Low-temperature sintering of mullite/yttria-doped zirconia composites in the mullite-rich region

Mullite/Y-TZP composites in the mullite-rich region, using powders of mullite prepared via the hydrazine method and a commercially available zirconia compound (ZrO2(2Y)), have been fabricated by sintering for 3 h at 1450 degrees C in air. The grain sizes of mullite and ZrO2(2Y) are changed with increased ZrO2(ZY) content; the former decreases from 0.25 mu m to 0.13 mu m, and the latter increases from 0.21 mu m to 0.35 mu m. High strength (780 MPa) and fracture toughness (5.4 MPa.m(1/2)) are obtained in the 50/50 (vol%) mullite/ZrO2(2Y) composite with 99.6% of theoretical density.