Characterization of the thermally contracting tungstates Ta/sub 22/W/sub 4/O/sub 67/, Ta/sub 2/WO/sub 8/, and Ta/sub 16/W/sub 18/O/sub 94/
An investigation of the properties of high-purity (> 99 wt %) tantalum tungstates (Ta/sub 22/W/sub 4/O/sub 67/, Ta/sub 2/WO/sub 8/, and Ta/sub 16/W/sub 18/O/sub 94/) included determination of density (bulk and theoretical), refined lattice constants, maximum use temperatures, microhardness, heat capacity, thermal expansion (contraction) and diffusivity, calculated thermal conductivity, and electrical resistivity. Usable to approx. = 1700 K in air or inert atmospheres, these tantalum tungstates have theoretical densities of 7.3 to 8.5 g/cm/sup 3/, are relatively soft (120 to 655 kg/mm/sup 2/ hardnesses), and are electrical insulators (6 x 10/sup 3/ to 2 x 10/sup 8/ ..cap omega...cm resistivities). The distinguishing properties of the materials are their thermal expansion (average CTE values from +0.6 x 10/sup -6//K to -5.1 x 10/sup -6//K at 293 to 1273 K), thermal expansion hysteresis with minimal observable microcracking, and thermal diffusivity (values from 1.6 x 10/sup -3/ to 3.2 x 10/sup -3/ cm/sup 2//s at 298 K) gradually increasing with temperature.
- Research Organization:
- Oak Ridge Y-12 Plant, TN
- OSTI ID:
- 6464027
- Journal Information:
- J. Am. Ceram. Soc.; (United States), Journal Name: J. Am. Ceram. Soc.; (United States) Vol. 61:3-4; ISSN JACTA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360203 -- Ceramics
Cermets
& Refractories-- Mechanical Properties
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
COHERENT SCATTERING
CRACKS
CRYSTAL STRUCTURE
DENSITY
DIFFRACTION
EXPANSION
FABRICATION
FRACTURE PROPERTIES
HARDNESS
LATTICE PARAMETERS
MECHANICAL PROPERTIES
MICROHARDNESS
PHYSICAL PROPERTIES
SCATTERING
SINTERING
SPECIFIC HEAT
TANTALUM COMPOUNDS
TANTALUM TUNGSTATES
THERMAL DIFFUSION
THERMAL EXPANSION
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TUNGSTATES
X-RAY DIFFRACTION