AN ANALYSIS OF THE WEAR BEHAVIOR OF SIC WHISKER-REINFORCED ALUMINA FROM 25-DEGREES-C TO 1200-DEGREES-C

This Paper describes a model for predicting the wear behavior of whisk er-reinforced ceramics. The model has been successfully applied to a s ilicon carbide whisker-reinforced alumina ceramic composite subjected to sliding contact. The model compares the frictional forces on the wh iskers due to sliding, which act to pull or push them out of the matri x, to the clamping or compressive forces on the whiskers due to the ma trix, which act to hold the whiskers in the composite. At low temperat ures, the whiskers are held strongly in the matrix and are fractured i nto pieces during the wear process along with the matrix. At elevated temperatures, differential thermal expansion between the whiskers and matrix can cause a loosening of the whiskers and lead to pullout durin g the wear process and to higher wear. The model, which represents the combination of an elastic stress analysis and a friction heating anal ysis, predicts a transition temperature at which the strength of the w hiskers equals the clamping force holding them in the matrix. Above th e transition, the whiskers are pulled out of the matrix during sliding , and below the transition the whiskers are fractured. The existence o f the transition gives rise to a dual wear mode or mechanism behavior for this material which has been observed in laboratory experiments. T he results from this model correlate well with experimentally observed behavior indicating that the model may be useful in obtaining a bette r understanding of material behavior and in making material improvemen ts.