Effect of ceria on the physical, mechanical and thermal properties of yttria stabilized zirconia toughened alumina

Alumina is a good engineering ceramic material, which has excellent thermal, chemical, mechanical and electrical properties. One of the inherent drawbacks of alumina is its low fracture toughness. This can be significantly improved by the addition of yttria stabilized zirconia, which improves both the flexural strength and fracture toughness. In tetragonal zirconia polycrystals, it has been found that the addition of ceria increases the fracture toughness substantially. In the present work, yttria stabilized zirconia toughened alumina (ZTA)-ceria composites for industrial ceramic applications have been studied. Test specimens such as pellets and rectangular bars were fabricated for yttria stabilized ZTA with various amounts of ceria additions (1-5 vol.%). The fabricated samples were sintered at a temperature of 1560 °C. The sintered samples were characterized for their physical properties such as bulk density, true density, percentage of porosity and linear shrinkage. X-ray diffraction patterns confirm the constituent phases present in the samples were alumina and zirconia. The samples were subjected to mechanical tests like modulus of elasticity, flexural strength, hardness and fracture toughness. Thermal expansion coefficient was also measured for different samples with various ceria additions. It was observed that the addition of ceria deteriorates the mechanical properties including fracture toughness of the yttria stabilized ZTA.