Abstract
The microfracture process during the bending tests of alumina ceramics typical bioinert bioceramics for artificaial joints was analyzed. 4 point bending tests were carried out in air, refined water, physiological saline and the simulated body fluid. In order to characterize the microfracture process, AE signals during tests were detected. A remarkable point in the AE generation pattern, at which AE activity increased rapidly, was observed before the final unstable fracture. It was understood that the stress at those critical point, σC, corresponds to critical stress for the maincrack formation due to the coalescence of microcracks and/or pores. The values of σC had similar tendency to the fracture strength, i.e. it was decreased in the simulated body environment. Consequently, it was demonstrated that the critical stress, σC, could be used as a new evaluation parameter, which is for the strength and life time of bioceramic materials.
