THE DEVELOPMENT OF NANOCRYSTALLINE CBN FOR ENHANCED SUPERALLOY GRINDING PERFORMANCE

CBN grinding wheels are increasingly used on a wide range of engineeri ng materials. This paper compares the grinding performance of monocrys talline (M-CBN) and polycrystalline (P-CBN) abrasives with a newly dev eloped nanocrystalline (N-CBN) abrasive, when grinding nickel-based su peralloys. The N-CBN grits possess average crystal grain diameters les than 1 mu m compared to average primary grain diameters of 2.3 mu m f or P-CBN. It was found that the nanocrystalline CBN grits possess high er fracture strength which give reduced wear rates and yield an order of magnitude increase in grinding wheel life. Analysis of the cutting edge distribution shows that the reduced wear rate of N-CBN is due to the predominance of a micro-fracturing mode of abrasive wear. The size of this micro-fracturing is considerably smaller in N-CBN than in P-C BN.