MODELING OF GRAIN-SIZE-DEPENDENT MICROFRACTURE-CONTROLLED SLIDING WEAR IN POLYCRYSTALLINE ALUMINA

To quantify grain-size-dependent sliding wear of polycrystalline alumina induced by grain-boundary microfracture, an attempt is made to extend and combine Cho et al.'s fracture mechanics analysis and Fu and Evans' simple microcracking theory. An analytical equation is derived to relate wear with microstructural parameters. Wear by intergranular microfracture occurs, provided that the combined stresses are greater than a threshold value. The critical sliding time to the wear transition decreases with increasing grain size, and the wear rate after the threshold is proportional to the grain size. The theoretical predictions are correlated with the lubricated sliding wear data of aluminas with different grain sizes reported by Cho et al.