Al_2O_3及びAl_2O_3系複合焼結体の微細組織による繰り返し疲労特性の変化

概要

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The cyclic fatigue properties of three kinds of toughened Al_2O_3 composites doped with SiC whisker, TiC and partially stabilized ZrO_2 particle were compared with results of four kinds of Al_2O_3 ceramics with different purities. The effects of stress amplitude and initial crack size on fatigue properties were investigated by using polished and pre-cracked samples. Furthermore, the accelerated phenomena on initiation and propagatation velocities of fatigue crack under cyclic loading condition were quantitatively assessed by the estimatation method using an experimental relation based on subcritical crack growth velocity and static fatigue data. As results, in the case of polished sample, the accelerated effect on fatigue that 99.99% and 99% Al_2O_3 ceramics typically showed was restrained in Al_2O_3 composites. The cyclic fatigue properties of Al_2O_3 composites used in this paper can be successfully estimated under wider condition of stress application from the data on static fatigue than the case of Al_2O_3 ceramics. On the condition that a sample was precracked by Knoop indenter, Al_2O_3 composites hindered the accelerated effect on fatigue crack propagation under cyclic loading as well. Especially, the cyclic fatigue data of pre-cracked ZrO_2/Al_2O_3 composite agreed well with the estimated value from static fatigue properties.
社団法人日本セラミックス協会の論文
1990-05-01