Effects of Oxygen on Friction of Steel (Wear of Steel at High Temperature–5th Report)

Abstract

The effects of oxidation on wear were studied by tests in O₂, N₂ and air. Wear losses were measured at various air pressure and at high temperature. Wear is profoundly effected by partial pressure of O₂, but not by partial pressure of N₂. In vacuum, a hard layer prevents separation of wear powder from the surfaces. The maximum of wear appears at 0.1∼1 mmHg partial pressure of O₂. This is because the metallic surfaces are in contact with each other and the oxide prevents the wear powder from attaching again to the surface. It is believed that the quantity of oxide decides the state of wear. Thin layer of oxide gives unfavorable effect from the wear point of view. From this series of study on wear at high temperatures, it is concluded that steels for hot working tool steel should be selected by its heat-resisting properties and oxidability, and that a thin oxidized surface accelerates wear at high temperature.