Theoretical analysis of steady-state texture formation during wear of a bi-material surface

Surface textures of very small scale are able to carry pockets of lubricant into heavily loaded contacts, leading to reductions in friction and wear. Recently, such textures have been produced by a new method in which two materials of differing wear properties are combined to form a composite surface. In a typical application, a distribution of individual wear resistant islands of small dimension relative to the overall contact size is used. Initially, these wear resistant regions may wear more slowly than the substrate material. Following this initial stage, a steady-state texture (height difference between these two regions) is reached, and this is maintained during further contact cycles where the linear wear rate is the same for both regions. This paper describes recent work on the development of a model based on the contact of rough surfaces which is able to predict the steady-state height difference between the two phases of the bi-material surface. The method has application in the design of textured surfaces.