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1 1. CORlROS ION RESEARCH
PERIOD ENDING DECEMBER 20,
W. R. Grises, Materials Chemistry Division
Most of the effort on corrosion was
expended in dynamic tests of the ZrF4-
bearing fluoride me1 ts. These s tudies
have been primarily concerned with the
effect of various additives to the melt
on the corrosion behavior of Inconel.
It was found that additions of ZrH,
and NaK to the fuel mixture inhibit
the corrosive attack. Other tests of
fluoride corrosion have been performed
to determine the effect of crevices,
temperature, and pretreatment of the
fluoride and the resistance of various
oxide coatings and ceramic bodies.
Several Tnconel loops circulating the
fuel mixture NaF-ZrF4 -UF, (46-50-4
mole %)exhibited more severe corrosion
than was previously encountered in
such tests; this is believed to be due
to the lower purity of the fluoride
mixtures recently prepared in large-
batch apparatus.
Temperature-dependence tests and
experiments on the effects of various
additions on the corrosion behavior of
the hydroxides were carried out. How-
ever, the maintenance of a hydrogen
atmosphere is the only proved means of
controlling hydroxide corrosion.
The work on liquid metal corrosion
was concentrated on the operation of
thermal convection loops of two types
to study the mass transfer properties
of lead. One of the most critical
variables in lead corrosion was found
to be the cleanliness of the lead and
the container. However, even the
purest lead prepared to date cannot be
satisfactorily contained in Inconel at
temperatures above 500°C. The in-
vestigation of the stability of Be0 in
NaK was continued, but additional ex-
perimentation is required to make an
e va 1 ua t ion,
W. D. Manly, Metallurgy Division
W. W, Savage, ANP Division
FLUORIDE CORROSION IN STATIC AND
SEESAW TESTS
D. C, Vreefand L. R. Trotter
E. E. Hoffman J. E. Pope
Metallurgy Division
F. Kertesz C. R. Craft
H, J. Buttram R. E. Meadows
Materials Chemistry Division
1952
Oxide Additives. Static tests were
run in Inconel tubes €or PO0 hr at
816°C with the fluoride mixture
NaF-KF-LiF-UF4 (10.9-43.5- 44.5- 1.1
mole X) plus approximately 10%additions
of ferric oxide, nickel oxide, and
chromic oxide. These tests were run
to determine whether the presence of
these oxides, which may also be present
on Inconel, would increase the cor-
rosion by fluorides. In these tests,
the nickel oxide and ferric oxide had
little or no effect on the extent of
corrosion. The addition of chromic
oxide apparently increased corrosion.
The results are summarized in Table
11.1. Similar tests are being run
with oxidized Tnconel specimens to
determine whether increased corrosion
can be expected on oxidized Tnconel.
Comparison of Liquid- and Vapor-
Phase Corrosion. Sections of the
testing tube used in some of the tests
run with the fluoride mixture NaF-KF-
LiF-UF, (10.9-43.5-44.5-1.1 mole %)
for 100 hr at 816°C were removed, both
from above and from below the bath
level, for metallographic examination.
The corrosive attack noted on all
sections examined would seem to indi-
cate that attack can be expected on
metals exposed to the vapor phase of
the fluoride mixture. The sections of
type 304 stainless steel exposed to
the vapor phase appeared to be attacked
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