Critical impact velocity in the solid particles impact erosion of metallic materials

Abstract

Solid particles impact erosion of metallic materials proceeds through two kinds of damage processes. One is the removal of material due to repeated plastic deformation, and the other is cutting. These processes occur simultaneously and the ratio of each contribution to the total damage depends not only on the impact angle (the predominant parameter) but also on the impact velocity. As the impact velocity goes down, a solid particle tends not to skid on the target material surface, and hence the cutting damage is reduced. At a certain lower velocity, the particle does not skid at all, resulting in no cutting damage but plastic deformation damage only. This velocity was defined as the “critical impact velocity”. In this study, the methodology to determine the critical velocity through a measurement of the coefficient of friction was established, that is, the dynamic friction coefficient during skidding and the static friction coefficient during rolling without skidding. In order to measure the coefficient of friction at the moment of particle impact, a rotating target apparatus was developed. The critical impact velocity thus determined depended on the hardness of both material and particle, as well as on the shape and size of the solid particles.