DEVELOPMENT OF ZrO2/CaAl4O7 COMPOSITES FROM HIGH ALUMINA CEMENT AND DIFFERENT m- ZrO2

Y. L. BRUNI; F.N.BOOTH; M.P.ALBANO; L.B. GARRIDO; E.F. AGLIETTI

Congreso; 59 Congresso Brasileiro de Cerámica; 2015

Composites containing calcia stabilized ZrO2 and CaAl4O7 (CA2) as main phases weredeveloped from mixtures of monoclinic ZrO2 and high alumina cement (HAC) as asource of CaO by uniaxial pressing of the powder mixtures and sintering at 1300 and1400 °C. Two commercial m-ZrO2 powders having mean particle sizes of d50=0.44 μm(fine) and d50=8μm (coarse) were used. The crystalline phase constitution, densification and compressive strength was evaluated to determine the effect of processing parameters (CaO content in the powder mixture, ZrO2 particle size and sintering temperature) on physical and mechanical properties. The cubic ZrO2 content increased from 10 to 29 vol% for 5 and 30 mol% CaO in ZrO2 respectively, and with further increase to 50 mol% CaO the proportion of c-ZrO2 reduced to 19 vol%. Porous ceramics processed with the coarse ZrO2 attained porosities between 37 and 44 % and had interconnected pores with mean size of 2 μm. Composites produced from fine ZrO2exhibited high densification (porosities between 11 and 17 %), low mean pore size(~0.02 μm) at 1400°C resulting in a high compressive strength (350 MPa).