INDENTATION FATIGUE OF HIGH-PURITY ALUMINA IN FLUID ENVIRONMENTS

The influence of environment on the cyclic fatigue behavior of a high-purity alumina bioceramic was investigated using the repeated indentation technique. Tests were conducted in the presence of water, a variety of alcohols, toluene, and simulated physiological fluid environments. The results show that these environments do not have any detectable effect on the damage produced by single indentations, but those containing water cause a significant degradation in cyclic fatigue resistance which cannot be quantified in terms of known subcritical crack growth behavior in static fatigue. It is concluded that the effects of fluid environments on the growth of cyclically driven cracks must be an integral part of the mechanism responsible for cyclic fatigue in ceramics.