SUPPLEMENTAL REPORT

OPTIMIZED DEPOSITION PARAMETERS & COATING 

PROPERTIES OF COBALT PHOSPHORUS ALLOY 

ELECTROPLATING FOR TECHNOLOGY INSERTION RISK 

REDUCTION

(ESTCP Project WP-0411)

Ruben Prado & John Benfer

Naval Air Systems Command

Diana Facchini

Integran Technologies, Inc.

Keith Legg

Rowan Technology Group

October 2010

Final Version
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Standard Form 298 (Re . 8-98) v Prescribed by ANSI Std. Z39.18
Table of Contents 

1.0 Introduction............................................................................................................ 1

1.1 Background........................................................................................................ 1

1.2 Objectives .......................................................................................................... 1

2.0 Process Window.................................................................................................... 2

2.1 Methods ............................................................................................................. 2

2.2 Results – Exploratory DOE ................................................................................ 6

2.3 Results – Optimization DOE............................................................................. 11

3.0 Data acquisition................................................................................................... 17

3.1 Methods ........................................................................................................... 17

3.2 Results ............................................................................................................. 18

3.3 Summary and discussion ................................................................................. 24

4.0 Producibility ......................................................................................................... 25

4.1 Inner Diameter plating demonstration .............................................................. 25

4.2 Outer Diameter plating demonstration ............................................................. 28

5.0 Cost Benefit Analysis........................................................................................... 31

5.1 Background...................................................................................................... 31

5.2 Assumptions..................................................................................................... 31

5.3 Cost-Benefit Analysis for FRC-SE.................................................................... 36

5.4 Optimum Method of Adoption........................................................................... 41

6.0 Conclusion........................................................................................................... 42

7.0 Summary............................................................................................................. 43

8.0 Appendix: Rod & Seal Test ................................................................................. 46

8.1 Hydraulic Seal and Piston Rod Coating Evaluation of nCoP............................ 46
WP-0411 Supplemental Report 1 October 2010

1.0 INTRODUCTION

1.1 BACKGROUND

At the conclusion of SERDP program (PP-1152) to develop Nanocrystalline Cobalt 

Phosphorus Alloy Plating (nCo-P) as an alternative to hard chrome plating for IDs, the 

coating exhibited good wear and corrosion resistance, with no hydrogen embrittlement 

(even without heat treating) and a fatigue debit similar to that of hard chromium 

electroplate (EHC).

At the beginning of the ESTCP program (WP-0411) the deposition conditions were 

adjusted to make the coating coverage more uniform between the edges and center of 

flat specimens (i.e. more uniform as a function of current density). After a considerable 

amount of development and testing both at Integran Technologies Inc. and at NAVAIR 

Jacksonville, the team had resolved most of these issues.

Subsequent hydrogen embrittlement testing of samples performed with new deposition 

conditions resulted in a coating that was embrittling to high strength steel substrates 

with or without embrittlement relief baking. Furthermore, the fatigue data set generated 

with the above deposition conditions was rejected due to invalid failure locations in the 

samples.

1.2 OBJECTIVES

The goals of this study were to define and optimize the process window for producing a 

high quality non-embrittling coating and to also perform a rapid fatigue analysis

screening via rotating beam test protocol. In pursuit of these objectives, the following 

tasks were performed:

• Process Window Definition and plating parameter optimization using a design of 

experiments approach

• Data Acquisition using the optimized plating parameters

• Producibility Evaluation using the optimized plating parameters

• Cost Benefit Analysis using the optimized plating parameters
WP-0411 Supplemental Report 2 October 2010

2.0 PROCESS WINDOW

2.1 METHODS

2.1.1 Design of Experiments

The process window was determined using a standard Design of Experiment (DOE) 

approach. Input variables were current density, pulse frequency and duty cycle. The 

plating bath was operated as specified by the Technical Data Sheet by Integran

Technologies Inc. which includes optimized ranges for plating parameters and resulting 

material properties. Two experiments were conducted:

1. Exploratory DOE: The exploratory DOE was designed to define the initial 

operating window and the effects of operating variables on deposit properties. 

Here, a 23 full factorial design with a centerpoint was used, as shown in Table 1.

(high=1, low=-1, center pt=0)

2. Optimized DOE: Following the exploratory DOE, the optimized DOE was 

designed to downselect the final plating parameters for data acquisition, 

producibility and cost-benefit tasks. Here, a L8 mixed 2-4 level design was used, 

as shown in Table 2.

(For CD: low=1, mid-low=2, mid-high=3, high=4. For Frequency: low=0, high=1. 

For Duty Cycle: high=0, low=1)

TABLE 1

EXPLORATORY DOE INPUT VARIABLES.

Coded Variables

Current 

Density Frequency Duty Cycle

1 1 1

1 1 -1

1 -1 1

1 -1 -1

-1 1 1

-1 1 -1

-1 -1 1

-1 -1 -1

0 0 0
WP-0411 Supplemental Report 3 October 2010

TABLE 2

OPTIMIZED DOE INPUT VARIABLES.

Coded Variables

Current 

Density Frequency Duty Cycle

1 0 0

2 0 0

3 0 0

4 0 0

1 1 1

2 1 1

3 1 1

4 1 1

The output variables are described in detail below. They included appearance, 

composition and microstructure, adhesion, current efficiency, thickness, hardness, 

internal stress, and hydrogen embrittlement. Experimental design and data analysis was 

performed with the aid of Minitab statistical software.

2.1.2 Sample Preparation

Three types of coupons were prepared using the plating conditions defined in Table 1 & 

Table 2 for use in subsequent tests. Figure 1 illustrates coupon types as described 

below:

a) Flat Coupons: 1”x4” ASTM A36 (similar to AISI 1018/mild steel) coupons coated 

on one side with 0.010” in thickness nCo-P.

b) Stress Strips: thin copper strips with two legs that are epoxy coated on opposing 

sides. When opposing sides of legs are plated, the legs deflect under the stress 

of the coating. 

c) Hydrogen embrittlement bars: ASTM F519, Type 1a1 bars, coated on a 1” 

section centered on the gage (i.e. 0.5” above/below gage) with 0.003” in 

thickness nCo-P. Four bars per plating condition. Hydrogen relief baking was not 

performed on the Exploratory DOE samples. For the Optimized DOE samples, a 

hydrogen relief bake at 375oF for 24 hr was applied within 1 hr of plating.
WP-0411 Supplemental Report 4 October 2010

(a) (b) (c)

FIGURE 1. IMAGES OF TEST COUPONS, INCLUDING (A) FLAT COUPONS, (B) 

STRESS STRIPS AND (C) HYDROGEN EMBRITTLEMENT BARS.

2.1.3 Appearance

Flat coupons were visually examined for coating uniformity, nodules, dendrites, pits, 

pores, cracks and other defects.

2.1.4 Composition and Microstructure

Composition and microstructure evaluations were conducted on the flat coupons. The 

composition of the deposits was determined using Energy Dispersion Spectroscopy 

(EDS). The crystal structure and grain size of the coatings was characterized using Xray diffraction (XRD) techniques. A specific coating composition was not targeted. 

Rather, the composition was monitored to verify that there were no detrimental effects 

due to the changes in the operating conditions.

2.1.5 Adhesion

Adhesion testing was conducted on the flat coupons per ASTM B571 (“Standard 

Practice for Qualitative Adhesion Testing of Metallic Coatings”). Coupons were bent 

repeatedly, back and forth, through an angle of 180° until failure of the basis metal 

occurred. The fractured region was then examined at low magnification for separation or 

peeling of the coating. Attempts were then made to pry the coating with a sharp blade to 

assess whether there was any lift off of the coating which would indicate unsatisfactory 

adhesion.

2.1.6 Current Efficiency and Thickness

Plating efficiency and thickness were evaluated on the flat coupons. The plating 

efficiency was calculated for each of the samples by recording the mass of the sample 

before and after plating to obtain the total mass of the coating. The theoretical mass, mt, 

was calculated using Faraday’s Law:
WP-0411 Supplemental Report 5 October 2010

F

A i t

n

M

m

Co

t

⋅ ⋅ ⋅

= (1)

where:

MCo is the atomic mass of cobalt

n is the valence of cobalt

A is the plating area

i is the current density

t is the plating time

F is Faraday’s constant

The cathode current efficiency, CCE, was then calculated by:

t

a

m

m CCE = (2)

where:

ma is the measured coating mass

Coating thickness was determined by calculating the difference in thickness of the flat 

coupons before and after plating, as measured with a micrometer.

Throwing power was not explicitly evaluated as part of the DOE, however, it was 

assessed as part of the producibility evaluation using the down selected plating 

parameters. 

2.1.7 Hardness

Hardness was evaluated on metallographically prepared cross-sections of the flat 

coupons. The microhardness of the coatings was determined using a Vickers Indenter 

with a 100 g load.

2.1.8 Internal Stress

Internal stress was evaluated on the stress strips. The deflection of the strips was 

measured using a deposit stress analyzer. This was then used to calculate the internal 

stress, S, according to:

K

W

UD S

3 = (3)

where: 

U is the measured deflection of the strips

D is the coating density

W is the coating weight

K is the strip calibration constant
WP-0411 Supplemental Report 6 October 2010

2.1.9 Hydrogen embrittlement

Hydrogen embrittlement testing was conducted in accordance with ASTM F519

(“Standard Test Method for Mechanical Hydrogen Embrittlement Evaluation of 

Plating/Coating Processes and Service Environments”). Hydrogen embrittlement bars 

were subjected to a sustained tensile load of 75% of the notch fracture strength (NFS) 

until (a) failure or (b) 200 hr had elapsed. For the Exploratory DOE only, samples 

sustaining 200 hr loading were then step-loaded in increments of 5% NFS per hour until 

failure. Results were therefore expressed in time to failure or % NFS.

The exploratory DOE for hydrogen embrittlement testing was utilized as a screening tool 

to identify near-optimized plating ranges. Step-load increases were performed on 

coupon sets that passed the hydrogen embrittlement criteria to increase the fidelity of 

the obtained data. The hydrogen embrittlement testing conducted as a part of the 

follow-on optimization DOE was intended to confirm that the selected optimized plating 

conditions satisfied HE pass/fail criteria.

2.2 RESULTS – EXPLORATORY DOE

2.2.1 Appearance

Results of the appearance evaluations are summarized in Table 3. Uniformly smooth 

and shiny deposits were produced at all plating conditions tested. However, the 

severity of edge dendrites varied with plating conditions. Table 3 ranks the samples in 

order of the severity of edge dendrites observed. The current density was found to 

have the most significant effects on edge dendrites, followed by duty cycle, then

frequency. The most severe edge dendrites were produced with high current density, 

low duty cycle and low frequency.
WP-0411 Supplemental Report 6 October 2010

TABLE 3

RESULTS OF APPEARANCE EVALUATIONS.

Factors Responses

Current 

Density Frequency Duty Cycle Rank1 Images

1 -1 -1 1

1 1 -1 2

1 -1 1 3

1 1 1 4

0 0 0 5
WP-0411 Supplemental Report 7 October 2010

TABLE 3 (continued)

RESULTS OF APPEARANCE EVALUATIONS

1 Rank: most severe edge dendrites to least severe edge dendrites.

Factors Responses

Current 

Density Frequency Duty Cycle Rank1 Images

-1 -1 -1 6

-1 1 -1 7

-1 -1 1 8

-1 1 1 9
WP-0411 Supplemental Report 8 October 2010

2.2.2 Composition and Microstructure

The results of the composition and microstructure testing are summarized in Table 4.

Statistical evaluations of the data indicate that the deposit phosphorus content 

increases with decreasing current density, but does not vary with frequency or duty 

cycle in the ranges evaluated. 

All deposits were found to be nanocrystalline, with a hexagonally close packed grain 

structure. Neither the grain size nor the microstructure was found to vary with current 

density, frequency or duty cycle in the ranges evaluated.

TABLE 4

RESULTS OF COMPOSITION AND MICROSTRUCTURE EVALUATIONS.

Factors Responses

Current 

Density Frequency Duty Cycle 

Composition 

(wt%P)

Grain 

size

(nm)

Microstructure

1 1 1 1.2±0.1 6 Nanocrystalline

1 1 -1 1.1±0.2 5 Nanocrystalline

1 -1 1 1.1±0.1 5 Nanocrystalline

1 -1 -1 1.1±0.1 5 Nanocrystalline

-1 1 1 1.4±0.1 8 Nanocrystalline

-1 1 -1 1.5±0.1 8 Nanocrystalline

-1 -1 1 1.3±0.1 8 Nanocrystalline

-1 -1 -1 1.4±0.1 8 Nanocrystalline

0 0 0 1.2±0.1 6 Nanocrystalline

2.2.3 Adhesion 

The results of the adhesion testing are summarized in Table 5. Two failures were 

observed, however these did not correlate with any of the operating conditions. 

Therefore, it is suspected that activation process rather than the plating process was 

responsible for the adhesion failures. The activation process is an immersion for 3 

minutes in an acid dip. It is susceptible to contamination.
WP-0411 Supplemental Report 9 October 2010

TABLE 5

RESULTS OF ADHESION EVALUATION.

Factors Responses

Current 

Density Frequency Duty Cycle

Adhesion

(Pass/Fail)

1 1 1 Pass

1 1 -1 Pass

1 -1 1 Pass

1 -1 -1 Fail

-1 1 1 Pass

-1 1 -1 Pass

-1 -1 1 Fail

-1 -1 -1 Pass

0 0 0 Pass

2.2.4 Current Efficiency and Thickness

The results of the current efficiency and thickness testing are summarized in Table 6. 

Statistical evaluations of the data indicate that current efficiency does not vary with 

current density, frequency or duty cycle in the ranges evaluated. Thickness was found 

to decrease with decreasing current density (for the same plating time) but did not vary 

with frequency or duty cycle in the ranges evaluated. The thickness distribution was 

found to vary with duty cycle, with lower duty cycles resulting in increased edge buildup.

TABLE 6

RESULTS OF CURRENT EFFICIENCY AND THICKNESS EVALUATIONS.

Factors Responses

Current 

Density Frequency Duty Cycle

Thickness

(thou)

Current 

Efficiency

(%)

1 1 1 11.4 80

1 1 -1 7.2 73

1 -1 1 12.4 90

1 -1 -1 7.2 85

-1 1 1 8.0 81

-1 1 -1 8.6 83

-1 -1 1 9.1 86

-1 -1 -1 7.4 77

0 0 0 12.2 84
WP-0411 Supplemental Report 10 October 2010

2.2.5 Hardness

The results of the hardness testing are summarized in Table 7. Statistical evaluations of 

the data indicate that hardness increases with decreasing current density, but does not 

vary with frequency or duty cycle in the ranges evaluated.

TABLE 7

RESULTS OF HARDNESS EVALUATION.

Factors Responses

Current 

Density Frequency Duty Cycle

Hardness 

(VHN)

1 1 1 506

1 1 -1 499

1 -1 1 515

1 -1 -1 528

-1 1 1 534

-1 1 -1 537

-1 -1 1 536

-1 -1 -1 546

0 0 0 515

2.2.6 Internal Stress

The results of the internal stress testing are summarized in Table 8. A tensile residual 

stress was observed for all plating conditions evaluated. Statistical evaluations of the 

data indicate that residual stress does not vary with current density, frequency or duty 

cycle in the ranges evaluated.

TABLE 8 

RESULTS OF RESIDUAL STRESS EVALUATION.

Factors Responses

Current 

Density Frequency Duty Cycle

Residual 

stress

(ksi)

1 1 1 13.6

1 1 -1 13.5

1 -1 1 13.3

1 -1 -1 12.0

-1 1 1 14.6

-1 1 -1 12.2

-1 -1 1 15.2

-1 -1 -1 13.8

0 0 0 14.2
WP-0411 Supplemental Report 11 October 2010

2.2.7 Hydrogen embrittlement

The results of the hydrogen embrittlement testing are summarized in Table 9. Results 

are shown as time to failure (hours) for bars that failed prior to the 200 hr threshold, or 

as %NFS at failure for bars that surpassed the 200 hr threshold and were subsequently 

step-loaded.

Despite having not been baked for hydrogen embrittlement relief after the coating was 

applied, over 50% of the samples tested were able to sustain the 75% NFS load for 200 

hr. Statistical evaluations of the data indicate that hydrogen embrittlement does not vary 

with current density, frequency or duty cycle in the ranges evaluated.

TABLE 9

RESULTS OF HYDROGEN EMBRITTLEMENT EVALUATION.

Factors Responses

Current 

Density Frequency Duty Cycle

Hydrogen Embrittlement

(hours to failure or % NFS)

Bar 1 Bar 2 Bar 3 Bar 4

1 1 1 40 121 193 193.1

1 1 -1 85% 100% 100% 100%

1 -1 1 49 57 58 80%

1 -1 -1 85% 90% 90% 100%

-1 1 1 136 193 200 80%

-1 1 -1 80 80 121 193

-1 -1 1 85% 100% 100% 100%

-1 -1 -1 85% 90% 100% 100%

0 0 0 80 123 137 80%

2.2.8 Summary and Conclusions

Several properties were found to be independent of the plating parameters, including: 

current efficiency, hydrogen embrittlement, internal stress, adhesion and microstructure. 

Composition and hardness were found to vary with current density. Severity of edge 

dendrites were found to vary with all parameters evaluated. 

For further evaluation in the optimization DOE, four current densities were selected with 

two pulsing conditions as input variables. The output variables remained unchanged. 

2.3 RESULTS – OPTIMIZATION DOE

2.3.1 Appearance

Results of the appearance evaluation are shown in Table 10. Deposits were found to be 

generally uniformly smooth and shiny, however surface nodules formed at low current 

density for both pulse conditions. These were found to be less severe at the lower duty 

cycle. As was previously observed, the severity of the edge dendrites increased with 

increasing current density. The edge dendrites were the most severe for the low duty 
WP-0411 Supplemental Report 12 October 2010

cycle/high frequency condition. These results are consistent with those previously 

obtained for the Exploratory DOE.

TABLE 10

RESULTS OF THE APPEARANCE EVALUATION.

Current 

Density

Pulse Condition

0 1

1

2

3

4

2.3.2 Composition and Microstructure

The results of the composition and microstructure testing are summarized in Table 11. 

Statistical analysis of the results indicate that the deposit phosphorus content increases 

with decreasing current density, but does not vary with pulse conditions. 

All samples were found to be nanocrystalline, with a hexagonally close-packed 

microstructure. Statistical analysis of the results indicates that the grain size and 

microstructure do not vary with current density or pulse conditions. Results obtained 

here for the composition and microstructure are consistent with the trends observed for 

the Exploratory DOE. 
WP-0411 Supplemental Report 13 October 2010

TABLE 11

RESULTS OF THE COMPOSITION AND MICROSTRUCTURE EVALUATIONS.

Factors Responses

Current 

Density Frequency Duty Cycle

Composition

(wt%P)

Grain 

size

(nm)

Microstructure

1 0 0 1.9±0.1 15 Nanocrystalline

2 0 0 1.9±0.1 11 Nanocrystalline

3 0 0 1.9±0.2 8 Nanocrystalline

4 0 0 1.6±0.1 8 Nanocrystalline

1 1 1 2.1±0.1 12 Nanocrystalline

2 1 1 1.9±0.1 11 Nanocrystalline

3 1 1 1.9±0.2 10 Nanocrystalline

4 1 1 1.8±0.1 8 Nanocrystalline

2.3.3 Adhesion

The results of the adhesion testing are summarized in Table 12. Two failures were 

observed, however these did not correlate with any of the operating conditions. 

Therefore, it is suspected that the activation process (i.e. inadequate surface 

preparation due to operator error) rather than the plating process was responsible for 

the adhesion failures.

TABLE 12

RESULTS OF THE ADHESION EVALUATION.

Factors Responses

Current 

Density Frequency Duty Cycle

Adhesion

(pass/fail)

1 0 0 Fail

2 0 0 Pass

3 0 0 Pass

4 0 0 Fail

1 1 1 Pass

2 1 1 Pass

3 1 1 Pass

4 1 1 Pass

2.3.4 Current Efficiency and Thickness

The results of the current efficiency and thickness testing are summarized in Table 13. 

Statistical evaluations of the data indicate that current efficiency does not vary with 

current density, frequency or duty cycle in the ranges evaluated. Thickness was found 

to decrease with decreasing current density (for the same plating time) but did not vary 

with frequency or duty cycle in the ranges evaluated. These results are consistent with 

the trends observed for the Exploratory DOE. 
WP-0411 Supplemental Report 14 October 2010

TABLE 13

RESULTS OF THE CURRENT EFFICIENCY AND THICKNESS EVALUATIONS.

Factors Responses

Current Density Frequency Duty 

Cycle

Thickness

(thou)

Current

Efficiency

(%)

1 0 0 10.6 90

2 0 0 9.2 89

3 0 0 9.7 90

4 0 0 10.2 87

1 1 1 12.1 89

2 1 1 9.0 89

3 1 1 10.9 86

4 1 1 10.0 90

2.3.5 Hardness

The results of the hardness testing are summarized in Table 14. Statistical analysis of 

the results indicates that the hardness increases with decreasing current density, but 

does not vary with pulse conditions. These results are consistent with the trends 

observed for the Exploratory DOE. 

TABLE 14

RESULTS OF THE HARDNESS EVALUATION.

Factors Responses

Current Density Frequency Duty 

Cycle

Hardness

(VHN)

1 0 0 591

2 0 0 574

3 0 0 560

4 0 0 547

1 1 1 586

2 1 1 567

3 1 1 557

4 1 1 549

2.3.6 Hydrogen Embrittlement

Property evaluations revealed that only the edge dendrite severity varied with the 

pulsing conditions, and that the low duty cycle condition was preferred to minimize their 

severity. Mid-range current densities were preferred to increase the hardness and 

maintain a uniformly smooth and shiny appearance.
WP-0411 Supplemental Report 15 October 2010

As a final screening, hydrogen embrittlement testing was conducted on samples 

produced using the low duty cycle condition at current densities of mid-low, mid-high 

and high. Within 1 hr of plating, test samples were baked at 375oF for 24 hr. Hydrogen 

embrittlement testing was then conducted per the methods described in Section 2.1.9. 

All samples were found to sustain the 75% NFS load for 200 hr, indicating that the 

coatings passed hydrogen embrittlement testing.

2.3.7 Summary and Conclusions

The final downselected plating parameters were a duty cycle and frequency of low and 

a current density of mid-high.
WP-0411 Supplemental Report 17 October 2010

3.0 DATA ACQUISITION

Once the process window had been established, additional data were obtained with the 

new optimized deposition conditions.

3.1 METHODS

3.1.1 Microstructure and stress

Microstructure and stress were evaluated per the methods described in Section 2.1.4

and Section 2.1.8, respectively.

3.1.2 Adhesion

Adhesion was evaluated per the methods described in Section 2.1.5.

3.1.3 Porosity Test

Flat coupons were cross-sectioned and examined using optical and scanning electron 

microscopes for signs of voids and porosity.

3.1.4 Hydrogen Embrittlement

Hydrogen embrittlement testing was conducted per the methods described in Section 

2.1.9. Within 1 hr of plating, test samples were baked at 375oF for 24 hr. In an industrial 

setting, baking could occur up to 4 hrs prior to plating, provided the part is not subjected 

to stresses.

3.1.5 Corrosion

Corrosion testing was conducted in accordance with ASTM B117 (“Standard Practice 

for Operating Salt Spray (Fog) Apparatus”). Two mild steel coupons (4”x4”) were coated 

on one side with 0.003” nCo-P at Integran Technologies Inc. and two mild steel coupons 

(4”x4”) were coated with 0.003” EHC at FRC-SE. The backs and sides of the coupons 

were masked to prevent uncoated steel from being exposed to the test. Samples were 

left in the as deposit condition and subjected to salt spray testing for 165 hrs. Following 

testing, samples were visually examined for signs of red rust. The surface composition 

of the samples was also evaluated by μ-EDXRF for the presence of iron.

3.1.6 Fatigue 

Fatigue testing consisted of rotating beam fatigue in lieu of axial fatigue testing as 

defined the whitepaper proposal to minimize cost and to improve the turnaround time of 

the fatigue data. Fatigue testing was conducted on bare, nCo-P-coated and EHCcoated test samples. Test samples were 4340 steel (260-280 ksi) hourglass bars as 

shown in Figure 2, and their surfaces were unpeened. The unpeened condition was 
WP-0411 Supplemental Report 18 October 2010

motivated in order to meet NAVAIR approval requirements and to better understand the 

fatigue sensitivity of the coating without introducing additional external variables. Twenty 

specimens were coated with 0.006” nCo-P at Integran Technologies Inc., twenty were 

coated with 0.006” EHC at FRC-SE, and twenty remained bare. Coatings were ground 

to 0.003” using low-stress grinding techniques, and were longitudinally polished to a 16 

μinch Ra finish. 

FIGURE 2. ROTATING BEAM FATIGUE BAR GEOMETRY.

Rotating beam fatigue testing was conducted in laboratory air at ambient temperature. 

Loads were spread between 85% of tensile yield strength (Fty) and the runout load (107

cycles), with no more than four points per load. Load and cycles to failure were used to 

generate S-N curves for bare, nCo-P-coated and EHC-coated specimens.

3.1.7 Immersion testing

Fluid compatibility was not expected to change significantly, as the deposit 

microstructure and composition has not changed significantly. The optional fluid 

immersion testing was therefore not conducted in this study. It was expected to be 

revisited during the next stage of the program.

3.1.8 Wear and hardness testing

Hardness was evaluated per the methods described in Section 2.1.7.

Abrasive wear resistances of the nCo-P and EHC baseline were evaluated by Taber 

wear testing in accordance with ASTM D4060 (“Standard Test Method for Abrasion 

Resistance of Organic Coatings by the Taber Abraser”). Flat mild steel coupons (4”x4”) 

were coated with 0.002” nCo-P at Integran Technologies Inc. or 0.002” at FRC-SE. 

Testing was conducted using CS-17 wheels at FRC-SE.

3.2 RESULTS

3.2.1 Microstructure and stress

Figure 3 shows a portion of the X-ray diffraction pattern for the nCo-P deposit. The 

deposit was found to be nanocrystalline, with the HCP crystal structure typically found in 

cobalt, and an average grain size of 8 nm.
WP-0411 Supplemental Report 19 October 2010

FIGURE 3. PORTION OF THE X-RAY DIFFRACTION PATTERN FOR NCO-P 

DEPOSIT PRODUCED WITH THE OPTIMIZED PLATING CONDITIONS.

Deposit stress was found to be 10-15ksi tensile.

3.2.2 Adhesion

As shown in Figure 4., examination of the fractured surface revealed no signs of 

coating delamination or flaking, indicating that the sample passes adhesion testing.

FIGURE 4. IMAGE OF THE FRACTURE SURFACE FOLLOWING BENDING.

3.2.3 Porosity Test

As shown in Figure 5 examination of the coating cross-section revealed no signs of 

cracks pores or voids, indicating that the sample is free of gross porosity. This is in 

contrast to EHC, which exhibits microcracking.
WP-0411 Supplemental Report 20 October 2010

FIGURE 5. OPTICAL MICROGRAPH OF THE CROSS-SECTION OF THE NCO-P 

DEPOSIT USING NITAL ETCHANT.

3.2.4 Hydrogen Embrittlement

No failures were noted after 200 h at the sustained load of 75% NFS, indicating that the 

coating passes hydrogen embrittlement. This behavior is similar to that of EHC, which is 

known to pass hydrogen embrittlement testing when a similar bakeout is performed 

following plating.

3.2.5 Corrosion

As shown in Figure 6a, examination of the EHC-coated panels following 165 h salt fog 

exposure reveals an orange/brown discoloration across the entire panel. Surface 

composition analysis reveals the presence of iron and chromium, as shown by the μEDXRF spectra in Figure 6a indicating that red rust has formed. By contrast, the 

nCoP-coated panels following salt fog exposure exhibit a golden brown discoloration. 

Surface composition analysis reveals the presence of cobalt, but with no iron as shown 

by the μ-EDXRF spectra in Figure 6b indicating the absence of red rust but likely a 

surface oxide. These results indicate that nCo-P exhibits superior corrosion resistance 

to EHC.

nCo-P

Substrate
WP-0411 Supplemental Report 21 October 2010

(a)

 

(b)

FIGURE 6. IMAGES AND μ-EDXRF SPECTRA FOR THE SURFACES OF (A) 

EHC- COATED AND (B) NCO-P-COATED MILD STEEL FOLLOWING 165H 

SALT FOG EXPOSURE.

3.2.6 Fatigue 

As shown in Figure 7 below, fatigue data shows a significant fatigue debit for EHC 

coating compared to bare material. In comparison, the nCo-P coating shows a fatigue 

life similar to the bare material at lower loads. At lower applied loads there appears to 

be a debit compared to bare, however, this is not nearly as severe as the debit exhibited 

by the EHC coated material. Therefore, nCo-P exhibits significantly enhanced fatigue 

performance compared to EHC.

Substrate 

Corrosion

Coating 

Oxidation
WP-0411 Supplemental Report 22 October 2010

FIGURE 7. ROTATING BEAM FATIGUE RESULTS SHOWN AS AN S-N CURVE.

3.2.7 Wear and hardness testing

The microhardness was found to be 560 VHN as-deposited. The results indicate that 

nCo-P has lower hardness than EHC.

The results of the Taber Wear test are shown in Table 15. The Taber Wear Index was 

found to be 17.23 mg/1000 cycles for nCoP, and 4.15 mg/1000 cycles for EHC, 

indicating that EHC has superior abrasive wear performance to nCo-P.
WP-0411 Supplemental Report 23 October 2010

TABLE 15

TABER WEAR TEST RESULTS FOR NCO-P & EHC COUPONS.

Cycles

Weight (g)

nCo-P Coupon 

#3RZ2057

nCo-P Coupon 

#4LZ2056

Cr Coupon

#3L

Cr Coupon

#4R

0 128.7596 131.1900 118.1269 121.4091

1000 128.7399 131.1713 118.1206 121.4052

2000 128.7218 131.1539 118.1167 121.3975

3000 128.7047 131.1367 118.1143 121.3938

4000 128.6855 131.1219 118.1068 121.3906

5000 128.6684 131.1034 118.1051 121.3869

6000 128.6525 131.0859 118.1015 121.3819

7000 128.6346 131.0704 118.0977 121.3777

8000 128.6175 131.0545 118.0951 121.3727

9000 128.6016 131.0378 118.0873 121.3726

10000 128.5850 131.0200 118.0865 121.3666

Total Wt Loss 

(mg/1000 cycles)

17.46 17.0 4.04 4.25
WP-0411 Supplemental Report 24 October 2010

3.3 SUMMARY AND DISCUSSION

Type of 

Performance 

Objective

Primary 

Performance 

Criteria

Expected Performance

(Metric) Result

Actual 

Performance

Objective Met?

Quantitative Internal Stress No specific requirement. 10-15 ksi -

Quantitative Microstructure

Microstructure includes items such as 

grain size and crystal structure. For 

nCo-P coatings, grain size shall be 

less than 100 nm and crystal structure 

shall be HCP.

Nanocrystalline 

(8 nm grain 

size), hexagonal 

close-packed 

structure

Yes

Quantitative Microhardness

Microhardness of as-deposited 

coatings shall be no less than 650 

VHN. Microhardness shall be capable 

of being controlled through heat 

treatment up to 800 VHN.

560 VHN (asdeposited) No

Qualitative Porosity

Coatings shall be free of pits, pores 

and microcracks when observed 

microscopically.

No cracks, 

pores or voids Yes

Quantitative Fatigue

Low-cycle and high-cycle rotating 

beam fatigue testing shall be 

conducted for nCo-P coatings of 

0.003” thickness on 4340 steel 

substrates heat treated to 260-280 ksi. 

Cycles-to-failure at different stress 

levels shall be determined and 

standard S/N curves shall be 

generated. The S/N curves for the 

nCo-P coatings shall lie on or above 

those for EHC coatings.

Credit vs. EHC. 

Comparable to 

bare at LCF, 

debit compared 

to bare at HCF.

Yes

Quantitative

Wear

Abrasive wear tests shall be conducted 

using the Taber wear test apparatus in 

accordance with ASTM D4060 using a 

CS-17 wheel. The wear rate of the 

nCo-P coating shall be less than or 

equal to EHC.

17.23 mg/1000 

cycles No

Quantitative Corrosion

In salt-fog corrosion tests, time until 

observing corrosion product for nCo-P 

coatings should be less or equal to 

time for EHC coatings (ASTM B117).

No red rust after 

165 h Yes

Quantitative Hydrogen 

embrittlement

A coating thickness of 0.003” of nCo-P 

shall be deposited onto ultra-highstrength steel Type 1a1 ASTM F519 

specimens. Specimens loaded to 75% 

of notch tensile stress must pass 200 

hour test (after a hydrogen bake)

Passed 200 h 

sustained load Yes

Qualitative Adhesion

No spalling or delamination of the 

coating from the substrate when tested 

in accordance with ASTM B571.

No delamination 

or flaking Yes
WP-0411 Supplemental Report 25 October 2010

4.0 PRODUCIBILITY

Producibility testing was conducted by Integran Technologies Inc. using the optimized 

plating conditions due to hardware failures at FRC-SE. Components were provided by 

FRC-SE. The coating was applied to both internal diameter sections and outer diameter 

sections as described below.

4.1 INNER DIAMETER PLATING DEMONSTRATION

4.1.1 Component Description

The demonstration piece for internal diameter plating was a J52 coupling, as shown in

Figure 8. This part was 4340 steel and required plating on a small 1” wide band on the 

inner diameter of the part.

FIGURE 8. J52 COUPLING USED FOR THE INNER DIAMETER PLATING 

DEMONSTRATION.

4.1.2 Methods/Setup

A process flow chart shown in Figure 9 summarizes the operations completed in 

preparing the demonstration part for plating. The demonstration part as-received did 

not require stripping of previous coatings on the desired plating area.

In order to mask the part for plating, several methods of masking were employed. First, 

the plating area was covered using generic black tape. Next, holes found on the bottom 

of the part were plugged with plastic plugs. Plugs were trimmed in order to facilitate 

application of maskants. Electroplating tape was used to mask the remaining holes on 

the surface. Enthone Stop-Off #1 was then applied by brushing and dipping and allowed 

to cure. Once the part was sufficiently masked, the plating area was uncovered by 

removing the black tape.
WP-0411 Supplemental Report 26 October 2010

The area to be plated was then alconox scrubbed using a Scotch Brite pad. Use of 

higher mesh pads is recommended in order to reduce appearance of scratches in the 

final deposit. Next the part was attached to the plating rack. After checking for 

electrical continuity, the part was then immersed in the alkaline cleaning solution. It was 

then electrocleaned for 3 minutes at a current density of 50 mA/cm2 followed by a 

rinsing step. The part was then activated using a mineral acid (5% HF/30% Sulfuric 

Acid) for 1 minute at an anodic current density of 300 mA/cm2 (live entry). Following 

activation, the part was rinsed, and then plated with nCoP with the optimized pulse 

condition identified in Section 2.0. A flow eductor was attached in order to facilitate flow 

at the plating area. Following plating, the part was removed and rinsed. The part was 

then de-racked, and manually de-masked.

FIGURE 9. PROCESS FLOW CHART FOR J52 SHAFT ID PLATING.
WP-0411 Supplemental Report 27 October 2010

4.1.3 Results

The as-deposited electroplate on the J52 coupling was smooth and shiny. No pits or 

cracks were observed. A few isolated nodules including some small dendrites were 

present along the plated edge of the ID which is not uncommon in areas where higher 

current densities are expected. Some imperfections were noted, consistent with how the 

part was received. The average as-deposit thickness was 0.011”± 0.00076”. Following 

plating, the part was machine ground to a surface finish of 16 microinches Ra or better. 

The aim of grinding the plated part was to evaluate machinability characteristics. A 

runout of the edges was not performed as this was not required for the evaluation. 

J52 COUPLING FOLLOWING FRC-SE MACHINING OF ID PLATED AREA
WP-0411 Supplemental Report 28 October 2010

4.2 OUTER DIAMETER PLATING DEMONSTRATION

4.2.1 Component Description

The demonstration piece for outer diameter plating was a J52 shaft (section), as shown 

in Figure 10. This part was 4340 steel and required plating on a small 2” wide band on 

the outer diameter of the part.

FIGURE 10. J52 SHAFT (SECTION) USED FOR THE OUTER DIAMETER PLATING 

DEMONSTRATION.

4.2.2 Methods/Setup

A process flow chart shown in Figure 11 summarizes the operations completed in 

preparing the demonstration part for plating. The demonstration part as received had a 

corroded surface where it was previously plated. In order to prepare the part for plating, 

the substrate was abrasively blasted using aluminum oxide media with a mesh size of 

120. Upon inspecting the part, there was a pit present along the outline of the 

plated/non-plated interface.

In order to mask the part for plating, several methods of masking were employed. First, 

lead tape was adhered along the border of the area to be plated. Next, generic masking 

tape was applied to the area to be plated. This helped to prevent any maskant from 

covering the plating surface. The rack, consisting of two threaded rods and two hose 

clamps, was then connected to the part to allow for electrical contact. Then, using 

Electroplater’s tape, the remaining uncovered areas were masked. Enthone Mask-off 

No.1 was then applied on top of the tape. The area to be plated was then uncovered by 

removing generic masking tape.

The area to be plated was scrubbed with a cleaning pad. Use of higher mesh pads is 

recommended in order to reduce appearance of scratches in the final deposit. Next the 
WP-0411 Supplemental Report 29 October 2010

part was immersed in the alkaline cleaning solution. It was electrocleaned for 3 minutes 

at a current density of 50 mA/cm2

. The part was rinsed and then attached to a rotator 

assembly. The part was activated using a mineral acid (5% HF/30% Sulfuric Acid) for 1 

minute at an anodic current density of 300 mA/cm2 (live entry). The part was rinsed and 

then plated with nCo-P with the optimized pulse condition Section 2.0. A flow eductor is 

attached in order to facilitate flow at the plating area. Once plating was complete, the 

rotation was stopped, the part was removed and was rinsed. Finally, the part was deracked and manually de-masked.

FIGURE 11. PROCESS FLOW CHART FOR J52 SHAFT OD PLATING.
WP-0411 Supplemental Report 30 October 2010

4.2.3 Results

Many small nodules were scattered along the surface of the plated J52 Shaft. This is 

consistent with electroplating of thick coatings. Some small dendrites were seen along 

the plated edges which is typical in high current density areas. Some imperfections 

were noted, consistent with how the part was received. The average deposit thickness 

prior to machining was 0.014”± 0.0001”. Following plating, the part was machine ground 

to a surface finish of 16 microinches Ra or better. The aim of grinding the plated part 

was to evaluate machniability characteristics. A runout of the edges was not performed 

as this was not required for the evaluation. 

J52 SHAFT SECTION FOLLOWING FRC-SE MACHINING OF OD PLATED AREA
WP-0411 Supplemental Report 31 October 2010

5.0 COST BENEFIT ANALYSIS

5.1 BACKGROUND

This section contains a Cost Benefit Analysis carried out using the C-MAT (Calculation 

for Material Alternative Technologies) Decision Tool, whose development was funded 

by SERDP/ESTCP. Cost data has been reviewed to reflect new processing conditions 

(including current density, hence plating speed).

5.2 ASSUMPTIONS

1. The plating workload is based on the actual number of parts processed, taken 

from shop records, and an estimate of the average part size. Most calculations 

in the present analysis (except environmental costs) therefore reflect the cost per 

square foot plated.

2. The workload is based on JAX chrome plating data for 2006 (see Table 16 - 18). 

Note that current OD plating approved for HVOF is being migrated. The nCoP 

coating is being considered for both ID & OD workload. Only the ID workload (all 

of which is J52 engine parts) for JAX chrome plating operations will be included 

as a worst-case scenario.

3. The calculations assume plating tank sizes of 1000 gals for each of the stripping, 

activation, and plating operations in both the Cr and nCo-P process lines. The 

masking tanks (wax for Cr, peel coat for nCo-P) are assumed to be smaller at 

700 gals, and the Co anode tank for nCo-P only 10 gals.

4. It is assumed that the plating tanks are dummy plated once a month for Cr and 

once a week for nCo-P, and that each dummying requires 1 hr of labor.

5. 24/7 operation is assumed for:

• Plating tank heating (by steam) for both Cr and nCo-P plating

• Total water usage (makeup + rinse water)

• The Cr6+ scrubber, and also EPA NESHAP monitoring of Cr6+ (monitoring 

actually required only when Cr plating operations occur)

6. Power required for the activation step is ignored in both cases, because it is 

small.

7. For nCo-P plating, it is assumed that the anodes will be Ti rods, Co plated in a 

special Co anode tank (rather than electrolytic Co squares in a basket). The rods 

will be plated to a thickness of 20 mils, enabling 10 ID parts to be plated from 

each anode rod in 1-2 runs.

8. Hazardous waste:
WP-0411 Supplemental Report 32 October 2010

• At JAX, Cr6+ waste from all Cr stripping and chromating operations is 

combined with waste from the Cr plating line. But the Cr6+ waste numbers 

used in this analysis, including the $53,625 annual cost of scrubber energy 

and maintenance, are estimates for plating operations only.

• The quantity of Cr6+ solid waste is based on 2006 data. (This number has 

been decreasing annually as more Cr plating work is migrated to HVOF.)

9. EPA NESHAP non-compliance fines are not included in the environmental costs 

for Cr plating, since such fines have never been levied on JAX. However, the 

penalties are substantial resulting in $32,500 per day per violation.

10.OSHA monitoring costs for Cr plating are not included in the cost model either. 

This is because it has been found that the exposure level of plating personnel to 

Cr6+ under typical plating conditions barely registers on the monitoring 

equipment, so that ongoing monitoring is not required. However, an annual skin 

test is carried out.
WP-0411 Supplemental Report 33 October 2010

TABLE 16

FRC-SE GENERAL COST DATA.

Cost item Quantity Unit Source/Comments

Workload

# ID parts Cr plated per year 85 NAVAIR FRCSE Production, 4/18/07 

Average ID part plated area 0.4 sq ft NAVAIR FRCSE Production, 4/18/07

ID plating workload 34 sq ft Same workload assumed for nCo-P plating

OD plating workload 144 sq ft NAVAIR FRCSE Production, 4/18/07

Total (ID + OD) workload 178 sq ft 

ID area ratio 19%

OD area ratio 81% OD workload gradually being migrated to HVOF

Average ID plating process time 8.43 hr ISSC JAX Materials Engineering, 3/28/07 – includes 0.30 

hr for baking step (both Cr and nCo-P)

Actual process time depends on part configuration

Rates

Labor rate - direct $65.00 $/hr NADEP JAX, 2005* – generic burdened rate

Material - indirect 1.74% of direct

Water utility rate $0.00 $/gal NADEP JAX, 2005* – rate used for rinse and makeup 

water

Electricity utility rate $0.07 $/kWh ISSC JAX Environmental Logistics, 3/6/07 – rate used 

for plating power

Steam utility rate $ 1–1.50 $/hr ISSC JAX Environmental Logistics, 3/28/07 – rate used 

for plating tank heater power (Cr – nCoP)

Inflation rate 0%

Discount rate 3%

Depreciable life of equipment 15 yr

Salvage value 10%

Hazardous waste disposal

Cr6+ solid waste $1.03 $/lb NADEP JAX, 2005* – hazardous waste rate

Cr6+ rinsewater $0.85 $/gal NADEP JAX, 2005* – 2% of EHC rinsewater treated

nCo-P solid waste $0.03 $/lb NADEP JAX, 2005* – solid waste rate

nCo-P rinsewater $0.85 $/gal NADEP JAX, 2005* – 0.2% of nCo-P rinsewater 

assumed treated

* Data from “Infrared Reflectance Imaging Technique (IRRIT), Baseline and Alternative Cost Data, Engineering Estimates, 

and Assumptions”
WP-0411 Supplemental Report 34 October 2010

 

TABLE 17

FRC-SE EHC COST DATA.

Cost item Quantity Unit Ann fixed Unit Ann 

Cost

EHC adoption 

Initial stripping & plating chemicals $4,800 $

Total adoption $4,800 $

EHC Summary costs

Direct production labor $265 $/sq ft $47,190 

Indirect production labor $1.91 $/sq ft $340 

Direct materials $26 $/sq ft $4,690 

Indirect materials $0.46 $/sq ft $82 

Utilities $86 $/sq ft $15,385 

Environmental $560 $/sq ft $99,611 

Total $940 $/sq ft $167,298

EHC breakdown 

Water use: rinse + makeup 87,600 gal/yr $209 

Water use /sq ft $1.18 $/sq ft 492 gal/sq ft

Plating power /sq ft $23.74 $/sq ft 323 kWh/sq ft $4,226 

Tank heater power (steam) $61.52 $/sq ft 8,760 hr/yr $10,950 

Utilities total $86.43 $/sq ft

Scrubber energy cost $280.90 $/sq ft $50,000 $/yr

Scrubber maintenance cost $20.37 $/sq ft $3,625 $/yr

Stack testing, inspection $44.83 $/sq ft $7,980 $/yr

NESHAP monitoring $158.89 $/sq ft 432 hr/yr $28,283 

NESHAP reporting, training $3.68 $/sq ft 10 hr/yr $655 

Haz waste management $4.97 $/sq ft 13.5 hr/yr $884 

Haz waste disposal 6,500 lb/yr $6,695 

Haz waste disposal /sq ft $37.61 $/sq ft 37 lb/sq ft

Wastewater treatment 1,752 gal/yr $1,489 

Wastewater treatment /sq ft $8.37 $/sq ft 10 gal/sq ft

Environmental total $559.61 $/sq ft $99,611 $/yr
WP-0411 Supplemental Report 35 October 2010

TABLE 18

NCO-P COATING COSTS.

Cost item Quantity Unit Ann fixed Unit Ann Cost

% workload replaced – ID EHC 19%

Average ID part plated area 0.4 sq ft

ID plating workload 34 sq ft

Average ID plating process time 8.43 hr

nCo-P Summary costs

Direct production labor $280 $/sq ft $49,790 

Indirect production labor $2 $/sq ft $358 

Direct materials $42 $/sq ft $7,480 

Indirect materials $1 $/sq ft $130 

Utilities $66 $/sq ft $11,761 

Environmental $9 $/sq ft $1,554 

Total $399 $/sq ft $71,073 

nCo-P breakdown 

Water use: rinse + makeup 262,800 gal/yr* $628 

Water use /sq ft $3.53 $/sq ft 1,476 gal/sq ft

Plating power /sq ft $1.03 $/sq ft 14 kWh/sq ft $183 

Tank heater power (steam) $61.52 $/sq ft 8,760 hr/yr $10,950 

Utilities total $66.07 $/sq ft

Scrubber energy cost $0.00 $/sq ft $0 $/yr

Scrubber maintenance cost $0.00 $/sq ft $0 $/yr

Stack testing, inspection $0.00 $/sq ft $0 $/yr

NESHAP monitoring $0.00 $/sq ft 0 hr/yr $0 

NESHAP reporting, training $0.00 $/sq ft 0 hr/yr $0 

Haz waste management $0.00 $/sq ft 0 hr/yr $0 

Haz waste disposal 2,167 lb/yr $65 

Haz waste disposal /sq ft $0.37 $/sq ft 12 lb/sq ft

Wastewater treatment 1,752 gal/yr $1,489 

Wastewater treatment /sq ft $8.37 $/sq ft 10 gal/sq ft

Environmental total $8.73 $/sq ft $1,554 $/yr

* Estimate based on high bath temperature, with bath heated 24/7

Note: Depreciation not included in these costs
WP-0411 Supplemental Report 36 October 2010

5.3 COST-BENEFIT ANALYSIS FOR FRC-SE

5.3.1 Capital cost

Capital cost (Table 19) depends on whether an existing line is to be modified or a new 

line is to be installed. In either case the pulse plating rectifier, carbon filtration and 

plating tank for anode production are required. But modifying an existing line avoids the 

requirement for additional tanks.

Note that we assume that the anode will typically be in the form of a plated rod rather 

than Co chips in a basket. This is because for many ID coating applications plated rod 

is the only viable approach, which requires the installation of a plating tank even if it is 

used for only some of the part production.

5.3.2 Direct manufacturing cost

Most of the labor cost of electroplating is involved with masking, demasking, setup, 

insertion and removal from the plating tank, and maintaining the plating system. The 

shorter plating cycle for CoP has little effect on the labor hours. Because the nCoP bath 

requires more maintenance for carbon filtration, and anode rods must be plated, the 

labor hours are somewhat higher for nCoP. In addition, the cost of chemicals is higher, 

TABLE 19

NCO-P CAPITAL AND ADOPTION COSTS.

nCo-P capital cost

Stripping tank, rectifier & wiring $130,000 

Maskant tank $45,000 

Activation tank, rectifier & wiring $130,000 

Plating rectifier & wiring* $130,000 

Carbon filtration equipment* $6,000 

Co anode tank* $4,000 

Total $445,000 

nCo-P adoption cost (initial chemicals)

Stripping chemicals $29,600 

Maskant $15,000 

Plating chemicals $18,100 

Chemicals for anode tank $3,000 

Total $65,700 

Inflation rate 0%

Discount rate 3.00%

Depreciable life of equipment 15 yr

Salvage value 10%

* For modification of existing plating line
WP-0411 Supplemental Report 37 October 2010

as is the cost of utilities because of the higher bath temperature, which requires more 

make-up water.

The direct cost of nCo-P vs hard chrome plating is summarized in Table 20. The nCo-P 

direct cost is about slightly higher than hard chrome plating. However, when we add in 

the indirect costs and the environmental costs nCo-P costs $400/sq ft while hard 

chrome costs $940/sq ft (Table 17 and Table 18). This is of course a very high unit 

cost, which comes about because, as shown in Table 16, the plating volume is less 

than 200 sq ft/year, spreading all the fixed costs over a very small production volume. 

This unit cost would obviously be very much lower if the total workload were larger.

5.3.3 Cost-benefit for replacing full plating line

Table 21 shows the 15-year metrics for replacement of an entire line in an existing 

plating shop (which is equipped with all the necessary facilities, including heating and 

air handling). The cumulative cost for the relacement is shown as a function of time in

Figure 12.

TABLE 21

15–YEAR FINANCIAL PERFORMANCE FOR TOTAL LINE REPLACEMENT AT 

FRC-SE.

-2 sigma Value +2 sigma

NPV ($53,711) $222,830 $499,370 

IRR 12% 15% 17%

ROI 13% 17% 21%

Payback 

period 13.7 8.5 5.9

TABLE 20

DIRECT PRODUCTION COST PER SQUARE FOOT 

COMPARISON.

Cost per sq ft plated nCo-P EHC

Direct production labor $280 $265

Direct materials $42 $26

Utilities $66 $86

$388 $377
WP-0411 Supplemental Report 38 October 2010

($600,000)

($400,000)

($200,000)

$0 

$200,000 

$400,000 

$600,000 

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Net Present Value (NPV)

Year

NPV - Cost based

NPV

-2 std dev

-1 std dev

+1 std dev

+2 std dev

FIGURE 13. NPV AS A FUNCTION OF NUMBER OF YEARS INCLUDED IN ITS 

CALCULATION FOR TOTAL LINE REPLACEMENT AT FRC-SE (WITH 2σ LINES).

-$800,000

-$600,000

-$400,000

-$200,000

$0

$200,000

$400,000

$600,000

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Year

Cumulative cost, with 2-sigma lines

FIGURE 12. CUMULATIVE COST AS A FUNCTION OF TIME FOR TOTAL LINE 

REPLACEMENT AT FRC-SE (WITH 2σ LINES).
WP-0411 Supplemental Report 39 October 2010

Note that in Table 21, the Internal Rate of Return and the Return on Investment are 

both annualized returns, not total returns, and they are based on the annual cost saving. 

For this reason the IRR and ROI can both be positive even when the NPV is negative, 

because the cumulative cost always slopes down. This is illustrated in the plot of Figure 

13 which shows how NPV varies as a function of the number of years over which the 

NPV calculation is run. Note that NPV can still be negative even beyond the payback 

period, when cumulative cost has gone negative, because NPV discounts the value of 

money in the out years.

Although nCo-P is a more expensive process than hard chrome plating, and although it 

requires capital investment, it saves money because it eliminates the need for the Cr6+

scrubber, which costs more than $60,000 per year to maintain. What this means, 

however, is that adopting nCoP will only be cost-effective if it is used to completely 

eliminate hard chrome. If the scrubber is retained for other processes, or the chrome 

plating line is maintained, then savings will not be realized.

5.3.4 Cost-benefit for modifying existing plating line

In many cases nCoP will be implemented in an existing line. In this case only the items 

in Table 19 that are marked with an asterisk will need to be purchased as capital 

equipment. In that case the NPV is significantly higher and the payback far faster 

because of the lower front-end cost of $140,000 instead of $445,000 (see Figure 14 &

Figure 15).

TABLE 22

15–YEAR FINANCIAL PERFORMANCE FOR PLATING LINE MODIFICATION AT 

FRC-SE.

15 year -2 sigma Value +2 sigma

NPV $481,358 $737,410 $993,463

IRR 36% 42% 47%

ROI 31% 42% 53%

Payback period 3.7 2.6 2.0
WP-0411 Supplemental Report 40 October 2010

5.3.5 Effect of rework

Hard chrome plating is a very forgiving process that continues to plate even when tank 

chemistry or plating conditions are not optimum. It has been found that nCo-P, on the 

other hand, is much more sensitive to contamination in the bath, particularly in the form 

of hydrocarbons. Contamination causes holidays in the coating, necessitating stripping 

and replating. While contamination can be controlled through proper bath maintenance, 

-$1,400,000

-$1,200,000

-$1,000,000

-$800,000

-$600,000

-$400,000

-$200,000

$0

$200,000

$400,000

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Year

Cumulative cost, with 2-sigma lines

FIGURE 14. CUMULATIVE COST AS A FUNCTION OF TIME FOR PLATING LINE 

MODIFICATION AT FRC-SE (WITH 2σ LINES).

($400,000)

($200,000)

$0 

$200,000 

$400,000 

$600,000 

$800,000 

$1,000,000 

$1,200,000 

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Net Present Value (NPV)

Year

NPV - Cost based

NPV

-2 std dev

-1 std dev

+1 std dev

+2 std dev

($400,000)

($200,000)

$0 

$200,000 

$400,000 

$600,000 

$800,000 

$1,000,000 

$1,200,000 

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Net Present Value (NPV)

Year

NPV - Cost based

NPV

-2 std dev

-1 std dev

+1 std dev

+2 std dev

FIGURE 15. NPV AS A FUNCTION OF NUMBER OF YEARS INCLUDED IN ITS 

CALCULATION FOR PLATING LINE MODIFICATION AT FRC-SE (WITH 2σ LINES).
WP-0411 Supplemental Report 41 October 2010

including carbon filtration and periodic dummying, we would expect that the incidence of 

rework would increase to some extent with the use of a more sensitive process.

Rework requires that the part be demasked, stripped, remasked and replated. The 

result of increased rework is illustrated in Figure 16 assuming hard chrome rework is 

essentially zero, which is FRC-SE experience.

It is clear that, because it adds to production cost, rework reduces the payback from the 

technology. If rework increases to 20% the NPV drops to zero. It is therefore very 

important to maintain tank performance and ensure proper operator training in both tank 

maintenance and processing methods.

5.4 OPTIMUM METHOD OF ADOPTION

As we have seen, adoption of nCo-P will impose a net cost unless it completely 

replaces chrome plating. nCo-P plating will not begin to realize savings until the chrome 

scrubber is removed. If the changeover takes several years as components are tested 

and qualified then savings will not begin until chrome plating is completely eliminated 

and the scrubber shut down. Thus the optimum method of adoption is to qualify and 

move to production with the new coating as quickly as possible.

($800,000)

($600,000)

($400,000)

($200,000)

$0 

$200,000 

$400,000 

$600,000 

0% 5% 10% 15% 20% 25% 30%

NPV

nCo-P rework rate

FIGURE 16. NPV AS A FUNCTION OF REWORK RATE (TOTAL PLATING LINE 

REPLACEMENT).
WP-0411 Supplemental Report 42 October 2010

6.0 CONCLUSION

Optimized plating deposition parameters were obtained using a Design of Experiment 

(DOE) approach. These parameters were validated through supplemental testing and 

found to be non-embrittling with improved fatigue and neutral salt fog corrosion 

performance as compared to hard chromium electroplate. The nCoP deposit did exhibit 

reduced hardness (560 VHN) and reduced taber wear abrasion performance as 

compared to hard chromium electroplate. 

Producibility evaluations were performed utilizing a J52 Shaft section and a J52 

Coupling component. Optimized plating parameters were successfully demonstrated on 

both ID & OD areas. The above plated components were then finished machined at 

FRC-SE with no observable defects.

Final established and optimized parameters are:

• Current Density: 125 mA/cm2

• Frequency: 25 Hz 

• Duty Cycle: 50%
WP-0411 Supplemental Report 43 October 2010

7.0 SUMMARY

nCo-P is an alternative electroplating process to EHC. The coating is very similar in 

appearance to EHC. The difference between this coating and standard cobalt-, nickelor EHC-based coatings is the grain size of the deposit. 

Nanocrystalline metals and alloys:

Electrodeposited nanocrystalline metals and 

alloys have an average grain size of roughly 5-15 

nm. This is a reduction of about 1000 times that 

of the grain size of standard polycrystalline 

electrodeposited coatings. These nanocrystalline 

coatings have fully dense and equiaxed 

microstructures; as the coating is built up there is 

no grain growth or columnar growth. Typical 

properties that are improved by reducing the 

grain size to the nanocrystalline scale include:

Hardness: Up to 3-5X increase

Yield Strength: Up to 5-9X increase

Ultimate Tensile Strength: Up to 3-5X increase

Coefficient of Friction: Up to 50% reduction

nCo-P Process (Table 23): Like EHC, nCo-P is produced by electrodeposition. 

However, there are some key process differences as detailed below: 

Anodes: Consumable cobalt anodes are used for the nCo-P process. These include 

cobalt pieces held in titanium baskets (OD plating and large ID plating), or cobalt-coated 

titanium rods (small ID plating). This is in contrast to EHC which uses non-consumable 

lead anodes. 

Pretreatment: Like for EHC, recommended pretreatments vary with substrate material.

Pretreatment steps are similar to EHC with one notable exception, in that activation 

does not take place in the plating tank. A separate process tank(s) is required for this 

step.

Masking: Wax-based maskants used for EHC cannot be used for the nCo-P process. 

Alternate dip and brush-on maskants are under investigation. Select electroplater’s 

tapes can be used.

Efficiency and Plating Rate: The nCo-P process is significantly more efficient than EHC, 

thus resulting in much higher plating rates and increased process throughput.

Environmental: In contrast to EHC, air emissions from the nCo-P process do not 

contain harmful Cr6+. Air emissions from the nCo-P process are below the OSHA PEL 

for cobalt. No scrubbers are required for the nCo-P process, however, local ventilation 

is suggested to remove steam from the area for worker comfort.

Hydrogen Embrittlement: Due to the high current efficiency, less hydrogen is generated 

for the nCo-P process compared to the EHC process. Nonetheless, hydrogen 

embrittlement relief bakeouts are currently recommended for high strength steels. This 

is similar to practices used for EHC.
WP-0411 Supplemental Report 44 October 2010

Bath stability: The plating bath is very stable with only minor additions being required 

for pH balance and for the alloying compound. Since the anodes are consumable, no 

additions of cobalt salts are required.

Equipment: Similar electroplating equipment to EHC is required (i.e. tank, heater, pump, 

filter, buss bars, DI water supply, electrical connections to rectifier), however, the 

materials of construction must be compatible with the nCo-P plating bath. Unlike EHC, 

a pulse rectifier is required for the nCo-P process.

nCo-P Properties (Table 24): There are a number of key properties of the nCo-P that 

improves the performance when compared to EHC.

Appearance: The coating is similar in appearance to EHC.

Corrosion Protection: The coating has significantly improved corrosion protection over 

EHC, owing to the fully dense structure of the nCo-P coating.

Sliding Wear: The volume loss of material in sliding pin on disc wear tests is roughly

one half that of EHC. Preliminary rod-seal wear testing suggests that nCoP has 

comparable seal leakage to EHC.

Lubricity: The coefficient of friction is approximately 20% less than EHC.

Abrasive wear: EHC does have higher abrasive wear performance. nCo-P may not be 

the most appropriate choice for EHC replacement in applications where abrasive wear 

mechanisms are known to operate. It is recommended that these be thoroughly 

reviewed and tested on a case-by-case basis.

Hardness: EHC has higher hardness. However, hardness does not necessarily 

correlate with sliding wear behavior, as evidenced by the improved sliding wear 

performance of nCo-P compared to EHC.

Fatigue: In early testing, nCo-P has shown significantly improved fatigue performance 

compared to EHC. In some cases, the nCo-P fatigue performance is comparable to the 

bare material.

TABLE 23 COMPARISON OF NCO-P AND EHC PROCESSES.

nCo-P EHC

Cathodic Current Efficiency 85-95% 15-35%

Deposition Rate 0.002”-0.008” per hour 0.0005”-0.001” per hour

Anodes Consumable cobalt Non-consumable lead

Hydrogen Embrittlement Post-plate bakeout required Post-plate bakeout required

Emission Analysis Below OSHA limits Cr+6
WP

-0411 Supplemental Report 45 October 2010

EHC

Microcracked

-

Min. 600 VHN

-

<1%

9-11 x 10-6 mm3/Nm

0.7

Severe

4 mg/1000 cycles

0.003” thick

Fail 165 h

0.004” thick

Protection Rating 2

(ASTM B537) @ 1000 hours

Cracked – Exceeds cohesive 

strength

Significant debit compared to 

bare at all loads.

nCo-P

Free from pits, microcracks and 

pores

8-15 nm

550-600 VHN (as-deposited)

600-750 VHN (heat treated)

2-7%

6-7 x 10-6 mm3/Nm

0.4-0.5

Mild

17 mg/1000 cycles

0.003” thick

Pass 165 h

0.002” thick

Protection Rating 7

(ASTM B537) @ 1000 hours

10-15 ksi (Tensile)

Comparable to bare at high loads.

Small debit compared to bare at low 

loads.

Credit compared to EHC.

Applicable 

Standard

N/AN/A

ASTM B578ASTM B489

ASTM G99ASTM G99ASTM G99

ASTM D4060

ASTM B117

N/AN/A

Test Method

Visual and 

microscopic 

inspection

X-Ray Diffractometry

Vickers 

Microhardness

Bend Test

Pin on Disc

(Al O2 3 Ball)

Pin on Disc

(Al O2 3 Ball)

Pin on Disc

(Al O2 3 Ball)

Taber Wear

(CS-17 wheels)

Salt Spray

Internal Stress Test

Rotating Beam 

Fatigue

Property

Appearance and 

porosity

Grain Size

Hardness

Ductility

Adhesive Wear

Coefficient of 

friction

Pin Wear

Abrasive Wear

Corrosion

Deposit Stress

Fatigue

TABLE 24 COMPARISON OF NCO-P AND EHC PROPERTIES.
WP-0411 Supplemental Report 46 October 2010

8.0 APPENDIX: ROD & SEAL TEST

8.1 HYDRAULIC SEAL AND PISTON ROD COATING EVALUATION OF NCOP

Rod and seal testing was performed in accordance with the HCAT Joint Test Protocol 

(JTP) to determine nCoP coating compatibility with common hydraulic and pneumatic 

seal materials. This JTP had been developed for testing HVOF coated rods (30 

September 2003). The detailed test report is summarized in AIR 4.3.5 “Test Report For 

Hard Chrome Alternatives Team Phase III Hydraulic Seal and Piston Rod Coating 

Evaluation of Nanocrystalline-Cobalt-Phosphorus”. Four rods were prepared at Fleet 

Readiness Center Southeast (FRC-SE) and sent to Integran Technologies Inc. for nCoP 

electroplating.

8.1.1 Test Summary

Different surface finish conditions were evaluated on each of the four rods as follows: 

(1) 12-16 min Ra, (2) 6-9 min Ra, (3) superfinished to <4 min Ra, and (4) heat treated at 

300°C to maximize coating hardness, then ground to 6-9 min Ra. Each rod was tested 

against the same four seal configurations in the HVOF JTP: (1) MIL-P-83461 O-ring and 

PTFE cap strip, (2) MIL-P-83461 O-ring and 2 backup rings, (3) Fluorosilicone O-ring 

with PTFE cap strip, (4) Spring energized PTFE seal. As there were only four positions 

on the test equipment for different coatings/conditions, hard chrome controls were not 

run simultaneously.

8.1.2 Test Execution

The original test plan included fluid temperatures ranging from -40°F to 275°F, with 

~80,000 sinusoidal full strokes superimposed with ~480,000 dither strokes. However, 

during testing, an incorrect computer stroke profile had been selected and run for the 

first five days of testing. At that time testing was stopped and the test sponsor 

authorized a revised test schedule to adjust the cycles to equate approximately to that 

originally planned. Hydraulic pressure ranged from between 2500-3000 psi.

8.1.3 Test Results – Leakage Rates

Leakage rates for all coating finishes are shown in Figure 17. For comparison, EHC 

data from prior testing (not done in the same test as nCo-P) are also included. Leakage 

rates for all nCo-P coating finishes were acceptable for the duration of the test. Failure 

criterion is a leakage rate exceeding 1 drop for 25 full strokes, although this is different 

than the combination with the dither strokes. The superfinished nCo-P rod resulted in 

the least accumulated leakage over the test duration, followed by the heat treated rod, 

while the rougher ground finishes resulted in the highest leakage (6-9 and 12-16 min Ra 

finishes). For one seal configuration during 1 hour near the end of the test very slightly 

exceeded this rate (24.4 cycles per drop), however, this configuration leaks by design at 

cold temperatures so it wasn’t considered significant. 
WP-0411 Supplemental Report 47 October 2010

Rod/Seal Leakage

MIL-P-83461 O-ring w/ Capstrip Vs 4 Rods

0

10

20

30

40

50

60

0 10 20 30 40 50 60 70 80 90 100 110 120 130

Test Hours

Leakage (mL)

Ground 12-16 in Ra Ground 6-9 in Ra Ground 12 Superfinish <4 min Ra

Heat treated 300°C Ground 6-9 min Ra

Cr O-ring/cap

Rod/Seal Leakage

MIL-P-83461 O-ring w/ 2 backup ring Vs 4 Rods

0

10

20

30

40

50

60

0 10 20 30 40 50 60 70 80 90 100 110 120 130

Test Hours

Leakage (mL)

Ground 12-16 in Ra

Ground 6-9 in Ra Ground 12 Superfinish <4 min Ra

Heat treated 300°C Ground 6-9 min Ra

Cr O-ring/backups

Rod/Seal Leakage

Spring Energized PTFE Vs 4 Rods

0

10

20

30

40

50

60

0 10 20 30 40 50 60 70 80 90 100 110 120 130

Test Hours

Leakage (mL)

Ground 12-16 in Ra

Ground 6-9 in Ra

Ground 12 Superfinish <4 min Raseal

Heat treated 300°C Ground 6-9 min Ra

Cr SE PTFE

Rod/Seal Leakage

Fluorosilicone O-ring w/ PTFE Cap Vs 4 Rods

0

10

20

30

40

50

60

0 10 20 30 40 50 60 70 80 90 100 110 120 130

Test Hours

Leakage (mL)

Ground 12-16 in Ra Ground 6-9 in Ra

Ground 12 Superfinish <4 min Ra

Heat treated 300°C Ground 6-9 min Ra

Cr FS O-ring/cap

FIGURE 17. LEAKAGE RATES FOR NCO-P COATINGS WITH VARIOUS SURFACE 

FINISHES AND DIFFERENT SEAL CONFIGURATIONS. FOR REFERENCE, EHC 

DATA FROM PRIOR TESTS ARE INCLUDED.

8.1.4 Test Results – Seal Condition

At the conclusion of the test, rods and seals were removed from the test fixture, 

inspected and photographed, and then shipped to Supfina Inc. where seals were 

disassembled and inspected. Seal damage was noted for certain configurations. The 

AIR 4.3.5 test report concluded that the cap-strip seals failed due to excessive wear, 

and the seals with the most wear were noted on the rods with rougher finish. Seal 

images are available in the full report. Their recommendation was that a better 

simulation of flight conditions would incorporate a test under loaded conditions, 

including side loads.