Abstract
From some microscopic observations, the appearance of many cavities (slip-shaped wear scars) was found on the wear surface of MgO in the steady state after the vibrational sliding of 104 cycles. The less rate of wear in this state not only depends on the decrease of fatigue damage on the wear surface, which is due to the decrease of contact pressure at a real contact point, but may be explained by a phenomenon that many of the wear fragments were packed into the cavities without being accumulated in the wear interface. It is suggested that rolling contact of the wear fragments in the interface play a significant role in making the cavities. The cavities, however, were not produced at the condition below the amplitude of 60μm because the wear was too less.
Internal creack which appears to be independent from various types of surface damages was found within the areas about 50μm under the wear surface of MgO and was parallel to the surface (cleavage plane). In this case, there is a possibility that the surface material would be locally removed if the internal creack was connected with another type of creack perpendicular to it.
