Abstract
A new functionally graded zirconia-mullite/alumina ceramic (FGZM/A) and its constituent separated single zirconia-mullite/alumina (ZM/A) layers were designed and synthesized by reaction sintering of zircon and alumina. Influence of MgO addition, different sintering temperature and sintering time on the mineral composition, densification parameters, microstructure, mechanical and thermal properties of FGZM/A and in separated ZM/A layers were investigated. Results showed that the tailored FGZM/A ceramic gave a continuous homogeneous structure without sharp interface. MgO addition enhanced the densification parameters in term of apparent porosity and bulk density, microstructure and compressive strength of ZM/A system with a little effect on the hardness, fracture toughness, thermal expansion and thermal shock resistance. FGZM/A in presence of MgO showed a gradient in its properties from one layer to the other. It recorded an average values of all the separated composites made from single layers through the different properties which reflect the strong interfacial bonding and homogenous distribution of powders in its different layers. (c) 2013 Elsevier B.V. All rights reserved.