ORNL-2106 - the Molten Salt Energy Technologies Web Site

tests of the Lindsay Mix specimens, no significant
differences were found.
Metallographic polishing and examination of the
rare-earth oxide specimens before and after ex-
posure to the sodium indicated that the specimens
may have been slightly weakened by the tests,
but there was no microscopically visible corrosion,
as shown in Fig. 3.2.20. Metallographic examination
of the lnconel capsules revealed slight surface
roughening to a depth of less than 0.5 mil
in spots on the inner surfaces that contacted the
liquid sodium and the Lindsay Mix specimens.
There was no surface roughening and no attack
of the Inconel capsule that contained the Sm 0
? 3
specimen and sodium. Spectrographic examinations
of the inner surfaces of the three capsules
did not reveal any rare earths.
The corrosion resistance to molten sodium shown
by the Lindsay Mix dith a density of 6.58 g/cm3
prompted further tests that were designed to approximate
more closely the expected operating
conditions and for which a Lindsay Mix body with
the proposed density and configuration was used.
PERIOD ENDING JUNE 10, 1956
The purposes of these tests were to determine
the relationship of the apparent porosity of the
Lindsay Mix body for water to that for molten
sodium and to study the corrosion resistance of
the body and lnconel when separated by only a
small thickness (approximately 0.05 in.) of sodium.
A hollow cylinder of porous Lindsay Mix body
was used that was nominally 0.9 in. OD, 0.5 in.
ID, and 1 in. long, with a density of 3.53 g/cm3
and an apparent porosity to water of 53.5%. This
body had an apparent porosity of 52% to sodium
after exposure to static sodium for 100 hr at
130OoF in an evacuated lnconel capsule. To
determine the apparent porosity of the body to
sodium, the sodium was allowed to cool and
solidify around the body at the end of the 100-hr
test period. The test capsule was then opeiied
in a helium atmosphere, the excess sodium was
removed from the surfaces of the body with plastic
scrapers, and the body and its absorbed sodium
were weighed. The absorbed sodium was then
removed by vacuum distillation, and the body was
again weighed. The apparent porosity of the body
Fig. 3.2.20. Rare-Earth Oxide Specimens (63.8 wt X Sm20,-26.3 wt X Gd2O3-BaJance Primarily
Other Rare-Earth Oxides) (a) in As-received Condition and (b) After Exposure to Static Sodium in an
lnconel Container for 500 hr at 1500OF. Unetched. SOOX. Reduced 5.5%.
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