AN INVESTIGATION OF THE BeF$sub 2$-ZrF$sub 4$ SYSTEM (in Russian)
Journal Article
·
· Doklady Akademii Nauk SSSR (U.S.S.R.) English translation currently published in a number of subject-oriented journals
OSTI ID:4694744
Calculated amounts of (NH/sub 4/)/sub 2/BeF/sub 4/ and (NH/sub /sub 4// sub 3/ZrF /sub 7/ were mixed together in a nickel or platinum crucible and heated in a current of CO/sub 2/ to drive off the ammonium fluoride. The mixture was homogenized at 380 to 400 deg C for 30 hours in an argon atmosphere of 100 to 120 mm Hg std in order to suppress the volatilization of zirconium fluoride. The mixtures were subjected to x-ray and thermal analyses. A reversible alpha in equilibrium BETA transformation of ZrF/sub 4/ was observed at 690 deg C. Melting of zirconium fluoride took place at 903 deg C. The quartzlike form of BeF/ sub 2/ was found in mixtures homogenized at 400 deg C. A rhombic modification of BeF/sub 2/ was formed in the presence of small amounts of zirconium fluoride, but this modification was converted to the quartz-like form of BeF/sub 2/ after homogenizing at 400 deg C. Only one incongruently-melting compound having the composition BeZrF/sub 6/ was found in the BeF/sub 2/-- ZrF/sub 4/ system. The temperature of the peritectic reaction for the formation of this compound was 712 deg C. The eutectic between BeZrF/sub 6/ and BeF/sub 2/ was at a temperature of 578 deg , and 80 mol% of BeF/sub 2/. A phase diagram of the BeF/sub 2/-ZrF/sub 4/ system is presented. (TTT) which the phonon contribution is even higher than the electronic contribution. The increased thermal conductivity is due to the presence of strong covalent bonds between the boron atoms in the hexaborides. (TTT) Thermodynamic calculations and tests showed the feasibility of TiO/sub 2/ and Nb/sub 2/O/sub 5/ reduction by calcium carbide (CaC/sub and by calcium cyanamide (CaCN/sub 2/) at 1000 deg C. (R.V.J.)
- Research Organization:
- Moscow State Univ.
- NSA Number:
- NSA-17-028842
- OSTI ID:
- 4694744
- Journal Information:
- Doklady Akademii Nauk SSSR (U.S.S.R.) English translation currently published in a number of subject-oriented journals, Journal Name: Doklady Akademii Nauk SSSR (U.S.S.R.) English translation currently published in a number of subject-oriented journals Vol. Vol: 149; ISSN DANKA
- Country of Publication:
- Country unknown/Code not available
- Language:
- Russian
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