Microripple formation and removal mechanism of ceramic materials by solid-liquid slurry erosion

The phenomenon of the formation of microripples on ceramic materials and re moval mechanisms in solid-liquid slurry erosion has been studied and a new theory is proposed. This theory which is suited for slurry-erosion process of brittle materials, is based on experimental observations and differs fro m the existing ones which are for erosion process of ductile materials. In order to determine the origin and development of surface ripples, four engi neering ceramic materials, i.e., alumina, reaction bonded silicon carbide, sialon and PSZ zirconia were eroded by a solid-liquid slurry jet in laborat ory tests. The erosion mechanisms for these ceramic materials involve both plastic deformation and brittle fracture. Microripple patterns were found o n all of these tour materials, depending on the experimental conditions. Op tical and scanning electron microscopy investigations revealed that when ro unded silica sand was used as erodent, the predominant erosion mechanisms a re fractured, and fractured particles are removed in the case of SiC, while PSZ zirconia, sialon and alumina display both the brittle mode of fracture together with the ductile mode of ploughing. To compare with the ceramic m aterials and to gain a better understanding of ripple formation of material s, the ripple formation of a typical ductile metal, aluminium was also test ed. (C) 1998 Elsevier Science S.A All rights reserved.