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ANP PROJECT PROGRESS REPORT
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ORNL-LR-MYC (4638
KF 20 40 60 80 ZrF,
ZrF4 (mole %)
Fig. 23.2. Effect of Composition on Heat of
Vaporization of ZrF, in KF-ZrF, Mixtures.
114
method in concentrations from 100 to 45 mole %
FeCI, in KCI. Pressure vs composition curves
obtained at 850 and m0C are shown in Fig. 2.3.6;
these are typical of the curves obtained at temperatures
from 700 to 1050OC. The strong deviation
from ideality suggests that the FeCI, is complexed
in the liquid at these temperatures. Since the
experimental evidence was obtained in phase equilibrium
studies of the compound K FeCI, in the
solid state, it is interesting that t K e same stoichiometry
may apply to the complex in the liquid.
The strong depression of the vapor pressure below
45 mole % precludes further experimental efforts
with the Rodenbush-Dixon technique. The transpiration
method will be used to complete the
experimental curve on the KCI-rich side of the
graph.
The phase diagram for the FeCI,-KCI system,
shown in Fig. 2.3.7, was determined by two ex-
peri mental techniques. First, both conventiona I
cooling and differential cooling curves were ob-
tained on small melts, and, second, quenched
samples were prepared by the gradientquenching
techniques used in this laboratory. Petrographic
examination of the quenched and slowly cooled
samples revealed two well-defined compounds in
the solid state, K,FeCI, and KFeCI,. Both
compounds appear to have solid-state transfor-
mations, and K,FeCI, melts incongruently.
TABLE 2.3.2. SUMMARY OF VAPOR PRESSURES FOR THE SYSTEM RbF-ZrF4
Composition Constants Heat of Vaporization
Ex perimenta I Temperature (mole %) of ZrF,, blv
Range (%) A B (kco Vmole)
Zr F, RLF
800-850
725-825
750-825
750-875
775-875
775-950
850-975
900-1 050
1000-1200
1125-1275
81.6
74.6
70.0
65.1
60.0
54.8
50.4
45.2
40.0
35.0
18.4
25.4
30.0
34.9
40.0
45.2
49.6
54.8
60.0
65.0
10.778
10.359
9.808
9.1 43
8.789
8.307
7.555
7.512
7.290
7.296
9,506
9,189
8,790
8,358
8,078
7,902
7,310
7,794
8,146
8,790
43.5
42.1
40.3
38.3
37.0
36.2
33.5
35.7
37.3
40.3
. -.
.