PREPARATION OF ZrWMoO8-CONTAINING COMPOSITES WITH ZERO THERMAL EXPANSION PROPERTY USING Al(NO3)3.9H2O AS A SINTERING AID

Mixed oxide β-ZrWMoO8-containing composites with monoclinic zirconia (m-ZrO2) were prepared in search for zero thermal expansion ceramics over a wide temperature range. Thermomechanical analyzer (TMA) results indicate that the thermal expansion coefficients of the β-ZrWMoO8-containing composites decrease with increasing amount of β-ZrWMoO8 and that the composite with 50 wt. % β-ZrWMoO8 and 50 wt. % m-ZrO2 exhibits near-zero thermal expansion from 30 to about 600oC. However, its relative density is low. The addition of a small amount of Al(NO3)3.9H2O as a sintering aid increases the density (possibly because the Al3+ ion promotes sintering and densification) while affecting the structure and thermal expansion only insignificantly.