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Title: New Oxide Materials for an Ultra High Temperature Environment

Abstract

In this project, a new oxide material, Hf 6Ta 2O 17 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 Hf 6Ta 2O 17 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 Hf 6Ta 2O 17 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 HfO 2 and Ta 2O 5 and verified the low thermal conductivity of Hf 6Ta 2O 17 superstructure on these samples. We have completed a preliminary analysis of the oxidation kinetics for Hf 6Ta 2O 17, which shows an initial parabolic oxidation kinetics.

Authors:
 [1]
  1. Univ. of Wisconsin, Madison, WI (United States). Dept. of Materials Science and Engineering
Publication Date:
Research Org.:
Univ. of Wisconsin, Madison, WI (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
OSTI Identifier:
1408528
Report Number(s):
11-13-2017
13SC005272
DOE Contract Number:  
SC0010477
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Oxides; High Temperature; oxidation phase stability

Citation Formats

Perepezko, John H. New Oxide Materials for an Ultra High Temperature Environment. United States: N. p., 2017. Web. doi:10.2172/1408528.
Perepezko, John H. New Oxide Materials for an Ultra High Temperature Environment. United States. doi:10.2172/1408528.
Perepezko, John H. Mon . "New Oxide Materials for an Ultra High Temperature Environment". United States. doi:10.2172/1408528. https://www.osti.gov/servlets/purl/1408528.
@article{osti_1408528,
title = {New Oxide Materials for an Ultra High Temperature Environment},
author = {Perepezko, John H.},
abstractNote = {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.},
doi = {10.2172/1408528},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Nov 13 00:00:00 EST 2017},
month = {Mon Nov 13 00:00:00 EST 2017}
}

Technical Report:

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