NATIONAL BUREAU OF STANDARDS REPORT

9834

SURFACE PROTECTION OF MARAGING STEEL

QUARTERLY PROGRESS REPORT No. 9

January 1 to March 31, 1968

Picatinny Arsenal Project

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

To

.Commanding Officer

Picatinny Arsenal, Dover, N. J. O 78OI

Attn: Code SMUPA DL-2

Liquid Rocket Propulsion Laboratory

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

For
THE NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards 1 provides measurement and technical information services

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NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT

31201+65 April 1, 1968

NBS REPORT

9831+

SURFACE PROTECTION OF MARAGING STEEL

BY

'

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

QUARTERLY PROGRESS REPORT No. 9

January 1 to March 31, 1968

for

Picatinny Arsenal Project

Order No. Al-S-RFOS^-Ol-Dl-GG

to

Commanding Officer

Picatinny Arsenal, Dover, N. J. O 78OI

Attn: Code SMUPA DL-2

Liquid Rocket Propulsion Laboratory

IMPORTANT NOTICE NATIONAL BUREAU OF S'

for use within the Government, and review. For this reason, tf whole or in part, is not autho Bureau of Standards, Washingti

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

»ss accounting documents intended

subjected to additional evaluation

! listing of this Report, either in e Office of the Director, National

by the Government agency for whjch

:opies tor its own use. <NB^>

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

SURFACE PROTECTION OF MANAGING STEEL

A. Objectives of Project

1. To investigate the effect of various metallic coatings on

Maraging steel for their ability to protect the steel from contact with

mixed hydrazine fuel, for their ability to resist corrosion by mixed

hydrazine fuel, and for freedom from catalytic effect on the decomposition of mixed hydrazine fuel.

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. "Background" measurement . The background rate obtained

from the mercury manometer units decreased slightly from 0.0058 to

0.0050 cm^/day.

b . Decomposition rates due to various metals at l60°F . Dat

a

for units previously on test show little change in trend for the most

part. However, there was a small increase in rate for Hg-22, containing

a specimen coated with a thin silver deposit. The increase may have

been due to porosity in the silver coating. Also, a nearly doubled rate

for PA-26 (nickel) was believed due to stopping of a previous leak. A

number of new units had been put under test but data from them were not

presented because of the shortness of the test period.

1
, *
2. Results of experiments on kinetics of fuel decompositions .

a. Effect of porosity of coatings . The rate coefficients,

based on the areas of Maraging steel exposed through pores in silver

coatings, increased a small amount but maintained nearly constant ratios.

b. Effect of area of glass and fuel volume . The continuing

results confirm the earlier conclusion that the rate of decomposition

of fuel depends primarily on the volume of the liquid phase. Decomposition in the vapor phase and/or at the glass-vapor interface apparently

does occur but at a much smaller rate

.

c. Effect of contact between metal and fuel vapor . Rate of

decomposition of fuel due to contact of vapor with Maraging steel (Unit

Hg-38) increased gradually from a very low initial value to a rate approaching one-half that for Maraging steel in contact with liquid fuel.

Condensation of liquid on the specimen was suggested as an explanation

of the effect.

3. Plating of cylindrical Maraging steel tanks

Two tanks, 26 inches long by 3.^6 inches ID, were plated for

testing at Picatinny Arsenal. One was plated with electroless nickel

and one with cadmium.

C. Progress During Current Report Period

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

materials at l60°F .

a. "Background" rate . The rate of evolution of gas from

MHF-3 fuel in "blank" mercury manometer test units has continued a slow

2
» * . »
3

decrease. The average is now 0.0044 cm /day for units Hg-2 and Hg-15

,

down from 0.0050 cm /day at the end of the preceding quarterly period.

b. Effects of various metals . Tables 1-3 show the cumulative

results to the end of March 1968. The relative reactivity of the various metals is as follows:

Low activity: silver, cadmium, electroless nickel, zinc,

tin-nickel alloy, tin, 347 stainless steel, 50-50 leadtin solder, tungsten, titanium-6 A1-4V, aluminum foil,

titanium-3Al-llCr-13V

.

Intermediate activity: gold, lead, nickel, chromium,

stainless Maraging steel.

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

iron, AM 355 stainless steel, electroless nickel (borohydride), electroless nickel (alkaline bath), Ineo-7l8.

The relative activity of a metal or coating in contact with

fuel is not an indication of its corrosion resistance to fuel. Some of

the metals, such as molybdenum, induce a high rate of decomposition of

fuel but are not corroded. Others, particularly zinc, cause fuel to decompose at a low rate but are severely corroded. Details on corrosion

are given in the following section on the examination of exposed specimens (par. C-5)«

The behavior of the Type AM 355 stainless steel, and of the

electroless nickels prepared from the borohydride and alkaline types of

plating baths require special comment.

(l) Type AM 355 stainless steel . The decomposition rate

coefficient reported last quarter (Test Unit Hg-44, Table l) , based on

3 2 only 22 days exposure, was 0.0084 cm /day /cm , higher than found earlier

for type 347, hut not excessive. However, during the past quarterly

3
'
period the rate has accelerated markedly, with an average coefficient to

March 31, 1968 of 0.066 cm /day/cm . We do not know the cause. One may

hypothesize the following: (l) The passive film has been lost; (2) Some

constituent, perhaps by exposure due to loss of the passive film, has a

specific accelerating action (molybdenum?). A duplicate of Hg-^4,

No. Hg-5^, has been set up and is yielding essentially the same initial

3 2

rate as did Hg-44; namely, a coefficient of 0.0087 cm /day/cm for the

first 27 days.

(2) Electroless nickel deposited from the borohydride

type bath . The first unit prepared with borohydride electroless nickel

contained a specimen plated by a process that is reported to result in

incorporation of several percent of boron in the deposit [Narcus

,

Plating 94, 380 (1967)]* It was extremely active, with a coefficient

3 2

of gas evolution at room temperature of 0.31 cm /day/cm ; at l60°F gas

was evolved so rapidly that measurements could be made only over a period

2 3 of a few minutes. The 15 cm specimen caused evolution of 8.7 cm of

3 2

gas in 12 minutes, leading to a coefficient of 71 cm /day/cm , or a calculated tank pressure (per Table l) of 752,000 psi in one year.

'

In view of this unexpected result we decided to try a proprietary borohydride type electroless nickel that is reputed to give

a nearly pure nickel deposit, i.e. nearly boron-free. The results,

based on only 27 days exposure, are shown in Table 1, Unit No. Hg-58 . 3 2 The coefficient of 0.0l8 cm /day/cm is reasonably comparable to our

results for pure nickel.

(3) Electroless nickel deposited from the alkaline type

plating bath. This type of electroless nickel is also highly active,

based on 29 days exposure.

We do not consider the results described above for the

boron-containing electroless nickel or for the deposit from the alkaline

bath to be final without further checking. However, they do indicate

that some factors not now known may cause high decomposition rates,

and serve as a warning that processes or procedures that are superficially similar to acceptable ones may not be trusted without investigation.

Other units in Table 1 placed under test this period,

but not already referred to, are Hg-55 (stainless Maraging steel) and

Hg-57 (nickel electroplated on Maraging steel).

2. Results of experiments on the kinetics of fuel

decomposition .

a. Effect of porosity of coatings . Data on the effect of

synthetic pores in silver coatings on Maraging steel are given in

Table 1+. There has been no significant change from the rate coefficients

given in our. preceding report (No. 8). Hence, the conclusions stated

there still hold; • namely , that the rate of fuel decomposition is roughly

proportional to pore area, and that the silver in the silver-Maraging

steel couple appears to have a marked effect on accelerating the rate at

the exposed Maraging steel. Nevertheless, the exposed area is so small

that the high specific rate is not significant.

5
4

-
An additional unit that has been set up and is now undergoing

leak-checking contains a similar synthetic pore specimen with cadmium

as the coating metal.

Unit Hg-51, in Table k, is also related to these porosity

tests. Since, as has previously been discussed, it appears that a bimetal electrolytic effect may be a factor in both gas evolution and

basis metal corrosion, the specimen in Unit Hg-51 was designed to test

this effect. The specimen, approximately ^ cm long, was prepared by

plating one end, approximately one-half the total surface, with cadmium.

The most distant point on the exposed Maraging steel is thus about 2 cm

3 2

from the cadmium. The rate coefficient of 0.017 cm /day/cm , based on

exposed Maraging steel, is only one-fourth to one-sixth that for Maraging

steel alone (Unit Hg-23, Table 1; 3^7-^ s Table 3). Hence, the cadmium

appears to have a marked inhibiting action over a considerable distance.

b . Effects on fuel decomposition of (a) areas of glass or

metal exposed to liquid and vapor and (b) fuel volume . The results for

experiments designed to show the effects of glass or metal areas and fuel

volume are given in Table 5* Rate coefficients for units Hg-35 and Hg-37

have decreased, but the general conclusions reached previously are unchanged. The coefficient for Hg-35 is now very close to that for Hg-2

and Hg-15, with nearly the same volume of fuel. It is decreasing, approaching the latter with increased time, in line with the behavior of

Hg-2 and Hg-15 . This low rate occurs even though the glass-vapor

area in Hg-35 is five times that in Hg-2 and Hg-15 , indicating that the

decomposition at the glass-vapor interface is negligible.

6
'

,
The rate for Hg-36 is still about five times that for Hg-2

and Hg-15 , and the ratio of fuel volumes is also 5, indicating that the

homogeneous liquid phase decomposition is predominant. In Hg-36, the

six- fold increase in glass-liquid interface (in comparison with Hg-35)

could be the important factor in increasing the rate. However, this

is ruled out by the comparison between Hg-36 and Hg-37* In the latter

set the glass-liquid areas are the same,but the fuel volume is one-half

as large in Hg-37 as in Hg-36, while the rate is decreased correspondingly

by a factor of 2.J. Thus, while the ratios are not quantitatively comparable, they are close enough to what would be expected on the basis of

liquid-phase decomposition to show that the latter is the dominant factor.

c. Effect of contact between metal and fuel vapor . The rate

of decomposition of fuel where the Maraging steel is exposed only to the

vapor phase (Hg-38, Table 5) has increased again this quarter to a value

approximating one-half that of Maraging steel in liquid fuel. This indicates that condensation of liquid on the metal surface becomes an increasingly important factor with increase in time.

d. Effect of ratio of metal area to fuel volume . Four test

units with large areas, respectively, of electroless nickel and of pure

nickel in contact with fuel and with varying fuel volume were prepared

during the preceding quarterly period and partial preliminary data were

shown in Table 6, Report No. 8, January 1, 1968. Their performance has

been erratic with the result that no conclusions can be drawn. It was

found on review that the metal surfaces were prepared with hydrochloric

7
.

*4
acid as a cleaning dip rather than nitric acid, normally used for these

metals. Nitric acid is normally used because of its passivating effect.

Conyersely, hydrochloric acid removes the passive film from these

petals, This may be a factor in their erratic effect on fuel decomposition, New units will be set up that avoid this uncertainty.

3. Decomposition of Aerozine-50 fuel in contact with

various materials at l60°F .

At the request of Mr. Wahling Ng of Picatinny Arsenal, tests

haye been started on exposure of several materials to Aerozine-50 fuel.

Four test units contain, respectively, type 301 stainless steel-cryogenic

form, titanium (6A1 , bV) 9 lQ% Maraging steel, and Teflon (TFE). One unit

contains only Aerozine^-50, for the purpose of determining the inherent

decomposition rate of the fuel itself. Tests have been underway for too

^hort a time to generate meaningful results.

H. Exposure of various materials to oxidizers at l60°F . The program has been expanded, at the request of Mr. Wahling Ng,

Of Picatinny Arsenal ? to include the exposure of various materials to

oxidizers used with rocket fuels. The purpose is to determine rates of

corrosion of the materials and rates of decomposition of the oxidizers.

The oxidizers to be tested are IRFNA (red fuming nitric acid inhibited

Vith Q.J +_ 0.1% hydrogen fluoride 1 and NTO (nitrogen tetroxide containing

0,6 +_ 0,2% nitric oxide}. Because of the high vapor pressure of the NTO

at test temperature Cabout 100 psi) it is necessary to use bomb-type test

Units, Four units have been purchased, including accessory equipment...

such as valyes and gages, but delivery of only two is complete. These

*Aged type.

8
'
are now "being leak-tested at 300 psig, Leaks that occurred initially

appear to have "been eliminated hy gasket modifications. They will "be

loaded with test materials in the near future. The test materials to

be subjected to oxidizer exposure are as follows:

IRFNA: Teflon,, bare Maraging steel

NTO: Teflon, bare Maraging steel, and Type 301

cryogenic form stainless steel

5 . Examination of specimens and MHF-3 fuel after

tests at l60°F .

The results of the examination of specimens and fuel removed

from the units dismantled during the present quarterly period are summarized in Table 6. Photomicrographs of cross-sections of the various

metals after exposure are shown in Figures 1 to 13.

a. Corrosion of metals . Of all the metals so far examined

after exposure at l60°F, only zinc and nickel underwent extensive corro

sion. All of the others showed either no loss of weight or, at most, a few milligrams, corresponding to thickness loss of a few microinch (e.g

the thickness corresponding to U.8 mg loss of silver, Unit No. 3^A, is

12 microinch, However, part of this loss was probably mechanical and

part due to dissolving of the underlying Maraging steel.)

.

There is no correlation between activity of a metal in accelerating decomposition of fuel and corrosive attack of the metal. Thus,

bare molybdenum, one of the most active decomposers, was uncorroded,

while zinc, one of the least active with respect to fuel decomposition,

was severely corroded.

9

Zinc was also most severely corroded at room temperature Csee

preceding report). Cadmium was less corroded at l60°F than at room

temperature. Figure 5 shows that it underwent some pitting attack.

Weight loss data for cadmium and electroless ::nickel (Units Hg-3 and

Hg-U) are not given because these coatings were partially amalgamated.

Accidental amalgamation spoiled a few early tests. This difficulty

was eliminated by use of the glass frit shown in Figure 3, Report No. 7,

October 1, 1967

,

Data on corrosion of nickel is contradictory. The specimen

in Unit No. 316-1 showed little attack. This was a welded specimen, and

no effect of the weld on the coating was seen. On the other hand, the

nickel coating in Unit No, 3^7-Ni was yisibly etched where it had been

in contact with liquid fuel. Weight loss could not be determined

because the outside of the tube was severely corroded from submersion

in the water bath. However, the high concentration of salts in the

fuel, together with the dark green color of the fuel, are evidence that

considerable corrosion .of the nickel occurred. This unit (similar to

Figure 3, Report No, 1, April 1, 12661 was sealed with end plugs made

of aluminum, It is possible that the aluminum in the a.luminum-nickel

couple had an accelerating effect on the corrosion of the nickel. In

Unit No. '316-1 the nickel was in the form of a strip specimen, electrically insulated from the stainless steel bomb by placement in a glass

cup liner.

10

The silver plates in Units 3^A-D (Table h and Table 6 )_ vere

coated with a hard yellow film which was difficult to remoye. Crosssections of the ’’pores” on these specimens showed some under-cutting of

the silver deposit due to dissolving of the underlying Maraging steel

close to the interface (Figure 13), but yery little attack of the exposed Maraging steel at greater distance from the silver.

b . Effects on MHF-3 fuel caused by exposure to -the metals

in the test units . The concentrations of salts dissolved in the fuel

were determined by evaporating a known volume of fuel and weighing the

residue. Because of the small weight-loss of most of the metals or

coatings one would expect to find only small amounts of salts in solution in the fuel. This was the case as seen in Table 6. A determination of the dissolved solids in the original fuel yielded- a value of

0.0U g/l. Hence, the amounts shown are in no case worth. special comment except in the case of Unit No. 3^7*~Ni. The latter has already

been discussed in the preceding paragraph C>5a (p. 10).

Salts that were obtained from the fuel, combined with what

could be scraped from specimens, were tested for detonability , with

negative results.

11

D. New Work

1. Tests of special metals . Duplicates and modifications of a number of the specialinterest metals are now being put under test. These tests include

nickel and modifications of electroless nickel, such as heat-treatment

and special cleaning before exposure,

2. Tests with oxidizers

In addition to the units described aboye in paragraph k

,

several stainless steel bombr-type units, similar to No. 316-1, are being

made in the NBS shops for use with IRFNA, A small tank (8 M x 2” diam.

)

made with cryogenic form type 301 stainless steel was supplied by

Picatinny Arsenal. It is to be assembled with fittings and pressure

gage and tested with NTO at 90°F. A specimen of 6o6l-T6 aluminum alloy

coated with Teflon was also supplied for exposure to either IRFNA or

NTO at l60°F.

3 . Other specimens supplied by Picatinny Arsenal

a. One specimen of Maraging steel coated with Teflon, to be

tested in MHF-3 at l60°F.

b. One specimen of 7075 aluminum alloy coated with Teflon,

to be tested in Aerozine^-50 at l60°F.

k. Examination of terminated units

Units for which there is no need for longer testing will be

dismantled and examined as time permits. Howeyer, it has been requested

by Mr. Ng, of Picatinny Arsenal, that materials which show promise

*Unaged type.

12
-

*
remain under test for up to three years , This will alter our planned

termination schedule and will result in a larger number of units under

test

.

13

*

t

<
TABLE 1

Summary of Test Data for Materials Exposed to MHF-3 at l60°F

Test

unit

number

Coating

or

metal

Area of

specie

men

cm^

Time

under

test

days

Gas*

evolved

3

cm

Rate*

coeffi

cient

cm3/day/ cm2

Calculated**

tank pressure

after 1 year

• xxx

Psl g

present previous

Hg-lX Silver 16.0 123 None Zero — None

Hg-3X

Cadmium 21.7 V73 8.6 0.0014 0.0016 15

Hg-U

X Electroless

ni ckel 19.6 458 14.5 0.0016 0.0016 17

Hg-5

X

Tungsten 24.8 358

xx

46.0 0.0051 0.0052 54

Hg-6

x

Gold 22.9 222 49.0 0.0095 — 94

Hg-f Zinc 15.6 34l

XX

15.4 0.0029 0.0030 31

Hg- 8

X Tin-nickel

alloy (65-35)

24.0 358

xx

51.0 0.0060 0.0057 63

Hg-9

X

Cob alt 16.1 199^ — 0.94 — 9,900

Hg-llXTin 15.2 432 Zero Zero Zero Zero

Hg-12 Electroless

ni ckel 22.2 432

xx

10.4 0.0011 0.0012 12

Hg-13X Cadmium 3.5.5. 85 1.0 0.0019 — 20

Hg-Ht 347 Stainless

steela 13.2 429 Zero Zero 0.00006 Zero

Hg-l6

Cadmium . ' (thin) 9.4 311 0.2 0.0001 0.00007 1

Hg-22 Silver

(thin) 16.0 367 39.0 0.0066 0.0058 70

Hg-23 18$ Maraging

steela 17.0 371** 485 0.097 0.098 1,030

Hg-2U Si Molybdenum 4.8 368

^

217 0.123 0.135 1,300

Hg-25 Iron

9, 4.4 365**

60 0.037 0.045 390

Hg-2T Cadmium

(thin) 10.6 263 1.9 0.0007 0.00066 7

Hg-28 347 Stainless

steel3. 6.5 261 5.1 0.0030 0.0013 32

Continued
TABLE 1 (cont'd.)

Summary of Test Data for Materials Exposed to MHF-3 at l60°F

Test Coating Area of Time Gas* Rate* Calculated**

unit or

specimenunder

test

evolved

0

coefficient

tank pressure

after 1 year

number metal cm^ days cm cm3 /day/ cm2 psig

present previous

Hg-29 Silver 14.5 263 Zero Zero Zero Zero

Hg-30

b Titanium3, (l3V,llCr ,3Al)

15.0 93 0.3 0.0002 — . 2

Hg-31 Cadmium 14.7 245 Zero Zero Zero Zero

Hg-32 Tin 13.0 263^ lU.7 0.0045 0.0049 48

Hg-33 Solder 50/50

lead-tina 15-3 245 Zero Zero Zero Zero

Hg-39 Inco 7l8

a 12.0 109 120 0.092 0.067 970

Hg-1*3

Stainless Maraging steel3. 15.0 l6l 17.4 0.0072 0.0097 76

Hg-44 Stainless steel , type AM 355 a 11,4 114**

7^.0 0 .066 0.0084 670

Hg-45 Titaniuma alloy , 6A1 , 4V

13.3 115 Zero Zero Zero Zero

Hg-48 Aluminum3 12.5 107 . 0.8 0.0006 — 6

Electroless

Hg-1+9 Nickel ( Al— • kaline bath)

12.6 29 84.0 0.23 2,400

Hg-50 Chromium 17.0 115 24.0 0.012 0.013 130

Hg-5lt

Stainless8- steel AM 355

11.5 27 2.7 0.0087 — 92

Hg-55 Stainless Maraging steel3 l6 . 6 27 10.3 0.0230 — 243

Hg-57 Ni ckel i4.o 27 3.8 0.0101 — 106

Hg-58

Electroless nickel (Proprietary

- borohydride

)

ib .

2

27 6.8 0.0177 — 187

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.

^Dis continued.

XX

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

was collected, 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.

Vapor deposited foil from Commonwealth Scientific Corp.

TABLE 2

Results of Tests in Units Equippped with k mm Teflon Valves , Supplied by Picatinny Arsenal.

Temperature, l60°F.

Test

unit

number

Coating

or

metal

Area of

specimen

cm^

Time

under

test

days

Gas*

evolved

3

cm

Rate*

coefficient

2

cm / day/ cm

Calculated**

tank pressure

after 1 year

• psig

present previous

PA-17

X Silver 17.3 55 Unable to obtain tight valve closure

PA-18 Lead 19.1 55

ti »» it it it it

PA-19X,XX

Zinc 15.8 279 56 0.017 17

PA-20X,XXIron 5.6 193 — 0.23 2 ,U00

v* yy PA-21 5 Molybdenum 3.6 308 — 0.083 880

pa-26

xx Nickel 17.0 283’ 3**3 0.05^ 0.0b3 570

* Cumulative total, corrected for background rate and to 1 atmosphere

pressure

.

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

x

Discontinued.

XX

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

was collected, due to temporary leaks, or to interrupted collection due

to high rate.

TABLE 3

Results of Tests of Materials Exposed to MHE-3 at l60°F

in Stainless Steel Bomb-Type Test Units

Test

unit

number

Coating

or

metal

Area of

specimen

cm^

Time Gas * under evolved

test

days cur

Rate*

coefficient

g cm?/day/ cm

present previous

Calculated**

tank pressure

after 1 year

Psig

3l6-lx Nickel l6.0 463 169 0.023 0.023 240

347-1* Lead 20.5 454 40 0.0043 0.0041 45

3^7-^ lQ% Maraging

steel

l4.0 295 308 0.075 0.05 750

347-Nix Nickel 82 456 1193 0.033 0.033 310

*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

Dis continued.

TABLE k

Data on Decomposition of MHF-3 Fuel at l60°F in Special Test Units

Effect of Porosity in Coatings of Silver on Managing Steel

Test

unit

number Description

Time

under

test

days

Gas

evolved

3

cm

Rate

coefficient ^ cm

0

/ day /cm

of exposed MS

present previous

Hg-3i+a

X

Silver on Maraging steel,

20 pores, 0.013" diam.

,

MS area 0.0*+9 cm^

201 38.8 3.9 l+.o

Hg-3i*bx

Silver on Maraging steel,

200 pores, 0.013" diam.,

MS area 0.1+2 cm^

205 85.1 1.02 1.0

Hg-3l+cX

Silver on Maraging steel,

.200 pores, 0 . 026 ” diam.,

MS area 1.29 cm^

189 127.0 0.55 0.58

Hg-3l*dx Silver on Maraging steel,

1 pore, 0.22” diam.,

MS area 0.39 cm^

19*+ 97.0 1 . 1+0 1.38

Hg-51

Cadmium on Maraging steel

with 1/2 of MS surface 62 8.*+ 0.017* . —

exposed

Rate coefficient is calculated on "basis of exposed Maraging steel.

(Total specimen area: 15.*+ cm^; exposed Maraging steel: 8 cm^.)

Discontinued.

Effect

of

Fuel

and

Vapor

Volume

and

Interfacial

Variables 0Po O CM *

•H LCN p p P vo > O o CM CM 00 0 O o O O o

>> ft . • • . . 0 «p

ft o o o o o

-P

cd

—

ft 00§

-P 1—1 P -ft" VO o * 0 p- o oo CO CO

0- o o CM o -=t 0 o o O o o

ft . • • . . ft o o o o o P0

"" 0 J> 00 o LT\ c— 00 c— 3 ft a • . • . . o o o CM ~=T -ZI- H CM > CO 0 ** u 0 0 -p 0 a ft 0 >5 O D— ON 00 CM •H 0 0? VO O o 1—1 P

EH p -p ft ~=t CM CM CM CM 001 1—1

ft *

pq 0 o CM c— § a5

-P ft a | | 1 1 • 0 cd o l j 1 1 On

<HO 0

ft 'S r> P < 1CO ft O 0 CO o CM

ft O cd ft a LCN P -=r VO i—1

-P cd i—1

cd o 00 C-— ft- CM ft- •H <+H O > 1—1 P

CO ft o 0

ft -P 1 ft a P CO •H CM o M CO P a LT\ LTN CM CO LTN o cd ft o CM CM LCN LTN

<D i—1

•H P i—1 Q P O fH ( o

<H •H O -P

ft ft 0 •H o oo_

-P ft ft a CO t— t— vo ON

cd O cd o 00 LCN ft CO 0 > p 0 P P P 3 O i— ft i o •H 00 > P a p LTN LCN oo a1 o 00 CM LCN tft •H P P

ft-P

CO a O O o o vo £ ft o i—1 P 1—1

CM p O 0 P •H ft H CO P P

ft 0a • •H s CM O o CM CM a • • • . o CM LCN LCN CM CM • ><

ft / ^ N -P -p 0 LTN LT\ VO C— CO

CO0

EH

•H ft CM rH 00 OO 001 00 § 3 A) Ad Ao 1bO Ad 1bD

ft

W

ww ft ft ft

.The

metal

is

lQ%

Maragipg ’

steel.

The

rate

is

crn

/day/cm

of

Maraging

steel

area.

Total

days

under

test

are

not

equal

to

number

of

days

during

which

gas

was

collected.

¥
Results

of

Examination

of

Fuel

and

Specimens

After

Prolonged

Mutual

Exposure

at

l60°F 0 0 rH *

-p E> 0 * rH oo

op) OO o t— rH H i—1 3 rH CM ft r- CM CM o oo

cd o ft \ * • 0 • • • CO CO bD O o VO PS o o o o do

•Hs

Pi -Pd

<D CO O ft ft o ft oo

CO

COo

ft

bC

PS •H

"§oo 5

co

Pi < ft ft PS 0 o 0 0 -p 0 a -p

Pi 0 CVJ •H •H O Pi H o O ft LON •H ft -H o 1 0 1 | d CM

-P O g • o 1 ft 1 1 P O • O -H o CO op) o d ft 0 Pl

op) -p PS 0 • 0 a 0 ft •H d bD O

ft rd p) 0 o bD •H O ft

Pl 0 Pi CO

P> -H rH 1 0 1 1 o ft -P • o • . Pl 1 0 1 O o bD cd rH ft op) O • p •H O 0 0 >> cd bD

<D O PS ft

U ft a > 0 o Pi Pi ft Pl cd 3 LON

Pi Pl -P CO • cd O MO i—I 0

pio 0

ft

ft•H

CO •H

S>

PS NO

Ed0H

cd0

01 ft

Pi

cd ft 0 . ft o 1 OO 0

bC 0 bC 0 ft 1 ft • 1 ft ft # 0 v / o a o P o 0 Pi o | 0 d l 0 rH o rH d r—1

rH p o 0 cd ft 0 ft d bD

Pl H cd ft rH cd a cd ft 0 O ft d PS £3 •H P ft a !> h •H i—1 3 O t— 3 ft CM t— 0

•rH i—I O o 3 rH OO bD 0 i—1

bD d OO - On -p O cd oo rH On 0 >> • -ft i—1

ft LON H 3 H o cd 0 PS bC CM i—1

vo O C— cd 0 rH cd rH LON o p •H • cd • d 0 • S • d • o

CO ft CM a i—1 0 ft bD 1 1 3 d o 3 0 vo • [•— rH 0 rH a O d rH O H a CM ft p ft •H rH !>> E>> •H 0 0 O O 0 Pl rH 0 i—I O ft

rH Pi On 0 ft CM rH ft CO rH 0 vo ft LON •H

-P cd O 0 0O Pl •H ft OO cd rH C— cd Pl CM •H i—| o

ft •H On > oo CD 0 d CO •H cd -ft- •H 0 i—1

Pl OO 0

bD ft bD CM vo ft 0 vo ft 0 H ft rH LON Pi •H •H • r\ • d • Pl • Pl d • p CO 0 PS CM 0 rH • o H 1 1 cd o O cd o vo r—

rs •H H -p r-f 0 H ft Ed H ft CM r\ •H S >—-- 0 d

ft P rd ft 3 Pt > H ft • rH 0 0

bD | 1 O •H cd H ft

PS ft 0 ft > > ft CO o LON •H • o 0 H On ft 00 Ift o O CM CM o

ft > •H 0 •H • o • H ft • •H • • d • Pl

cd cd rd d gEj i—1

CM H 00 a CM -p CM • rH 0 o o ft 0 cd cd 0 Pi a o d a ft 0 •H d od co d ft ft o •H

rH •H O d 15 0 Pl

cd ft O 0 CM a LON 3 ft" o Pl 00

•H rd CM 0 CM • rH i—1

Pl CO o 0

ft bD O PS LON 0 d OO d C— t— d •H •H bC ON ON -p 1 •H CM 15 LON d o ft

Pl 0 • • *H | • o • 3 • *H H 15 O • o ft ft rH Pi O ft 0 o 0

ft > 0 ft d 0 d 0 0 ft PS

•rH 0 O 0 d •H

ft 1 ft d ft d ft 0 O o 0 0 oo ft" ft VO X oo ft OO •H OO 0 rH # •rH ft Pi Pj >5 vo > LON •H LON 0 t— •H LON 0 LON Pl ft"

Pl O Ps 3 Cd ft- o -ft 0 -ft -ft 0 ft" 0 OO 00 o 0 0 0 ft 1—1 0 •H 0 PS O | ft rH PS Ed PS Ed i—| 0 -

0

b0

E>s • • •> # !>» PS Pi ft 0 • • 0 o 0 jj •H 0 rd OO ft CO d 0 LON ft t- rH -=J" ft rH 'S CO ft oo bD -ft •H -ft 0 d rH •H rH 1—1

LON •H OO 0 cd •H CM •rl ft 00 0 •H ft 0 ft • pj

cd Pi cn rH > Pi rH P 15 rH O p- 1 1 bD h Pl rH Pl h Pl

cd cd ft 0 cd 3 3 oj bD 0 0 Pi d 0 0 0 <D

PS i—irH i—1

cd ft rH 1—1 i—1

•H H cd O o ft O •H o o o

ft Pi ft 15 id

cd o 0 i—1

rH rH O rH rH rH (H oo a •H 0 ft 0 •H 0 rH ft 0 rH 0 0 p (D PS P) Ph d Ed d 0 o d ft d is d tS] $

Ph fft ft ft ft ft ft fH

Pl •H

ft 0 rH • • rH • • Ed • • . . .. .. •H ft 1 0 1 0 1 0 00 0 ft 0 LON 0 t-— (D ft vo ft b

ft C— ft 1 ft | ft | -p 1 p rH o -ft O -ft O bD o bD o bD o bD o d 00 Ed OO Ed OO id PS Ed PS Ed PS Ed PS a
d

-P

PiOo

VO

ft

1-1

-p CO 0 1—

* 3 ft t> 0 * VO OO • OO t— vo t— VO vo

Pi rH rH P rH o o d rH o o o o o

ft 3 O ft \ . 0 • • . • • • Pi CO 0 tuO o o d o o o o o o 0 0 Pl o o <H •H •rH Pl

Pi o Pl - O o O o 1 ft * 0 O 0 -p

Pl 0 ft

Pl 0 LTV bO CVJ rH . O Pl i—

CVJ •H rH o > •H ft •H O rH 1 1 O o 0 cd -P O a o • 1 1 • o o • CO O •H o 0 o o o CO d Pd •H

ft cd d -p d

bD d

Pl 3

•H ft »• • • +3 <H o bo 0 • bD *—>» 3 o Pl Pl -p a 0 00 o ft •H rH 0 1 p U~N 1—

o O ^ p -p o • ft 1 bD j oo • p o o taO cd rH 0 •H • o 3 o CO •H o •H Pl LTN P

cd 0 o ft p o > > 0 d 0 1—

rH d -P rH n CO

cd -P 3

'd * OO

bfl COw rH 0 00 q 0 co d oo

—

o a o • h • 3 • 3 • H b- Pi 00 0 o ft ft o o o

Pi o rH c 0 O •H a a LTN LTV ft CVJ b— Pi oo H CVJ LTN CVJ •H H on ft" o 00 0 vo co •H 1—

p- vo O cd t

rH cd ft •H CO p i—

ft H o CVJ 0 Pl bO CVI 00 rH 1—

ft -p b- CO 00 vo

P- •H . » P » d * •H • > . • • ca <H LTN OO 1 o d o > ON O ON o co

C\J • 0 cd i—

H d d d H o 0 H 0 0 0

rH ft- +3 vo p LTV -p 00 -p oo >5 CVJ b- LTN -p d CVI ft rH VO •H vo 3 o ON rH vo p •H b- •H CVJ 0 ft Pl co O CVJ P o o CVJ b£ ft bC CVI Pi 00 cd 1—

ft O b- -P CO 00 vo

•H •H » d » P . > • • •H . . . 0 Pl LTN p CO o 0 o P On > On o CO

•H CVJ 0 ft H rH

r\ o d d q

cd 3 P 0 3 ft P

b£ i 0 Pi 0 d 3

Pi ft 0 H 3 3 d O

•H • o 0 rH o o 00 0 1 P 1 3 VO O 00 CVJ ft" ft •H 0 •H • • 1 1 • • • . 3 cd p Pl a CVJ Pl CVJ Pl Pl Pl CVJ Pl CVJ CVJ CVJ O -p 0 0 0 0 0 o a a a a a

•H •H •H •H •H

(H O O O O O 3 -P 0 ft 0 0 0 0

•H P Pl CO Pl Pl Pl ft

ft bO ca LTN ca ca ca CVJ ca LTN vo oo

•H •H b£ 1 VO 1 1 o ON CO On

Pl 0 1 • 1 1 • • • H > • o * • • 1—1 # o o o 0 0 0 0 0 P d d d d d d d d d d i •H •H •H •H •H o o 0 0 0 0 0 0 0

•H ft Pl Pi

b CO 0 CVI 0 00 0 00 0 1—1 0 LTN On _zj" Pi O X d cd LTV Pl OO Pl o\ Pl o Pl o Pl o CO On 0 0 0 d 00 ft 1—1 oo CVJ CVJ rH r-1 ft O o O O O

Pd Pd Pd Pd Pd

ttO Pl Pl • • . • • H 0 0 0 0 0 0

CO ft 00 -P o -p b- -P ON -P vo ft CVJ vo t—

CO cd •H VO •H •H o •H On •H 00 •H o p" <H

0} Pi CQ ft ft CVI ft P H P oo LTN ft- o p £ > > > > • • • < < C Pl Pi Pl Pl Pi ft- ft" ft- bO cd 3 3 3 3 oo oo 00

Pl rH 0 0 0 0 0

•H cd rH rH rH rH rH 0 0

-p Pi -p O O O O O 3 3 3 3 o 0 Pd o a l rH H i—

rH rH 0 0 0 o Pl 0 p 0 0 0 o 0 bD 0 bD g bp bD ca P ca d ft d S d C d <1 3 < 3 <1 k1 ft ft ft ft ca ca ca

Pl +3 0 • • H • • o • • rH .. • • • • . 

•H ft co 0 rH 0 CVJ 0 CVJ 0 0 0 0 0 d i -P 1 -P 1 -P 1 -p < ft P ft o ft Pl ft ft P bO o bO O <1 o <5 o P" o ft- O ft" o ft O

Pl ft Pd ft Pd ft Pd ft Pd 00 Pd 00 Pd oo Pd 00 Pd

Removal

of

stubborn

surface

film

probably

removed

some

silver.

Original

fuel

contained

0.04

g/l

of

dissolved

solids.

Tabulated

values

are

totals,

not

corrected

for

this

factor.


Figure 1. (3l6-l) Cross-section of nickel on welded Maraging

steel after 1+63 days in contact with MHF-3 fuel at

l60°F. Welded area is in center of picture. The nickel

coating (horizontal white lines) covered the welded

Maraging steel uniformly. No attack of the nickel coating is evident. Copper (darker bands) was plated over

the nickel coating for protection during polishing.

30X. Modified Fry’s etchant.

Figure 2. (3l6-l) Cross-section of nickel-plated Maraging steel

after ^+63 days exposure to MHF-3 fuel at l60°F. Good

coverage of rather rough surface of Maraging steel

(bottom) is shown. No attack on nickel (white band)

surface is evident. Darker band above nickel is

polish-protective copper overlay. 250X. Modified

Fry’s etchant.
HIM*;; %


Figure 3* (31+T-Ni) Cross-section of nickel-plated Maraging steel

tube after h^6 days in contact with MHF-3 fuel at l60°F

The shallow pit in the nickel coating (light band at

top) is of uncertain origin. Slight roughness of

surface of nickel believed due to attack of fuel.

250X. Modified Fry’s etchant.

Figure h. (.3^7-1) Cross-section of lead-plated Maraging steel

after b^k days in contact with MHF-3 at l60°F. Identification of bands: Bottom (mostly white zone), Maraging steel; center, lead plate (darker band); top

(thick, black-edged band), copper coating applied after

sectioning as polishing support. As-plated unevenness

of the lead deposit is reflected in the copper coating.

Little, if any, attack on the lead is evident. 250X.

Modified Fry’s etchant.



Figure 5. (Hg-3) Cross-section of cadmium plate (band through

center of photo) on Maraging steel after ^73 days exposure to MHF-3 fuel at l60°F. Irregular etch-corrosion

of the surface of the cadmium is evident. The Maraging

steel is below and a polish-protective copper deposit

above the band of cadmium plate. 150X. Chromic acid

etchant

.

Figure 6. (Hg-U) Cross-section of electroless nickel on Maraging

steel after H58 days exposure to MHF-3 fuel at l60°F.

Shown are one edge and part of the sides of the specimen

with the Maraging steel at the center surrounded by the

white band of nickel, and the thick protective copper

overlay applied after sectioning. 30X. Modified Fry’s

etchant

.



Figure 7* (Hg-4) Cross-section of center of specimen of Maraging

steel plated with electroless nickel after ^58 days of

contact with MHF-3 fuel at l60°F. The nickel (white

band at center) shows little evidence of attack. Very

slight unevenness at surface of deposit (top) is likely

the as-plated condition. 250X. Modified Fry’s etchant.

Figure 8. (Hg-5) Cross-section of tungsten deposit on Maraging

steel after 358 days in contact with MHF-3 fuel at

l60°F. The tungsten is the light band in the center

with the Maraging steel below and the copper protective

plate above. There was practically no attack of the

tungsten. 250X. Modified Fry’s etchant.



Figure 9* (Hg-7) Surface of zinc-plated Maraging steel after

3kl days exposure to MHF-3 fuel at l60°F. This photo

shows tightly adherent, dense scale (darker area)

partially removed from specimen. All the zinc deposit

was affected. 30X. No etch.

Figure 10. (Hg-8) Cross-section of nickel-tin alloy coating on

Maraging steel after 358 days exposure to MHF-3 fuel

at l60°F. Banded structure of deposit (lighter diagonal strip) due either to interruption during plating,

or to a spontaneous cyclic phenomenon during deposition. Unevenness of surface may be due to chipping of

the brittle coating during polishing, rather than to

attack by fuel. 250X. Modified Fry’s etchant.



Figure 11. (Hg-ll) Cross-section of tin-plated Maraging steel

after ^32 days exposure to MHF-3 fuel at l60°F. Maraging steel is at bottom of photo with the tin immediately

above. Apparent grain structure in deposit appeared

without an etch. Roughness of surface of tin coating

thought to be as-plated condition. 250X No etch.

Figure 12. (.PA 20 ) Cross-section of iron foil exposed to MHF-3

fuel for 193 days at l60°F, Iron is dark band at

center with polish-protective nickel layers, above and

below. Evidence of some pitting attack may be seen

in upper surface of the iron. 250X. Modified Fry’s

etchant

.


*
Figure 13. (3U-A) Cross-section of silver-plated Maraging steel

with artificial pore after 205 days exposure to MHF-3

fuel at l60°F. The layers, top to ‘bottom, are: white

nickel polish-protective coating, silver deposit, and

Maraging steel. Some undercutting of the silver,

which has been filled in with nickel, is evident;

otherwise, there is little effect on the exposed Maraging steel. 250X. Modified Fry’s etchant.
M+