Abstract
Fracture toughness test of bioceramics using alumina compact tension specimen was carried out in air and water. During this test acoustic emission signal emitted by microcrack nucleation were recorded by piezoelectric transducers. The response function of the specimen was determined by pencil lead breaking used as a simulated source. Then acoustic emission source function emitted by microcrack nucleation was also determined by inverse calculation using obtained response function. From acoustic emission source function, size and nucleation velocity of microcrack were understood. Consequently, it was understood that microcracks with 6.6〜17μm of diameter and 9.5〜47m/s of nucleation velocity were nucleated in air. On the other hand, in water, the radius was 13〜22μm and the nucleation velocity was 26〜86m/s. Then quantitative microcrack characterization was carried out.
