Stability range of MoC (hP2). II. Thermodynamic properties of generalized Lewis acid-base intermetallics
The ..gamma..-MoC phase with the hexagonal WC structure was prepared without the presence of metal stabilizers at temperatures below 1000/sup 0/C. This phase was found to be thermodynamically stable at low temperatures and decomposed to Mo/sub 2/C and graphite at 1400 K. Using equilibrium and thermodynamic data, the thermodynamic quantities of this phase were calculated as S/sup 0//sub 298//R = 4.41 +/- 0.3 and ..delta..H/sub 298//sup 0//R = -3430 +/- 800 K. Part II. Oxide equilibration and solid-state galvanic cell experiments were used to study thermodynamic properties of binary Lewis acid-base stabilized transition metal alloys. The activity of vanadium was determined in alloys of vanadium with platinum group metals such as Rh, Pd and Ir at 1000/sup 0/C. The activities of titanium in titanium-iridium alloys and of niobium in Nb/sub 2/Ir were determined at 1400/sup 0/C. The ternary phase diagram of V-Pd-O at 1000/sup 0/C was obtained. Based on the vanadium-palladium results, a partial titration curve of palladium by vanadium was constructed. The excess partial molar Gibbs free energy of vanadium at infinite dilution was found to be -36.4 kcal mol/sup -1/ at 1000/sup 0/C. The results of this study are in agreement with the predictions of Brewer's theory of transition metal alloy acid-base behavior.
- Research Organization:
- Lawrence Berkeley Lab., CA (USA)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 6976723
- Report Number(s):
- LBL-25340; ON: DE88011941
- Resource Relation:
- Other Information: Thesis. Portions are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
IRIDIUM ALLOYS
PHASE STUDIES
MOLYBDENUM CARBIDES
CHEMICAL PREPARATION
OXIDES
PALLADIUM ALLOYS
RHODIUM ALLOYS
VANADIUM ALLOYS
CRYSTAL-PHASE TRANSFORMATIONS
EXPERIMENTAL DATA
FREE ENTHALPY
PHASE DIAGRAMS
THERMODYNAMIC PROPERTIES
ALLOYS
CARBIDES
CARBON COMPOUNDS
CHALCOGENIDES
DATA
DIAGRAMS
ENERGY
INFORMATION
MOLYBDENUM COMPOUNDS
NUMERICAL DATA
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
PLATINUM METAL ALLOYS
REFRACTORY METAL COMPOUNDS
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS
360202* - Ceramics
Cermets
& Refractories- Structure & Phase Studies