Finishing of Advanced Ceramics

This project deals with both fundamental and applied aspects of finishing of advanced ceramics, such as silicon nitride Si3N4 balls for hybrid bearing applications using the magnetic float polishing MFP technology developed under DARPAs Ceramic Bearing Technology Program CF 33615-92-C-5933. On the fundamental side, an understanding of the material removal mechanisms involving both mechanical and chemo-mechanical polishing CMP as well as thermal aspects of polishing were considered. improvements in the quality of the finished balls in terms of surface finish Ra 5 nm and sphericity 0.15-0.25 mm and the development of prototype equipment for increasing the batch size by almost an order of magnitude i.e. from about 10 balls of 12 mm diameter per batch with the small apparatus to about 80 balls per batch with a large apparatus for polishing were investigated on the technology side. The processing time for finishing a batch of balls was about 20 hours.