hz) for 4 minutes sonication. Subseque ntly the seeded support was removed from the seed suspension, and placed horizontally. Furt her this was sonicated for 2 minutes. Finally, the supports were taken out of the reactor and rinsed in fresh toluene in order to remove multilayered crystals.

Procedure (2) : Deposition of surfactant silic a composite by aerosol coating 3 0 m l d r y T o l u e n e + 3 m l 3 C P

- T M S

+ S u p p o r t ( d r i e d a t 1 2 0 o C o v e r n i g h t )

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o

r t

v

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t i c

a l l y P

u r

g

e a r g

o

n

F u n c t i o n a l i z e d s u p p o r t 2 0 m g C a l c i n e d M C M

- 2 2
p o w d e r

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S o n i c a t

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e 2 S a n d w i c

h t h

e s u p p

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r t w i t

h t w

o c o

v

e r

P l a c e s u p p o r t v e r t i c a l l y P l a c e s u p p o r t h o r i z o n t a l l y

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 29 A sol was freshly prepared each time aerosol coating was carried out as follows. 14.24 g. Brij-56 was mixed with 308.64 g water, 31.66 g TEOS and 12.77 g 0.07 M HNO 3 in a capped Pyrex bottle. The mixture was sonicated (Branson 1210, 50/60 Hz) for 3 h resulting in a turbid but homogeneous sol. This sol was aged for about 1 h and then charged into a humidifier (kaz).
The supports were placed horizontally onto wire gauze (polished side up) and exposed to an aerosol cloud generated by the underlying humidifier into an enclosed space that housed the gauze and supports. This allowed heavy aerosol droplets to settle on the support surfaces. After the coatings, the supports were left to dry overnight.

Procedure (3) : Calcination at 300°C The films were calcined in air at 300°C for 4 hours w ith a 0.5°C/min ramp rate.

Procedure (4) : Deposition of MCM-22 particles by chemical attachment Prior to seed deposition the polished supports we re dried at 120 °C overn ight in a drying oven, apparatus required during the experi ments were dried at 80 °C at least overnight prior to the experiments. The substrate which was supported by a Teflon holder was loaded vertically into a specially designed glass reactor which was under continuous purge with argon. First 30 mL of dry toluene and then 3 mL of 3-chloropropyltrimethoxysilane were quickly transferred to the reactor from argon-purged containers. The reactorwas then closed and connected to a watercooled condenser (15 °C). The solution was refluxed for 3 h at 110 °C under a gentle argon stream. After this the support wa s taken out, washed in fresh to luene and dried for about 15 min
at 120 °C.

In a separate step 15 mg of precalcined MCM-22 seeds and 40 mL of dr y toluene were charged into a dry reactor under argon flow. The suspension was sonicated for 1hour (seed dispersion) after which the functionalized s upport was then quickly introdu ced into this suspension under argon purge. The support was positioned hori zontally using a Teflon holder with the functionalized silica layer facing upwards. The mixture was refluxed for 5 h at 110 °C. The reactor was then closed and placed in a soni cator (Branson 1210, 50/60 Hz ) for 1 min sonication to get a substrate with MCM-22 deposit. 1 4

. 2 4 g B r i j 5 6 + 3 0 8

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. 6 6 g T E O S + 1 2

. 7 7 g H N O 3 ( 0

. 0 7 M )

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A e r o s o l c o a t i n g

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 30 Microwave‐assisted ionothermal synthesis of SAPO‐11 Ionothermal synthesis uses ionic liquid instead of water as the solvent. An ionic liquid is a substance that only consists of ions and has a melting temperature below 100 o C. The most significant advantage of this method is that th e whole process can be carried out in an open vessel rather than in a sealed Teflon ® -lined autoclave; consequent ly, the syntheses occur at ambient pressure due to the negligible vapor pr essure of ionic liquid even at an elevated temperature. SAPO-11 is one of the first succe ssful example for zeolite ionothermal synthesis 25

, which was prepared under ambient pressu re in a convection oven for 68 h at 150 o C using 1- methyl 3-ethyl imidazolium bromide ([emim]Br) as both solvent and template. This recipe is also successful under microwave heatin g where only one hour was needed for the crystallization due to the rapid microwave absorption of ionic liquids 26 . The primary idea of this project is to prepared a SAPO-11 coating on AA 2024-T3 usi ng ionothermal synthesis and microwave radiation, which presents a short time, ambient pressure deposition process for zeolite.

Synthesis of SAPO

­ 11 coating on AA 2024

­ T3 A synthesis mixture with molar composition: 32[emim]Br:1Al(OC 3 H 7 ) 3 :0.25tetraethyl orthosilicate (TEOS):3H 3 PO 4 :0.8HF was prepared and then stirred for 4 h at 100 o C. AA 2024- T3 substrates were pretreated by an Alconox detergent solution. The s ubstrate was then fixed vertically inside the synthesis mixture in the Teflon vessel designed for MARS5 (CEM Co.) microwave reaction system. The unsealed vessel was then quickly heated to 150 o C and held at the temperature for 2 h under microwave radiation. After the synthesis, the coated sample was thoroughly washed with DI water and acetone a nd dried with compressed air. The synthesis procedure was repeated once or twice with fresh synt hesis solution. SAPO-11 coatings on AA 2024-T3 are confirmed by the X-ray diffraction (XRD) (Fig.5-13c). No other by-products are found. The preferred orientation is evident for the SAPO-11 co atings. AEL consists of a 10- 3 0 m l d r y T o l u e n e

+ 3 m l 3 C P

- T M S

+ S u p p o r t ( d r i e

d a t 1 2 0 o C o v e r n i g h

t ) S u p p

o

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F u n c t i o n a l i z e d S u p p o r t 1 5 m g C a l c i n e d M C M

- 2 2 p o w d e r

+ 4 0 m l d r y t o l u e n e

S o n i c a t

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ur

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- 2 2

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 31 membered ring (0.40 ×0.65 nm) channel parallel to the c-axis of the crys tal. The strong (002) reflection peak in the SAPO-11 XRD pattern indicates that the one-dimensional channels are perpendicular to the Al alloy surface.

Figure 5-13 SEM pictures and XRD pattern of SAPO11 on AA 2024-T3

BTSM

­ MEL coatings It can be seen from the cross-sectio nal SEM picture of SAPO-11 coating ( Figure 5-13b) that the film consists of two major components: the dens e barrier layer adjoinin g the metal and a porous layer extending from the barrier layer to the ou ter surface of the film, wh ich is similar to the anodized film of Al alloys. This kind of structur e has the advantage of be ing able to be dyed. In order to obtain the maximum corrosion resistan ce, the porous coating must be sealed. A nanozeolite filled silane was used as the sealing agent. Se veral aspects were considered for choosing it: (1) silane has very good adhe sion properties, which can act as a binder layer between zeolite coating and the polymer topcoat; (2) silane fi lm itself has good corrosion resistance for Al alloys; 27 (3) nano-particle filled silane films offer better mechanical properties and MEL nanocrystal filled silane films also improve the corrosion resistance. A dilute 1,2-bis(triethoxysilyl)me thane (BTSM) solution was prepar ed by adding silane to a DI water and ethanol mixture. The volume ratio of BTSM:DI water:Ethanol was 1:1:20. Acetic acid was then added to adjust the pH of the solution in the range of 4.5~5. Th e solution was then stirred at room temperature for aging at least 24 hours before a MEL gel was added. MEL concentration in the solution was about 20 ppm. The SAPO-11 co ated sample was polished on a Buehler, Ecomet 3 grinder-polisher using 0.05 μ m silica slurry and thor oughly cleaned with DI water and acetone under sonication. Then the na noparticle suspension was spun on it at room temperature on a Laurell spin coater. Af terward, the sample was heated at 80 o C overnight and then 200 o C for 30 min.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 32 DC polarization test DC polarization testing was carried out with Solartronpotentiostat SI 1287 in a threeelectrode Flat Cell (Princeton Applied Research Model K0235) with a Pt counter electrode and a saturated calomel electrode (SCE) as the reference electrode. The corrosive medium was 0.1 mol/L NaCl aqueous solution. The samples were immersed in the corrosive medium for 30 min prior to the DC polarization test with a sweep rate of 1 mV/s. Figure 5-14 shows that bare AA 2024-T3 pits at its open circuit potential (OCP) (ca. -0.5 V SCE ). That is, the pitting corrosion occurs once the metal is immersed in the corrosive media. This OCP corrosion is related with the intermetalli cs of Cu in Al matrix and the presence of Cl in the electrolyte. OCP of SAPO-11 (ca. -0.65 V SCE ) coated samples are more negative than bare AA 2024-T3, which means the AEL coatings inhi bit the OCP corrosion of the samples. The corrosion current density of SAPO -11 coated samples is about tw o orders of magnitude smaller than that of the bare Al alloy. The pitti ng potential is slightly hi gher than the OCP of AA 2024- T3, which means the favored sites for pit initiation, mostly the copper intermetallics, are at least partially covered by the SAPO-11 coatings. The BTSM-MEL modified SAPO-11 coating has very good corrosion resistance. The OCP is more negative than -0.9 V and the corrosion current is less than 10 -8 mA/cm 2 . The pitting potential also increases to -0.4 V, even higher than the pure Al at similar conditions 28 . The DC polarization behavior of BTSM-MEL spin-on coating directly on bare AA 2024-T3 is also tested. It does sh ow good corrosion resistance but the combination of SAPO-11 coating and BTSM-MEL sealing shows the best anticorrosion performance in this work. Figure 5-14 DC polarization curves for bare and coated AA 2024-T3 in 0.1mol/L NaCl at room temperature: (a) Bare AA2024-T3, (b) SAPO-11 coated, (c) SAPO-11with spin-on BTSMMEL coated, (d) spin-on BTSM-MEL coated.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 33 Task 2. Zeolite/topcoat systems

We have gone through three evolutions of zeol ite coating syntheses on AA-2024-T3 (see Task 1- 2, Figure 5-4). The primer and/or topcoat systems applied to the zeolite coatings is organized based on the different zeolite generation on whic h the primer and/or topcoat was applied.

Much of the poor adhesion of the CARC topcoat (MIL-PRF-64159) to Generation-1 zeolite coatings has been contributed to the fact of no QC for the synthesis and the thinness of the zeolite coatings (0.5-2 um thick) . The first Generation-3 zeolite coatings (7.5 um thick) were painted with a VOC-free topcoat (5 samples) or a self-priming topcoat (5 samples) and had extremely non-uniform topcoat application and blistering occurred af ter 168 hours of salt-fog exposure. The VOC-free and self-priming topcoats were applied at Deft (Irvine, CA) in a trial run (The visit by UCR to Deft was primarily aimed to observe an d learn the deposition technique) and ASTM standards were not followed. Our latest testing of zeolite (Generation – 3) coatings with primer and/or topcoat applications showed that coating systems with chromated primers with and without topcoat had no delami nation from the zeolite surface after 3100 hours of salt-fog exposure.

Zeolite (Generation - 1)

CARC topcoat (Mil-PRF-64159) Five aluminum 2024-T3 panels were coated with zeolite of 0.5-2 um thic k at UCR and delivered to China Lake. The panels were then sent to the Army Research Laboratory (ARL) to be coated with CARC topcoat. The panels were coatedon one side with the CARC topcoat (Mil-PRF64159) and coated with primer on th e other side to keep corrosion from contaminating the salt fog chamber. These panels were then scribed and tested in salt-fog (ASTM B117, see Task 3.4 for details).

Results: No adherence of th e CARC topcoat to zeolite.

Zeolite (Generation - 2)

No zeolite/topcoat or zeolite/primer/topcoat system was tested for the Generation – 2 zeolite coatings. Salt fog testing of the bare zeolite coatings (Generation – 2) was pe rformed (see results in Task 3.4).

Zeolite (Generation - 3)

VOC-free topcoat (Deft product #55W-002, Deft, Irvine CA) and Self-Priming topcoat (TT-P2756A from Deft, Irvine, CA) Once the 7.5 um thick ZSM-5 coating samples were developed and chosen as the benchmark, they were applied with topcoats at Deft (Irvine CA) in a trial run (The visit by UCR was primarily aimed to learn the deposition technique ). Five panels were applied with VOC-free topcoat and five panels were applied with self-priming topcoats . These panels were then sent to China Lake for salt-fog testing (ASTM B117). The results showed blisteri ng of topcoats after 168 hours salt-fog exposure (S ee Task 3.4 for details).

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 34 Zeolite/Primer, Zeolite/Primer/ Topcoat and Zeolite/Topcoat

Forty nine (49) zeolite (Gener ation – 3) coated AA-2024-T3 pane ls were prepar ed and painted by Deft (Irvine, CA), following ASTM guidelines. Figure 5-15 shows the matrix of primers and topcoats applied to the zeolite coating.

Figure 5-15 Primers and topcoats applied to zeo lite coatings following ASTM and MIL specs.

Salt-fog (ASTM B117) and adhesion (wet and dr y) testing were performed at NAWC, China Lake (See Task 3.4 for details).

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 35 Task 3.1: Laser Scanning Confocal Microscopy (LSCM) characterization of coating surfaces

• Quantitative Surface Imaging by LSCM UCR initially provided six samples of the high- silica ZSM-5 zeolite coating on 2024-T3 Al substrates with the following nomenclature: M, Q, P, 8, H, and K. Three samples each of the high-silica ZSM-5 zeolite co ating on 2x3 cm of 2024-T3 Al, 6061-T6 Al, and 7075-T6 Al substrates with the following nomen clature: A, B, and C for each sy stem were later received for further analysis. All samples were imag ed using the LSCM under 2000x magnification. Figure 5-16 and Figure 5-17depict the optical and height ma ppings and surface profiles of systems 8 and P. Figure 5-18 depicts regions of the surface on coating H wh ere there is an “over-growth” of the zeolite coating. Figure 5-19 and Figure 5-20 depict the optical , height mappings, and filtered surface profiles of the zeolite coating system on 6061-T6 Al and 7075-T6 Al substrates.

Figure 5-16 LCSM Optical (a), Height Mapping (b), and Surface Profile (c) of Coating 8

Figure 5-17 LCSM Optical (a), Height Mapping (b), and Surface Profile(c) of Coating P

Surface profiles in Figure 5-18c, Figure 5-19c and Figure 5-20c suggest that th ere is an effect of the Al substrates on the surface mo rphology of the zeolite coating.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 36 Figure 5-18 Mapping (a), Surface Profile (b), and 3-dimensional Images (c) of coating H

Figure 5-19 (a)LCSM Optical, (b)Height Mapping, and (c) Surface Profile of Zeolite Coating on 6061-
T6 Al

Figure 5-20(a)LCSM Optical, (b) Height Mapping, and (c) Surface Profile of Zeolite Coating on 7075-
T6 Al

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 37 RMS Roughness

Coating roughness measurements were calculated to obtain informati on on coating surface structure. Analysis of RMS roughness suggests th at there is a differen ce in surface roughness between the three Zeolite coatings systems

. Table 5-1 lists RMS roughness values for each coating system.

Table 5-1 Surface Roughness for ZSM-5 on different Al alloy substrates

2024-T3 6061-T6 7075-T6

A 1.15±0.01 0.80±0.03 1.17±0.05

B 1.59±0.01 0.92±0.34 0.92±0.06

C 2.73±0.10 1.29±0.07 1.05±0.06

On large scale, the ZSM-5 coating on 2024-T3 Al has the largest structur al fluctuations (1-3

μ m 2 ), which yield higher roughness values. Moreover, these results sugge st that the ZSM-5 coating on 6061-T6 Al and 7075-T6 Al substrat es have similar stru ctural morphologies.

• Scaling Analysis & Optimized Filtering for LSCM Images The scaling analysis technique employed for this analysis was developed to obtain measures of changes in surface morphology to gain insight in to small-scale surface structural changes

. The roughness of the coating surface was characterized in terms of scaling exponents to obtain power- law correlations.

The roughness ( w

, the average RMS deviation in surface heights from a center plane) is measured for increasing areas of l 2 where the dependence of the roughness on l gives rise to a power law relation characterized by the roughness exponent α at time t :

w L ( l,t ) ~ l α

α is obtained from the scaling dependence of the local width on l :


## [ ]

x l L 

### txhtxhtlw 2

2 

### ),(),(),( −≡

h(x,t) is the height of a single-valued surface at location x, h l ( x, t) is the average height of the local data at time t, t is the exposure time, and l is the size of local su rface patches.

Figure 5-21 shows the results of local sc aling analysis applied to LSCM data collected from ZSM-5 coated 2024-T3, 6061-T6 and 7075-T6 Al sample s. As with all analys es in this study, the results represent averages of three different scan s for each sample. Results show that there is not Figure 5-21 Local scaling for LSCM filtered images ( α value shown inside)

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 38 a significant difference in complexity (fractal dimension) between the three zeolite-substrate systems, however there is a large deviation between the three in surface roughnesses. The zeolite coating on the 2024-T3 Al substrates have the highes t roughness values, which suggests that this coating would perfor m the best as an adhesive pre-coat for CARC coatings.

The roughness exponent α represents the coating’s small-scal e structural change s (denoted by the linear region in Figure 5-21). These fluctuations occur within a 1 μ m scaling region. Outside of this region there is no longer a correlation between independent surface structures and largescale surface changes are m easured (RMS roughness).

Atomic Force Microscopy (AFM) was not employe d in this study due to limitation in height deviations of the microscope. The surface area th at can be imaged using AFM is limited to 100

μ m 2 with at most a 7 μ m variation in heights. The variati on in heights of the surfaces used in this study are >6 μ m. Previous work has shown that a 5x5 median filter of the LSCM image can be used to mimic the resolution of the AFM. However in this study, a 3x3 median filter is sufficient to remove artifacts on the surface struct ure. A more rigorous filter may result in a loss of information.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 39 Task 3.2: Instrumental analysis of coating degradation

• Dynamic mechanical analysis

Dynamic Mechanical Analysis employs the app lication of thermal analytical techniques to measure physical properties such as modulus, h eat capacity and linear coefficient of thermal expansion of the zeolite coatings. It is believed that this data will lend some insight into the adhesion of the coating to the substrate.

The coated specimens will be analyzed in two ways. The first set of experiments will apply a static stress scan, where the applied load will increase at a constant ra te over time. The second set of experiments will apply a constant or increa sing force at a constant frequency; this testing will occur at various frequencies. All experiments will be completed with both 3 point bending and single cantilever methods. The idea is to see if the composite or combined modulus of the coated samples shows any effect due to varying adhesion at the interface between the samples, when compared to independent modulus of the bare substrate and of the bare coating and if there any effect on the modulus resulting from cha nges in interface adhesion of the coating.

Figure 5-22 shows results from DMA analysis of the zeolite coating on 2024 Al vs. bare 2024 Al. Both have been tested in static stress. The modulus has been m easured but has to be correlated against the zeolite coa ting without the Al substrate. Moreover, the effect of varying coating thickness has to be addressed.

Figure 5-22 Stress/Strain curves for Zeolite on 2024-T3 Al & Bare 2024-T3 Al

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 40 • DC Polarization quality control testing development

For small 2x3 cm coupons we had been using epoxy to seal off the edges before electrochemical testing ( Figure 5-23). This has been effective for coupons , but this means the large panel has to be cut into small pieces for electrochemical tests.

To preserve the zeolite coated panels and to be able to characterize the same panel with both DC Polarization and EIS, as well as other tests such as salt-fog and UV exposure, we are using a test procedure which only requires a small scratch on one side of the panel for electrical contact for the DC Polarization and EIS tests ( Figure 5-24). This small cut can be easily sealed and put on the back side in the salt -fog tests. This allows us to correlate the DC Polarization and EIS results with salt-fog or UVexposure results. We can also use this quick and almost nondestructive method as quality co ntrol for the coatings. We can also use this setup to check th e uniformity of the coating by testing several spots on the same panel. Thus far it has been shown that our panels have unifo rm corrosion resistance. We have found that coatings synthesized together in the same reactor perform almost identically under electrochemical and mechanical testing. As a result, we routinely only perf orm quality control on one of the synthesis pair prior to additional sample testing (i.e. salt fog and UV exposure).

Figure 5-24 Left: Corrosion test cell that can test a 3x6” panel without sacrificing the panel. Right: Zeolite coated panel with scratch on one side for electrical connection.

DC Polarization testing procedure for qua lity control of zeo lite coated samples A small area of bare metal substrate is exposed on one side of the zeolite coated panel for electrical connection with copper conducting tape when panel is used as working electrode. A standard corrosion test cell is used as shown in Figure 5-24 Left. Three 1 cm 2 locations are tested on the same side of electri cal connection: 1” from top of pa nel (top), 3” from top of panel (middle) and 5” from top of panel (bottom). The corrosion media used is 5 wt% NaCl (0.856M NaCl), test areas were in contact with corrosion media 5 minutes prior to testing. Figure 5-23 2x3 cm coupon sealed by epoxy before electrochemical tests.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 41 Figure 5-25 Representative DC Polarization profiles of the 15 zeolite coated panels sent to China Lake for salt fog testing. S1 – actual DC polarization prof ile of S series, sample 1; B1 – actual DC polarization profile of B series, sample 1; B3 – actual DC polarization profile of B series, sample 3.

We sent 15 zeolite coated panels to China Lake with 5 of them DC polarization tested on the back and shown to have excellent corrosion resistance (S series) ( Figure 5-25, S1), 5 samples that were not tested but synthesis twins of S samples (A series), and 5 samples (B series) whose twins were tested by DC Polarization and s hown to have medium ( Figure 5-25,B1) to low corrosion current (10 -3.5

A/cm 2 ) ( Figure 5-25, B3). All 15 panels passed 2205 hours of salt fog tes ting (salt fog results shown later in this report). To date we have synthe sized hundreds of zeolite coated panels, greater than 99% of the coatings exhibit polarization prof iles similar those in Figure 5-25. Specifically, greater than 93% have polarization profiles similar to S1 and less than 7% demonstrate polarization pr ofiles within the range of B1 and B3 from Figure 5-25.

DC Polarization testing in 5 wt% NaCl as a quality control measure prior to salt fog testing appears to be an excellent predictor of salt fog performance for zeolite coated panels. It is likely that as long as there is not a complete lo ss of passivation during the DC Polarization testing the panels will pass 2000 hours exposure to salt fog.

DC Polarization testing in 5 wt% NaCl was also Figure 5-26 Representative DC Polarization profiles in 0.856 M NaCl of aluminum alloys and steels.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 42 performed on zeolite coatings ( 7.5 um thick) on other alum inum alloys (AA-5052-H32, AA6061-T6, AA-7075-T6) and zeolite coatings (4-5 um thick) on 3 different steels (S1008, S4130 and SS304-2b) Figure 5-26.

Task 3

­ 3: Quantitative/qualitative adhesion testing of coating to Al & steel substrates

• ASTM D3359-02 adhesion test UCR has carried out adhesion test according to ASTM D3395-02 on ZSM-5 coating on AA-2024-T3, AA-5052-H32, AA-6061-T4, and AA-7075-T6. This is a dry adhesion test involving cross-cutting through the coating to the substrate with a multi-blade knife followed by adhesive taping and peeling. Then the cut areas were examined using a low magnification glass (x6). The test kit and the rating protocol according to the damages are shown in Figure 5-27. 5B is the highest rating under this protocol. ZSM-5 coatings on all of the aluminum alloys tested received a rating of 5B (Table in Figure 5-28). Although the ASTM D3395-02 protocol does not require a high magnification microscope, we examined the cuts under high magnification microscope (x2000), and extremely clean cuts were revealed. There were no chipping and cracking into the coating after th e cutting operation. This is a clear indication that the coatings are strongly adhered to the substrate. High temperature calcination was also performed to see if the coating would behave differently. 5B rating wa s retained for all of the sa mples after calcination at 400 ° C for 2 hours.

• Mechanical cutting tests To test the properties of the zeol ite coating under mechanical stre ss, zeolite coated panels were cut using a standard lab shear ( Figure 5-29a). The cut area was examined by SEM ( Figure 5-29b& c). It can be seen that the cut was very clean, having no clack formation and propagation into the coating. Figure 5-27 ASTM D3359-02 test kit (left) and the rating protocol (right)

Figure 5-28 Adhesion rating on ZSM-5 coatings on aluminum alloys and a representative optical image of

the ZSM-5 coating on AA-6061 after adhesion test.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 43 Figure 5-29(a) Lab shear for cutting metal sheets, (b) SEM of the cut of ZSM-5 coating on AA-2024-T3 at low magnification, (c) SEM of the cut of ZSM-5 coating on AA-2024-T3 at high magnification.

• Mechanical hole punching

The ZSM-5 coated AA-2024-T3 3x6” panels were punched using standard punch in a machine shop. Very clean holes were generated ( Figure 5-30). Similar results were obtained on ZSM-5 coating on carbon steel S-1008. The edge of the hole was examined by SEM, and was found that no crack was formed along the cutting edge, showing excellent adhesion and mechanical properties of zeolite coating.

• ASTM D-2794-93 impact test Impact tests according to ASTM D-2794-93 were performed on ZSM-5 coated AA2024-T3 panels. Tests were performed on 2 um and 7.5 um thick coatings showing no crack formation or delamination of the zeolite coating. Photos of the experimental apparatus and the impacted area are shown in Figure 5-31. Clearly, when the impact is not enough to break the panel, it generates a dent that shows no Figure 5-30 Photograph of a ZSM-5 coated AA2024-T3 panel with punched holes

Figure 5-31 Photographs of the ASTM D-2794-93 impact setup from Gardner (a and b), impacted area of the 2 um thick ZSM-coated AA-2024 panel (c and d for

each side, and left mark for impact from 1 ft and right mark for impact from 2 ft) and impacted area of the 7.5 um thick ZSM-coated AA-2024 panel (e and f for each side, and left mark for impact from 1 ft and right mark for impact from 2 ft)

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 44 cracking of zeolite coati ngs. Once the impact is large enough, then both the coating and the panel were broken.

• ASTM D 522-93a bending test To examine the flexibility and adhesion of the zeolite coating, ZSM-5 coated AA-2024-T3 panels were tested according to ASTM D 522-93a. Ba sically the zeolite coat ed panels were bent around a metal cone and the coating experiences di fferent degrees of bending at different heights along the cone. Tests were performed on 2 um and 7.5 um thick zeolite coa tings. For both the 2 um and 7.5 um thick coatings, no cracking of the coating was obser ved along the whole height of the cone ( Figure 5-32)

Figure 5-32 Photos of the apparatus for ASTM D 522- 93a bending test (a); bent 2.0 um thick ZSM-5 coated AA-2024-T3 (b); bent 7.5 um thick ZSM-5 coated AA-2024-T3 (c).

• ASTM G154-00a UV exposure Ten panels of 7.5 um thick zeolite coated AA-2024- T3 were sent to Benet Labs for UV testing following ASTM G154-00a. Five panels were continuously exposed for 32 weeks and then tested by DC Polarization in 5 wt% NaCl ( Figure 5-34). Another 5 panels were removed from UV exposure at 7.23, 16, and 32 week intervals for DC Polarization testing in 5 wt% NaCl at UCR ( Figure 5-35). Each of the 10 panels was tested by DC Polarization ( Figure 5-33) prior to be being shipped to Benet Labs. The DC Polarization testing pr ocedure was described previously and the test setup is shown in Figure 5-24.

The legend for the line designations for Figure 5-33, Figure 5-34, and Figure 5-35 is shown in Figure 5-35 (bottom panel). In each Figure, one of the DC Polarization test sets has the line designations labeled. Figure 5-34 shows the DC Po larization in 5 wt% NaCl profiles of the five zeolite coated AA-2024-T3 coupons after 32 weeks of continuous UV exposure compared to the DC Polarization profiles prior to UV exposure. There was no decr ease in corrosion resistance after 32 weeks continuous UV expos ure. In all cases the polari zation profiles after UV exposure for 32 weeks showed improved corrosion resistance, reflected in a decrease in current density and more vertical traces for anodic passivity as co mpared to the polarizati on profiles before UV exposure. The DC Polarization profiles of sample 3-21-05 ( Figure 5-34) before and after UV exposure exemplifies the improved corrosion re sistance following UV exposure. Five zeolite coated AA-2024-T3 panels were tested by DC Pola rization in 5 wt% NaCl after incremental UV exposure (7.23, 16, 32 weeks) and th eir polarization profiles compared with those taken before UV exposure ( Figure 5-35). The purpose of the incremental UV exposure and DC Polarization testing at each interval is to monitor the effects of UV expos ure on corrosion resistance at different exposure times. Increased corrosi on resistance was observed after 7.23 weeks UV

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 45 exposure for all five samples and continued to improve with longer UV exposure times. Sample 3-16-05 ( Figure 5-35) was only UV exposed for a total of 16 weeks to provide a sample at a shorter UV exposure time for future comparative analyses.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 46 Figure 5-33 DC Polarization profiles of each zeolite coated AA-2024-T3 prior to UV exposure. See Figure 37 (bottom panel) for line designation legend

Figure 5-34 DC Polarization profiles of zeolite co ated AA-2024-T3 prior to and after 32 weeks continuous UV exposure. See Figure 37 (bottom panel) for line designation legend

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 47

Figure 5-35 DC Polarization profiles of zeolite coated AA-2024-T3 prior to and after 7.23, 16, and 32 weeks UV exposure.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 48 Task 3

­ 4: Conduct accelerated service simulation testing

ASTM B117 Salt‐fog testing on bare zeolite coating

Initial salt fog testing on thin (0.5 um to 2 um thick) (Generation-1) zeol ite coatings and coatings generated from differentially aged synthesis solutions during our coating optimization phase had inconsistent results, yielding many non-passing samples. During that process we optimized our synthesis process where we can reproducibly gene rate uniform zeolite coatings of variable, but controlled, thickness (0.5 um to gr eater than 13 um). Coating pe rformance is virtually identical between panels that are coated simultaneously in the same reactor. We have developed a quick, minimally invasive DC Polarization testing regi men (described previously in section 3.2) for quality control monitoring of zeolit e coatings prior to salt fog te sting. Currently, greater than 99% of zeolite coatings (7.5 um thick) produced will pass a very demanding DC Polarization quality control test in 5 wt% NaCl.

Following our optimized zeolite synthesis process, zeolite coatings (7.5 um thick) on AA-2024- T3 samples were salt fog tested for over 2000 hr s at China Lake with all samples passing. Salt fog testing (1000 hours) of machin e scribed zeolite coatings (7.5 um thick) demonstrated that rust, if present, was confined to the scribed area and there was no delamination of the zeolite.

Generation

­ 1 coatings (0.5

– 2.0 um thick) on AA

­ 2024

­ T3:

Five zeolite coated panels (0.5 um thick) were tested for corrosion perfor mance as a pretreatment according to Mil-C-81706, which requires the coa ting to be free from corrosion after 336 hours (2 weeks) of salt fog exposure. Figure 5-36 were taken of the zeolite panels after 336 hours of

exposure.

Figure 5-36 Zeolite coated panels after 336 hours of salt fog exposure
Three (Group 2) of the five panels have a significant nu mber of corrosion spots while two (Group 1) of the panels show very few corrosion spots. Based on these results new panels with a thicker zeolite coating were decided to be tested.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 49 Generation

­ 2 coating (7.5 um thick)

Five zeolite-coated aluminum 202 4-T3 panels with 7.5 um th ickness (with 3 different aging times of the deposition solution) were sent to China Lake for testing under neutral salt fog conditions, according to ASTM B-117. We thought 7.5 um would be a good thickness to start and likely to strike a balance be tween corrosion resistance and mech anical properties. The panels were in three different bundles, each with a diffe rent date, their preparation date. The dates indicated on the packages were 2-25-04 (two panels), 2-27-04 (two panels) and 3-1-04 (one panel). The panels w ith the same date w ere pr oduced in the same reactor. Thus the consistency of perfo rmance amo ng 2-25 and 2-27 w ill show that the coat ing depositio n procedure is very reproducible. The panels were labeled with permanent ink on one side (used as the back side) with the corr esponding dates that were on th e packaging. The packages that contained two panels with the same date were given “a” and “b” designations.

The panels were placed in a sa lt fog chamber on May 11 at 10:30 a.m. At intervals of 168 hours and 336 hours of exposure, the panels were rinsed with deionized water, dried, examined and photographed.

With one exception, all of the panels had a unifo rm appearance before exposure testing began. Panel 2-27-04b had a small streak that was grey in appearance but was slightly more reflective or shiny than the rest of the coating. See Figure 5-37 and Figure 5-38.

Figure 5-37 Panels 2-27-04a, 2-27-04b, and 3-1-04 before

exposure Figure 5-38 Close up of non-uniform coating section on panel 2-27-04b before

exposure. The streak or non-uniformity did not adversely affect the coating performa nce during the test.

The sole criterion by which a conversion coating is determined to “pass” the salt fog test is that there are to be no visible signs of corrosion whatsoever for a specific duration of exposure. Two critical times of inspection are 168 hours (1 week) and 336 hours (2 weeks). Many military systems require 336 hours of co rrosion resistance but some system s require only 168 hours. Of the five panels tested, four passed the 168 hour inspection with no signs of corrosion while one panel designated as 3-1- 04, was severely pitted ( Figure 5-39).

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 50 . After one week of salt fog exposure, another difference was observed on panel 2-27-04b (other than the streak in the coating). Immediately after removing panels from the salt fog, they were rinsed with DI water. A signi ficant portion of panel 2-27-04b had surface property differences ; specifically it did not wet evenly. There were other very sm all areas on other panels that would not wet evenly but they were significantly smaller than the sections on panel 2-27-04b. Darker sections seen in Figure 5-40, down the left side, are the areas that had differences in surface wetting from the rest of the coating.

The panels were returned to th e salt fog chamber and evaluated after 1000 hrs of exposure. Panels 2-27-04a and 2-27-04b ( Figure 5-41) are still passing and show no signs of corrosion.

Although panels 2-25-04a ( Figure 5-43) and 2-25-04b ( Figure 5-44) had some pitting corrosion on the surface after 336 hours of exposure, they were tested fu rther to determine if the pitting corrosion would worsen and delaminate the coating. The number of areas of pitting did not signi ficantly increase on the surface and the coating around these areas remained in tact. There is no sign of filiform corrosion, blistering or delamination. ( Figure 5-42)

The zeolite coating shows great promise as a viab le conversion coating. It appears that although a pit can form within the coating, the corrosion do es not undercut, delaminate or cause blistering in the surrounding coating; instead the corrosion area is limited in size.

Coating resistance and performance are virtually identical between panels that are coated simultaneously in the same reactor. Figure 5-39 Pitting corrosion visible on panel 3-1-04 after 168 hours of exposure.

Figure 5-40 Photo of panel 2- 27-04b after being rinsed with

DI water after 168 hours of

exposure

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 51

Figure 5-41 Panels 2-27-04a and 2-27-04b after 1000 hours of exposure Figure 5-42 Panels 2-25-04a and 2-25-04b after 1000 hours of exposure

Figure 5-43 Panel 2-25-04a and 2-25-04b after 336 hours of exposure. Figure 5-44 Close up of panel 2-25-04a after 336 hours of exposure

Generation

­ 3 coatings

Based on the previous testing resu lts, it appears that 7.5 um thick coating has sufficient corrosion resistance. Therefore we decide d to focus on 7.5 um coatings. We produced 25 zeolite coated panels with 15 of them without topcoat and 10 with topcoats. The topcoats were applied by Deft in a trial run in their facility. The S series ha ve been examined on the back by DC Polarization using the almost non destructive method describe d in Task 3-2 and shown to have excellent corrosion resistance. Series B are the non-tested (by DC Polarization) twins of the S samples. Series A are the non tested twins of 5 panels th at showed medium corrosion resistance (sulfuric acid, 10 -4 A/cm 2 ).

• Generation-3 coatings ( 7.5 um thick) on AA-2024-T3

ASTM B117 on zeolite coated AA2024-T3 panels : Based on the previous testing resu lts, it appears that 7.5 um thick coating has sufficient corrosion resistance. Therefore we decided to focus on 7.5 um coatings. 15 zeolite coated panels were

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 52 sent to China Lake for neutral salt fog testing (ASTM B117). Th e S series have been examined on the back by DC Polarization in 5 wt% NaCl using the almost non destructive method described in Task 3-2 and shown to ha ve excellent corrosion resistance ( Figure 5-25, S1). Series A are the non-tested (by DC Pola rization) twins of the S samples. Series B are the non tested twins of 5 panels that sh owed medium corrosion resist ance by DC Polarization ( Figure 5-25, B1 & B3). All 15 zeolite panels passe d 2205 hours of salt spray exposure. Figure 5-45, Figure 5-46 and Figure 5-47 are of the three sets of zeolite panels after 1000 hours salt fog exposure and Figure 5-48, Figure 5-49 and Figure 5-50 are of the three sets of panels after 2205 hours salt fog exposure. Discoloration can be seen on the bottom corners of se veral panels which are due to
color transfer of the wood that is used to hold the panels at the required 6 ° angle.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 53

Figure 5-45 Panels A1-A5 after 1000 hours of salt fog exposure. Panel surfaces are alternating smooth and rough from A1 to A5

Figure 5-46 Panels B1-B5 after 1000 hours of salt fog exposure. Panel surfaces are alternating smooth and rough from B1 to B5.

Figure 5-47 Panels S1-S5 after 1000 hours of salt fog exposure. Panel surfaces are alternating rough and smooth from S1 to S5.

After the zeolite panels were inspected and photogr aphed after 1000 hours th ey were returned to the chamber for further exposur e, for a total of 2205 hours.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 54

Figure 5-48 Panels A1-A5 after 2205 hours of salt fog exposure. Panel surfaces are alternating rough
and smooth from A1 to A5

Figure 5-49 Panels B1-B5 after 2205 hours of salt fog exposure. Panel surfaces are alternating smooth and rough from B1 to B5

Figure 5-50 Panels S1-S5 after 2205 hours of salt fog exposure. Panel surfaces are alternating rough and smooth from S1 to S5.
After 2200 hours of exposure, the only visible signs of corrosion were small areas along the outer edges of the pa nels designated S1-S5.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 55 The beginnings of corrosion along the outside edges of the panels, “edge effects”, are neglected within 0.25” when rating a coating according to pass/fail criteria. After 2205 hours of exposure the most significant corrosion, seen in Figure 5-51, is neglected and the coating meets passing criteria. All of the zeolite coatings were considered passing after the removal from the chamber after 2205 hours of exposure.

The edge effects were only observed on the S series. These samples had a small area of zeolite removed on the back side, exposing the metal substrate. None of the back sides of the samples being salt fog tested were sealed. Figure 5-52(left) shows the back si de of sample S2 after 2205 hours of testing. The right panel shows a similar zeolite sample with a small area of zeolite removed, exposing the bare metal prior to salt fog testing. The severe corrosion on the bare metal observed after the salt fog test and the fact that only those samples that had zeolite removed to expose bare metal dem onstrated edge effects suggests that the edge effects may be caused by the bare metal corroding. If the backs of samples that have had bare metal exposed for quality control testing are sealed prior to salt fog tes ting, the edge effects observed may be eliminated.

ASTM B117 testing on scribed zeolite coated AA-2024-T3 panels : Five (5) zeolite coated panels were machine scribed at Deft (Irvine, CA), and then exposed to neutral salt fog te sting for 1000 hours. Figure 5-53 shows that the only vi sible corrosion was within the scribe and that there was no delamination or pealing of the coating. Figure 5-51 Visible corrosion along the edge of panel S2 after 2205 hours of exposure
Figure 5-52 Back side of sample S2 from S series after 2205 hours salt fog testing (left panel), Non-salt fog tested zeolite panel with small area of zeolite

removed, exposing bare metal (right panel).

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 56 Figure 5-53 Machine scribed Panels after 1000 hours of salt fog exposure

• ASTM B117 testing of zeo lite coated steels (2006)

Fifteen (15) zeolite coated samples (5 each of SS304-2b, S4130, and C1008) with a coating thickness of about 5 um were given to China Lake on November 18, 2005 for salt fog testing (ASTM B117). We are testing a thinner zeolite coating of 5 um instead of our previous 7.5 um thick zeolite coatings for two reasons. The first reason is that the zeolite coated steel panels or their twins have undergone DC Polarization quality control testing in 5 wt% NaCl, demonstrating excellent corrosion resistance ( Figure 5-54). Secondly, we want to determine the thinnest coating that can match the excellent corrosio n protection throughout 2205 hours of salt fog te sting of the 7.5 um thick coatings on AA-2024-T3.

The criteria used to determine coating failure on steel panels was that visible edge corrosion could have no more than 1/8 inch of creep from the edge of the co ating and no more than 5 pits within the coating. After 168 hours of exposure, all of the steel samples were passing with the exception of 1 of the 5 1008 steel panels. After 336 hours of salt fog exposure, all of the samples were passing with the exception of 2 of the 5 1 008 steel panels. After 552 hours of exposure, multiple failures became evident within the 4130 steel panel set Figure 5-54 Representative DC Polarization quality control curves of 5 um think coatings on steels in 5 wt% NaCl . The far left black curve in

each panel is an internal lab standard used for comparative purposes

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 57 as well as the 1008 steel panel se t. The 304 stainless steel set began to fail af ter 3000 hours of

exposure. Table 5-2 is a summary of the bare zeo lite on steel panel performance data.
Table 5-2 Salt fog testing (ASTM B117) results for zeolite coatings on steels (2006)

Alloy Coating Results

S1008 Zeolite only 0 failures at 48 hours 2/5 failures at 168 hours 3/5 failures at 672 hour 3/5 failures at 1056 hours 5/5 failures at 1584 hours

S4130 Zeolite only 0 failures at 168 hours 1/4 failures at 336 hours 1/4 failures at 672 hours 4/4 failures at 1056 hours

SS304 Zeolite only 0 failures at 1584 hours 2/5 failures at 3100 hours

Carbon steel S1008: The 1008 steel panels in Figure 5-55 had good protection overall after 168 hours of exposure. Two of the 3 panels had small pits resulting in visible red rust. The panels tested for over 1000 hours to look for zeolite coating delamination and further pit formation. The same panels are seen in Figure 5-56 after 1056 hours of exposure. Once a pit had formed, the corrosion increased, as expected, but the zeo lite did not delaminate from the panel. It is clear from these photos that the zeolite was still protecting the majority of the su rface area on 3 of the 5 panels after 1000 hours.

High-strength steel S4130: Figure 5-55 Zeolite coated 1008 st eel after 168 hours of exposure

Figure 5-56 Zeolite coated 1008 steel after 1056 hours of exposure

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 58 The 4130 steel panels seen in Figure 5-57 had no failures after 168 hours of exposure. After 672 hours only one of the panels had pitting. Although the surfaces of the majo rity of the panels were corrosion free after 1056 hours of exposure, th ere were at least 5 co rrosion pits present on each panel ( Figure 5-58).

Figure 5-57 Zeolite coated 4130 steel after 168 hours of exposure Figure 5-58 Zeolite coated 4130 steel after 1056 hours of exposure

Stainless steel SS304-2b:

The 304 stainless steel panels just began to show sign of corrosion geminating from the edge of the hole in the panel after 3100 hours of exposure ( Figure 5-59).

The protection of steel panels und er salt fog conditions exceeds mo st military requirements. An increase in zeolite coating thickness may incr ease protection times even further by reducing corrosion pit formation.

Figure 5-59 Zeolite coated 304 SS after 3100 hours of exposure

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 59 • ASTM B117 testing of zeo lite coated steels (2008)

Another fifteen zeolite coated samples (5 each of SS304-2b, S4130, and C1008) with a coating thickness of about 5 um were tested by China Lake on March 12, 2008. Three different controls were used. The C1008 steel was Zn phosphate coated with MIL-DTL-11195. The SS304-2b received a nitric acid passivati on and the S4130 was Cd plated.

The C1008 sets were scribed. The zeolite coated samples failed by 24 hours of salt fog (Figure 5-60). The controls failed as well (Figure 5-61). Three out of the five zeolite coated SS304-2b samples passed 2376 hours of salt fog (Figure 5-62). All of the nitric acid passivated controls passed 2376 hours test (Figure 5-63) . The zeolite coated S4310 samples failed after 500 hours of salt fog (Figure 5-64), while th e Cd plated counterpart passed (Figure 5-65). The results were summarized in Table 5-3.

Table 5-3 Salt fog testing (ASTM B117) resu lts for zeolite coatings on steels (2008)

Steel Coating Results
C1008 Zeolite (Scribed) Failed by 24 h
C1008 Zn phosphate and coated with MIL- DTL-11195(Scribed) Failed by 24 h
SS304-2b Zeolite 3/5 passed 2376 h
SS304-2b Nitric acid passivation 5/5 passed 2376 h
S4130 Zeolite Failed by 504 h
S4130 Cd plated Passed by 504 h

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 60

Figure 5-60 Scribed Zeolite coated C1008 after 24 hours of exposure Figure 5-61 Scribed C1008 (Zn phosphate coated with MIL-DTL-11195) after 24 hours of

exposure

Figure 5-62 Zeolite coated SS304-2b after 2376 hours of exposure Figure 5-63 Nitric acid passivated SS304-2b after 2376 hours of exposure

Figure 5-64 Zeolite coated S4130 after 504 hours of exposure Figure 5-65 Cd plated S4130 after 504 hours of

exposure

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 61 ASTM B117 Salt‐fog testing on zeolite coating systems

Generation

­ 1 coating (0.5

– 1.0 um thick):

Aluminum 2024-T3 panels were coated with zeolite of 0.5-2 um thick at UCR and delivered to China Lake. The panels were then sent to the Army Research Laboratory (ARL) to be coated with CARC topcoat. The panels were coated on one side with the CARC topcoat (Mil-PRF-64159) and coated with primer on the other side to keep corrosion from contaminating the salt fog chamber.

The painted panels were scribed in an “X” configuration and placed
into the chamber while held at 15 ° from vertical. The unpainted panels were placed in the
chamber 6 ° from vertical. The panels were exposed to a salt fog according to ASTM B-117. Unpainted zeolite panels were also used to test the zeolite performance as a pretreatment.

All panels were first inspected after 19 hours of exposure. Upon initial inspection, it was evident that the CARC coating did not adhere to the zeolite ( Figure 5-66).

Although the CARC topcoat did not appear to be compatible with the zeolite directly, the primer adhered to the test panels and there were no signs of delamination between the primer and zeolite. Another test using pr imer and topcoat may s how that the zeolite coating performs well in a coating system. Becau se the topcoat came off of the panels very cleanly, the excess paint was trimmed away and the panels were allowed to remain in the salt fog chamber to test effects on the zeolite coating al one. After 524 hours of e xposure, the bulk zeolite coating showed almost no corrosion except wh ere the coating had been scribed (See Figure 5-67). Another interesting a nd positive aspect of the coating is th at the corrosion that can be seen within the scribed areas did not mi grate and damage the bulk coating. Figure 5-66 Aluminum panels coated with zeolite and CARC topcoat after 19 hours of salt fog exposure

Figure 5-67 Exposed zeolite surface after 524 hours of exposure after CARC removal.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 62 Generation

­ 3 coating (7.5 um thick)

VOC-free topcoat (Deft product #55W-002, Deft, Irvine CA) and Self-Priming topcoat (TT-P2756A from Deft, Irvine, CA)

Based on the previous testing resu lts, it appears that 7.5 um thick coating has sufficient corrosion resistance. Therefore we decide d to focus on 7.5 um coatings. We produced 25 zeolite coated panels with 15 of them without topcoat and 10 with topcoats. The topcoats were applied by Deft in a trial run in their facility. Five panels were applie d with VOC-free topcoat (Deft product #55W-002, Deft, Irvine CA) and five panels were applied with self-priming topcoat (TT-P2756A from Deft, Irvine, CA). Three of each of the topcoated panels were then sent to China Lake for salt-fog testing (ASTM B117). The S se ries have been examined on the back by DC Polarization using the almost non destructive met hod described in Task 3-2 and shown to have excellent corrosion resistance. Se ries B are the non-tested (by DC Polarization) twins of the S samples. Series A are the non test ed twins of 5 panels that showed medium corrosion resistance (5 wt% NaCl, 10 -4 A/cm 2 ).

From initial observation of the panels painte d with the VOC-free formulation, there were significant differences between the surfaces of the paint. Two of the panels had a smooth appearance while one had a rough “orange peel” look ( Figure 5-68a&b). During the scribing process, one coating peeled aw ay from the scribed area. ( Figure 5-68 c )

Figure 5-68 Zeolite panels 6-5-04, 6-10-04a and 6-10-04b with VOC-free self-priming topcoat before scribing (a) and after scribing (b). (c) close up view of zeolite panel 6-5-04 with topcoat
Three panels with designati ons 8-1-04, 10-16-04a and 10-16-04b were painted with a solventbased self-priming topc oat. The panels had a uniform appearance and showed no peeling or delamination during the scribing process.

All painted panels were placed in the chamber at an angle of 15 ° from vertical. After 168 hours (1 we ek) of exposure all painted panels had some degree of blistering between the zeolite and the paint along the scribe and significant blistering on the outer edges of some panels. Although blistering is a Figure 5-69 Panel 10-16-04b coated with (a) a VOCfree topcoat and (b) a solvent-based topcoat after 168 hours of salt fog exposure

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 63 performance failure for this test, the panels remained in the chamber for a total of 336 hours. The severity of the blistering increased and the panels were removed from the test. Figure 5-69 are photos of blistering area s after 168 hours of exposure of the VOC-free topcoat and the solvent-based topcoat, respectively.

The poor performance of these topcoa ts is contributed in part to their application to the zeolite coatings. Neither ASTM nor MIL specs were follo wed during the topcoat application; they were applied as part of a demonstrat ion of the topcoat application pr ocess. Based on these results, MIL specs will be adhered to during future primer and/or topcoat application.

Zeolite/Primer, Zeolite/Primer/ Topcoat and Zeolite/Topcoat

Forty nine (49) zeolite coated AA-2024-T3 panels were prepared and painted by Deft (Irvine, CA), following ASTM guidelines. Figure 5-15 shows the matrix of primers and topcoats applied to the zeolite coating following MIL specs.

Aluminum 2024-T3 panels, coated with zeolite, were painted and tested in a salt fog environment according to ASTM B-117. Panels were tested with primers alone, primers and topcoat, and one set was tested with a self-p riming topcoat. The primers include Mil-PRF-23377 Type I Class C (control), Mil-PRF-23377 Type I Class N and Mil-PRF-85582 Type I Class N. The topcoat applied over the primers was a Mil-PRF-85282 and the self-priming topcoat was a
TT-P-2756A.

Primed and painted panels were scribed with a 4-inch “X” which exposed bare metal before being placed into the test chamber. The pane ls were inspected at va rious time intervals, including 168 hours, 336, hours, 552 hours, 672 hours, 1056 hours, 1584 and 3100 hours. It should be noted that during the fi rst two weeks of the test, a c ity-wide power failure caused the chamber to lose power for approximately 4 days . Once power was restored, the chamber was calibrated and the test resumed.

Coating delamination and corrosion was evident on so me samples in the early stages of the test. The corrosion is thought to be due to flexing of the aluminum panels causing coating breaches. The samples that were provided were less th an 0.032 in thickness. While handling, it was obvious that the panels were flexing. Possible cr acking of the zeolite coating may have lead to corrosion within the bulk of some of the samples.

Table 5-4 summarizes the performance data of the tested coating systems. It should be noted that the test was st opped after 3100 hours.

Figure 5-70 are of the panel sets that had the chro mated Mil-PRF-23377 Type I primers applied. After 3100 hours of exposure, the scribed areas we re free of corrosion and the coating did not show signs of delamination from the zeolite surface.

Corrosion is evident within the scribed areas of the panel sets in Figure 5-71. The panels had the non-chromated Mil-PRF-23377 Type I primer. Thes e panels failed after 336 hours of exposure.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 64 Table 5-4 Summary of performance and exposure time

Alloy Primer Topcoat Result

Al 2024-T3 Mil-PRF-23377 Type I Class C Mil-PRF-85285 Passing at 3100 hours

Al 2024-T3 Mil-PRF-23377 Type I Class N Mil-PRF-85285 Partial failure at 168 hours Complete Failure at 336 hours

Al 2024-T3 Mil-P-85582 Type I Class N Mil-PRF-85285 Failure at 168 hours due to delamination

Al 2024-T3 Mil-PRF-23377 Type I Class C None Passing at 3100 hours

Al 2024-T3 Mil-PRF-23377 Type I Class N None Partial failure at 168 hours Complete Failure at 336 hours

Al 2024-T3 Mil-P-85582 Type I Class N None Failure at 500 hours

Al 2024-T3 ---------- TT-P-2756A Failure at 168 hours due to delamination

Figure 5-70 Zeolite coated 2024-T3 aluminum with Mil-PRF-23377 Type I Class C primer (a) without and (b) with Mil-PRF-85285 topc oat after 3100 hours of exposure.

Figure 5-71 Zeolite coated 2024-T3 aluminum with Mil-PRF-23377 Type I Class N primer (a) without and (b) with Mil-PRF-85285 topcoa t after 336 hours of exposure.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 65 In Figure 5-72, corrosion is evident within the scribe on the 3-25-05A panel after 336 hours of corrosion. Failure was observed after 500 hours of exposure.

Delamination between the coating system and the zeolite is evident in the scribedareas of the panels that contained the MilPRF-85582 Type I Class N primer and MilPRF-85285 topcoat ( Figure 5-73). The adhesion of the primer to the zeolite surface was affected by the addition of the topcoat.

The self-priming topcoat was delaminating from the zeolite surface and there was corrosion present within the scribes afte r 168 hours of exposure to the salt fog ( Figure 5-74).

Figure 5-73 Zeolite coated aluminum 2024-T3 panels with Mil-PRF-85582 Type I Class N primer

and Mil-PRF-85285 topcoat after 168 hours of

exposure Figure 5-74 Zeolite coated 2024-T3 aluminum with self-priming topcoat TT-P-2756A after 168 hours of exposure

Summary

The bare zeolite coating offers excellent co rrosion protection on 2024-T3 aluminum in the accelerated weathering tests. The reproducibility of the zeolite de position process is excellent. A simple alkaline detergent solution pretreatment is used for all aluminum alloys and steels. A single chemical formulation is used for generating zeolite coating on all metals. If the coating is breached, corrosion remains localized to the damaged area. The zeolite does not blister or delaminate from any damaged areas. It appears from the most recent test results that a consistent zeolite application has been achieved. After 2205 hours of salt fog exposure there is no visual difference between a rough or smooth zeolite surfaces.

A complete zeolite coating system passing 3100 hours of salt-fog exposure (ASTM B117) has been achieved. The chromated primer (Mil-PR F-23377) both with and w ithout topcoat (MilFigure 5-72 Zeolite coated aluminum 2024-T3 with

Mil-PRF-85582 Type I Class N primer after 336 hours of exposure

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 66 PRF-85285) showed no delamination of the primer or topcoat from the zeolite and there was no rust observed in the scribed area s after 3100 hours salt-fog exposure.

Task 3

­ 5: Examine substrate degradation and corrosion inhibition

– EIS test

EIS testing procedure

EIS testing was carried out at room temperature with Solartron potentiostat SI 1287 and Solartronimpedance/gain-phase analyzer SI1260 in a threeelectrode Cell (Gamry PTC1 Paint Test Cell) with a graphite rod counter el ectrode and a saturated calomel electrode (SCE) as the reference electrode (Figure 5-75). A ZSM-5 coated AA 2024-T3 was used as the working electrode with an exposed area of 15 cm 2 . A small area of bare metal substrate is exposed on one side of the coated panel for electrical connection with copper conducting tape (as shown in Figure 5-24, right). The corrosive medium was 0.5 mol/L NaCl aqueous solution. The impedance measurements were performed at an open circuit potential with applied 10 mV sinusoida l perturbations in the frequency range of 10 -2 -2*10 5 Hz with 10 steps per decades.

EIS measurement results

To date, a ten-day EIS test was measured. Du ring this period, the spec tra don’t change much(Figure 5-76). The bode plot for the ZSM-5 coated AA 2024 has two distinguishable timedependent processes. The time c onstant at high frequencies (10 3 ~10 5 Hz) is related to the capacitance of zeolite coating. The resistive plateau at 10 0 ~10 3 Hz represents the pore resistance of the zeolite film. The time c onstant at low frequencies (10 -2 ~10 0 Hz) is attributed to the capacitance of an intermediate layer present at the AA/ZSM-5 in terface. An intermediate layer was also reported for sol-gel coating 29 and chromate conversion coating 30 , although the composition is not clear. It is believed that th e intermediate layer is very important for the corrosion resistant coating since it is the la st barrier for the corrosive species.

A three layer model (Figure 5-77) was used to fit the data and expl ain the protective and degradation mechanism of ZSM-5 coating. One simulation example was given in Figure 5-77, which shows perfect fitting results. Since a 10-day EIS test is not enough to show the degradation of ZSM-5 coatings, no further explan ation was given here. A long-term EIS test is under investigation. Figure 5-75 EIS test cell

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 67 Figure 5-76 Impedance spectra during immersion in 0.5 mol/L NaCl solution. (a) Nyquist plot and (b) Bode plot

Figure 5-77 EIS model and fitting resultUnivers i Task 3

­ 6

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## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 69 Six zeolite coated 2024-T3 coupons and five uncoated 2024-T3 samples were labeled as shown in Table 5-5 Zeolite samples and bare AA 2024- T3 from UCR. The numbering sequence, provided in Table 5-5, is used throughout this report.

Table 5-5 Zeolite samples and bare AA 2024-T3 from UCR

UCR Zeolite Samples UCR AA 2024-T3 Samples
080619B 080620A 080620B 080621A 080621B 080626A 2024 T3-1
2024 T3-2
2024 T3-3
2024 T3-4
2024 T3-5

All samples were mounted on corrosion racks at the NASA Beach Corrosion Test Site, and remained in place for 12 months. Each rack was oriented so the face of each coupon was in direct exposure with the coastal marine at mospheric environment from the Atlantic Ocean (Figure 5-79 NAVAIR Panels at the NASA Beach Corrosion Test Site ).

Figure 5-79 NAVAIR Panels at the NASA Beach Corrosion Test Site

Coating performance parameters, with respect to corrosion control, were ascertained using the following methodologies:

• ASTM D1654 - Standard Test Method for Ev aluation of Painted or Coated Specimens Subjected to Corrosive Environments

• ASTM D610 - Standard Test Method for Evaluating Degree of Rusting on Painted Surfaces

• ASTM D714 - Standard Test Method for Ev aluating Degree of B listering of Paints

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 70 Gloss and color measurements were performed to determine aesthetic and technical parameters related to the coating systems.

ASTM D610 Standard Test Method fo r Evaluating Degree of Rusting on Painted Surfaces

All coupons were rated according to ASTM D 610 “ Standard Test Met hod for Evaluating Degree of Rusting on Painted Surfaces ”. ASTM D 610 rates the de gree of rusting on painted steel surfaces on a scale in which each rating numb er correlates to the area of a coupon that is corroded (Table 5-6 ASTM D 610 Rating Scale).

Table 5-6 ASTM D 610 Rating Scale

To determine the degree of corrosion emanating fr om the unscribed metal surface, a series of pictorial examples from ASTM D 610 were used as a reference. These reference diagrams are shown in Figure 5-80 Pictorial examples of rust type and gr ade (7-9) from ASTM D 610.Figure 5-81, and Figure 5-82. In accord with these illust rations, the type of co rrosion is reported as spot, general, pinpoint or hybrid; and the extent of corrosion is reported on a scale from 0-10 (worst-best).

A summary of the evaluations, according to AS TM D 610, is shown in Table 5-7 Summary of ASTM D 610 Ratings – Degree of Rusting on Pain ted SurfaceThe coating performance is color coded according to the extent of corrosion away from the scribe or edges of the samples. A perfect rating of 10 was color coded in green. A rating number from 7 to 10 (non inclusive of 10) was color coded in yellow. Finally, a rating below 7 was color coded in red.

Table 5-7 Summary of ASTM D 610 Ratings – Degree of Rusting on Painted Surface Description Rating No rusting or less than 0.01% of surface rusted. 10 Minute rusting, less than 0.03% of surface rusted. 9 Few isolated rust spots, less than 0.1% of surface rusted. 8
Less than 0.3% of surface rusted. 7 Extensive rust spots, but less than 1% of surface rusted. 6 Rusting to the extent of 3% of surface rusted. 5 Rusting to the extent of 10% of surface rusted. 4 Approximately 1/6 of the surface rusted. 3 Approximately 1/3 of the surface rusted. 2 Approximately 1/2 of surface rusted. 1 Approximately 100% of surface rusted. 0

Substrate / Code Conversion Coat Primer Topcoat Panel ID #s 4 Month 6 Month 9 Month 12 Month

2024 UC Zeolite None None 080619B 6 5 5 2

2024 UC Zeolite None None 080620A 10 10 10 8

2024 UC Zeolite None None 080620B 10 8 8 7

2024 UC Zeolite None None 080621A 7 7 6 6

2024 UC Zeolite None None 080621B 7 7 6 6

2024 UC Zeolite None None 080626A 6 5 5 5

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 71 The summary in Table 5-7 proves useful to show the degree of protection afforded by the different zeolite coated samples. All ratings that deviated from a pe rfect condition (10) were classified as pinpoint. It should be noted that neither a primer, nor a t opcoat was used on the 2024-T3 zeolite samples.

Figure 5-80 Pictorial examples of rust type and grade (7-9) from ASTM D 610.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 72 Figure 5-81 Pictorial examples of rust type and grade (4-6) from ASTM D 160

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 73 Figure 5-82 Pictorial examples of rust type and grade (1-3) from ASTM D 610

ASTM D714 Standard Test Method fo r Evaluating Degree of Blister ing of Paints

ASTM D714 is a test method that uses photographi c reference standards to evaluate the degree of blistering that may develop underneath a coat ing. The ratings are ba sed upon the size of the blister, as well as the distribution of anomalie s. Figure 5-83 ASTM D714-02 Blister Reference Photographs shows the template that was used to evaluate the size and dist ribution of blistering.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 74 Figure 5-83 ASTM D714-02 Blis ter Reference Photographs

A summary of the ASTM D 714 blister ratings ( by coating type) is shown in Table 5-8. A perfect rating value of 10 (ind icating no blisters) was color c oded in green. A system that exhibited blisters was color coded in red. Ye llow indicates that the coating had previously blistered.

No blistering was evident on any of the zeoli te coated aluminum su bstrates throughout the duration of exposure.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 75 Table 5-9. Summary of ASTM D 714 Ratings – Degree of Blistering

ASTM D2244 Color Measurements

Color can be a key aesthetic and technical consideration for a coating system. Color measurements were recorded on a ColorTec-PCM handheld portable color meter using the CIE L*a*b* format, D-65 illuminant, and a 10° observer. Briefly, a color’s "lightness" (L*) runs from light (white) to dark (black). A more reddish color will give a positive a* value and conversely, a more greenish color will give a negative a* value. As with the a* values, the more bluish color wi ll give a positive b* value, and a more yellowish color will give a negative b* value. A single number indicator of overall color change (delta E) was calculated by taking the square root of the sum of the squares of the lightne ss and color difference according to the following equation:

delta E= 

# ( ) ( ) ( ) fi fi fi 

### bbaaLL

− − − + + 2 2 2

Where:

L i = initial Lightness value a i = initial Red/Green value

L f = final Lightness value a f = final Red/Green value

b i = initial Blue/Yellow value b f = final Blue/Yellow value

As a general rule, a “ delta E” value of 1 is discernable by the human eye in a side-by-side comparison. However, in less than ideal lighting, a delta E value of 2 or 3 can still be considered the same color. Delta E values were calcul ated from the initial, and time dependent measurements after each exposure period. The delta E change in color for each coating type and duration of exposure is shown in Table 5-10. Color values for individual coupons are reported in Tables 11-14. Each value was based upon the average of three measurements for each sample.

As expected, significant changes in color were exhibited from white corrosion products that formed on the uncoated 2024-T3 aluminum substrat es. Significant change s in color were not seen (compared to the unprot ected aluminum) for the zeolit e coated specimens.

System Substrate / Code Conversion Coat Primer Topcoat Panel ID #s 4 Month 6 Month 9 Month 12 Month

UC 2024 UC Zeolite None None 080619B

2024 UC Zeolite None None 080620A

2024 UC Zeolite None None 080620B

2024 UC Zeolite None None 080621A

2024 UC Zeolite None None 080621B

2024 UC Zeolite None None 080626A

Color Code
No Blisters Previously Blistered
Blisters

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 76 Since a topcoat was not used in conjunction with the zeolite pretreatment, color values may be irrelevant for the zeolite coated product when used in the field.

Table 5-10. Average Delta E Color Calculations by Coating Type.

Table 5-11. Four Month Color Ratings

Table 5-12. Six Month Color Ratings Sample 4 Month Delta E 6 Month Delta E 9 Month Delta E 12 Month Delta E
2024 T3 24.26 23.89 31.09 22.36

080619B 5.92 5.69 5.34 5.78
080620A 6.74 6.87 6.43 6.37
080620B 6.16 6.04 5.81 5.75
080621A 3.31 3.30 3.45 3.40
080621B 3.39 3.27 3.16 3.07
080626A 5.18 5.26 6.04 5.76 Average Delta E Calculations by Group

Sample 4 Month
Delta E Initial L Intial a Initial b 4 month
L 4 month

a 4 month
b
2024 T3-1 22.441 51.84 -3.59 8.34 73.72 1.12 6.70
2024 T3-2 23.528 56.03 11.27 -7.51 72.08 0.97 6.27
2024 T3-3 34.792 51.43 11.09 -20.77 70.65 1.00 6.42
2024 T3-4 12.815 55.43 -0.60 2.70 67.94 0.80 5.10
2024 T3-5 27.711 53.89 -12.85 18.68 74.82 1.14 7.10

080619B 5.916 74.93 6.42 -2.93 75.45 2.12 1.10
080620A 6.743 74.44 6.16 -6.22 76.27 2.56 -0.82
080620B 6.162 74.76 6.34 -4.91 76.56 3.22 0.09
080621A 3.314 75.65 4.31 -3.26 75.57 2.27 -0.65
080621B 3.392 77.71 4.27 -2.52 78.17 2.49 0.33
080626A 5.182 68.44 3.02 1.08 71.51 0.70 4.55

Sample Delta E Initial L Intial a Initial b 6 month
L 6 month

a 6 month
b
2024 T3-1 21.860 51.84 -3.59 8.34 73.14 0.90 6.34
2024 T3-2 22.728 56.03 11.27 -7.51 70.93 0.88 6.15
2024 T3-3 35.297 51.43 11.09 -20.77 71.54 0.93 6.40
2024 T3-4 12.602 55.43 -0.60 2.70 67.74 0.63 5.10
2024 T3-5 26.977 53.89 -12.85 18.68 73.66 0.96 6.59

080619B 5.687 74.93 6.42 -2.93 75.64 2.16 0.77
080620A 6.873 74.44 6.16 -6.22 76.50 2.47 -0.80
080620B 6.041 74.76 6.34 -4.91 76.49 3.12 -0.10
080621A 3.304 75.65 4.31 -3.26 75.61 2.15 -0.76
080621B 3.269 77.71 4.27 -2.52 78.22 2.41 0.12
080626A 5.256 68.44 3.02 1.08 71.66 0.72 4.54

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 77 Table 5-13. Nine Month Color Ratings

Table 5-14. Twelve Month Color Ratings

ASTM D523 Gloss Measurements

Gloss can be a key aesthetic and technical consid eration for a coating system. The gloss meter records the amount of reflective illuminated light at specified angles of 20°, 60°, or 85°; and gives a value in gloss units (GU). The 60° geometry is used for most specimens, and is the initial angle used to determine whether the 20° or 85° angles may be more applicable. The 20° angle is used when the 60° angle gloss values are higher than 70 GU’s, while the 85° angle is used when the 60° angle gloss values are less than 10 GU’s. Gloss measurements were recorded using a ca librated BYK Gardner Tr i-Gloss portable gloss meter. Measurements were recorded in three locations on the face of each coupon, and the average of those three measurements is reported in Table 5-15.

The gloss measurements for the bare aluminum substrates were heavily influenced by the corrosion products that formed on the face of the unprotected samples. This phenomenon is as expected, and provides a control th at might be used to form a co mparison with the zeolite coated samples. Sample Delta E Initial L Intial a Initial b 9 month
L 9 month

a 9 month
b
2024 T3-1 20.655 51.84 -3.59 8.34 71.89 0.92 6.27
2024 T3-2 43.190 56.03 11.27 -7.51 95.81 -1.26 3.71
2024 T3-3 52.367 51.43 11.09 -20.77 96.04 -1.26 3.72
2024 T3-4 12.742 55.43 -0.60 2.70 67.77 0.76 5.57
2024 T3-5 26.482 53.89 -12.85 18.68 73.00 0.95 6.61

080619B 5.342 74.93 6.42 -2.93 76.88 1.88 -0.90
080620A 6.433 74.44 6.16 -6.22 75.39 2.67 -0.90
080620B 5.813 74.76 6.34 -4.91 75.56 3.30 -0.02
080621A 3.445 75.65 4.31 -3.26 75.47 2.14 -0.59
080621B 3.158 77.71 4.27 -2.52 77.55 2.47 0.07
080626A 6.041 68.44 3.02 1.08 72.46 0.69 4.94

Sample Delta E Initial L Intial a Initial b 12 month
L 12 month

a 12 month
b
2024 T3-1 19.168 51.84 -3.59 8.34 70.27 0.98 5.72
2024 T3-2 21.435 56.03 11.27 -7.51 69.15 1.06 6.02
2024 T3-3 32.962 51.43 11.09 -20.77 68.59 0.89 5.46
2024 T3-4 12.481 55.43 -0.60 2.70 67.65 0.81 4.81
2024 T3-5 25.737 53.89 -12.85 18.68 71.48 1.05 6.04

080619B 5.780 74.93 6.42 -2.93 77.12 2.04 0.14
080620A 6.371 74.44 6.16 -6.22 74.98 2.65 -0.93
080620B 5.748 74.76 6.34 -4.91 75.01 3.25 -0.07
080621A 3.402 75.65 4.31 -3.26 75.04 2.19 -0.67
080621B 3.067 77.71 4.27 -2.52 77.27 2.52 -0.04
080626A 5.760 68.44 3.02 1.08 72.13 0.69 4.84

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 78 Table 5-15. Gloss Measurements by Sample

Figure 5-84~5-89 show the digital pictures of those zeolite co ated and bare AA2024-T3 samples exposed at marine atmosphere on the rack up to 12 month (each sample’s position is labeled in Figure 5-84 ). Initial Gloss 4 mo. Gloss 6 mo. Gloss 9 mo. Gloss 12 mo. Gloss
2024 T3-1 98.2 9.3 3.9 2.5 1.8
2024 T3-2 51.2 3.4 1.8 1.6 1.3
2024 T3-3 109.0 4.4 3.1 2.0 1.5
2024 T3-4 145.0 1.9 1.5 1.1 1.0
2024 T3-5 105.0 7.8 4.8 3.4 2.3

080619B 9.4 7.8 6.6 8.1 8.2
080620A 13.1 13.8 11.6 13.6 12.9
080620B 10.2 13.7 12.8 14.5 13.2
080621A 2.6 3.3 3.8 3.9 2.8
080621B 40.8 37.8 28.3 32.6 22.2
080626A 10.7 8.7 7.1 7.2 5.9 Gloss Measurements

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 79 Figure 5-84 Sample position on rack

Figure 5-85 Initial photo documentation

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 80 Figure 5-86 Four month exposure Figure 5-87 Six month exposure

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 81 Figure 5-88 Nine month exposure Figure 5-89 Twelve month exposure

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 82 Task 4: Technology Transition

The corrosion resistant zeolite coating is protect ed by an issued US patent and one invention disclosure for the ionothermal synthesis pro cess has been filed. There have been regular enquiries from companies about the tec hnology (e.g., Metalast, VestaScience, UTEK Corporation, etc.). We have also submitted a demonstration pre-proposal lead by Navy China Lake to the ESTCP program. And now a full proposal is requested. We have recently demonstrated that zeolite coul d be possible replacement for hard chrome and cadmium. Since here mostly small parts are involved the pressure d vessel is expected to be of less concern. This may open up more commercialization prospects.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 83 

### Appendix
Publications 1) Cheng, X.L., Z.B. Wang, and Y.S. Yan, Corrosion-resistant zeolite coatings by in situ crystallization. Electrochemical and Solid State Letters, 2001. 4 (5): p. B23-B26. 2) Wang, Z.B., et al., Pure silica zeolite films as low-k dielectrics by spin -on of nanoparticle suspensions. Advanced Materials, 2001. 13 (19): p. 1463. 3) Wang, Z.B. and Y.S. Yan, Oriented zeolite MFI monolayer f ilms on metal substrates by in situ crystallization. Microporous and Mes oporous Materials, 2001. 48 (1-3): p. 229-238. 4) Mitra, A., et al., Synthesis and corrosion resistance of hi gh-silica zeolite MTW, BEA, and MFI coatings on steel and aluminum. Journal of the Electrochemical Society, 2002. 149 (10): p. B472-B478. 5) Lai, Z.P., et al., Microstructural optimization of a zeolite membrane for organic vapor separation. Science, 2003. 300 (5618): p. 456-460. 6) Li, S., et al., Micropatterned oriented zeolite monolayer films by direct in situ crystallization. Chemistry of materials, 2003. 15 (14): p. 2687-2689. 7) Li, S., Z.J. Li, and Y.S. Yan, Ultra-low-k pure-silica zeolite MF I films using cyclodextrin as

porogen. Advanced Materials, 2003. 15 (18): p. 1528. 8) Yan, Y., S. Li, and Z. Li, Pure-Silica-Zeolite Low Dielectri c Constant Films: Present and the Future. Zeolite News letters, 2003. 20 : p. 110-119. 9) Li, S., et al., TEM investigation of formation mechani sm of monocrystal -thick b-oriented pure silica zeolite MFI film. Journal of the American Chemical Society, 2004. 126 (34): p.
10732-10737. 10) Li, S., et al., Evaluation of pore structure in pure sili ca zeolite MFI low-k thin films using positronium annihilation lifetime spectroscopy. Journal of Physical Chemistry B, 2004.
108 (31): p. 11689-11692. 11) Li, S., et al., Molecular sieving in a nanoporous b-or iented pure-silica-zeolite MFI monocrystal film. Journal of the Am erican Chemical Society, 2004. 126 (13): p. 4122-4123. 12) Li, Z.J., et al., Effects of crystallinity in spin-on pure-silica-zeolite MFI low-dielectricconstant films. Advanced Functional Materials, 2004. 14 (10): p. 1019-1024. 13) Mitra, A., et al., Synthesis and evaluation of pure-silica -zeolite BEA as low dielectric constant material for microprocessors. Industrial & Engineering Chemistry Research, 2004.
43 (12): p. 2946-2949. 14) Yan, Y.S. and H. Wang, Nanostructured Zeolite Films , in Encyclopedia of nanoscience and nanotechnology , H.S. Nalwa, Editor. 2004, American Scientific Publishers: Stevenson Ranch. p. 1-19. 15) Li, Z.J., et al., Pure-silica-zeolite MEL low-k fil ms from nanoparticle suspensions. Journal of Physical Chemistry B, 2005. 109 (18): p. 8652-8658. 16) McDonnell, A.M.P., et al., Hydrophilic and antimicrobial ze olite coatings for gravityindependent water separation. Advanced Functional Materials, 2005. 15 (2): p. 336-340. 17) Munoz, R.A., D. Beving, and Y.S. Yan, Hydrophilic zeolite coatings for improved heat transfer. Industrial & Engineering Chemistry Research, 2005. 44 (12): p. 4310-4315. 18) Beving, D.E., et al., Corrosion resistant high-silica-zeolite MFI coating - One general solution formulation for aluminum a lloy AA-2024-T3, AA-5052-H32, AA-6061-T4, and AA7075-T6. Journal of the Electro chemical Society, 2006. 153 (8): p. B325-B329. 19) Hu, L.L., et al., Interfacial adhesion of nanoporous zeolite thin films. Journal of Materials Research, 2006. 21 (2): p. 505-511.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 84 20) Li, Y.S., et al., Microwave synthesis of LTA zeo lite membranes without seeding. Journal of Membrane Science, 2006. 277 (1-2): p. 230-239. 21) Li, Y.S., J. Liu, and W.S. Yang, Formation mechanism of microwave synthesized LTA zeolite membranes. Journal of Membrane Science, 2006. 281 (1-2): p. 646-657. 22) Li, Z.J., et al., Mechanical and dielectric properties of pure-silica-zeolite low-k materials. Angewandte Chemie-International Edition, 2006. 45 (38): p. 6329-6332. 23) O'Neill, C., et al., Durability of hydrophilic and antimicr obial zeolite coatings under water
immersion. Aiche Journal, 2006. 52 (3): p. 1157-1161. 24) Johnson, M., et al., Mechanical characterization of zeolit e low dielectric constant thin films by nanoindentation. Thin Solid Films, 2007. 515 (6): p. 3164-3170. 25) Cai, R., et al., Ionothermal synthesis of oriented ze olite AEL films and their application as corrosion-resistant coatings. Angewandte Chemie-International Edition, 2008. 47 (3): p.
525-528. 26) Cai, R. and Y. Yan, Corrosion-resistant zeolite coatings. Corrosion, 2008. 64 (3): p. 271-
278.

Presentations

1) Beving D.; Yan Y. 2003. Corrosion Resistant Zeolite Coatings: A General Coating for Aluminum Alloys. The American Institute of Chemic al Engineers National Meeting

, November 3-8, San Francisco, California. 2) Beving D.; McDonnell A.: Yan Y. 2004 , Corrosion Resistant Zeolite Coatings: A General Coating for Aluminum Alloys, American Chemical Society 227th National Meeting , March 28- April1, 2004, Anaheim, California. 3) Beving D.; McDonnell A.: Yan Y. 2004 , Corrosion Resistant Zeolite Coatings: A General Coating for Aluminum Alloys, The American Institute of Ch emical Engineers National Meeting , November 7-12, Austin, Texas. 4) McDonnell A. M. P.; Beving D.; Wang A.; Chen W.; Yan Y. 2005. Hydrophilic and antimicrobial zeolite coatings for gravity-independent water separation, Adv. Functional Materials, 15:336-339. 5) O’Neill C.; Beving D.; McDonnell A.; Chen W.; Yushan Y. 2005 , Hydrophilic and Antimicrobial Zeolite Coatings, The American Institute of Chemical Engineers National Meeting , October 30 - November 4, Cincinnati, Ohio. 6) O’Neill C.; Beving D.; McDonnell A.; Chen W.; Yushan Y. 2005 , Zeolite-A Coatings for Use in Condensing Heat Exchangers Onboard Manned Spacecraft, The American Institute of Chemical Engineers National Meeting , October 30 - November 4, Cincinnati, Ohio. 7) Mao Y.; Beving D.; Munoz R.; Yushan Y. 2005 , Hydrothermal Synthesis and Corrosion Resistance of Vanadium ZSM-5 Films, The American Institute of Chemical Engineers National Meeting , October 30 - November 4, Cincinnati, Ohio. 8) Mao Y.; Beving D.; Munoz R.; Yushan Y. 2005 , Hydrothermal Synthesis of Inorganic and Organic Nanocomposite ZSM-5 Films from Recycled Solution, The American Institute of Chemical Engineers National Meeting , October 30 - November 4, Cincinnati, Ohio. 9) Munoz R.; Beving D.; Mao Y.; Yushan Y. 2005 , Zeolite Y Coatings on Al-2024-T3 Substrate by a Novel Three-Step Synthesis Method, The American Institute of Chemical Engineers National Meeting , October 30 - November 4, Cincinnati, Ohio.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 85 10) Lai Z.; Tsapatsis M.; Beving D.; Yan Y. 2005 , Fabrication of Zeolite Films Using Layerby-Layer Depositions, The American Institute of Chemic al Engineers Na tional Meeting

, October 30 - November 4, Cincinnati, Ohio. 11) Beving D.; Anderson N.; O’Neill C.; Yan Y. 2005 , Corrosion Resistan t Zeolite Coatings: A General Coating for Aluminum Alloys, The National Association of Corrosion Engineers Tri-Service Corrosion Conference , November 14-18, Orlando, Florida. 12) Beving D.; Anderson N.; O’Neill C.; Yan Y. 2005 , Corrosion Resistan t Zeolite Coatings: A General Coating for Aluminum Alloys, The Electrochemical Soc iety National Meeting

, October 16-21, Los Angeles, California. 13) Beving D.; Anderson N.; O’Neill C.; Yan Y. 2006 , Salt Fog Accelerated Weathering Testing of High-Silica-Zeolite MFI Coatings on Aluminum Alloy 2024-T3, The Electrochemical Society Transactions , 1(9):65-72. 14) Guthrie S.; Beving D.; Yan Y. 2006 , Zeolite Hybrid Coati ngs on Metal Alloys for Chemical Resistance, Hydrophilicity and Microbiocidal Activity, The American Institute of Chemical Engineers National Meeting , November 12 - 17, San Francisco, CA. 15) O’Neill C.; Beving D.; Flores D.; Chen W.; Yan Y. 2006 , Durability of Hydrophilic and Antimicrobial Zeolite Coatings, The American Institute of Chemical Engineers National Meeting , November 12 - 17, San Francisco, CA. 16) O’Neill C.; Beving D.; Chen W.; Yan Y. 2006 , Zeolite A/ZSM-5 Hybrid Coating, The American Institute of Chemical Engineers National Meeting , November 12 - 17, San Francisco, CA. 17) O’Neill C.; Beving D.; Chen W.; Yan Y. 2006 , Antimicrobial and Hydrophilic Zeolite Coating, The American Institute of Chemical Engineers National Meeting , November 12 - 17, San Francisco, CA. 18) R. Munoz, Y. Kim, D. Beving, Y. Yan 2006 . High Silica Zeolite (ZSM-5) Coated Aluminum (Al-20204-T3): Mi cro-Structural Characteri zation by Laser Confocal Microscopy and Electrochemical Studies, Oral Presentation at 210th Meeting of The Electrochemical Society , October 29 – November 3, Cancun, Mexico. 19) R Munoz, J Liu, G Aguilar, Y Yan 2006 . Corrosion Resistant Hydrophilic Zeolite Coatings for Improved Heat Transfer, Poster Presentation at 210 th Meeting of The Electrochemical Society , October 29 – November 3, Cancun, Mexico. 20) R Cai, M Sun, Z Chen, D Beving, Y Yan, New s ynthesis route for corrosion resistant zeolite coatings, Poster Presentation at 212th ECS Meeting , October 7-12, 2007, Washington, DC,
USA. 21) D Beving, C O’Neill, N. Anderson, Y. Yan, Salt Fog Testing of Zeolite, Zeolite-Primer, and Zeolite-Primer-Topcoat Systems on AA-2024-T3, Oral Presentation at 212th ECS Meeting

, October 7-12, 2007, Washington, DC, USA. 22) R Beti, D Beving, Y Yan, Electronically Conduc tive Corrosion Resistan t Zeolite Coatings by in-situ Crystallization, Poster Presentation at 213th ECS Meeting , May 18-22, 2008, Phoenix, Arizona, USA.

## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 86 

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## SERDP PP1342: Zeolite Coating System

University of California, Riverside, CE‐CERT 87 21) Corma, A., et al., Delaminated zeolites: Combini ng the benefits of zeolites and mesoporous materials for catalytic uses. Journal of Catalysis, 1999. 186 (1): p. 57-63. 22) Roth, W.J. and J.C. Vartuli, Preparation of exfoliated zeolit es from layered precursors: The role of pH and nature of intercalating media , in Nanoporous Materials Iii . 2002. p.
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