Effect of Impurities and Sintering Temperature on Properties of MgO-CaZrO3 Ceramics

AbstractCaZrO3-MgO ceramics are useful as refractories in kilns for the cement production. The widely used method of manufacture of such ceramics is by sintering from m-ZrO2 and dolomite MgCa(CO3)2 mixtures. In this work, electrofused m-ZrO2 grains (fraction <M 325) and two Argentinean dolomites with different mineralogical compositions were used as raw materials. Ceramics were obtained by the conventional powder method of uniaxial pressing of such mixtures followed by sintering at 1400 to 1680°C. The influence of the different mineralogy of the dolomites and sintering temperatures on the properties of the composites was investigated. Ceramics had porosity of 20-30%, the representative microstructure as determined using SEM-EDX was constituted by CaZrO3 agglomerates of variable size (∼100μm), MgO grains (size < 50μm) containing some unreacted m-ZrO2 grains. The elastic modulus and flexural strength of the ceramics were correlated with the presence of impurities of the dolomite, porosity and microstructure