Grinding of Si3N4 Ceramic Balls with the Aid of Photo-Catalyst of TiO2

There are big needs from industry that the polishing process using loose abrasive be replaced by grinding process. This paper explores the possibility of replacement by investigating effects of the free radical reaction on the precision grinding performance. Free radicals were generated with the aid of TiO₂, a kind of photo-catalyst. Experiments were conducted on Si₃N₄ ceramic ball grinding with a metal bonded diamond wheel of SD8000 and SD16000. It is found that, for SD8000, the material removal rate increases by a factor of about 6 when adding 7.5 wt% of TiO₂ into grinding fluid. Ion exchanged water was used in this experiment. This increase in the material removal rate is expected to be due to the dressing effect of the free radicals of H and HO₂ in water, which are both very strong oxidizing agents. The free radicals of H and HO₂ are generated in the photocatalytic reaction process of TiO₂ with water and oxygen under ultraviolet rays. For SD16000 only adding 1 wt% of TiO₂ leads to a dramatic increase in material removal rate from 0.08 μm/hr to 0.55 μm/hr.