A Comparative Study of CaO-MUZ Composites Elaboration by Plasma Melting and Sintering Techniques

Abstract

CaO doped zirconia mullite (CaO-MUZ) samples were synthesized through plasma melting, plasma sintering, and conventional sintering using plasma reactor and high temperature furnace as the heating sources. The compositional ratio (wt) of silimanite, alumina, and zircon were taken as 47:38:15, and 4 wt% of CaO was added to the above compositional ratio for the synthesis of CaO-MUZ. A mixture of tetragonal and cubic zirconia phases have been observed in all the processed CaO-MUZ composites. This observation infers that though the available temperature in plasma sintered and conventionally sintered MUZ specimens is not sufficient for the transformation of monoclinic zirconia to cubic zirconia, the addition of CaO favors this transformation. The arrangement of close compacted small and large crystal grains in conventionally sintered specimen increases the bulk density, while the hardness remains lower in comparison to the plasma-sintered CaO-MUZ. The optical bandgap measurements predict that the CaO-MUZ composites can be used as suitable refractory materials for ceramic industrial applications. We report the suitability of heating sources and the impact of melting and sintering techniques on the structural, microstructural, mechanical, and optical properties of CaO-MUZ, so that one can choose appropriate synthesis techniques to achieve the desired product at the industrial scale.