Improved ball crater micro-abrasion test based on a ball on three disk configuration

An improved ball crater micro-abrasion test method has been developed that differs from the conventional ball crater method. A ball-on-three-disk (BOTD) configuration provides mechanical stability and three simultaneous measurements of abrasion. An inclined BOTD geometry allows the specimens to be totally immersed in abrasive, which allows the use of dry abrasives as well as slurries and pastes. Use of a rubber ball gives effective three-body abrasion and provides results that are highly correlated with the ASTM G65 method. Use of dry abrasive with a rubber surface, rather than use of slurries and a metal ball, provides cutting action that is closer to actual field conditions, and allows high temperature test. Flooding the substrate with abrasive also avoids the problems encountered in conventional ball crater tests in that it provides spherical scars even for large particle abrasives, and spherical geometry allows direct computation of the volume of wear. Modeling of the BOTD scar geometry indicates that the BOTD contact pressure is similar to the contact pressures used in the ASTM G65 test. The BOTD microabrasion method provided excellent ranking of the abrasion rates of bare steel and two thicknesses of a TiAlN coating.