Fabrication of Al₂O₃-ZrO₂~Ni Functionally Graded Pipes

The fabrication of Al2O3-ZrO2~Ni functionally graded pipes has been investigated by slurry coating and pressureless sintering process. Each slurry of Al2O3-ZrO2~Ni mixture and Ni was coated in order on the Al2O3-ZrO2 pipes formed by slip casting method with those slurries. The obtained laminar green pipes were 30 mm in diameter and approximately 90 mm in length. The laminar green pipes were sintered for 2 hours at 1430℃ in a vacuum. The structure of pipes fabricated by this method was optically and microscopically examined and the graded distribution was examined by an EPMA analysis of Al and Ni. The pipes with 2 layers of Al2O3-ZrO2 and Ni had crevices in the bonding interface. Some functionally graded pipes with 3 layers were free from cracks and warps without porosity, and each interface had the complete bonding.