The relationship between the change in stress intensity factor and wear rate at elevated temperatures for ceramics

An almost constant fracture toughness exists for the ceramic silicon nitride over a broad range of operating temperatures. However, Si₃N₄ specimens show significant wear rate increases as the operating temperature is increased. It is therefore impractical to use fracture toughness to express the wear rates within the temperature range of 25°C to 550°C. However, notable changes in the material stress intensity occur in the Si₃N₄ material over the same temperature range; these changes are conveniently employed for the expression of wear rate. A relevant relationship between the specimen's wear rate and the factored change in stress intensity is thus developed for a fatigue wear model having ceramic-ceramic mating over the temperature range of 25°C to 550°C. The regressions of the experimental results reveal that the foregoing relationship in terms of a polynomial form is better than a power form.