NBSIR 73-142

Codeposition of Wear-Resistant

Particles with Chromium

Corrosion and Electrodeposition Section

Metallurgy Division

Institute for Materials Research

National Bureau of Standards

Washington, D. C. 20234

March 1973

Annual Progress Report

January 1972=January 1973

Rock Island Weapons Laboratory

Order No. Ml-9-50938-(01)-Ml-Ml

Prepared for Research Directorate

Weapons Laboratory - RIA Rock Island Arsenal

Rock Island, Illinois 61201

John P. Young

NBSIR 73-142

CODEPOSITION OF WEAR-RESISTANT

PARTICLES WITH CHROMIUM

John P. Young

Corrosion and Electrodeposition Section

IVIetallurgy Division

Institute for Materials Research

National Bureau of Standards

Washington, D. C. 20234

March 1973

Annual Progress Report

January 1972-January 1973

Rock Island Weapons Laboratory

Order No. Ml-9-50938-(01)-Ml-Ml

Prepared for Research Directorate

Weapons Laboratory - RIA

Rock Island. Arsenal

Rock Island, Illinois 61201

U. S. DEPARTMENT OF COMMERCE, Frederick B. Dent, Secretary

NATIONAL BUREAU OF STANDARDS, Richard W. Roberts. Director
fif1
TABLE OF CONTENTS

Abstract

Ohoeotive

Page

INTRODUCTION 1

PROCEDURE 2

TESTS AND RESULTS 2

Various Hard Particles 2

Bath Life Test 4

Various Additives 6

Corrosion Protective Deposits Containing Hard Particles. ... 7

Cadmium 7

Zinc 8

Gun Tube 9

Heat -Treated Deposits 10

DISCUSSION 12

CONCLUSIONS 15

BIBLIOGRAPHY 16

FIGURES 17-34

Abstract

Several new hard particles were tried with the object of improving

wear-resistance of chromium deposits containing included particles over

the best previously tried material, tetra-boron carbide. Only hexa-boron

carbide was slightly better. During a bath-life test 5100 ampere-hours

per liter were run through a particle-including chromium bath. Build-up

of products of the monovalent -cation additive used was detected but bath

performance could be restored to normal by their removal . Heat treatment

of deposits showed reduction in wear-resistance of deposits heated to

400''C or over. A caliber 0.30 tube was plated with chromium having included particles with relatively good particle distribution throughout the

bore. Deposits of cadmium and zinc with included hard particles showed

some improvement in wear -resistance.

Objective

The experiments described in this report are attempts to improve

the wear-resistance of deposited coatings, mainly chromium, by incorporating hard particles in the deposits with the addition of inorganic additives

in the form of monovalent cations to the plating baths which contain the

hard particles in suspension.

CODEPOSITION OF WEAR- RESISTANT PARTICLES WITH CHROMIUM

INTRODUCTION

Previous annual reports on this project are dated January 26, 1971,

and March 1, 1972. The tests (170) described in this report are a continuation of the experiments for codepositing inorganic hard particles

with chromium. The main objective of the experiments made during this

period was the development of a practical bath and procedure for the incorporation of hard particles in chromium on a more or less production

basis. Further tests were made using inexpensive chemicals as bath

additives and several more types of hard particles were tested. A bathlife test was run to determine the effect of additives and particles on

the longevity of the chromium plating bath. As a practical experiment,

a gun tube was plated with chromium incorporating hard particles. In

addition to chromium, deposits of cadmium and zinc were made which included hard particles in cyanide baths. Test deposits were made on vertical

cathodes of copper or steel and a few were heat-treated after deposition

to check the effects of heating on wear, adhesion, and structure of the

deposit. All the hard particles tried were incorporated in chromium deposits at least to some degree when any of the monovalent cations tried

were present in the bath. Particles were included in the cadmium and

zinc deposits without additives although addition of thallium salts to

the zinc bath increased the amount of particles included. Ammonium nitrate

was effective as an additive in the chromium bath and only after several

thousand ampere-hours per liter of bath did deterioration of the bath

begin as evidenced by the decreased wear-resistance of the deposits.

-2-

PROCEDURE

The experimental equipment and the procedure for running the tests

were the same as for the previous work. To summarize, a 3-3/4" diameter

copper or steel disc, about 30 mils thick, was plated using a similar

sized lead anode parallel to the disc cathode with about 3/4" separation.

A one-liter chromium bath was used to which particles and chemicals were

added as the particular test required. Duration of deposition was varied

according to the current density used to give a deposit about 5 mils thick.

The deposit was tested for wear-resistance on a Tabor Abraser using the

CS-17 rubber bonded silicon carbide abrasive wheels. The deposit was

cross-sectioned and mounted in plastic for polishing, microscopic examination, photographing and making hardness measurements. The average amount

of inclusions in a deposit was determined by dissolving the chromium from

one-half of the disc, filtering out the residue, drying, and weighing.

TESTS AND RESULTS

Various Hard Particles

Up to this point in our investigation, chromium deposits with incorporated diamond particles resulted in the best wear-resistance. The next

best wear characteristics were given by incorporated tetra-boron carbide

particles. An effort was made to find particles that would impart greater

wear-resistance to chromium deposits than B^C. One of the large abrasive

suppliers especially prepared without charge six super-hard particles and

a seventh type of hard particle was purchased from another company. The

particles were as follows: AlB^^* ^4^, B^C, CrB^, BSi^W^, TiB^, and TiC.

The average siz-e of the particles was about 25 ym. Scanning electron

-3-

micrographs of two of the types of particles (Fig. 1) show a rather wide

range of sizes which is not considered detrimental for our purpose.

The particle resulting in the best wear of a chromium deposit by a

small margin was B^C. The special B^C and the A1B^2 were very close in

imparting wear-resistance. Commercial silicon carbide particles of about

15 ym in size were used for comparison. The 200 g/1 CrO^ bath and a

vertical cathode were used for all tests. Three or four runs were made

using each type of particle at one or two temperature -current densities

and with two types of chemical additives. A summary giving the averages

of the results for tests of each type of particle is given below:

Particle Deposit

Type Hardness Hardness Wear Loss Inclusions

AlB 2 2300 KHN 675 KHN200 7.7 mg 0.18 wt

B4C 2800 669 7.5 0.27

BeC 3000 695 6.3 0.30

3Si3N4 3000 677 12.9 0.33

CrB2 3500 604 11.2 0.61

TiB2 2700 662 7.8 0.59

Tic 2500 640 12.2 0.83

Sic 2500 749 10.2 0.85

Glass powder 616 11.3 0.20

The detailed data from the tests indicated that specific combinations

of plating conditions and additives resulted in increased inclusion rates

of some particles. For example, TiB^ was included in substantially greater

amounts using LiNO^ at 45°/30 asd than at 55/50. Using TINO^ and LiNO^,

larger amounts of TiC were included at 45/30 than at 55/50. These instances

conform with the general observation throughout the program that fewer

particles are normally included at higher current density and temperature

conditions but this is not true for all combinations of particles and additives. Therefore, it cannot be taken for granted that an additive or a

set of plating conditions will result in the best particle inclusion rate

for a given particle because it is best for several others.

None of these special hard particles showed enough improvement in

wear -resistance when included in chromium to warrant their use in place

of some of the best of the more readily available particles already tested

although the B^C shows some superiority over all the others tested except

diamond.

During the tests of the CrB2 particles, some of the thallium and

cesium additions to the chromium baths were made in the crystal form.

The usual procedure was to add these components as a water solution in

four equal increments during the run» Additions as crystals did not

form the usual yellow precipitate and the effectiveness of the additives

seemed to extend throughout the run of 4 or 5 hours without partial period

addition to the bath as had been previously practiced. In a water solution of CrO^ the crystals were observed to dissolve very slowly.

Bath Life Test

The initial phase of this test consisted of eight runs. A new bath

was used for each of the first three runs; then five consecutive runs

were made in the same bath. All eight tests were made with 30 g/1 B^C

and 3 g/1 TINO^ in the baths. The wear -resistance was good for the three

runs in the new bath, about one-half the weight loss for hard, bright

chromium without inclusion, and the results are quite close. The tests

in the "used" bath indicate a slight decrease in wear-resistance for each

successive run as an increasing amount of current is put through the solution as shown in Fig. 2. Bath component concentration levels were maintained and no substantial decrease in the amount of included material in

-5-

in the deposits occurred throughout the test. Since the trivalent chromium

content of the bath remained within acceptable levels, it is probable that

the slight decrease in wear-resistance of successive deposits was due to

build-up in the bath of Tl or Tl compounds. Deposits and amounts of

included material did not appear to be adversely affected.

The second phase of the bath-life test consisted of 58 tests for a

total of 5100 ampere-hours per liter of chromium plating solution. Components of the solution were renewed as necessary to maintain the nominal

bath composition of 200 g/1 CrO^, 2H2SO^ and 30 g/1 B^C. Ammonium nitrate

at 1 g/1 was used as the monovalent cation additive for most of these tests.

Near the end of the experiment several tests were made with addition of

NH^NO^ and hardness of the chromium deposit returned to about 1000 KHN2QQ

and inclusions in the chromium dropped below 0.1 wt% indicating approximately normal deposits that would be expected from a standard chromium

bath. However, after about 3200 amp-hours per liter had been passed

through the bath, the spread of wear -resistance values obtained increased

substantially (as shown in Fig. 3) and the average wear-loss had about doubled at the end of the test or at 5100 ampere-hours. There were visible

encrustations on areas of the bath container where the bath was subject

to evaporation. This was assumed to be the result of the build-up of

NH^NO^ or its decomposition products. It was definitely not CrO^. At the

end of this series of tests, a total of nearly 40 grams of NH^NO^ had been

added to the bath.

The above indicates that there is probably a limit to the life of a

chromium bath when using NH^NO^ as an additive beyond v/hich deposit properties would not be acceptable. For all practical purposes even 3200 ampere-

hours per liter of bath represents a very long bath life in the practical

chromium plating bath. In addition it is entirely possible that the products of the additive could be removed from the bath by a simple procedure

such as cooling and decanting as they seem to be much less soluable than

CrOj.

During the bath-life experiment the use of a new wear-test abraser

was started. Comparison of the results obtained on the new and old machine

showed some difference in wear -resistance values so a factor was used to

make results compatible.

Various Additives

A number of runs were made using the additives previously tested to

some extent. As indicated in the section above, NH^NO^ was used in a

considerable number of tests and was found to be effective for incorporating particles in chromium deposits. However, the bath would tolerate only

about one-third as much NH^NO^ as TINO^ and still produce continuous, hard

deposits. More runs were also made using LiNO^ and CeNO^ and, of course,

TINO^. A general summary of the relative performance of the additives

during these tests is shown in Fig. 4 and is tabulated below:

Additive No . of Runs

in Av.

Most

Inclusions

(wt %)

Av. Inclusions

(wt %)

Least

Wear-Loss

(mg)

Av.

Wear-Lo

(mg)

39 3.89 0.762 3.9 8.2

LiNO^ 12 2.29 0.60 6.4 11.3

CeNO^ 4 1.65 1.26 8.2 10.0

TINO 45 1.41 0.41 3.0 8.6

-7-

All of the above deposits were made on vertical surfaces but include several

different types of particles and plating conditions of from 45°C/20 asd to

55/50. Several, but not necessarily all, of the conditions were used for

each type of additive. Figs. 4, 5, and 6 show the relative amounts of

inclusions and wear-loss respectively for lithium nitrate as compared

to thallium nitrate for runs under similar conditions. The lithium shows

wider fluctuations in both categories than does thallium nitrate.

Corrosion Protective Deposits Containing Hard Particles

Cadmium . A number of cadmium and zinc deposits were made which incorporated B^C and ^12^3 ^^^^ particles in an attempt to improve the wearresistance of a soft, protective coating. No chemical additives were

needed to include particles in cadmium and zinc deposits although one-half

to one gram per liter of thallium salts in the bath increased the amount

of included material in zinc.

The cadmium specimens were plated in a bath of the following nominal

composition

Cadmium oxide, CdO 22.5 g/1

Sodium cyanide, NaCN 100

Sodium hydroxide, NaOH 14

Gulac (organic grain refiner) 0.4

To this bath was added the ^4^ varying amounts from 10 to

30 g/1. The current density used for a particular deposit seemed to have

more effect on wear-resistance than the type or amount of hard particle

incorporated. All runs were plated at about 24°C. Below is a summary of

the cadmium deposits tested:

-8-

Current NoType of Max. Air Least A 1 r AV . Density Runs Particles Inclusions Inclusions Wear-Loss Wear -Loss

(asdj (.Wt -6 J (.Wt -g J (mg)

1 2 DO . 0

c; c Q DO . y

1 2 B.C (J . by U . D /

/I oy? Q 1

. i 2 4

4

It 1 .Oo ii no ly . o zo . y

3 1

II 1.11 27.8

4 1

II 1.48 32.0

5 1

II 1.08 25.2

1 2 0.58 0.38 53.8 64.7

2 4 M 0.64 0.58 33.3 43.8

3 3

II 0.88 0.62 34.8 36.3

5 1

II 0.60 47.1

The improvement in wear-loss for deposits with included particles was better

than two to one over deposits without particles for the best series of

tests. The B^C particles were incorporated more readily and resulted in

the greatest improvement in wear-resistance. Average inclusions per run

for B^C was 1.06 wt %, for Al^O^, 0.55 wt %. Average wear-loss for B^C

was 29.6 mg, for kl^^, 48.0 mg. Figures 7-9 are graphic presentations

I of data from tests of Cd deposits. Refinement of bath composition and

1

I plating conditions could quite possibly further improve the wear -resistance

I of cadmium coatings.

Zinc . The zinc bath used had the following composition:

Zinc sulfate, ZnS04 240 g/1

Ammonium chloride, NH4CI 15

Ammonium sulfate, (NH4)2S04 30

Licorice (grain refiner) 1

I

To this bath up to 30 g/1 B^C and ^^2^^ P^^^'^icles were added. Also,

several tests were run in a zinc bath containing thallium salts as well

' as hard particles which did increase the amount of inclusions in the deposits. A series of runs was made in the zinc bath with varying amounts

of particles in the bath and at several current densities as well as a

I

-9-

£ew runs using thallium. A summary of the tests is shown below:

Current No. Type of Max. Av. Least Av.

Density Runs Particles Inclusions Inclusions Wear -Loss Wear-Loss

(asd) (wt %) (wt %) (mg) (mg)

2 2 34.9 36.5

3 2 40.6 42.0

2 1 AI2O3 0.13 28.4

3 4 II 1.05 0.50 30.3 42.9

5 1

II 0.13 22.5

2 3 B4C 1.96 0.99 20.5 ZD . y

3 5 If 0.43 0.31 19.5 23.2

5 2 M 0.59 0.43 26.0 26.7

2 4 B C+Tl . 1.82 0.78 21.0 27.7

3 6 1.79 0.98 17.4 23.3

5 2

II 0.58 0.53 23.0 25.2

Since the current density seemed to have more effect on the wear- loss than

the amount of particles in the bath, all runs at a particular c.d . were

averaged together from baths containing ten to thirty g/1 of particles.

The improvement in wear -resistance for deposits containing hard particles

was not as great as for cadmium but there was some improvement at 2 and

5 asd with Al^O^ and with B^C in the bath. (See Figures 11 to 13 for

graphic representations of the data.)

Thallium increased the amount of included material at 3 asd but was

not effective in these tests at 2 and 5 asd. Wear-resistance was very

close with or without thallium, about two -thirds that of deposits without

inclusions. Average inclusions per run with Al^O^ was 0.32 wt %, with

B^C, 0.70 wt %. Average wear-loss for ^^2^^^ 36.6 mg, for B^C, 25.0

mg. Data from deposits formed with thallium in the zinc bath are shown

graphically in Figures 14 and 15.

Gun Tube

A 0.30 caliber machine gun tube furnished by the Rock Island Weapons

Laboratory was plated on the inside with chromium incorporating hard

-10-

particles by adding thallium and B^C powder to a standard 200 g/1 CrO^

bath. First, several steel tubes of approximately the same inside diameter

as the gun tube were plated experimentally to determine the correct equipment or fittings and plating conditions necessary to obtain a more or less

uniform coating on the tube bore. To obtain approximately the same deposit

thickness distributions as the original chromium plate in the tube bore,

0.0033" at the muzzle and 0.0025" at the breach, it was necessary to form

a one -eighth-inch diameter anode from pure silver wire and then copper

and lead plate it for protection from attack. Using this anode and a

temperature -current density ratio of 45/30, it was found that a reasonably

uniform deposit incorporating B^C particles could be applied to the simulated gun tubes. The gun tube bore, plated in a vertical position at

these conditions, had a deposit thickness at the muzzle of 0.0031" and

at the breech, 0.0027". The simulated gun tubes were sectioned and revealed inclusions of hard particles in the rather rough deposit even at

the top of the tube. Fig. 16 shows cross -sections at the top and the

bottom of one of these test specimens in which the distribution of the

chromium was rather poor but otherwise similar to the deposit in the gun

tube. It was later learned that the chromium deposit with incorporated

particles in the gun tube was broken from the bore surface rather quickly

under firing test conditions without much of a determination of its

"wearability.

Heat -Treated Deposits

Several particle-containing chromium deposits plated on copper were

heated in air to determine the effect, if any, on adhesion to the substrate
„->::T:
-11-

and wear qualities. After heating, mi Id bending of the specimens cracked

the chromium but no flaking, indicating loss of adhesion, occurred. Wearresistance was somewhat diminished on those deposits heated above 250°C

as is shown in the data below:

Initial* Heat- Resultant

Wear-Loss Treatment Wear-Loss

(mg)

12.8 400*'C - 1 hr 17.3

13.8 " " " 17.3

10.6 600*C " " 15.5

13.6 2S0*C 2 " 12.9

The normal heat -treatment of chromium plated parts to relieve possible

hydrogen embrittlement of the substrate is in the 200-300°C range so

chromium deposits with included particles should not be adversely affected.

Cross-sections of the heated deposits are shown in Fig. 17.

DISCUSSION

It was rather disappointing to learn that of the several new types

of particles tried, only one showed any improvement in wear-resistance

over the previously tested B^C. The particle giving improved wear when

incorporated in chromium was the closely related B^C and the improvement

was only slight. This means that for top wear -resistance diamond powder

must be incorporated in the deposits. The ejcpense of using diamond could

be reduced by using a smaller amount in the bath without seriously affecting incorporation rates. It is estimated that as little as 10 or even 5

g/1 instead of 30 g/1 would be effective in the bath. Since the amount

usually included in the deposit is 1 wt % or less, the depletion rate

would be minimal. However, in general B^C and even SiC give improved wearresistance when included in deposits and would probably be effective for

most uses.

-12-

Particles are included most effectively at 45°C or below and at

current densities of 50 and down to 20 asd with the most effective combination for most selections of additives and particles at 45°C and

30 asd. These conditions result in a deposition rate of about 1 mil per

hour and reasonable distribution. If required, higher temperatures and

current densities include some particles up to about 65 °C and 60 asd.

Some types of particles seem to be more readily incorporated than

others. This may be related to their ability to become electrically charged.

Shape, size, mass, and adsorption may also have some effect. For example,

nickel coated diamond is more readily incorporated than uncoated diamond

and Sic and CrB2 were incorporated more easily and in larger quantities

over a range of conditions than some other types that may not be as conductive .

Normally the life of a chromium bath is indefinite, requiring only

periodic additions of CrO^ to replace deposit and drag-out losses. The

life test run on the chromium bath containing additives for the including

of particles up to 5100 ampere-hours per liter showed that the only problem

was a build-up of the additive or by-products of the additive in the bath.

When the bath was treated for removal or reduction in concentration of

these by-products, it behaved normally again. The only exception was a

bath used with lithium nitrate as an additive. It seemed to contribute

to the build-up of ^'^2'^^ bath and prevent its reduction to CrO^

again. Deposits from a bath thus affected were dull and rough and uniformity of coverage was poor.

It is considered that in a large plating bath the use of the other

additives would not cause any problems as 5100 ampere-hours per liter of

-13-

bath represents a considerable amount o£ plating in a particle plating

operation.

Further tests of several of the additives used, mainly NH^NO^ and

CeNOj, confirmed previous results indicating that CeNO^ was most effective

for incorporating particles in a chromium deposit with minimal disruption

of the structure and characteristics of the chromium. However, it is

quite expensive and more common materials such as NH^NO^ are inexpensive

and adequate for practical operations. Probably the ultimate combination

according to present results would be CeNO^ and nickel coated diamond

particles added to a 200 g/1 CrO^, 2H2SO^ bath operated at 45°C and 30

asd for the best wear -resistant deposit.

Particles were incorporated on vertical cathodes in cadmium and zinc

deposits from the cyanide baths used without the use of an additive.

However, the use of thallium in the zinc bath enhanced the amount of particles included. It was not tried in the cadmium bath. Wear -resistance

was more than doubled for cadmium deposits containing hard particles.

Wear -resistance for zinc deposits containing hard particles was improved

but only by about 30 to 50%. It is possible that variation of mechanical

arrangement of the electrodes and bath composition could considerably

increase the amount of included material and thus perhaps the wear -resistance

Heating the chromium deposits in air oxidized the exposed copper basis

material extensively but only treatments at 400**C and above oxidized the

chromium. The reduction in wear-resistance at the higher temperatures was

expected as any softening of the chromium matrix reduces wear qualities

despite the presence of hard particles which were most likely unaffected

by the comparatively low temperatures used.

-14-

At the end of the program a few tests were made in a 200 g/1 CrO^

chromium bath using sodium fluosilicate as a catalyst plus an additive and

hard particles. Efficiency was very low and only a coarse, greenish colored

deposit was obtained which had completely unsatisfactory wear qualities.

There was no time to experiment with other fluoride catalysts or plating

bath combinations.

This program for incorporating hard particles in chromium deposits

has shown that many monovalent cations are effective when added to the

bath in amounts of about 3 g/1 or less over a range of plating conditions

and even on vertical cathodes. Without these additions no particles are

included from the standard chromiiam bath. However, the additives or the

included particles or both result in the deposition of softer, dull deposits under plating conditions that would normally yield hard bright

deposits. Wear -resistance is improved oA'^er bright, hard deposits only

because of the presence of hard particles in the chromium matrix. If

additives and conditions could be found that deposited bright, hard chromium with included hard particles, it is fairly certain that the improvement in wear-resistance would be many times that achieved in this program.

-15-

Conclusions

It is apparent from the work done on this program that it is entirelyfeasible to include hard particles in chromium deposits with a resultant

increase in wear-resistance. Properties of the chromium such as hardness

and brightness are diminished when particles are included either because

of the presence of particles in the deposit or because of the monovalent

cation added to the plating bath to effect their inclusion or both.

Inclusions of even less than 1 wt % of hard particles in the chromium

deposit can be effective in reducing wear. Boron carbide particles yielded

the best wear characteristic, with the exception of diamond, of any particles commercially available with very inexpensive silicon carbide a close

second. Bath-life using the additive is reasonably good and no impediment

is seen to scaling up the process for practical applications on at least

a semi -production basis. Particles are included in deposits on vertical

and horizontal surfaces as well as on the inside of tubes using suitable

internal anodes using plating conditions within the normal range for

chromium deposition.

-16-

Bibliography

M. Viswanathan, Occlusion Plating to Form Nickel Cermets, Metal Finishing

7]^, 1 (1973).

H. Brown and T. Tomaszweski, Occlusion Plating of Fluocarbon Resins,

U.S. Pat. 3,677,907.

D. W. Smith and P. D. Groves, A Study o£ the Mechanisms of Cement Electrodeposition, Trans. Inst. Met. Fin. 50,(1972).

Figure 1. SEM photos of B4C (top) and B^C hard

particles at about 1600X.

_r* P H

*—

4-. rH

f> • H

4-' t/) o O • 0 •

to

4J

Cj

,ri

•H t/1 o o

4-> to

i-HO

rj- •P +J •H

1/5 O C_3 P-i a) cQ

1—1

O C5fi

(I)

u o

rt to -i 0) c § o

lO

OS P o O 2

<D 1-1

0) I—

• H bOC X -H P c

nJ -H

CO

pcoo

CD

f-i

•H

to

00

>

•H

•H

CO

r-» —

O +-> z

^ CO 1—

t/J >s O

to 1—* CN •H C_5

CTJ o E S LO

00 CN CM O •H O

t/) X c P o

cn 10 -H

+-> <U -P •H P -H

CD C

4-1 O

•H CJ 1—

O 1 x: n

C^ P

\o

to P

CN •H

1—

cx,

00

00 \0

(Slu) ssox-JBSM

ID

to

to O

UU

i-HbO

/—

y

C2

t/) V)

4) I—

w O o •H > +-) CM • H f-l +J OS I—

(

•H13

W) 'O c

X) <u O

•H w

>

4-> o •H o

o

0

a.

u

3

•H

O

CM

00 oo

(Sui) ssoi-JBajvi

-20-

18

16

14

6

12 b ~ LiNOg • — TINO3

10

1 I

4 6 8

Run number

10

Figure 5. Comparison of effect of bath additives

under similar plating conditions.

-21-

22.9

T

20

18

16

14 «

O — LiN03 • TINO,

12

10

I

I

3 J

10

Run number

Figure 6. Comparison of effect of additives to Cr bath under similar plating conditions.

-23-

o o o

\0 CM

I

(Sni) ssox J^^M

-24-

Temp. = 24°C

C = Current density in asd

Inside ting = g/1 particles in bath

Radii = Inclusions 0-3 wt. %

I 1

Figure 8. Annount of inclusions in cadmium deposits.

Temp. = 34°C

C = Current density in asd

Inside ring = g/1 particles in bath

Radii = Wear loss . '5 mg _

Figure 9. Wear- loss of cadmium deposits with included particles.
\
Figure 10. Cadmium (top) and zinc deposits containing B^C particles plated from cyanide baths at 24°C/1 and 3 asd

respectively. No etch.

to

_ o

00 oCM

1—

<

1-1u

c; •H

+j • /—

•H

U

1-H 2 0 1 o1—

c

•H +J

X

N ClJ

o\°UX

O -P

4-> » ' to

to (U o -a c .-( -H o I c

•H ^ rt w

0)u

I—

o

c: •H

to

u o > <u

i-H •p < tn -H o o.

•H Ph

trt di 3

r-HOn

h-

CM

(U3

tao •H o o o

CM

(Sni) ssox JBSM

-28-

\0

C_3 CQ13

TJ

1—1, oH

4-> •H

t/) 4-> •H

(/) o&<D •

1 o o o

r—

eJ cN •H

to 4->

o\° o x:

4^3V ^ (/) ^tnO D

fS .-H 13 o 1 -H H ^ C

I/) <D X r—

5 O

O

c

1—

in B u o

> M-l

o

•1-4

I/) 3

t-lo

p—

3

H

o o

(Sui) ssox j;b9M

-29-
1

I
Temp. = 24°C

C = Current density in asd

Inside ring=g/1 particles in bath

Radii = Wear loss , '0

^

Figure 13. Wear-loss of zinc deposits with included particles.

CM
i

i
Temp. = 24°C B4C - 30 g/1

C = Current density in asd

Inside ring = g/1 TINO3 or TICI

Radii = amt. inclusions -^0 wt. %

Figure 15. Inclusions in zinc deposits using thallium.

ii

Figure 16. Chromium deposit on inside of stainless steel tube 3/8 inch ID

X 20 inches long. Chromium deposited at 45°C/50 asd in tube in

vertical position from bath containing 3 g/1 Tl NO3 and 30 g/1

B4C. Cross-sections taken from top, center, and bottom of tube

Hard particles resist polishing and leave "tails" of raised Cr.

No etch.

Figure 17. Heat-treated series. Top 250°C for 2 hrs , center 400°C

for 1 hr, bottom 600°C for 1 hr. Chromium deposited on copper from bath containing 3 g/1 Tl NO3. No etch.

FORM NBS-114A (I-7I) U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO.

NBSIR 73-142

2. Gov't Accession No.

3. Recipient's Accession No.

4. TITLE AND SUBTITLE 5. Publication Date

Codeposition of Wear-Resistant Particles

6. Performing Organization Code

7. AUTHOR(S) John P. Young

8. Performing Organization

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

I U. Fro iect/Taslc/Work Unit No. 3120468

11. Contract/Grant No.

12. Sponsoring Organization Name and Address

Research Directorate

Weapons Laboratory - RIA

Rock Island Arsenal

Rock Island, Illinois 61201

13. Type of Report & Period

Covered

Annual Progress 1/72-1/ 73

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here.) Several new hard particles were tried with the object of improving wear -resistance

of chromium deposits containing included particles over the best previously tried

material, tetra-boron carbide. Only hexa-boron ehlorido was slightly better. C^-rhi

During a bath-life test 5100 ampere-hours per liter were run through a particleincluding chromium bath. Build-up of products of the monovalent -cation additive

used was detected but bath performance could be restored to normal by their removal.

Heat treatment of deposits showed reduction in wear -resistance of deposits heated

to 400°C or over. A caliber 0.30 tube was plated with chromium having included

particles with relatively good particle distribution throughout the bore. Deposits

of cadmium and zinc with included hard particles showed some improvement in wear- resistance .

17. KEY WORDS

Bonding; cement; chromium; composite coatings; deposit hardness; dispersed phase;

dispersion hardened; electrodeposition; electro-inclusions; electroplating; mono- valent cation; occlusion plating; particle codeposition; particle inclusions; wear

resistance.

'3. AVAILABILITY STATEMENT

I I UNLIMITED.

HfOR official DISTRIBUTION. DO NOT RELEASE

TO NTIS.

19. SECURITY CLASS

(THIS REPORT)

UNCL ASSIFIED

20. SECURITY CLASS

(THIS PAGE)

21. NO. OF PAGES

34

22. Price

UNCLASSIFIED

USCOMM-DC 66244.P71