New Oxide Materials for an Ultra High Temperature Environment

Technical Report · Mon Nov 13 00:00:00 EST 2017

DOI:https://doi.org/10.2172/1408528· OSTI ID:1408528

Perepezko, John H. ^[1]

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1. Univ. of Wisconsin, Madison, WI (United States). Dept. of Materials Science and Engineering

In this project, a new oxide material, Hf₆Ta₂O₁₇ has been successfully synthesized by the controlled oxidization of Hf-Ta alloys. This oxide exhibits good oxidation resistance, high temperature phase stability up to more than 2000°C, low thermal conductivity and thus could serve as a component or a coating material in an ultrahigh temperature environment. We have examined the microstructure evolution and phase formation sequence during the oxidation exposure of Hf-Ta alloys at 1500°C and identified that the oxidation of a Hf-26.7atomic %Ta alloy leads to the formation of a single phase adherent Hf₆Ta₂O₁₇ with a complex atomic structure i.e. superstructure. The overall reactive diffusion pathway is consistent with the calculated Hf-Ta-O ternary phase diagram. Besides the synthesis of Hf₆Ta₂O₁₇ superstructure by oxidizing Hf-Ta alloys, we have also developed a synthesis method based upon the reactive sintering of the correct ratios of mixed powders of HfO₂ and Ta₂O₅ and verified the low thermal conductivity of Hf₆Ta₂O₁₇ superstructure on these samples. We have completed a preliminary analysis of the oxidation kinetics for Hf₆Ta₂O₁₇, which shows an initial parabolic oxidation kinetics.

• Research Organization: Univ. of Wisconsin, Madison, WI (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
• DOE Contract Number: SC0010477
• OSTI ID: 1408528
• Report Number(s): 11-13-2017; 13SC005272
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
Oxides
High Temperature
oxidation phase stability