Evaluation of Fatigue Property of HAp ceramics in Simulated Body Fluid
Details
Compact tension specimen of hydroxyapatite ceramics (HAp) was prepared and cyclic fatigue test was performed in air, deionized water and simulated body fluid (SBF) to investigate the fatigue property of HAp. The environment where fatigue limit stress (N_f=10^7) was the lowest was deionized water environment. Subsequently was SBF environment, air environment. Fatigue fracture was observed with scanning electron microscope (SEM) to clarify this mechanism. As a result, as for the fatigue fracture configuration, fracture in transgranular was observed with high stress condition. On the other hand, intergranular fracture was observed with low stress condition. That is to say, it was stress dependence type with a short life time of case, and it was environment dependence type with a long life time of case. In addition, two fatigue fracture configuration was observed to SBF environment when soak was done for a long time. The fracture surface which intergranular fracture and apatite precipitated surface was observed. By the time that apatite precipitated, improvement of fracture stress was shown in a S-N curve. Therefore, it was shown that fatigue limit stress had higher on SBF environment than deionized water environment.
