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Title: MoSi 2 Oxidation in 670-1498 K Water Vapor

Molybdenum disilicide (MoSi 2) has well documented oxidation resistance at high temperature (T > 1273 K) in dry O 2 containing atmospheres due to the formation of a passive SiO 2 surface layer. But, its behavior under atmospheres where water vapor is the dominant species has received far less attention. Oxidation testing of MoSi 2 was performed at temperatures ranging from 670–1498 K in both 75% water vapor and synthetic air (Ar-O2, 80%–20%) containing atmospheres. Here the thermogravimetric and microscopy data describing these phenomena are presented. Over the temperature range investigated, MoSi 2 displays more mass gain in water vapor than in air. The oxidation kinetics observed in water vapor differ from that of the air samples. Two volatile oxides, MoO 2(OH) 2 and Si(OH) 4, are thought to be the species responsible for the varied kinetics, at 670–877 K and at 1498 K, respectively. Finally, we observed an increase in oxidation (140–300 mg/cm 2) from 980–1084 K in water vapor, where passivation is observed in air.
Authors:
 [1] ;  [2] ;  [1] ;  [1] ;
  1. Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos New Mexico
  2. Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos New Mexico; Department of Nuclear Engineering, University of California, Berkeley, Berkeley California
Publication Date:
Report Number(s):
LA-UR-15-26638
Journal ID: ISSN 0002-7820
Grant/Contract Number:
AC52-06NA25396; NA0003180
Type:
Accepted Manuscript
Journal Name:
Journal of the American Ceramic Society
Additional Journal Information:
Journal Volume: 99; Journal Issue: 4; Journal ID: ISSN 0002-7820
Publisher:
American Ceramic Society
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Nuclear Science and Security Consortium; The Regents of the Univ. of California, Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Nuclear Energy (NE); USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation (NA-20)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; MoSi₂; Nuclear Fuel Cladding; Steam Oxidation
OSTI Identifier:
1259968
Alternate Identifier(s):
OSTI ID: 1407976