MECHANISM OF MIRROR-FINISH GRINDING OF SI LICON-NITRIDE CERAMICS

The mechanism of mirror-finish grinding of Si3N4 ceramics was studied under different grinding conditions using a diamond grinding wheel wit h large grain size (#800, #1200). The main results are summarized belo w, (1) A good mirror-finished surface with smaller surface roughness w as obtained under the grinding conditions of high grinding force and l arge theoretical wheel cutting distance, (2) By an ESCA analysis of th e mirror-finished surface, it was found that a surface layer comprised mainly of silicon and oxygen was generated, and that Si3N4 ceramics w ith extensive coverage of the surface layer had a good mirror-finish-g round surface. Judging from the above results, it was concluded that t he good mirror-finish-ground surface was a result of the plasticity pr oduced by the grinding heat at the contact zone between abrasive grain s and the workpiece.