Processing of ZrC–Mo Cermets for High Temperature Applications, Part II: Pressureless Sintering and Mechanical Properties |
| |
| Authors: | Sean E. Landwehr Gregory E. Hilmas William G. Fahrenholtz Inna G. Talmy |
| |
| Affiliation: | Materials Science and Engineering Department, University of Missouri, Rolla, Rolla, Missouri 65409;
Ceramic Science Group, Naval Surface Warfare Center Carderock Division, West Bethesda, Maryland 20817 |
| |
| Abstract: | Pressureless sintering of ZrC–Mo cermets was investigated in a He/H2 atmosphere and under vacuum. A large density increase was observed for specimens with >20 vol% Mo after heating at 2150°C for 60 min in a He/H2 atmosphere. The increase in density was attributed to the formation of Mo2C during heating and its subsequent eutectic reaction with Mo, which produced rounded ZrC grains in a Mo–Mo2C matrix. Sintering in vacuum did not produce the same increase in density, due to the lack of Mo2C formation and subsequent lack of liquid formation, which resulted in a microstructure with irregular ZrC grains with isolated areas of Mo. Mechanical properties testing showed a decrease in Young's modulus with increasing Mo content that was consistent with the models presented. Flexure strength of ZrC–Mo cermets sintered in He/H2 atmosphere materials increased with increasing Mo content from 320 MPa at 20 vol% Mo to 410 MPa at 40 vol% Mo. Strength was predicted by adapting theories developed previously for WC–Co cermets. |
| |
| Keywords: | |
|
|
