Microscopical Observations of Wear Surfaces on Sapphire

Abstract

Evidence for three possible wear mechanisms was observed by light and electron microscope examination of wear surfaces on sapphire (α‐Al₂O₃). Two of these mechanisms, plastic deformation and fracturing, leave characteristic wear patterns on the surface. The third postulated mechanism, chemical degradation, leaves an essentially smooth surface. The relative importance of these mechanisms depends on orientation of the single crystal, slide direction, load, speed, lubricant, and surface composition.