Pages 185-186
Microfracture process during bending tests of alumina, which is the typical bioceramics used for artificial joints, was evaluated by AE technique. 4 point bending tests were carried out in air, refined water, physiological saline and simulated body fluid. It was recognized in the AE generation behavior that the AE activity increased remarkably before the final failure. It was understood that the bending stress at those points, σ_c, corresponds to the critical stress for maincrack formation. The static fatigue behavior in physiological saline was also investigated. The time to failure under the stress higher than σ_c was smaller than that lower than σ_c. Consequently, it was demonstrated that the evaluation of σ_c is significant for the assessment of long-term-reliability of bioceramics.
