予き裂導入試験片を用いた構造用セラミックスの破壊靱性評価(第3報) : 高温域への適用性

概要

論文の詳細を見る
An investigation was made on the factors which affect the accuracy of the K_<IC> value for structural ceramics at high temperature region by single edge precracked beam (SEPB) method. A sharp pop in precrack was introduced in a rectangular specimen of a polycrystalline alumina and silicon carbide by bridge indentation technique. The precracked specimens were fractured by three points bending with a cross-head speed of 0.5 mm/min at a temperature from 800° to 1500℃ in air. The precracked specimens were also fractured at room temperature after annealing at a temperature from 800° to 1600℃ in air or vacuum. By comparing the K_<IC> values thus obtained, effects of crack healing and crack tip blunting on the K_<IC> values were discussed. The effect of healing and blunting on the K_<IC> values for an alumina measured at high temperatures was small owing to the weakened healing strength and active slow crack growth at these temperatures. On the other hand, the K_<IC> value for a silicon carbide increased remarkably due to the effect of oxidation products formed at high temperature.
1990-04-01