# Presentation: 177794

## NASA Corrosion Technology Laboratory

## NASA CORROSION TECHNOLOGY LABORATORY

**Multifaceted capability that**
**Conducts applied research**
**Develops new corrosion detection and control technologies**
**Investigates, evaluates, and determines materials performance and degradation in different environments in support of NASA, other government organizations, industry, and educational institutions**
**Provides consulting and testing services**
**Participates in educational outreach activities**

## NASA CORROSION TECHNOLOGY LABORATORY

**NASA CORROSION TECHNOLOGY LABORATORY**

**MISSION**
- 	To develop corrosion control and detection technologies and to investigate, evaluate, & determine material behavior in various corrosive environments
**FACILITIES**
- Atmospheric Exposure Site
- Cathodic Protection Compatibility Tank
- Seawater Immersion
- On-Site Laboratory
- Electrochemistry Laboratory
- Accelerated Corrosion Laboratory
- Coatings Application Laboratory
- Photodocumentation Laboratory

**Notes:**
Kennedy Space Center’s launch facilities are located within 1000 feet of the Atlantic Ocean.  Salt from the ocean combined with the launch vehicles’ acidic rocket exhaust make corrosion protection a high priority.  For these reasons, KSC maintains state-of-the-art corrosion research, testing and evaluation capabilities.  Facilities available for use include the Coatings Application Laboratory, Electrochemistry Laboratory, Immersion Tank, Marine and Atmospheric Exposure Site (With Immersion Tank), Accelerated Corrosion Laboratory and Photodocumentation laboratory. 

The Corrosion Engineering capability at the Kennedy Space Center (KSC) is evolving from a need for a better understanding of corrosion processes that affect our launch sites to a state of the art corrosion problems solution center.  Over the years, materials failures at KSC have been attributed to various forms of corrosion (e.g., atmospheric corrosion, stress corrosion cracking, pitting corrosion, crevice corrosion, intergranular corrosion, hydrogen embrittlement, corrosion fatigue, etc.). To address these issues, the NASA Corrosion Technology Testbed conducts applied research to identify technologies that will prevent such failures. 

New procedures have been developed for rapidly evaluating corrosion-resistant alloys, protective coatings, and other materials, enhancing the safety and reliability of the nation’s launch infrastructure and flight hardware. Much of the work accomplished within the lab has been presented at national and international conferences and published in technical journals, making KSC a major source of worldwide corrosion expertise.

## People

## KSC Atmospheric Corrosion Test Site

- Documented by ASM as one of the most corrosive naturally occurring environments.
- Actively maintained for over 35 years.
- Historical database for evaluation of new materials.
- On-site laboratory for real time atmospheric and seawater immersion corrosion investigations.
- Remote access network connectivity for data acquisition and real time video by the Internet.
- Instrumented for complete weather information.

**Notes:**
The KSC Beach Corrosion Test Site was established in the 1960s.  It is located at latitude 28.7° N, longitude 80.6° W, and approximately 100 feet from the high tide line.  Over the years, thousands of coated test panels, stress corrosion cracking specimens, and commercially produced components have been evaluated in the high salt, high humidity, high-UV Florida seacoast environment.

The site has approximately 600 linear feet of front row exposure for atmospheric corrosion specimens. Many types of test samples can be accommodated, including standard size test coupons (4"× 6"), stress corrosion cracking specimens, and full-scale test articles. These experiments can be performed in either a boldly exposed or sheltered configuration. Both power and data connections are available within the site to power test articles and record onboard data instrumentation outputs.

The KSC Beach Corrosion Test Site has the highest corrosivity of any test site in the continental United States. This means samples exposed at this site will weather or degrade at rates far in excess of the rates experienced at other sites. 

The KSC Beach Corrosion Site Laboratory is an on-site facility for conducting real time corrosion experiments, and it also houses the electronic instrumentation for the remote monitoring of corrosion experiments and weather conditions at the site. The laboratory provides humidity and temperature control for electronic instrumentation such as personal computers, data loggers, electronic balances, etc., and also provides temperature-controlled laboratory space for on-site corrosion experiments.

## Corrosion Rates

- S. Coburn, Atmospheric Corrosion, in Metals Handbook, 9th ed., Vol. 1, Properties and Selection, Carbon Steels, American Society for Metals, Metals Park, Ohio, p.720 (1978)

## Corrosion 

**Corrosion Rate as a Function of Distance from KSC Corrosion Test Site**

- J.D. Morrison, Report on the Relative Corrosivity of Atmospheres at Various Distances from the Seacoast, NASA-Kennedy Space Center, Report MTB 099-74, January 1980

## 
Two immersion tanks with a continuous once-through, filtered supply of seawater is used to evaluate test coupons, component hardware, or full scale test articles. 
Temperature, salinity, dissolved oxygen, conductivity and pH are closely monitored.
Can be utilized for the evaluation of protective coatings, metal alloys, reinforced concrete, composites and other materials in a seawater environment. 
Specialized tests can be designed to study impingement-corrosion, erosion-corrosion, cavitation and other velocity effects. 

- Two immersion tanks with a continuous once-through, filtered supply of seawater is used to evaluate test coupons, component hardware, or full scale test articles.
- Temperature, salinity, dissolved oxygen, conductivity and pH are closely monitored.
- Can be utilized for the evaluation of protective coatings, metal alloys, reinforced concrete, composites and other materials in a seawater environment.
- Specialized tests can be designed to study impingement-corrosion, erosion-corrosion, cavitation and other velocity effects.

**Seawater Immersion System**

**Notes:**
The seawater immersion system is utilized for the evaluation of protective coatings, metal alloys, reinforced concrete composites and other materials in an ocean environment. This system is composed of two immersion tanks with a continuous once-through, filtered supply of seawater, and has the ability to expose a variety of specimens, including test coupons, component hardware or full scale test articles.

This seawater is pumped directly from the Atlantic Ocean and is representative of surface oceanic conditions. (Natural seawater has been documented as more corrosive than artificial seawater or simple salt solutions.) Specialized tests can be designed to study impingement-corrosion, erosion-corrosion, cavitation and other velocity effects. Both 110 volt power and data acquisition connections are available at the facility to power test articles and record onboard data instrumentation outputs. The water in the tanks is continuously monitored for salinity, temperature, dissolved oxygen, and pH.

The inlet to our site is on the open ocean providing:
a continuously refreshed source of clean, natural seawater, with seasonal water temperatures that vary from 20 to 28C.

The site has the capability of exposing samples in a wide variety of racks and sample configurations. The flowing seawater tanks are especially useful for replicating exposures in industrial facilities using seawater piping systems.

## State-of-the-art instrumentation and equipment for corrosion measurements including direct current (DC) and alternating (AC) current methods.

Polarization resistance
Tafel extrapolation
Potentiodynamic scanning
Cyclic polarization
Electrochemical impedance spectroscopy

- Polarization resistance
- Tafel extrapolation
- Potentiodynamic scanning
- Cyclic polarization
- Electrochemical impedance spectroscopy

**Electrochemistry Laboratory**

## Novel Electrochemical Test Cells

**Micro-Electrochemical Cell**
- The cell can measure the corrosion properties of areas between 1 mm and 1 μm in diameter
- Ideal for measuring properties of welded samples or studies of localized corrosion

**Crevice Free Corrosion Cell**
- Minimizes crevice corrosion during electrochemical testing
- Controlled atmosphere for use under a variety of conditions

## Equipped with state-of-the-art coating application equipment with conventional, airless, and plural component spray capabilities.

Maintains an inventory of standard steel and aluminum test panels.

Ensures that coatings are applied in a prescribed and consistent manner to SSPC, NACE International and military specifications.

- Maintains an inventory of standard steel and aluminum test panels.
- Ensures that coatings are applied in a prescribed and consistent manner to SSPC, NACE International and military specifications.

**Coatings Application Lab**

**Notes:**
All candidate coating test panels are prepared in the laboratory to provide evaluation of the ease of application and assessment of any potential difficulties in applying coatings to real structures.

Manufacturers' recommendations are used to prepare and apply the coatings using industry standard spray techniques.  Variations in humidity, temperature, etc., are eliminated by applying candidate coatings indoors in a temperature controlled paint spray booth.  Variations in application are minimized by using the same painter for all candidate coatings.

The coatings laboratory has facilities for abrasion, gloss, adhesion testing, and many other physical and chemical tests necessary to characterize material properties.  Coating systems that pass initial screening are judged ready for field evaluation at the KSC Beach Corrosion Test Site or for exposure in the accelerated testing laboratory.

Purpose
All candidate coating test panels are prepared in the laboratory to provide evaluation of the ease of application and assessment of any potential difficulties. Capabilities
Most coatings are delivered as wet samples from suppliers and manufacturers. Manufacturer’s recommendations are used to prepare and apply the coatings using industry standard spray techniques. Variations in humidity, temperature, etc., are eliminated by applying candidate coatings indoors in a temperature controlled paint spray booth. Variations in application are minimized by using the same painter for all candidate coatings.
 An inventory of standard steel and aluminum test panels is maintained. Carbon steel test panels are normally composite panels that provide opportunities to evaluate the effectiveness of coatings applied over edges, weld spatter, and in crevices.

SSPC – The Society for Protective Coatings

## Accelerated Corrosion Laboratory

- Salt fog testing to study the ability of a material to resist corrosion.
- Capabilities include traditional salt spray techniques, as well as advanced cyclic and acidic methods.

## Surface Analysis

**Surface Analysis**

- State of the art electron microscopes and experienced staff study corrosion mechanisms through surface chemistry, depth profiling, and composition mapping.  Techniques available for surface analysis include:
- TEM  (Transmission Electron Microscopy)
- SEM  (Scanning Electron Microscopy)
- XPS   (X-Ray Photoelectron Spectroscopy)
- AES   (Auger Electron Spectroscopy)
- Rutherford Backscattering Spectroscopy
- SIMS (Secondary Ion Mass Spectrometry)

##  

Smart Coating Development (NASA)
Self-cleaning coatings (NASA)
Corrosion Resistant Tubing for Shuttle Launch Sites (NASA)
Polysiloxane Coating Development (NASA)
Galvanic Coatings for Protection of Steel in Concrete (NASA)
Non-chrome Conversion Coating Evaluation (Navy)
Airplane Wing Study (Air Force)
Seawater Immersion Studies of Welds for Military Applications (Navy)
Launch Site Coating Development and Evaluation (Air Force)
Single Coat/Rapid Cure Marine Tank Lining Evaluation (Navy)
Antifouling Coating Test and Evaluation (Navy) 
Chloride Rinse Agent Investigation (Army)
Support Equipment Paint Replacement Project (NASA)
Electrochemical Evaluation of Coatings for Solid Rocket Motors (Thiokol)
VAB/LCC Roof (Reinforced Concrete) Corrosion Study (NASA)
Refractory Concrete Study (NASA)
Urethane Replacement Study (NASA)
Depainting/Surface Preparation Study (NASA)
Cryogenic Storage Corrosion Study (NASA)

- Smart Coating Development (NASA)
- Self-cleaning coatings (NASA)
- Corrosion Resistant Tubing for Shuttle Launch Sites (NASA)
- Polysiloxane Coating Development (NASA)
- Galvanic Coatings for Protection of Steel in Concrete (NASA)
- Non-chrome Conversion Coating Evaluation (Navy)
- Airplane Wing Study (Air Force)
- Seawater Immersion Studies of Welds for Military Applications (Navy)
- Launch Site Coating Development and Evaluation (Air Force)
- Single Coat/Rapid Cure Marine Tank Lining Evaluation (Navy)
- Antifouling Coating Test and Evaluation (Navy)
- Chloride Rinse Agent Investigation (Army)
- Support Equipment Paint Replacement Project (NASA)
- Electrochemical Evaluation of Coatings for Solid Rocket Motors (Thiokol)
- VAB/LCC Roof (Reinforced Concrete) Corrosion Study (NASA)
- Refractory Concrete Study (NASA)
- Urethane Replacement Study (NASA)
- Depainting/Surface Preparation Study (NASA)
- Cryogenic Storage Corrosion Study (NASA)

**Representative Projects**

**Notes:**
Airplane Wing Study – Air Force Commissioned study for determining UV and internal corrosion effects for new coatings.

Launch Site Coatings – Ablative Coatings

Corrosion of Food Processing Equipment – Evaluation of a materials resistance to a disinfecting reagent

Depainting/Surface Preparation Study – Rocket motors, launch towers etc.

## 	Performance of Chemical Rinse Agents on Aircraft Alloys Exposed to a Seacoast Environment

	Four chloride rinse agents (CRAs) were evaluated for use on military aircraft, missiles, and various components. 

- 	Four chloride rinse agents (CRAs) were evaluated for use on military aircraft, missiles, and various components.

**Project Highlights**

**Notes:**
The investigation was undertaken to compare the relative corrosion-reducing effectiveness of four chloride rinse agents (CRAs) considered for use to rinse military aircraft.  The CRAs were commercial products that were formulated to remove chloride ions.  The corrosive effects of the CRAs on these coupons were presented and compared to the corrosion performance on these same alloys that were rinsed with demineralized water, rinsed with seawater, and not rinsed.  Collectively, the four CRAs and the three controls – demineralized water, seawater, and no rinse – are known as rinse agents.  Demineralized water is the benchmark used to rank the respective CRAs.  This study was performed at the KSC Beach Corrosion Test Site.

Eight materials were selected to evaluate the CRAs: 4340 carbon steel, C-250 maraging steel, 7075-T6 and 2024-T3 aluminums, magnesium, titanium, and two different martensitic stainless steels (AM-355 and PH13-8Mo).  These alloys are representative of materials utilized in military aircraft.

These flat panel specimens were exposed to the aggressive marine conditions present at the KSC Beach Corrosion Test Site.   The specimens were exposed for a period of two years and systematically rinsed on a weekly basis.  The materials were evaluated after one and two years of exposure.  A quantitative evaluation of the weight loss which results from the removal of corrosion products at the end of the experiment was performed.  Qualitative evaluations were made of the degree of pitting using ASTM G 46, (Standard Guide for Examination and Evaluation of Pitting Corrosion).   Also, the chemical-induced delamination of the aluminum samples was documented.  Scanning electron microscopy and an ultrasonic analysis was used to accomplish these evaluations.

The results of the study indicated that the CRAs sprayed on the 4340 carbon steel gave a definitive ranking of effectiveness in reducing corrosion.  Three of the CRAs performed better than rinsing with demineralized water.  The other CRA (along with seawater and no rinse) resulted in a greater degree of corrosion when compared to rinsing with demineralized water.
Two chemical rinse agents were more effective than demineralized water in reducing corrosion on the aluminum and magnesium alloys under similar exposure and rinsing conditions.  It is important to report that one chloride rinse agent performed very well on the 7075-T6 aluminum alloy, while the other performed better on the 2024-T3 aluminum.
Two of the chloride rinse agents used in the study performed poorly, and had a damaging effect on the aluminum and magnesium samples. 

## 	Corrosion Resistant Tubing for Space Shuttle Launch Sites

The performance of a series of corrosion-resistant tubing materials were investigated under simulated launch site environment conditions.
Long-term atmospheric exposure
Electrochemical methods
Surface analysis techniques 
The investigation resulted in the selection of a material which requires little maintenance.

- The performance of a series of corrosion-resistant tubing materials were investigated under simulated launch site environment conditions.
- Long-term atmospheric exposure
- Electrochemical methods
- Surface analysis techniques
- The investigation resulted in the selection of a material which requires little maintenance.

**Notes:**
The objective of the project was to examine various types of corrosion-resistant tubing for replacement of the existing tubing at the Kennedy Space Center Space Shuttle launch sites.  The standard specifications at the launch pad call for construction using tubing made from 300 series stainless steel.  While the 300 series stainless steel is usually the material of choice for modern high performance piping systems, it can exhibit problems in high chloride environments.  These concerns led to an investigation of a replacement tubing alloy that would reduce the occurrence of corrosion problems.  If a more corrosion resistant alloy could be utilized, it would contribute to decreased risk of injury to personnel, reduced maintenance costs, reduced downtime, and better reliability.

Eleven different types of tubing alloys were selected for testing.  The tubing alloys tested were low-carbon and Mo-containing austenitic, super-austenitic, duplex, and super-ferritic stainless steels, along with Ni-Cr-Mo alloy, Ni-Mo-Cr-Fe-W alloy, and an austenitic Ni-base super-alloy.  
Samples were fabricated into tubing assemblies containing flairs, bends, and welds connected with fittings typically used for handling gases and other pressurized fluids.  These assemblies were pressurized with gaseous nitrogen before being placed at the Beach Corrosion Test Site.  The test matrix simulates four separate conditions that are experienced at the launch facilities.  They are summarized as follows:  normal seacoast unsheltered, normal seacoast sheltered, acid/unsheltered environment, and acid/sheltered environment.

A total of 98 tubes were mounted on four stands.  Two of the four racks were sprayed once every two weeks with an acid/alumina slurry to accelerate the corrosive effects.  The acid/alumina slurry was used to simulate solid rocket booster deposition commonly found at the launch pad.  Two of the four racks, one with acid/alumina slurry exposure and one without, have a protective roof (cover) to simulate partial shelter.  

The results were reported in terms of relative corrosion resistance, as well as the various types of corrosion experienced.  The workability, welding, and bending characteristics were assessed and tabulated.  Metallography and Scanning Electron Microscopy were performed on the failed tubing to determine the extent of the corrosion damage.  In addition, X-ray photoelectron spectroscopy (XPS) and energy dispersive spectroscopy (EDS) were used to examine the welds and surface oxide of the chosen material.

The recommended alloys were AL6XN and 254 SMO as proper materials to replace the existing 300 series stainless steels at the shuttle lunch pads.  These materials were chosen based on their corrosion performance.  An estimated present day value (PW) comparison between the two over a 20-year period was determined.  As a result of this analysis, the AL6XN material was chosen to replace the tubing present at the Space Shuttle launch pads.  Based upon economic considerations, this choice was estimated to produce a savings of 48% over using 300 series stainless steels for the 20 year replacement cycle calculated.  

As a part of the same study, the electrochemical evaluation of the materials was initiated.  DC and AC impedance measurements were conducted under conditions which were less corrosive than, similar to, and more corrosive than the conditions present at the Kennedy Space Center launch pads.  Cyclic polarization and electrochemical impedance measurements corroborated the results obtained under accelerated atmospheric conditions, and were reported.

## Corrosion Resistance of Welds for Military Applications

Welded samples were exposed to fresh Atlantic flowing seawater.
The galvanic effect between the welded material and base alloy was investigated.
Pitting of welds and base materials was investigated and characterized.

- Welded samples were exposed to fresh Atlantic flowing seawater.
- The galvanic effect between the welded material and base alloy was investigated.
- Pitting of welds and base materials was investigated and characterized.

**Notes:**
This investigation centered upon the corrosion resistance and evaluation of a series of filler welds and welding techniques.  Lehigh University contracted with the NASA Corrosion Technology Testbed at Kennedy Space Center through the USTDC contract to perform these services.  The testing protocol consisted of three tasks. The first primary task was to expose welded samples of AL-6XN stainless steel coupons in our seawater immersion facility for six-months, while continuously monitoring their corrosion potentials.  The second task was to investigate the galvanic effect between the weld area material and the base alloy.  Finally, the third task investigated the pitting characteristics of the welds and materials through electrochemical methods.

## Support Equipment Coating Study

Coating systems are evaluated for use on support equipment at the KSC launch sites.
Composite test panels are used to investigate the performance of:
Zinc primer systems 
Powder coat systems

- Coating systems are evaluated for use on support equipment at the KSC launch sites.
- Composite test panels are used to investigate the performance of:
- Zinc primer systems
- Powder coat systems

**Notes:**
The referenced project involved the evaluation and eventual selection of coatings to be used on KSC ground support equipment and facilities. 

The corrosion of ground support equipment at the Kennedy Space Center is a persistent problem that results in extensive maintenance and high replacement costs.  To counteract these problems the referenced project studied a variety of commercial zinc primer systems, and rated their ability to prevent corrosion of the underlying C-channel composite test panels.  In addition to the zinc primer systems, four powder-coat coating systems were added to evaluate the corrosion protection properties of the organic barrier layer on the zinc primer layer.
Experimental Design
The zinc-rich primers in the study were selected from various manufacturers and were applied in the coatings application laboratory to 4” × 6” carbon steel c-channel composite test panels in a matrix consisting of multiple sets of four replicates.  One replicate set was bare zinc primer (un-topcoated) while the remaining replicate panel sets were top coated with one of the three zinc system topcoats.  The powder coat panels were prepared and coated offsite and delivered to KSC for placement into the study.  

The rating process consisted of adhesion testing, gloss measurements, and visual evaluations of the coating surfaces.  Photographs were taken at the start of the 18-month exposure period and at six-month increments.  A complete set of coated test panels was provided for the destructive adhesion testing.  The adhesion tests were performed on new un-exposed coated test panels using ASTM D 4541-95 (Standard Test Method for Pull-Off Strength of Coatings Using Portable Adhesion Testers) as a guideline.  The zinc primer and powder coat panels were tested for strength of adhesion at room temperature, and after heating to 750° Fahrenheit for a period of 24 hours and allowed to cool.  

Gloss measurement data was recorded at the start of the 18-month exposure period and on six-month increments using a portable gloss meter with a 60° angle.  Specular gloss measurements were made using ASTM D 523 (Standard Test Method for Specular Gloss) as a guide.  The zinc coating system panels were placed at the KSC beach corrosion test site on November 20, 2001.  Visual Ratings were performed for all of the test panels at the end of the 18-month exposure period and ratings were compiled using the Society for Protective Coatings SSPC-VIS 2 (Standard Method of Evaluating Degree of Rusting on Painted Steel Surfaces).  The general rust grading scale runs from a value of 10, which indicates that less than or equal to 0.01% of the surface corroded, to a value of 0 indicating that greater than 50% of the surface was corroded.  Each panel from the set of four was evaluated using this standard and averaged to give a final rating for that coating system.  
C-channel composite test panels were used to
Exposure results concluded that all un-topcoated bare zinc primers performed best, with visual ratings of 10.  The topcoated zinc primer coating systems performed well scoring visual rating values between 7.5 and 10, and the powder coat systems performed poorly ranging from 2 to 3.5. 

## Chromate Coating Replacements for Military Aircraft 

The effectiveness of replacements to currently used chromate conversion coatings is being investigated.

The coating system matrix utilizes:
Four aluminum substrates
Nine pretreatments
Five primers
Two topcoats

- The effectiveness of replacements to currently used chromate conversion coatings is being investigated.
- The coating system matrix utilizes:
- Four aluminum substrates
- Nine pretreatments
- Five primers
- Two topcoats

**Notes:**
The project centered on the evaluation and selection of chromate coating replacements for military aircraft.  
The study was designed to determine the effectiveness of environmentally compliant coating technologies to replace chromate-inhibited coatings on aluminum materials used in military aircraft.  The objective was accomplished by exposing 960 coated aluminum coupons to the harsh, outdoor marine environment at the NASA Kennedy Space Center Beach Corrosion Test Site (BCTS).   

The systematic evaluation of the coating systems was performed on four different aluminum alloys.  The coating systems evaluated were composed of a combination of nine pretreatments, five primers and two topcoats.  Fifteen coupon racks were designed and constructed to accommodate 64 coupons each, and were oriented in a matrix of 8 rows and 8 columns to expose the specimens to the salt spray from the Atlantic Ocean.  The racks were placed on the stands at the Kennedy Space Center Beach Corrosion Test Site on December 10, 2001.  The systems were ranked using ASTM D1654 (Standard Test Method for Evaluation of Painted or Coated Specimens Subjected to Corrosive Environments).

The coupons were visually inspected at 6-week intervals, and intensively evaluated at 4, 8, and 12 months.  All blisters were measured one-sided, from the scribe to the creepage front.

As a direct result of the initial experimental evaluations, the customer has extended the project for an additional two years to specifically delineate the characteristics of the better performing coating systems on the alloys of interest.  As a consequence of this study, the operational lifetime of the aircraft may be extended. 

## Smart Coating for Corrosion Sensing and Protection

- __________________________

_*basic*__* pH conditions at localized corrosion *__*cathodic*__* sites*_

- Microcapsules indicating localized corrosion

## Smart Coating for Corrosion Sensing and Protection

- Microcapsules – different size

**Smart Coating for Corrosion Sensing and Protection**

## Smart Coating for Corrosion Sensing and Protection

- Microcapsules in paint responding to basic pH conditions

**Smart Coating for Corrosion Sensing and Protection**

## Corrosion Performance of a 30 Year Old Chromated Primer

- Orbiter Enterprise
**Steven F. Udvar-Hazy Center at Dulles International Airport**
**Smithsonian's New National Air and Space Museum**

## 	Corrosion Performance of a 30 Year Old Chromated Primer

The Orbiter Program heavily relies upon the corrosion protective ability of PRC-Desoto’s Super Koropon Primer, MB0125-055
Covers most structure, bonding surface for thermal protection, protects critical components

- The Orbiter Program heavily relies upon the corrosion protective ability of PRC-Desoto’s Super Koropon Primer, MB0125-055
- Covers most structure, bonding surface for thermal protection, protects critical components

- Control Cross Section

- Enterprise Cross Section

**Notes:**
No one knows how long the Koropon will last.  The original Desoto data sheet indicated a five to ten year age life.  A recent Koropon age life assessment placed a 30 year minimum on Koropon.  This assessment was based on in-service data (Koropon has existed for about 35 years).  

The age life of  Koropon can be based on a variety of factors:  Inspection for presence of corrosion,  the visual appearance of the film (mainly color), the MB0125-055 corrosion requirement (no corrosion after 1500 hrs in salt fog chamber)., and the typical corrosion performance of fresh primer ( 2000 plus hours in salt fog chamber).

Background Information:

Some of the oldest known Koropon is on the Orbiter Enterprise.  In 2004 the Smithsonian gave members of the Materials and Process team from Boeing Huntington Beach permission to remove certain materials from the Orbiter Enterprise to assist in predicting the age life of the Koropon.  One of the Koropon access panels was removed from the bulkhead wall between the crew compartment and the payload bay.  The access panel was 6” by 10” and made of 2024-T8  aluminum.  The panel was conversion coated per Mil-C5541 with Koropon primer to approximately 6-9 tenths of a mil thick (0.006 in).  The date stamped on the access panel was 10 MAR 1975.  

The control panel was prepared from a 3” by 10” 0.032” 2024-T3 aluminum.  The panel was coated with koropon, but no conversion coating.

Both panels were scribed and salt fog tested for 1500 hours.  The Enterprise panel performed poorly compared to fresh Koropon and compared to traditional Koropon performance.  There was pitting in the scribe on the Enterprise panel after 500 hours and blisters were observed away from the scribe after 1000 hours.  There was no corrosion observed on the control panel after 1500 hours.

Huntington Beach:

In an attempt to explain these results, Eric from Boeing Huntington Beach M&P performed a series of test to verify the chrome level in both the Enterprise panel and the control panel using various analytical instruments;  energy dispersive x-ray (XEDS) spectroscopy, inductively coupled plasma spectroscopy (ICP), and electron spectroscopy for chemical analyses (ESCA).  The results from this work showed that the chrome content varied from one instrument to another.  With XEDS, no chrome was found in the Enterprises panel, but chrome was found in  the control panel.  The results from the ICP showed 80% less chrome content in the Enterprise Koropon than the control panel koropon.  With ESCA, Chrome was found in the Enterprise panel, but it appeared to be oddly distributed.

KSC:  

A Quanta 3D Dual Beam focused ion beam/scanning electron microscope was used to mill a trench and view a cross sections of the primer from both the Enterprise panel and the control panel.  Energy dispersive spectroscopy was then used to identify the distribution of elements within the primer cross section.  The SEM EDS images indicate that there is less chrome in the Enterprise film than the control film and that it is not distributed very will within the primer.

Conclusion:

The 30 year old Super Koropon primer does not meet any of the benchmark levels for corrosion performance;  (1)  Material specification, MB0125-055 does not allow any corrosion over 1500 hours  (2)  Koropon panels normally last 2000 hours plus in the salt fog chamber  (3)  Control panel in this test lasted 1500 hours with no corrosion.  The reduced corrosion performance of the Enterprise primer may be due to the much lower chrome levels.  The chrome appeared to have an uneven distribution in the Enterprise primer.  The reduced and unevenly distributed chrome levels can not be explained thus far.  This may however, be due to the degradation of the primer due to age.  Work is continuing to establish the age life of Koropon primer.

## Micro-electrochemical Study of Corrosion of a Friction Stir Weld

**Notes:**
The corrosion behavior of friction stir welded Aluminum alloy 6061-T6 was studied using a micro-electrochemical cell.  The micro-electrochemical cell has a measurement area of about 0.2 mm2 which allows for measurement of corrosion properties at a very small scale.  The corrosion and breakdown potentials were measured at many points inside and outside the weld along lines perpendicular to the weld. The breakdown potential is lower inside the FSW than the bulk metal. The open circuit potential was the same at all points sampled. The results of electrochemical measurements were correlated to micro-structural analysis.  The corrosion behavior of the friction stir welded samples was compared to a tungsten inert gas (TIG) welded sample of the same material. The measured breakdown potentials and open circuit potentials across the TIG weld were statistically the same at all points measured.
The breakdown potentials for the FSW sample at -12 and 5 mm distance are significantly different from all other points
All breakdown potentials for the TIG weld sample are statistically the same
The open circuit potentials for both samples are statistically the same

## Self Cleaning Coatings

- Spacecraft, spacecraft assembly areas and crew quarters in Space Station, Shuttle, and CEV are susceptible to contamination from industrial and biological contaminants
- Develop self-cleaning coatings that can either be applied directly to metal surfaces with little affect to the other properties of the metal or be incorporated into current paints.

## The NASA Corrosion Technology Laboratory also works with federal organizations, industry, and commercial laboratories

- University of Central Florida
- Florida Institute of Technology
- Texas A&M
- Louisiana Tech
- North Dakota State University
- University of Florida
- University of Texas
- Lehigh University
- The Ohio State University
- Northern Illinois University

**Affiliations**

**Academic**

## Website

**http://corrosion.ksc.nasa.gov/**
- Capabilities
- Weather Data Files
- Publications and Reports
- Photo Archive
- Corrosion Fundamentals
- Contact Information

## http://corrosion.ksc.nasa.gov/

## 
NASA Corrosion Technology Laboratory
http://corrosion.ksc.nasa.gov

Contact Information

Luz Marina Calle, Ph.D.
Lead Scientist
NASA Corrosion Technology Testbed
Mail Code KT-E
Kennedy Space Center, FL 32899

Phone: 321-867-3278
e-mail: Luz.M.Calle@nasa.gov

**NASA Corrosion Technology Laboratory**
**http://corrosion.ksc.nasa.gov**
_**Contact Information**_
- Luz Marina Calle, Ph.D.
- Lead Scientist
- NASA Corrosion Technology Testbed
- Mail Code KT-E
- Kennedy Space Center, FL 32899
- Phone: 321-867-3278
- e-mail: Luz.M.Calle@nasa.gov

## Acknowledgement

- Melanie Chan
- Joe Curran