TiO_2の破壊じん性に及ぼすマイクロクラックの影響

概要

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Pressureless sintered TiO_2 bodies were annealed to change their grain sizes from 10 μm to 59 μm. Microstructural observations of the specimens indicated that the spontaneous critical grain size of TiO_2 was about 20 μm, and the mean length of network of microcracks was about 1.5 mm. The thermal expansion analysis indicated that the volume fraction of spontaneous microcracks was about 1.5×10^<-3>. The grain size dependences of Young's modulus and fracture stress ensured the spontaneous microcracking. Fracture toughness K_<IC> was measured by a chevron-notched beam method. K_<IC> took a constant value below the critical grain size, but it was reduced to about 65% above the critical grain size. The reduction of K_<IC> could be estimated quantitatively using the length and volume fraction of microcracks.
社団法人日本材料学会の論文
1992-04-15