Thermally induced evolution of morphology on ceramic surfaces in a thermionic converter

Journal Article · Wed Jan 01 04:00:00 EST 1997 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.52012· OSTI ID:664842

Zavadil, K R ^[1]; Olson, D L ^[2]; Klinkov, A E ^[3]

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1. Sandia National Laboratories P.O. Box 5800 Albuquerque, New Mexico87185-0342 (United States)
2. Team Specialty Services 901 University Blvd. SE Albuquerque, New Mexico87106-4439 (United States)
3. JS INTERTEK 123182Moscow Kurchatov Sq. 1 (Russian Federation)

The morphology of alumina and scandia ceramics exposed to controlled vacuum and diffusion modes in a thermionic converter has been studied. Evidence for vaporization at a temperature of 1770 K is manifest in the resulting surface morphologies of both ceramics, consistent with reported sample mass loss. Alumina shows intergranular relief with the formation of terrace-step structure on the grain surfaces. Terrace formation is not directly observed on scandia, however the development of vertical structure and maintenance of voids indicates that vaporization is initiated by structure at the grain edges. Extensive Sc{sub 2}O{sub 3} re-deposition occurs on the scandia surface, possibly mediated by the presence of molybdenum and tungsten. Evidence exists for refractory metal secondary phase formation in this deposit in the form of Sc{sub 6}MO{sub 12} (M=W or Mo). Alumina also shows evidence for materials{close_quote} interactions in the form of tantalum assisted vaporization which significantly alters the terrace structure. {copyright} {ital 1997 American Institute of Physics.}

• Research Organization: Sandia National Laboratory
• Sponsoring Organization: USDOE
• DOE Contract Number: AC04-94AL85000
• OSTI ID: 664842
• Report Number(s): CONF-970115--
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 387; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

30 DIRECT ENERGY CONVERSION
ALUMINIUM OXIDES
CHEMICAL REACTIONS
GRAIN BOUNDARIES
MORPHOLOGICAL CHANGES
NESDPS Office of Nuclear Energy Space and Defense Power Systems
OPTICAL MICROSCOPY
SCANDIUM COMPOUNDS
SCANNING ELECTRON MICROSCOPY
SPACERS
SURFACE PROPERTIES
THERMIONIC CONVERTERS
VAPORIZATION HEAT
X-RAY DIFFRACTION