Tribological behavior of alumina in the mild wear regime.

摘要

Wear of an alumina sphere sliding against alumina plates has been investigated as a function of sliding distance and load, ranging from 9.8 to 98.2 N. Three distinct wear regimes are observed. In early sliding, the wear volume is proportional to the load and increases with sliding distance to the power of 0.3, regardless of load. Micro-chipping is dominant in this wear regime. After a certain distance, the wear volume increases linearly with sliding distance and to the power 5.4 of the load at the intermediate loads of 44.5 to 80.1 N. Micro-indentation experiments on the worn surfaces indicate grain boundary weakening during sliding due to fatigue. Inter- and trans-granular fracture is the predominant mechanism in this wear regime. At the lower range of loads of 9.8 and 19.6 N, constant wear rates are not observed even at the longest sliding distances measured. At the highest load of 98.2 N, an abrupt increase in wear occurs after short sliding: macro-fracture takes place due to high hertzian stresses.;The wear behavior of alumina is discussed in terms of fracture mechanics, and contact geometry and stresses. Except for the rapid wear at the highest load of 98.2 N, the wear resistance of these materials is very high. Large variations in wear have been observed not only with operating conditions but also with different materials. The environmental effects on friction and wear of alumina are much smaller than for other ceramic materials.