Wear Resistance of SiO ₂ ‐Doped Y‐TZP Grinding Media During Wet Milling

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°C in water and in a nonaqueous solvent, isoparaffin. A rapid increase in the media wear rate of SiO ₂ ‐undoped media at 60°C 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 ₂ O ₃ and/or ZrO ₂ by OH ⁻ was inhibited by an 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 ₂ O 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.