K. Das et al., EFFECT OF YTTRIA ON MECHANICAL AND MICROSTRUCTURAL PROPERTIES OF REACTION-SINTERED MULLITE-ZIRCONIA COMPOSITES, Journal of the European Ceramic Society, 18(12), 1998, pp. 1771-1777
Mullite-zirconia composites containing 0 to 7 mol% yttria were prepare
d by reaction sintering process from Indian coastal zircon flour and c
alcined alumina. The main raw materials were attrition milled. Samples
were isostatically pressed and sintered at temperatures of 1400 to 16
50 degrees C with 2h soaking time. The resulting composites were chara
cterised in terms of phase compositions, martensitic start (M-S) tempe
rature, mechanical properties and microstructural features. The presen
ce of yttria results in a dense composite material at a comparatively
low temperature. Addition of yttria increases the tetragonal zirconia
fraction and reduces the Ms temperature. Yttria goes into solid soluti
on which was detected by EDX analyses. The effect of yttria on thermal
expansion coefficient, room temperature flexural strength, hardness,
fracture toughness is discussed. (C) 1998 Elsevier Science Limited. Al
l rights reserved.