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Processing of ZrC–Mo Cermets for High Temperature Applications, Part II: Pressureless Sintering and Mechanical Properties
Author(s) -
Landwehr Sean E.,
Hilmas Gregory E.,
Fahrenholtz William G.,
Talmy Inna G.
Publication year - 2008
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2007.02231.x
Subject(s) - cermet , materials science , sintering , eutectic system , microstructure , metallurgy , pressureless sintering , reducing atmosphere , molybdenum , atmosphere (unit) , flexural strength , composite material , ceramic , thermodynamics , physics
Pressureless sintering of ZrC–Mo cermets was investigated in a He/H 2 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/H 2 atmosphere. The increase in density was attributed to the formation of Mo 2 C during heating and its subsequent eutectic reaction with Mo, which produced rounded ZrC grains in a Mo–Mo 2 C matrix. Sintering in vacuum did not produce the same increase in density, due to the lack of Mo 2 C 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/H 2 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.