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Properties and Microstructure of Molybdenum Disilicide–β′;‐SiAlON Particulate Ceramic Composites
Author(s) -
Huang Chao M.,
Yuh Chao Y.,
Farooque Mohammad,
Zhu Dong,
Xu Youren,
Kriven Waltraud M.
Publication year - 1997
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.1151-2916.1997.tb03201.x
Subject(s) - sialon , materials science , composite material , fracture toughness , microstructure , ceramic , molybdenum disilicide , ceramic matrix composite , vickers hardness test , toughness , residual stress , scanning electron microscope , flexural strength , molybdenum , metallurgy
Particulate ceramic composites that were composed of a combustion‐synthesized β′;‐SiAlON matrix and dispersed MoSi 2 particles were hot pressed at 1600°C in a nitrogen atmosphere. The physical and mechanical properties of the composites that contained 15, 30, and 45 vol% MoSi 2 were evaluated. The average four‐point bend strength, fracture toughness, and Vickers hardness of the composites were in the ranges of 500‐600 MPa, 3‐4 MP·am 1/2 , and 11‐13 GPa, respectively. The measured mechanical strength and hardness were very similar to the values that were predicted from the rule of mixtures. The fracture toughness of the combustion‐synthesized β′;‐SiAlON (2.5 MPa·m 1/2 ) was apparently enhanced by the MoSi 2 particles that were added. The increase in the fracture toughness was predominately attributed to the residual thermal stress that was induced by the thermal expansion mismatch between the MoSi 2 particles and the β′;‐SiAlON matrix. The composites showed improved electrical conductivity and oxidation resistance over monolithic β′;‐SiAlON. High‐resolution transmission electron microscopy examination of the composites indicated that the MoSi 2 was chemically well compatible with the β′;‐SiAlON.