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Si 3 N 4 /SiC‐Platelet Composite without Sintering Aids: A Candidate for Gas Turbine Engines
Author(s) -
Pezzotti Giuseppe
Publication year - 1993
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.1151-2916.1993.tb03757.x
Subject(s) - materials science , sintering , composite number , composite material , ceramic , flexural strength , grain boundary , hot pressing , particle (ecology) , phase (matter) , carbide , silicon carbide , isotropy , microstructure , oceanography , chemistry , physics , organic chemistry , quantum mechanics , geology
A dense and isotropic Si 3 N 4 composite body containing 25 vol% of α‐SiC platelets, with average particle size of 24μm and aspect ratio of 8 to 10, was fabricated by hot isostatic pressing without any addition of sintering aids. In this composite, desirable properties for structural ceramics to be used in long‐term high‐temperature applications are conveniently combined: a fracture resistance comparable with that of Si 3 N 4 sintered with conspicuous amounts of additives, as well as a superior time‐dependent strength and deformation behavior up to 1400°C, was found. The high‐temperature reliability in the present composite was improved further than that of the additive‐free Si 3 N 4 , mainly due to mechanisms operating in the wake of the crack. The key to the attainment of a valid synergism between nitride and carbide phase resides both in the presence of pure SiO 2 glassy phase at the grain boundary and in the morphology of the reinforcement.