Characterization of topographical changes during lubricated wear

Experiments on lubricated wear are conducted and profiles of the wearing surfaces are studied. Two types of cross-correlation coefficient are introduced: one compares the profiles obtained at the same position before and after sliding for a fixed duration, and the other compares the profiles at different positions on the same wear track. It is found that the former represents a characteristic of the wearing mode, while the latter quantitatively gives the degree of two dimensionality of the topography.