Role of Atmospheric Oxidation in High Speed Sliding Phenomena

Abstract

An experimental study of the role of oxidation in inhibiting metallic interaction between metal surfaces sliding at high speeds (up to 66 m/sec) is described. Metallic interaction was detected by microscopic examination of the surface damage after sliding. By using hardened steel, information concerning surface temperatures was deduced from subsequent hardness measurements. At light loads the metal surfaces were severely torn, but at higher loads the tearing became less severe. Above a certain load which depended on the speed tearing was almost eliminated from at least one of the surfaces. Other experiments supported the conclusion that this was due to the increased oxidation associated with the greater frictional heating, and that severe wear at high loads was due to a process of oxide disintegration. Under these conditions the wear rate increased rapidly with increase in load or speed, whereas the wear associated with metallic tearing at light loads showed little increase with load, and decreased with increasing speed. The friction coefficient decreased with increasing load and with increasing speed. The shapes of the underlying bodies influenced the average surface temperatures and therefore the wear and surface damage and create differences even for a pair of mating surfaces.