NBSIR 74-599

Mechanical Properties of

Electrodeposited Brass

Fielding Ogburn and Christian E. Johnson

Corrosion and Electrodeposition Section

Metallurgy Division

Institute for Materials Research

National Bureau of Standards

Washington, D. C. 20234

October, 1974

Final Report

A.E.S. Research Project 33

Prepared for American Electroplaters' Society

56 Melmore Gardens

East Orange, NJ 07017

NBSIR 74-599

MECHANICAL PROPERTIES OF

ELECTRODEPOSITED BRASS

Fielding Ogburn and Christian E. Johnson

Corrosion and Electrodeposition Section

l\^etallurgy Division

Institute for Materials Research

National Bureau of Standards

Washington, D. C. 20234

October, 1974

Final Report

A.E.S. Research Project 33

Prepared for American Electroplaters' Society

56 Melmore Gardens

East Orange. NJ 07017

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

NATIONAL BUREAU OF STANDARDS. Richard W. Roberts, Director

Abstract

Electrical resistivity, density, hardness, wear rate, tensile strength,

internal stress, and ductility of el ectrodeposi ted 70-30 brass were measured

and mi crostructures were observed. The deposits were obtained from a high

speed cyanide bath designed to deposit 70-30 brass. Included are property

data for deposits of other compositions obtained from the same bath under

conditions other than normal.

I Introduction

Published data on the physical and mechanical properties of electrodeposited brass and other copper alloys have been compiled by Saf ranak^^

.

The data available for brass prior to that compilation was' limited to •

measurements of electrical resistivity and hardness with some observations

of the microstructure . The absence of data on tensile strength and

ductility led to the investigation reported here and during the 'course of

which measurements v/ere made of electrical resistivity, hardness, wear,

density, tensile strength, and significant strain (nominal elongation) at

fracture. Although the plating bath v/as selected for the deposition of

70-30 brass, alloys of otiier compositions were obtained and data from some

of these are included in this report. (Table I).

II Preparation of Plating Solutions and Deposits

A. Solutions

All the deposits for wliich properties were measured were obtained from

a high speed cyanide type bath with a nominal composition of:

CuCN • 60 g/1

Zn(Cf02 7.5 g/1

Na CN 120 g/1

KOH 45 g/1

Two baths of this same nominal composition were made up using "plating grade"

copper cyanide, "purified" zinc cyanide, reagent grade sodium cyanide, U.S. P.

potassium hydroxide, and distilled water.

<~ For purification purposes, each bath was heated to 60°C and 10 g/1

of activated carbon was added and kept in suspension by mechanical stirring

while holding the temperature for one to one and a half hours. The solutions

were filtered through filter paper into the plating tank and them dummied

with a corrogated cathode for about 35kC (10 A hr /per litre) at about

50 k/\/ (5rr^/cm^).

At this point the treatment of the two baths took slightly different

courses. Bath A was given a second carbon treatment, filtered, and analyzed

for copper, zinc, and free cyanide. To adjust the bath composition; additions

were made to a 3 litre portion of the bath. This v;as given a carbon treatment and filtered into the bath. Deposits 15 through 33 were obtained from •

this bath. At that time, the carbon treatment was repeated and 7 g/1 of

i KOH were added. Subsequently, deposits 35 through ^2 were obtained from

this bath. This bath had operated for at least 4.4 MC (1220 A hr ) when

deposit 42 was completed.

Bath B v/as not given any further carbon treatment. Minor additions were

made to bring the composition to the desired levels. Deposits 43 through 46

were obtained from this bath.

The initial compositions of the bath after purification and just

prior to depositing the first test specimens were:

Bath A Bath B

Cu .

•

. 41 g/1 41 g/1

Zn . 4.1 g/1 4.4 g/1

"Free cyanide" 49 g/1 4G g/1

The Cu and Zn values were obtained by iodometric titrations, the free

cyanide by the silver nitrate titration. The analytical procedures used

were designed for plant control purposes and are not highly precise. In

effect, the copper and free cyanide concentrations were not adjusted and

j the zinc concentration was adjusted initially and during use of the batli

2 2 to give a deposit composition of about 70-30 at 200 A/m (20 niA/cm ).

Additional information on the composition of the plating bath is

j given by the results of semiquantitative spectrochemical analyses shown

in Table 2. The analyses for the plating baths were of residues from air

evaporation of bath samples. One sample, "purified bath" was taken from

Bath B after the purification process. The other, "used bath" was taken

from Bath A after the last deposit was obtained. The analyses do not

show any variation betv/een the two samples. Table 2 also reports an analysis

of a brass deposit which shows traces of Ag, Bi, Fe, Mg, and Ni. Silicon

present at the 0.01-0.1% range, v;as the only othe r impuri ty detected.

These analyses, of course, do not provide information about organic impurities

[21

A few deposits were also obtained from a bath described by Roehl et al^

The actual make-up was CuCN 90 g/1, ZnO 5.3 g/1 , NaCN 110 g/1, and NaOH 60 g/1

This bath was given essentially the same purification treatment as Bath B.

Deposits from this bath were not tested because of the difficulty of getting

sound deposits of the thickness required for property measurements. Good

quality thin deposits, for wfiich the bath was designed were obtained. Smooth

deposits about 50 m thick, were produced; but they were quite dark in color.

Fig. 1 is a photomicrograph of a cross-section of one of these deposits and

it is evident that the top portion of the deposit had a nodular structure.

-3-

The anode was sampled at two locations for copper analysis. Cuttings

from one edge and drillings, 6 mr\ deep, from the center showed 67% copper.

A semiquantitative spectrochemical analysis is reported in Table 2.

B. Operating Variable

The effect of solution composition on the deposits was not a part of

this investigation.

Composition control involved occasional small additions of Cu(CN) or

Zn(CN)2 on the basis of analyses of deposits. The free cyanide was determined periodically by the silver nitrate titration. The carbonate content

was determined twice. After the last deposit from Bath A, it was found

to be 22.5 g/1 as NaCO^ and after deposits 43 and 44 from Bath B it was

5.2 g/1.

The solution agitation was roughly controlled by regulation of the

flow through a filter-pump unit and through a perforated blind tube. This

flow was adjusted to provide optimum uniformity of deposit composition.

The temperature uniformity throughout the bath was maintained by this

vigorous agitation. It was held at 65 ± 1°C with automatic equipment.

The plating current was controlled to ± 5%.

C. Equipment

The plating bath was contained in a rectangular glass battery jar,

30 X 30 cm, filled to a depth of about 38 cm to hold 32 liters of solution.

To obtain fairly uniform current distribution, the 20 x 35 cm cathode was

held in a cathode box open at the top and towards the anode. The box was

15 cm deep and was constructed of teflon and polypropylene held together

with stainless steel screws.

The temperature was automatically controlled with a sensing element

in the plating bath which controlled 2 quartz heaters in a water jacket

fornied when the battery jar was placed in a water filled wooden tank.

-4-

Continuous filtration was provided v;ith a conimercial filter-pump unit.

The cartridges were rated 15 pm. A dynel cartridge was used for deposits 15

to 33 and a polypropylene cartridge was used for deposits 34 to 46. The

cartridges were cleaned before use by leaching successively in ethyl acetate,

chloroform, ana hot 10-^ sulfuric acid. They were then rinsed with a solution

containing 120 g/1 of sodium" cyanide, and 45 g/1 potassium hydroxide and

finally with distilled water. The pump and filter housing were constructed

of polypropylene and the pump shaft was 304 stainless steel. The unit v/as

immersed in the bath at one side of the tank with the intake at the bottom.

The outlet was connected to a polypropylene tube parallel to the cathode and

at the bottom of the cathode box about 11 cm from the cathode. The latter

tube was closed at the end and there were -two rows of small holes in the

tube, one facing the cathode and the other facing upward. The solution

emerging from these holes provided the bath agitation.

The anodes virtually covered one wall of the square battery jar

opposite the cathode. These were bagged in a polypropylene fabric which

had been cleaned in the same manner as described for the filter cartridge.

D. Deposits

The starting cathode was prepared by nickel plating a type 304 stainless

steel sheet about 20 x 35 x 0.08 cm. The stainless steel was first polished

and buffed with an emery compound. Then it was degreased, pumice scrubbed,

rinsed with 1:1 nitric acid, rinsed with distilled vyater, plated with about

10 pm of nickel from a low pH Watts bath containing 2 g/1 of saccharin,

rinsed with distilled water, and transferred to the brass plating bath.

The nickel starting sheet was used because of previous experience pre-

[31 paring copper deposits for the determination of mechanical properties'- .

-5-

After brass plating, the edges of the cathode v/ere trimmed and the deposits

were easily separated from the stainless steel. The nickel, v;hich adhered

to the starting face of the brass v;as dissolved anodically at 6V in a solution

containing, in parts per volume, 50 of cone. H2S0^, 50 of 85% of H^PO^,

and 5 of water. The removal of the nickel involves the loss of less than

0.2 ym of the initial brass deposit. Most of these brass deposits were

75-100 pm thick although a few were about 40 ym. At least 2 cm of border

all the way around each brass sheet was removed and discarded. The specimens

required for property measurements were cut from the remaining portion of

the sheet.

For wear tests, adherently plated deposits were used. The starting

sheets for these deposits were 1010 steel panels, flashed with copper from,

a cyanide bath, plated with 12 urn of acid copper followed by 10 ym of

Watts nickel. The brass was then plated adherently over the nickel surface.

Thickness variation over each deposit was about ± 10%, the same as

reported by Lamb et al for copper from cyanide solutions. Current density

variation would have been about the same. Variation of composition {% copper)

of a deposit ranged from at least ±0.1 to about ± 3 percentage points with

a median of about ± 0.6.

Ill Measurement of Deposit Characteristics

• A. Composition

The composition of each deposit was assumed to be entirely copper and

zinc with only trace quantities of other elements. The copper content was

determined by the conventional method of electrodepositing the copper on a

platinum gauze cylinder. The zinc was not determined except by difference.

These determinations are accurate to the nearest 0.05 percentage unit.

One semiquantitative spectrochemical analysis was made of a deposit from

Bath A. Table 2 gives a summary of that analyses and shows the major

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impurity to be silicon at the 0.01 to 0.1% level. Other impurities are

Ag, Bi , Fe, Mg, and Ni . Organic materials are not included in the analysis.

Copper and zinc contents are dependent on agitation, solution composition,

and current density. It is practically impossible to keep all of these

variables uniform over the surface of the cathode or to reproduce closely

from one cathode to another. The variation of composition v/ithin a deposit

v/as about ± 0.6 percentage points for copper content. The variation of

average composition between duplicate deposits is judged by comparing

deposit 23 with 24, 43 with 44, and 45 with 46 in Table 1. The greatest

difference is 2% copper.

Deposits 15, 18, and 23 differed by degree of solution agitation, it

appears that reducing the agitation leads to a greater copper content.''

Early in this investigation, deposits were made at several different

[41 current densities. As with the data reproduced by Brenner^ a plot of

2

copper content vs. current density showed a minimum near 1/2 A/ dm . Current

2 densities of 1.33 and 2.0 A/dm gave deposits with about the same copper

content.

Structure

The photomicrograph of deposit #43 in Fig. 2 shows the typical fine

grain microstructure of 70-30 brass deposited at current densities in the

100-200 A/m^ (10-20 mA/cm^) range. Deposit //28 was an exception to this

in that it had a slightly coarser grain structure near its surface.

2 The deposits, obtained at current densities of 25 to 75 A/m (2.5 to 7.5

2 mA/cm ), had a coarser grain. The maximum grain size was obtained in deposit

2 2

#29, at 50 A/m (5 m,A/cm ), shown in Fig. 3. These deposits were less than

60% copper.

Deposit :723, 71% Cu, was examined by x-ray diffraction. There was no

preferred orientation detected and only the alpfia phase was detected. If

-7-

another phase had been present at less than the 5% level it v;ould probably

have not been observed. The grain size was estimated at 0.025 ym. This

method of measuring grain size does not distinguish between twin boundaries

and grain boundaries.

B, Internal Stress

The internal stress was measured with a Brenner- Senderhoff spiral contractometer, using the precautions described by the inventors'- . The estimated accuracy of individual determinations of stress is ± 2.1 MN/m (0.21

kgf/mm^) (300 psi).

The stress measurements are summarized in Table 3 for approximately

50 ym deposits. The values given for the % copper in each deposit is subject

to two errors. The sample for analysis was obtained by partially dissolving

the deposit in 1:1 nitric acid. The top layers would be part of the sample

for analysis and the bottom layers would not. To the extent that deposit

composition varied with thickness or time, the sampling would not be representative. Also any selective dissolution of the alloy components would

introduce an error.

Another uncertainty to interpretation of these data is the effect of the

2 carbonate content of the bath. For the stress measurements made at 133 A/m

2 (13.3 mA/cm ), the sodium carbonate concentration was about 22 g/1. For the

2 '2 stress measurements made at 200 A/m (20 mA/cm ), the carbonate content is

estimated to be a little more than half that amount. Everything considered,

2

It appears that the current density from 1.33 to 2 a/dm is associated with a

small decrease in internal stress.

Variation of stress with thickness (time) is indicated in Fig. 4 for a

typical stress measurement. 'The stress is directly proportional to the ratio

of the dial rotation to the deposit thickness (time). These data indicate

that the stress does not vary with deposit thickness. This is in keeping

-8-

rsi

with the observations of Lamb et al*"- for small-grain deposits of copper.

For large-grain deposits, tensile stress tends to decrease with increasing

thickness.

^ Density of Deposits

The density values reported in Table"4 were determined for 1/2 gram

samples cut from brass adjacent to specimens used for the bulge tests. The

compositions were determined by gravimetric analysis for copper of each of

the entire 1/2 gram samples used for the density measurements. These latter

measurements v/ere made using the two liquid hydrostatic method^^-^. The

3

float was calibrated with copper specimens. Their density of 8.934 Mg/m

[31 had been determined from measurements made by Lamb et al*"- by the conventional

hydrostatic method. Each specimen was measured twice and the reported. val ues

3

have a standard deviation of 0.0017 Mg/m based on the duplicate measurements.

3

The accuracy of the values is estimated to be ± 0.01 Mg/m .

A plot of this data, Fig. 5, indicates,' as expected, that the density

is primarily dependent on the copper and zinc content of the alloy. For

comparison purposes, the plot includes data for wrought alloys taken from

the ASM handbook^'^^.

Electrical Resistivity

The specimens used for measuring electrical resistivity were strips 0.5

cm wide and 15 cm long. These were held in a, jig with current contacts at

the ends and voltage contacts 9.99 cm apart. A com.mercial mil lohmrneter with

an accuracy of about 1% full scale was used. It-v/as calibrated with a 1 milliohm standard resistor. Cross-sectional areas were obtained from length, mass,

and density, which was either a measured value for the deposit or estimated

from the composition of the deposit.

Of the four quantities used to calculate the resistivity, the resistance

measurement was the least precise. This measurement was made at least twice

for each specimen. The spread between duplicate measurements was, at most,

0.2 pohm^ cm.

'-Each composition and resistivity value in Table 5 is an average for

•three specimens cut from the same el ectrodeposi t. The spread between the three

specimens was 0.25 to 0.4 yohm. cm for deposits 29, 35, 43, and 44; 1.07 yohm.

cm for deposit 32, and less than 0.2 yohm. cm for the others. The spread for

deposit 32 is clearly out. of line with the other results. All the measurements

for the resistivity determinations of 32 were repeated and checked. We note,

however, that the 3 specimens of deposit 32 contained 51.0, 52.6, and 53.1%

copper. A large change in resistivity could be expected in this range as

suggested by Fig. 6. .

'

. " • .

The bath to bath reproducibility of the data is indicated by deposits 24

and 46 having resistivities of 8.14 and 7.57 yohm. cm respectively and comingfrom different baths and by deposits 35 and 43 with resistivities of 8.54 and

8.41 yohm. cm. • '.

Fig. 6 indicates how this data relates to that of Andreeva et al^^^ and

to metal lurgical ly prepared copper-zinc alloys when these data are plotted

against composition. The spread of our data and the difference between our

ro-|

data and that of Andreeva et al suggests that factors other than the

copper-zinc composition influence resistivity.' Grain size and non-metallic

impurities could be pertinent factors which depend on the conditions of

deposition.

Tensile Strength and Ductility

To obtain tensile strength and ductility data, the hydraulic bulge test^^*^-^

was used. The procedures and equipment used were the same as described by Lamb

et al^"*^-^ with some minor differences. The test specimen was always placed

so that the substrate side became the convex side of the bulge. Because a

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number of specimens fractured along the edge of the bulge where it met the

clamping ring, the radius of that edge v;as increased from about 3/64 inch to

1/8 inch and the data obtained with the smaller radius v/as discarded. This

change did not completely eliminate fracture at the edge. The rate of loading

of the 42.5 mm diameter bulge was reduced to less than 1 lb. /5s. This last

change did not materially alter the tensile strength and strain data for the

13 deposits retested.

Specimens that fractured along the clamped edge of the bulge are not

included in the reported data. The specimens for wnich data are reported

fractured in several different ways: as a slit a few millimeters long,

radially from the center to the edge along 6 to 8 different paths, one

fracture across the bulge, as an irregular shaped hole several millimeters

in length or diameter, and various combinations of these.

Following the practice of Lamb et al^''"'-', the nominal tensile strength

calculated on the basis of initial thickness of the test specimen and the

significant strain are reported in Table 6. These cjuantities correspond to

tensile strength and nominal elongation obtained by conventional pull tests

of brittle materials^"*^-^. The data in Table 6 are averages of the number

of specimens indicated. The copper composition is from the analysis of the

fractured specimens.

The precision of the tensile strength data may be judged by the spread

of measurements on panels of the same deposit which is never greater than

± 6.4/0 of the mean. Deposits 23 and 24 with average tensile strengths of

1036 and 952 MP were obtained at the same operating conditions as were

deposits 43 and M with average tensile strenths of 886 and 924 MP. As

expected, the significant strain data is not highly reproducible. Individual

measurements of specimens from the same deposit varies by a ratio as great as

3.6 to 1. Statistically speaking these strain data are not homogeneous and

-11-

the spread is greater than can be attributed to errors in the length measurements used to calculate the strain. This suggests variability of material

within each deposit rather than measuring errors.

For purposes of comparison, 70-30 wrought brass, 68% cold work, has a

tensile strength of about 680 MPa (99,000 psi) and an elongation of 37oS'^'^

The tensile strengths obtained in this investigation are significantly greater

n 1 than those attributed to Nystrom by Safranak"- . It is of interest to note

the dependence on thickness shown by Nystrom' s data:

ym psi MPa

7.5 58,000 . . 410

10.8 69,100 .490

13.9 73,900 520

Our values of 600-1100 MPa are for brass of thicknesses of 32 to 98 ym

deposited under somewhat different conditions.

Hardness

Hardnesses of deposits were measured on metal lographical ly mounted and

polished cross sections. A Knoop indentor was used on a commercial microhardness testing machine with a 200 g load. For hardness measurements of

deposits 23, 24, 36, and 37; three specimens were cut from each deposit:

from the top, middle, and bottom sections and from the right and left sides.

Each specimen was measured three times. Since the averages for each specimen

differed insignificantly from each other, only the deposit averages are

reported. For the other deposits, six measurements were made on one specimen

and the average reported for each deposit.

The hardness data is given in Table 1. The reproducibility of these data

may be judged by comparing the following pairs of duplicate deposits, 23 with

24, 36 with 37, 43 with 44, and 45 with .46. The greatest spread is 11 HK^qq

or 3^0. These data do not show a clear relation between hardness and composition

as do the data of Andreeva et al'- summarized by Safranak^ This is partly

because the composition of the hardness specimen was not measured directly but

assumed to be the average for the deposit. Also our data shov/ the deposits

with 45 to 50% copper to be softer than the 65-75% copper deposits; the reverse

of that reported by Andreeva et al . This difference is statistically significant

and suggests that hardness is influenced by factors other than the copper and

zinc content. Grain size and non-metallic impurities could be pertinent

factors which are dependent on the conditions of deposition.

For deposits with 68 to 70% copper, the hardnesses are 300 to 350 HK^qq.

These compare to a hardness of 93 Rockwell B (about 200 HX) for 69% cold worked

wrouQht, 70-30 brass^'^-^. The el ectrodeposi ts of other compositions are also

harder than the corresponding wrought brass. There is, however, no clear

relation between hardness and tensile strength of our electrodeposi ted material

as there is for the wrought material.

Wear Testing

Wear data were obtained with a Taber Abraser on the adherently plated,

flat specimen. Several variations of test procedures were explored to find

reproducible conditions with which the loading of the abrasive wheels with

brass powder would not be objectionable.

It was found to be convenient to break the procedure up into a series

of repetitive operations or runs. Each run consisted of dressing the abrasive

wheel with 150 grit silicon carbide paper for 50 cycles at a load of 1000 g and

running the test piece with the same wheel and a load of either 500 or 1000 g

for 5000 cycles for which the weight loss was determined. Initially the test

specimen was subjected to 3 runs using a resilient, coarse abrasive wheel

(CS-17) at 1000 g to cut in a track on the fresh surface. Then to establish

a uniforni, abraded surface, 10 runs were made with a resilient, medium abrasive

wheel (G5-10) at a 500 g load. The wear rate was then determined by measuring

-13-

the average weiglit loss of the test specimen during 20 runs vntli the same medium

abrasive wheel with the 500 g load.

20 wear runs were made on each of three specimens cut from the same brass

plated cathode sheet. Tv;o such sheets were tested along with one test specimen of rolled brass sheet {63% Cu, 35% In, 2% Pb) . The results may be

suninarized as follows: - •

Panel %Cu Current Density Wt. Loss

Rolled Brass " 63 .

' 8.4 g/1000 cycles

39. 72 133 A/m^ (13.3 mA/cm^) 10.3

41 70 200 A/m^ (20.0 mA/cm^) 7.2

The v/eight loss data for each panel is an average of three values having a spread

of + 15%. The difference between the two panels is real. The significance of

the difference, however, is unknown in as nluch as this test has not been

• correlated with service conditions and the reproducibility of the test between

laboratories is unknown.

Discussion

The data which would characterize el ectrodeposited 70-30 brass are given

in Table 7. These data were obtained from those deposits with 68 to 72%

2 2

copper plated at current densities of 130 to 200 A/m (13-20 mA/cm ). The

ranges for each property are not fully explained by variations in current

density and copper content, or by measurement inaccuracy, but also reflect

other parameters. Such parameters could be deposit impurities, structure,

grain orientation, etc. caused by variations of solution agitation; hydroxide,

ammonium, carbonate, and free cyanide content of solution; and current

distribution. Comparison of these data with tliose compiled by Saf ranak^''

,

reveal differences which may be attributable to differences in solutioii composition and operating conditions. Differences in hardness, of course, may

well be due to difference in metiiods and techniques of measurement.

The additional data given in Table 1 may be of general interest, but

should not be regarded as representative of electrodeposi ted brass.

-15-

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Table 2

SPECTROCHEMICAL ANALYSIS FOR METALLIC IMPURITIES

Residue from Evaporation of

Brass Purified Used Brass

Element Anode Bath Bath Deposit

Ag .001-. 01 <.001 <.001 <.001

Al — .001-. 01 .001-. 01

Bi <.001 • - — — <.001

B — .1-1 .1-1

Ba — .Ol-.l • .Ol-.l . —

Ca -- .Ol-.l .Ol-.l

Cu >10 >10 >10 >10

Fe .001-. 01 .001-. 01 .001-. 01 • <.001

K 1-10 1-10

Mg <.001 — ' — <.001

Mn -- <.001 <.001

Na >10 >10

Ni <.001 -- — <.001

Si .Ol-.l .1-1 , .1-1 .Ol-.l

Ti .001 -.01

Zn >10 1-10 1-10 >10

NOTE: >, greater than; <, less than; not detected; values given

as weight percent.

Other elements checked for but not detected include As, Au, Cd, Ce,

Co, Cr, Ga, Ge, Hf, In, Ir, La, Mo, Nb, P, Pb, Pd, Pt, Re, Rh , Rv,

Sb, Sc, Sn, Sr, Ta, Th, V, Y, Yb, Zr.

U and W were checked for in the anode and deposit. Hg, Os, Sm, Te,

and Tl were checked for in the bath residue.

-17-

Table 3

INTERNAL STRESS

Composition of Deposit Current Density stress

n/ in \^ /~i f rpm ^ KQT/ lira

70 200 11,900 8.4 82

69 200 11,600 8.2 80

AVE: 69.5 200 11,800 8.3 81

69 133 1 2,900 9.1 89

71 133 13,600 9.6 94

AVE: 70 133 13,300 9.4 92

1 A/m^ =0.01 A/dm^ = 0.001

2

niA/cm

Table 4

Density

Deposit Cu (%) Density

Mg/m"*

^ (g/cm^)

27 47.3 8o23

32 50.6 • 8.29

44 • 63.3 8.42

43 68.6 8.50

46 69.0 8.50

18 70.8 8.54

23 70.9 8.53

45 71.8 . 8.54

15 77.4 8.64

Table 5

Resistivity

Deposit %. (Cu) ' Average

No. Average Resistivity

. y ohm cm

15 77.7 6.23

18 - 70.0 8.03

24 - 70.3 8.14

27 46.7 5.04

28 . 77.4 6.39

29 47.7 4.11

30 69.2 8.26

31 47.4 4.77

32 52.2 5.45

35 69.0 . 8.58

43 67.7

.1

8.41

44 65.7 -.. 8.38

45 71.6 7.91

46 69.9 7.57

Each value is an average of the data from each

of three specimens.

-20-

Table 6

Tensile Strength and Significant Strain

Tensile Strength

Deposit % Cu MP PSI" 6 Number of

Uo. Specimens

Measured

15 78.4

^ 1129 163,700 .011 3

18 71 .6 946 137,200 .008 5

23 70.8 1036 150,300 .011 3

24 71.1 952 138,000 .009 2

27 47.7 881 127,800 .010 5

28 77.8 1088 157,800 .025 5

29 48.7 621 90,000 .034 3

31 48.0 986 143,000 .011 1

32 51 .0 734 106,500. .008 2

34 83.7 955 138,500 .068 . 4

43 69.1 886 128,500 .005 2

44 65.4 924 134,000 .008 1

46 70.8 1005 145,750 .009 4

-21-

Table 7

Properties of Electrodeposi ted Brass 68-72% Copper

Resistivity 7.6-8.6 y ohm-cm

iJensity 8.50-8.54 Mg/m^

Hardness, HK200 - 306-351

Tensile Strength (nominal) 886-1036 MPa

Elongation (significant strain at fracture) 0.5-1.1%

Internal Stress ' 81-94 MPa

'li

-22-

References

[1] William II. Safranak, "The Properties of Electrodeposited Metals and

Alloys".

[2]'^E.J. Roehl, E. Michel, and L.R. Westbrook, Plating, 4^, 403 (1955).

[3] V.A. Lamb, C.E. Johnson, and D.R. Valentine; J. El ectrochern. See ,

117. 291C (1970).

[4] A. Brenner; El ectrodeposi tion of Alloys , Academic Press, Inc., New

York (1953), Vol. 1, p. 447.

[5] A. Brenner and S. Senderhoff; J. Res. Nat. Bur. Stds., 42, 89 (1949).

[6] A.D. Franklin and R. Spal ; Rev. Sci. Instr ., 42_, 1827 (1 971 ).

'F. Ogburn; to be published in 1 975.

[7] Metals Handbook, Vol. 1, 8th Ed., American Soc. for Metal s, Novelty,

Ohio, 1961.

[8] G.P. Andreeva, N.P. Fedot'ev, P.M. Vyachesl avov , and I. Ya. Pal'mskaya;

J. Appl. Chem. (USSR), 35, 1229 (1953).

i ( [9] H. Imai, Sci. Rep. Tohoku Imp. Univ., H, 5, 313 (1922).

[]0] T.A. Prater and H.O. Read; Plating, 36, 1221 (1 949); 37., 830 (1950).

[11] V.A. Lamb, C.E. Johnson, and Donald R. Valentine; J. Electrochem. Soc ,

117, 3430 (1970).

-23-

Fig. 1 .

Photomicrograph of cross-section of brass deposit from bath described

by Roehl . Deposit about 50 ym thick.

Fig. 2 .

Cross-section of deposit #43. Thickness: 71 miti.

-is*'

3-

Cross-section of deposit #29. Thickness: 79 ym.

DIAL

ROTATlOrJ

0 20 40 60 60

Figure 4.

Variation of internal stress with time of platin

-27-
I

I

\

1
8.0

8.6

8.4

O Electrodoposeted

O V/rought ASM L73

o

•

o

o

o

o

8.2

o

8.0

50 60 70

COPPER 7o

80

Figure 5.

Density vs. Composition.

^ Electrodeposited , this ivesticotion — Eleclrodeposited , Andreeva et al [8] — Cast annealed , Imai [9]

OS given by Andreeva et al [8]

Wrought, ASM [7]

'

60

COPPER

100

or

Figure 6.

Resistivity vs. Composition.

-29-
I