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ANP lJHO JECT QUARTERLY PHOGRESS REPORT
-. ~ .- ........
TABLE 11.13. ANALYSIS OF CORROSIVE ATTACK BY SODIUM IN FIGURE 8 LQOP
.
~ __ ___.
....... . __ ......... ....... ~ .____ .-..-.
- .......... ____
Heat exchanger
section
Hot section
Cold section
TEMPFmTURE
(OF)
1320
1300
1350
1320
750
1100
TIME
(hr)
2700
1000
2'100
1000
27 00
1000
were also continued in an effort to
aid in the identification of the
corrosion products.
Interaction of Fluorides urith
Structural Netals (H. S. Powers, J. D.
Redman, L. G. Overholser, Materials
Chemistry Division). Investigation of
the reaction of chromium and iron with
molten NaF-KF-LiF eutectic has con-
tinued. Special emphasis has been
placed on the behavior of K2NaCrF6 and
K2NaFeF6 when contacted with the
eutectic in the temperature range from
600 to 1000°C. The filtrates col-
lected at various temperatures in the
range from 500 to 800°C have been
subjected to chemical analysis, as in
the past, and the residues and filtrates
have been examined by x-ray diffraction.
In a number of experiments, 3 w t %
of K2NaCrF6 was added to samples of
the NaF-KF-LiF eutectic. The mixtures
were heated at 800 to 1100°C under an
atmosphere of helium for several hours
and then filtered at various teinpera-
tures in the range from 500 to 800"C,
and the residues and filtrates were
examined. Heating of the K2NaCrF6 at
temperatures up to 1100°C prior to its
addition to the eutectic did not
affect its solubility, and the temper-
ature of equilibration of this compound
with the eutectic prior to filtration
was unimportant. Solubility was, how-
ever, a function of temperature of
filtration. The filtrate collected
at 500°C contained 400 to 500 ppm Cr,
whereas the filtrate obtained at either
152
...
2
1
2
1
2
1
ATTACK
Occasional depressions, to 1 m il deep
. -
Numerous small depressions, to 0.25 mil deep
No noticeable corrosion or erosion
650 or 800°C contained 2000 to 3000
ppm Cr. Microscopic examination re-
vealed that most of the Cr was present
as K2NaCrF6, which indicates that this
compound is appreciably soliible in the
NaF-KF-LiF eutectic at elevated temper-
atures. X-ray examination shows that
in some runs, materials other than
KzNaCrF6 have been present, including
K,CrF6, Cr203, and KNaLiCrF,.
Similar experiments in which Cr was
added to the eutectic as metal instead
of as K2NaCrFs showed that Cr20J, Cr,
and K,NaCrF, were present after the
i n t e r a c t i on. Add i t ion a 1 p rod u c t s t ha t
have not yet been identified were also
found.
A study of the solubility of K,NaFeF6
in the NaF-KF-1iF eutectic and the
NaF-KF-LiF-UF,, mixture at 600 and
800°C was made. It was found that with
2.5% of K2NaFeF6 the solubility in
both fluoride mixtures and at both
temperatures of filtration was 6000 to
7000 ppm. Apparently, all the K,NaFeF,
added was dissolved.
Since the presence of oxidation
products in a number of the filtrates
indicated that the digestion and
filtration apparatus in which a blanket
of helium is used does not exclude
oxygen completely, two new types of
reaction- fi ltration equipment have
been designed and fabricated that
should eliminate oxidative effects.
Air Oxidation of Fuel Mixtures
(R. P. Metcalf, F. F. Blankenship,
Materials Chemistry Division). The