CaZrO3-MgO structural ceramics obtained by reaction sintering of dolomite-zirconia mixtures

Abstract

Processing and properties of two fine grain and dense CaZrO3-MgO based composites obtained by reaction sintering of pure ZrO2 and dolomite (CaMg(CO3)2) are described. Two dolomites with different levels of impurities were used to fabricate the materials: high purity (impurity content ≈1.2 wt.%, material DBZ) and impure dolomite (impurity content ≈6.12 wt.%, material DNZ). Mixtures (molar 1:1) were attrition milled and the reaction and sintering processes were studied using dynamical techniques (DTA-TG and dilatometry). Adequate sintering schedule was selected using the controlled sintering technique. The role of impurities on the physical characteristics, microstructure and mechanical properties of the obtained composites was analysed. Noticeable changes in microstructure, porosity, grain size and phases, were observed as function of final sintering temperature at 1350, 1400, 1450 °C, and impurity content. The obtained microstructures are discussed on the basis of the phase equilibrium relationships.