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Effect of the Grain Boundary Thermal Expansion Coefficient on the Fracture Toughness in Silicon Nitride
Author(s) -
Peterson Irene M.,
Tien TsengYing
Publication year - 1995
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.1151-2916.1995.tb08667.x
Subject(s) - materials science , fracture toughness , silicon nitride , grain boundary , composite material , thermal expansion , sintering , grain boundary diffusion coefficient , grain boundary strengthening , silicon , toughness , metallurgy , microstructure
The effect of thermal expansion mismatch stress between silicon nitride and different grain boundary phases on the fracture toughness of silicon nitride was investigated. Different sintering aids in the Y‐Mg‐Si‐Al‐O‐N system produced silicon nitride specimens with very similar micro‐ structures but different grain boundary phase compositions and different values of fracture toughness. The fracture toughness of the silicon nitride increased as the thermal expansion coefficient of the grain boundary phase increased. The presence of tensile residual stress at the grain boundary caused by thermal expansion mismatch between the silicon nitride and the grain boundary phase enhanced crack deflection and grain bridging.