High Temperature Mechanical Properties of Polyphase Ceramics Based on Silicon Nitride.
Abstract
Results for the four year effort concerning the high temperature mechanical properties of polyphase ceramics based on Si3N4 are described. Initial work showed that subcritical crack growth at high temperature was caused by cavitation. Phase equilibria work identified the lowest melting eutectic in the Si3N4-Mg2SiO4-MgO portion of the Si-Mg-O-N system and linked the volume fraction of the residual glassy phase to material composition. Subsequent creep studies related creep mechanism to composition through the volume fraction of the glassy phase. Creep resistance was observed to increase after a pre-oxidation treatment. Other work at Rockwell International Science Center showed that oxidation produced compositional changes and that the detrimental glassy phase was a fugitive of oxidation. Recent work culminated this study to show that the high temperature strength of polyphase Si3N4 could be at least doubled through compositional changes induced by oxidation. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1981
- Accession Number
- ADA102121
Entities
People
- B. I. Davis
- D. R. Clarke
- F. F. Lange