Development of superabrasive stone for mechanochemical superfinishing

One of the effective methods for obtaining an ultra-precision surface is utilization of the mechanochemical reaction that occurs at the interface between a tool and a workpiece. A thermodynamic analysis suggested that cerium oxide CeO2 in contact with steel oxidizes the steel surface. Then, steel specimens embedded in CeO2 powder were heated to 773 K in a vacuum, and their surfaces were closely analyzed by X-ray diffractometry. As a result, peaks of Fe3O4 together with α-Fe were recognized by their diffraction patterns. On the basis of this finding, vitrified superabrasive stones containing CeO2, i.e., cBN/CeO2 stones, were made and their performances were evaluated through the superfinishing of bearing steels. Experiments showed that cBN/CeO2 stone is superior in surface finish to conventional cBN stone because of the synergistic effect of the mechanical action of the cBN abrasive and chemical action of the CeO2 abrasive.