| 摘要 |
A methodology for finishing of HIP'ed Si3N4 balls from the as-received condition by magnetic fluid polishing. It involves mechanical removal of material initially using harder abrasives with respect to the workmaterial (of different materials of progressively lower hardnesses and finer grain sizes) followed by final chemo-mechanical polishing (CMP) using preferably a softer abrasive for obtaining superior finish with minimal surface or subsurface defects, such as scratches, microcracks, or pits on the Ni3N<4> balls. High material removal rates (1 mu m/min) with minimal subsurface damage is obtained with harder abrasives, such as B4C or SiC (relative to Si3N4) due to the use of a flexible support system, small polishing loads (1 N/ball), and fine abrasives but high polishing speeds (compared to conventional polishing) by rapid accumulation of minute amounts of material removed by microfracture. Final polishing of the Si3N4 balls using a softer abrasive, such as CeO2 (that chemomechanically react with the Si3N4 workmaterial) results in high quality Si3N4 balls of bearing quality with a superior surface finish and damage-free surface. |
