フッ素添加Si_3N_4-SiCセラミックスの機械的性質に及ぼす界面構造の影響

概要

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Changes in interface chemistry and, accordingly, in interface structure of a Si_3N_4-SiC ceramic, due to the presence of fluorine, was found to markedly affect the mechanical response of the material. Owing to a lowered cohesive interface strength, as a consequence of fluorine segregation at grain and phase boundaries, an increased fraction of intergranular fracture was monitored upon crack propagation. Moreover, in comparison to undoped specimens, fluorine-doped samples revealed markedly higher creep rates, which are related to a decrease in the apparent grain-boundary viscosity. The experimental results allow a correlation between the macroscopic mechanical properties and the atomic interfacial glass structure. A glass structure model is presented, which emphasizes the influence of broken(non-bridging)bonds on the bulk mechanical performance of Si_3N_4-SiC-based composites.
社団法人日本セラミックス協会の論文
1998-01-01