NATIONAL BUREAU OF STANDARDS REPORT

9976

COMPATABILITY OF PROTECTIVE COATINGS , MATERIALS, AND LIQUID PROI LLAlilc

Q ARTERLY PROGRESS REPORT NO. 12

October 1 to December 31, 1968

For

Picatinny Arsenal Project

Order No. Al-8-RF03^-01-Dl-GG

To

Commanding Officer

Picatinny Arsenal, Dover, . J. 07801

Attn: Code SMJPA --2 Liquid Rocket Propulsion Laboratory

<NBS>

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards1 was established by an act of Congress March 3,

1901. Today, in addition to serving as the Nation’s central measurement laboratory,

the Bureau is a principal focal point in the Federal Government for assuring maximum application of the physical and engineering sciences to the advancement of technology in industry and commerce. To this end the Bureau conducts research and

provides central national services in three broad program areas and provides central national services in a fourth. These are: (1) basic measurements and standards,

(2) materials measurements and standards, (3) technological measurements and

standards, and (4) transfer of technology.

The Bureau comprises the Institute for Basic Standards, the Institute for Materials

Research, the Institute for Applied Technology, and the Center for Radiation Research.

THE INSTITUTE FOR BASIC STANDARDS provides the central basis within the

United States of a complete and consistent system of physical measurement, coor- dinates that system with the measurement systems of other nations, and furnishes

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following areas of science and engineering:

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and Frequency.2 THE INSTITUTE FOR MATERIALS RESEARCH conducts materials research leading to methods, standards of measurement, and data needed by industry, commerce,

educational institutions, and government. The Institute also provides advisory and

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areas of materials research

Analytical Chemistry—Polymers—Metallurgy — Inorganic Materials — Physical

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THE INSTITUTE FOR APPLIED TECHNOLOGY provides for the creation of appropriate opportunities for the use and application of technology within the Federal Government and within the civilian sector of American industry. The primary functions

of the Institute may be broadly classified as programs relating to technological meas- urements and standards and techniques for the transfer of technology. The Institute

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1 Headquarters and Laboratories at Gaithersburg, Maryland, unless otherwise noted ; mailing address Washington, D. C. 20234.

2 Located at Boulder, Colorado 80302.

3 Located at 5285 Port Royal Road, Springfield, Virginia 22151.
NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT

3120465 January 1, 1969

NBS REPORT

9976

COMPATABILITY OF PROTECTIVE COATINGS, MATERIALS, AND LIQUID PROPELLANTS

By

J. P. Young, G. I. Reid, and V. A. Lamb

QUARTERLY PROGRESS REPORT NO. 12

October 1 to December 31, 1968

For

Picatinny Arsenal Project

Order No. A1-8-RF034-01-D1-GG

To

Commanding Officer

Picatinny Arsenal, Dover, N.J. 07801

Attn: Code SMUPA DL-2

Liquid Rocket Propulsion Laboratory

IMPORTANT NOTICE NATIONAL BUREAU OF ST

for use within the Government,

and review. For this reason, the whole or in part, is not author Bureau of Standards, Washingto

the Report has been specifically

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST) on October 9, 2015

;s accounting documents intended

subiected to additional evaluation

listing of this Report, either in

; Office of the Director, National

iy the Government agency for which

opies for its own use.

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

COMPATIBILITY OF PROTECTIVE COATINGS, MATERIALS, AND LIQUID PROPELLANTS

A. Objectives of Project

1. To investigate the effect of various coatings and materials for

their ability to withstand* the corrosive effects of hydrazine fuels and

oxidizers, and for freedom from catalytic effect on the decomposition

of fuels and oxidizers.

2. To develop procedures for applying coatings, disclosed as satisfactory under part (l), to the interior surfaces of rocket and missile

fuel tanks of complex shape.

B. Summary of Progress in Preceding Quarter

1. Decomposition of MHF-3 fuel in contact with various materials

a. Decomposition rates due to various metals at l60°F

The activity of metals in contact with IlHF-3 listed in Table 1

did not undergo significant changes. The units containing AM355 stainless

steel and stainless Maraging steel were still giving considerably different rates for comparable units and a third unit for each had been set up.

Electroless nickel from the alkaline bath gave a lower rate in a second

unit after special pretreatment of the specimen but was still higher by

a factor of 20 than the rate for standard electroless nickel. Heattreated standard electroless nickel gave no increase in rate of fuel

decomposition above that for a similar untreated deposit. The rate for

Teflon coated Maraging steel decreased to about one-half its initial

value indicating decreasing reactivity of the coating or its components

with time.

2. Results of experiments on kinetics of fuel decomposition

a. Effect of porosity of coatings

The activity of the cadmium-plated Maraging steel containing

synthetic pores and of the half-plated specimen decreased further, confirming the. protective action of the cadmium. A Maraging steel specimen

with one-half plated -with electroless nickel was put under test.

b . Effect of ratio of metal area to fuel volume

No significant changes were observed for units for which the

range of area to volume was from 0.5 to 6.8, having rates still in the

normal range for nickel.

3. Decomposition of Aerozine-50 fuel at l60°F

The background rate for this fuel decreased by a factor of over

40 percent for the period. Two units, one containing Teflon coated

7075-T6 aluminum and one Maraging steel were disassembled and the fuel

replaced to see if the high rate is confirmed with the new change of

fuel.

4 . Exposure of materials to oxidizers at l60°F

The pressure in units containing IRFNA increased sharply near the

end of the quarter and they were disassembled and the oxidizer replaced.

Slight increases in rate were shown by -units containing NTO.

5 . Examination of specimens and MHF-3 fuel after tests at l60°F

Both specimens examined were bare lQ% Maraging steel. One had

been exposed to fuel in a stainless steel bomb and one in a glass test

unit. There was no apparent attack of the surface and negligible weight

2

loss but microscopic examination of the surface revealed coloration

believed to be oxide.

Salts in the fuel were about three times greater for the fuel in

the stainless steel bomb unit than for that in the glass unit, indicating

pick up from the walls and ^ fittings of the bomb.

C. Progress During Current Report Period

1. Decomposition of MHF-3 fuel in contact with various

materials at l60°F

a. "Background" rate

The average rate of evolution of gas from MHF-3 fuel in blank

(no specimen) mercury manometer test units Hg-2 anc( Hg-lp has decreased

3 slightly from 0.00^1 cm /day at the end of the preceding quarterly period

3 to 0.0039 cm /day for the present period,

b . Effects of various metals

Table 1 and Figure 1 contain the cumulative results to the

end of December 1968. The relative reactivity of the various specimens

is as follows

Low activity : silver, cadmium, 50/50 lead-tin solder,

electroless nickel (standard acid bath), zinc, tin-nickel

alloy, tin, 3^7 stainless steel, tungsten, aluminum, lead,

titanium alloys 6A1-4V and 3Al-llCr-13V , and Teflon coated

Maraging steel.

Moderate activity : gold, nickel, stainless Maraging steel,

electroless nickel (Prop, borohydride bath) , and chromium.

High activity : cobalt, lQ% Maraging steel, molybdenum,

iron, AM 355 stainless steel, electroless nickel (alkaline

bath), Inco-7l8.

3

(l) Behavior of recent units

. I //

/

The units listed in Table 1 containing AM 355 stainless

steel (Hg-44, Hg-54) and stainless Maraging steel (Hg-43, Hg-55) are

still giving considerably different rates of reactivity for comparable

units. The third unit for 'each type of steel, under test during the

past quarter, gave no confirmation of the rates previously obtained.

There is some indication that variation in the oxide film on the specimens may be responsible for different rates of fuel decomposition for the

same type of steel.

(2) Oxidized metals

Three specimens were oxidized in air. at a low temperature (about 300 °C) for several hours until the clean metal surface had

acquired a light straw-colored film. The metals were AM 355 stainless

steel, electrolytic nickel and stainless Maraging steel. These specimens were set up in units Hg-745 75, and 76 , respectively. Although the

units have been under test for too short a time to obtain confirmed results , initial indications are that the thermally oxidized surfaces of

AM 355 stainless steel and nickel are considerably less reactive with

MHF-3 than clean or chemically oxidized surfaces.

( 3 ) Other new tests

Test units containing solid electroless nickel and

solid electroplated cadmium are being set up at the request of Mr. Ng of

Picatinny Arsenal. Four other test units containing phosphatized Maraging steel, Maraging steel oxidized in air, thin (O.OOCl") cadmium and

electroless nickel plated on Maraging steel will soon be ready for test.

k

/ .

•

/

2. Results of experiments on the kinetics of fuel decomposition

a. Effect of the porosity of coatings

There was a further decrease in the rate of fuel decompos

of the cadmium plated Maraging steel specimen with one-half of the Maraging

steel surface exposed (Hg-5l) and the cadmium plated Maraging steel specimen

with "pores" drilled to expose the Maraging steel (Hg-63)* This indicates continued excellent protection "by the cadmium in electrical contact with the exposed areas of Maraging steel.

The specimen consisting of electroless nickel on Maraging

steel with one-half of the Maraging steel surface exposed (Hg-Tl) gave

a higher rate during its first period of testing than that for either

Maraging steel or electroless nickel alone.

"b . Effect of ratio of metal area to fuel volume

Continued observation of units listed in Table 3, for which

there is a range of area to volume of 0.5 to 6.8, has shown no significant changes. The rate coefficients are still in the normal range for

nickel, independent of the variation of the area to volume ratio.

During the current period, data have been obtained on the

rate of fuel decomposition in a unit in which a large area of electroless nickel of the standard type is exposed to fuel (Unit No. 70,

Table 3). The area to volume ratio in this unit is 6.0, in comparison

with the ratio of 0.5 and 0.8 in units 4 and 12 which were tested early

in the program. In spite of the large variation of A/V, the rate coefficient is nearly the same for the three units, namely, 0.0017, 0.0016,

5

3 2

and. 0.0012 cm /day/ cm , respectively. Thus, the independence between

the rate coefficient and A/V is confirmed for another kind of metal.

3. Decomposition of Aerozine-50 fuel in contact with

various materials at l60°F

Results of the exposure tests are given in Table 4. The background rate for this fuel in a test unit without a specimen has conti n2 ued to decline from a previous value of 0.0087 cm /day to 0.0063. No

new data are given for Maraging steel (Hg-59A) and Teflon coated aluminum (Hg-69A) . Although the units were disassembled and reassembled

with new fuel the fuel decomposition rates were still so high that reliable readings could not be obtained.

4 . Exposure of various materials to oxidizers at l60°F

Results of the nine bomb-type test units are given in Table 5

and Figure 2. The two oxidizers used are NTO (nitrogen tetroxide inhibited with 0 . 6+0 . 2% of nitric oxide) and IRENA (red fuming nitric acid

inhibited with 0 .^+0 .!% of hydrogen fluoride).

During this period the units containing IRFNA again underwent

a rapid increase in pressure 60 to 90 days after the oxidizer had previously been renewed. Renewal of only the inhibitor did not retard the

reaction, probably because of the metal salts in solution. Apparently

the inhibitor is gradually consumed at the l60°F test temperature and

then attack on the walls and fittings of the bomts causes the sharp pressure rise and build up of salts ih the oxidizer. Renewal of the complete

oxidizer after cleaning the unit , including the fittings, restores the

original rate of pressure rise. It is apparent that at the test

6

temperature of l60°F, inhibitor is consumed fairly rapidly and that

after 60 to 90 days, severe attack of stainless steel occurs. Since

the ratio of the area of the specimen to that of the stainless steel

of the bomb is small, it becomes impossible to reliably evaluate the

rate of gas formation due to contact of the oxidizer with the specimen.

The latter effect is swamped by the much larger factor of attack on the

bomb. At the end of some period, corrosion of the specimen can be evaluated, but even this might be affected significantly by presence in the

oxidizer of salts derived from the bomb.

It thus appears that a different test method for evaluating

v IRFNA must be developed.

D. New Work

1

' Tests of special metals

About a dozen modifications of, or coatings on, metals of special

interest are being readied for test. Other metals and coatings will be

set up for testing as requested.

2. Tests with oxidizers

The NBS Safety Office has furnished material containing directions and safety precautions for handling CTF (chlorine trifluoride)

oxidizers and does not object to the use of small quantities in the

laboratories. Tests using this oxidizer can start when the materials to

be tested are decided upon and test units are available.

3 . Examination of terminated units

Fuel and metals in units for which there is no need for further

testing will be examined as necessary.

7

*+• Coating fuel tanks

Two one-half scale fuel tanks have been modified in the NBS shops

and are now being heat treated. They will be plated, one with electroless nickel and one with cadmium, when shop work has been completed.

8

TABLE 1

Summary of Test Data for Materials

Exposed to MHF-3 at l60 °F

* * Test

unit

number

Specimen Area of

specimen

cm2

Time

under

test

days

Gas

evolved

3 cm 0

Rate

coefficient

cm3 / day/ cm2 previous present

Calculated

tank pressur

after 1 year

psig

Hg-2

Hg-15

Background

Background

-)

) av. —

771 2.81 0.0041 0.0039 —

Hg-12 Electroless

nickel

22.2 696 15.1 0.00098 0.00098 10

1 Hg-lU 347 Stainless

steela 13.2 705 0 0.00004 Zero Zero

I Hg-l 6 Cadmium (thin) 9.4 678 7-9 0.001 0.0012 13

Hg-22 Silver (thin) 16.0 629 104.2 0.0089 0.0104 109

H'g-27 Cadmium (thin) io .6 537 5-2 0.0010 0.0009 10

Hg-28 347 Stainless

steela 6.5 533 7.1 0.0023 0.0020 21

Hg-29 Silver 14.5 534 1.8 0.0002 0.0002 2

Hg-30 Titanium8' 5

"'3 (l3V,llCr.3Al)

15.0 364 0 Zero Zero Zero

Hg-31 Cadmium 14.7 522 0.6 0.00005 0.00008 1

Hg-32 Tin 13.0 524 23.6 0.0038 0.0035 37

Hg-33 Solder 50/50

lead-tina 15.3 522 Zero Zero Zero Zero

Hg-39 Inco 7 l 8a 12.0 390

XX

180.7 0.1001 0.1120 1183

Hg-43 Stainless Maraging steela 15-0 434 37-5 0.0060 0.0058 6 l

Hg-44 Stainless steel

type AM 35

a 11.4 306

^

133.9 0.0792 0.0883 932

Hg-45

o Titanium alloy

( 6ai, 4v)

13.3 386 Zero Zero Zero Zero

Hg-48 Aluminum^ 5 C 12.5 383 0.7 0.00022 0.00015 2

9

TABLE 1 (cont.)

Summary of Test Data for Materials

Exposed to MHF-3 at l60°F

Test

unit

number

Specimen Area of

specimen

cm2

.

Time

under

test

days

K Gas

evolved

3 cm 0

* Rate

coefficient

cm 3 /day/ cm2 previous present

Calculated

tank pressui

after 1 yeai

psig

Hg-49 Electroless

nickel

(Alkaline bath)

12.6 369^ 152.4 0.236 0.228 2409

Hg-50 Chromium 17.0 390

XX

91 0.0203 0.0199 210

Hg-52 Electroless

nickel

(Alkaline bath)

13.0 228

XX

39.7 0.0303 0.0187 197

Hg-54 Stainless steela AM 355

11.5 306

^

57.7 0.0198 0.0335 353

Hg-55 Stainless Maraging steela 16.6 306xx

63.1 0.0203 0.0176 186

Hg-57 Nickel i4.o 313 21.8 0.0067 0.0050 53

Hg-58 Electroless 14.2

nickel (Propri-

( Proprietary horohydride

298 83 0.0184 0.0196 207

Hg- 6l Electroless

ni ckel

(Heated to 800°C)

12.2 229 3.1 0.0011 0.0011 12

Hg-68 Teflon (on

Maraging steel)

lk.2 198 11.4 O.OO 58 o.oo4i 43

Cumulative total, corrected for "background rate and to 1 atm. pressure.

Based on a tank in the form of a cube, 1 cu. ft. volume, 10$ ullage.

XDiscontinued

XX

Total days under test are not equal to number of days during which gas was collect

due to temporary leaks, or to interrupted collection due to high rate. aThese specimens are solid metal. All others are coatings on 18$ Maraging steel.

^Titanium alloy, 13$ V, 11$ Cr, 3$ Al. Similar to alloy B120VCA.

QVapor-deposited foil from Commonwealth Scientific Corp.

10

TABLE 2

Data on Decomposition of MHF-3 Fuel at l60°F

in Special Test Units

Effect of Porosity in Coatings of Cadmium on Maraging Steel

Test Time Gas

* Rate

unit under evolved coefficient

number Description test cm 3 /day /cm2 days cm3 previous present

Hg-51 Cadmium on Maraging steel

with 1/2 of MS surface

exposed - 8 cm2

339 27-8 0.012 0.013

Hg-63 Cadmium on Maraging steel

with 200 0 . 026 " diam.

218 6 ** 0.03 0.027

pores. MS area 1.04 cm2

Hg-71 Electroless nickel on 13 55-6 0 0.355

X

Maraging steel with 1/2 of

MS surface exposed - ih cm2

*Rate coefficient is calculated on basis of exposed Maraging steel only.

**Rate coefficient based on pore area: 1.0U cm 2

.

"^Highest rate for either Maraging steel or electroless nickel alone was 0.098.

11

TABLE 3

-pao

CMSO

eOO c— VO CM

O ON CO -d OO 1—

r

—

1—

•H CD

rtf U-N LTN VO LTN oo o o o P O O o O o o o o Pi • « • • • • 0Oo 3

cm o o o o o o o o

fd oo

VOHd 0 0 !> d H O O

i>0)

ooS

.0

£— E- uo oo 00

oo 1—1 VO -d o\ t— 00 CM 00 i—

(—

CM lr\ i

1 • • • 1 1 LT\ 1 1 i—

i—

rHO>0d

P"H

d 0s 0

'd

-p0

in ON OO C\J 00

•H

d 0 aj CM LTN -3" CO

EH 3 -P r—

CM

VO CM

LTN VO

-d

CO VO

EP ON -d VO

O

-pd03

<|> E— CO VO lr\ CO o LTN CO • • * • • • • O oo VO 00 o 1—1 vo o o i—

d

-P

(l) SPoO

•H

-pdK < 1—

—d cm o O o vo CM CO

VO

On

CM

CM

-P

d S o O o 1—

CO

O i—

CM 0 0 a S d H i—

rH

H POdo

°H

-pd

•H>PO

-Po0PPW

O ..—. •H >_ -p

p- •H 0 d

CJ *3 0 r—

0 O n >

EDdHoo

•H co d 6 a1 o

•H

pi

d

d -P O 0s O co t— t"- LON CM

Pi S • • . • d O LT\ co VO OO > i—

rH CM -d

vo

E- -d

On

LTN

E— VO 0O CM LTN CO ld- ON

CM

r

—CM oo -d l—

00 CM

d

r

1 d

d

O *H o O O

r

—

Or

—

1—1 d 0 0 0

Pi 0 Pi PI

H CJ

d o 0 0 O O O O •H •H •H •rH Pi -p -p -p -P d £ d m d a -p -p •p •P

•rH •H •H •iH •rH

r

—

•H

r

—

r

—

'd cd

Mw

d •H

-p -P 0 vo LTN vo VO d; o CM 0 •H rg -d VO vo CM i E

-d i

1 0 - d 1 1 1 1 e— 1 1 1 Eh p P ED ED ED <L| -d ED ED hD d M K W Cd 00 Id W d

12

sheet

TABLE 4

Test Data for Materials Exposed to Aerozine-50

at 160 °F

* * Test

unit

number

Coating

or metal

Area of

specimen

cm2

Time

under

test

days

Gas

evolved

cm 3

Rate

coefficient

cm 3 /day/ cm2 previous present

Calculated

tank press

after 1 ye

psig

Hg-53A' 301 Stainless

steela (cryogenic form)

14.7 154 65.6 0.0257 0.0290 306

Hg-56A None

(Background)

276 1.73 0.0087- 0.0063 —

Hg—59A Maraging steel

steela ’ b

15-2 0.8 41.2 — 3.39 35,760

Hg-60A g Titanium lU.5 278 Zero Zero Zero Zero

Hg-62A Teflon (TFE)

a 17-5 278 0.1 0.00003 0.00002 Zero

Hg-69A Teflon coated

7075-T6 Alb

14.2 0.33 9.4 — 2.01 21,170

* Cumulative total, corrected for background rate and to 1 atm. pressure.

Based on a tank in the form of a cube, 1 cu. ft. volume, 10 % ullage.

cLAChes e specimens are uncoated, solid material.

Gas evolved too rapidly to obtain accurate reading this quarter.

13

TABLE 5

Results of Tests of Materials Exposed to Oxydizers

at l60 °F in

Stainless Steel Bomb-Type Test Units

* * ** Bomb Specimen Area of Time Gas Rate Calculated

unit

number

specimen

2 cmr

under

test

days

evolved

3 cm 0

coefficient

cm 3 /day/ cm2 previous present

tank pressur

after 1 year

psig

Inhibited red fuming nitric acid

RFN-1 Teflon (TFE) 14.5 145 15.5 0.0189 0.0074

xx

78

RFN-2 Stainless steel

(301 Cryogenic form

aged)

l4 .

153 9.4 0.0135 0.0042 44

RFN-3 Maraging steel 13.6 158 Zero Zero

1 Zero Zero

RFN-4 Teflon on 6061-T6 A115-1 165 6.5 0.0012 0.0026 28

RFN-5 None (Background) — 32 1.27 — 0.038 —

Nitrogen tetroxide

301-NT0X Stainless steel

(301 Cryogenic form

un- aged)

338 210 Zero Zero Zero Zero

NT0-1 None (Background) — 115 5-8 — 0.0417 —

NT0-2 Teflon (TFE) 19.9 184 24.1 0.0120 0.0066 69

NT0-3 Stainless steel

(301 Cryogenic form

aged)

14.7 207 3-8 0.0028 0.0013 13

NT0-4 Maraging steel 13.6 180 2.4 0.0015 0.00099 10

NT0-5 Titanium

(6ai, Uv)

13.4 77 1.0 0 0.00097 10

Cumulative total, corrected for background rate and to 1 atm. pressure.

Based on a tank in the form of a cube, 1 cu. ft. volume, 10 % ullage.

X

Tested at 90°F.

These lower rates for IRFNA 'were obtained after a sharp pressure rise due to

attack on the surface of the bomb by the oxidizer because of apparent depletion oj

the inhibitor at l60°F required replacement of the oxidizer and inhibitor as ex- plainted in the text.

14

i

Rete

of

gas

evolution

from

MHF-3

in

contact

with

indicated

metals

and

Teflon

at

l60°F.

301

Stainless

steel

(90°F)

Cumulative

gas

evolution

as

indicated

by

pressure

increase

resulting

from

contact

of

above

materials

with

NTO

and

IRFMA

at

l60°F.