Effect of surface topography on the dynamics of the abrasive particles during micro-abrasion

Abstract

During abrasive wear, the wear mechanism has been shown to be associated with the movement of the active particles present at the wear interface: rolling, evidenced by indentations on the worn surface, and sliding, which produces scratching and/or ploughing. Particle dynamics can vary with tribological parameters such as different combinations of ball and specimen materials, applied load, slurry concentration, abrasive material, ball condition and equipment configuration (fixed or free-ball). In this article, the effect of surface topography of both the ball and the specimen on the dynamics of the abrasive particles and micro-abrasion wear is investigated for SiO2 abrasive particles. The effect of the ball surface topography was investigated using a fixed-ball rig, zirconia balls (Sa=0.06, 0.34, and 0.54µm) and stainless steel specimens (Sa=0.10µm). When the roughness of the ball increased, the wear mechanism changed from sliding to mixed and then to rolling and the micro abrasion coefficient k increased substantially, the difference between the smoothest and the roughest ball being around 510%. The effect of the specimen surface topography was investigated using a free-ball rig, AISI 52100 steel balls (Sa=0.82µm) and tool steel specimens (Sq=0.025µm and 0.414µm). The influence of the directionality of the specimen surface finish was also analyzed by conducting tests parallel and perpendicular to the grinding marks using three slurry concentrations. The effect of the topography of the specimens on wear coefficients and mechanisms was much less pronounced than that found for the ball topography. For the highest slurry concentration (20wt%), k increased for the rougher specimens (around 23%) and a slight change in mechanism occurred from mixed (sliding in the center and rolling at borders of craters), to sliding. This effect was less significant for lower concentrations. The influence of surface directionality on abrasive wear was negligible.