ムライトセラミックスの1200℃での静的疲労及び破壊靭性値

概要

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The fatigue behavior for mullite ceramics containing 71, 72 and 74 wt% Al_2O_3 (71A, 72A and 74A) was meas ured at 1200℃ by the static fatigue technique. The frac ture toughness was evaluated from the slow crack growth magnitude (fatigue fracture surface) com bined with the applied stress. The crack growth parameter (N) of 71A, 72A and 74A was 17, 23- 24 and 26, and the fracture toughness (K_<IC>) was 4.3, 2.4 and 1.7MPa-m^<1/2>, respectively. These tendencies cor respond to a decrease of the glass phase in the grain boundary. The fracture modes of the grains in the fa tigue fracture surface for 71A was intergranular frac ture in equiaxial crystals and transgranular fracture broken in the rod like crystals, for 72A intergranular fracture in equiaxial crystals and transgranular frac ture broken in slightly remained rod-like crystals, and for 74A only intergranular fracture. The fracture mode in the catastrophic fracture surface was transgranular for 71A, 72A and 74A. It was considered that the frac ture toughness of munite at 1200℃ increased with a decrease of Al_2O_3 content because the crack tip became blunter by increasing the glass phase.
1994-09-01