Wear Resistance of SiO_2-Doped Y-TZP Grinding Media During Wet Milling

摘要

Grinding media 1 mm in diameter, containing 0.4 and 0.7 wt% SiO_2, were fabricated using Y-TZP powder prepared by the liquid-phase method. The wear resistance of media for grinding, with and without the addition of BaTiO_3 powder, was evaluated at 20-80℃ in water and in a nonaqueous solvent, isoparaffin. A rapid increase in the media wear rate of SiO_2-undoped media at 60℃ was observed using water as a solvent, but little wear was observed for isoparaffin. The operating time until a rapid increase in the wear rate was observed in water increased with the increase in the grain size of the Y-TZP media. When the media wear became stable, the media surface was observed to be smooth. This suggested that the hydration reaction of Y_2O_3 and/or ZrO_2 by OH~- was inhibited byrnan increase in the grain size, and as a consequence, the decay of the grain boundaries was suppressed. In contrast, several traces of grain loss from the grain boundaries were confirmed on the worn surface of the media when a rapid increase in the wear rate was observed. The wear resistance for grinding BaTiO_3 powder using SiO_2-doped and -undoped media was also investigated. The wear for SiO_2-undoped media increased drastically with increasing slurry temperature; however, the wear for SiO_2-doped media did not increase, but was low and stable, regardless of the slurry temperature. This indicated that the hydration reaction of Y_2O_3 and/or ZrO_2 by OH~- was further inhibited by the segregation of SiO_2 at the grain boundaries, and hence SiO_2-doped Y-TZP media have high wear resistance, even with increased slurry temperature.