Accession Number : ADA115947

Title :   Oxidation of Non-Oxide Ceramics.

Descriptive Note : Final rept. Feb 75-Feb 82,

Corporate Author : CASE WESTERN RESERVE UNIV CLEVELAND OH DEPT OF METALLURGY AND MATERIALS SCIENCE

Personal Author(s) : Mitchell,T E ; Heuer,A H

PDF Url : ADA115947

Report Date : 25 May 1982

Pagination or Media Count : 22

Abstract : Oxidation mechanisms of SiC were determined. It was found that cristobalite nucleates at the SiC/SiO2 interface with appreciable heterogeneous nucleation during the first hour. Identical oxidation mechanisms were found for both single crystal and sintered polycrystalline SiC. Oxidation of yttria stabilized silicon nitride was investigated to determine the cause of the catastrophic oxidation at 1000C. At high temperature, SiO2 covers the entire surface, but at low temperature it does not. This allows the unstable yttria silicon oxynitride phases to form and cause catastrophic failure. No evidence of the effect of tungsten was noted. (Author)

Descriptors :   *Ceramic materials, *Silicon compounds, *Oxidation, *Single crystals, Tracer studies, Oxygen, Silicon carbides, Silicon nitrides, Sintering, Grain growth, Porosity, Spherulites, Diffusion, Equilibrium(General), Polycrystalline, Nucleation, Electron microscopy

Subject Categories : Physical Chemistry
      Ceramics, Refractories and Glass
      Crystallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE