Fabrication of Ceramic-Metal Functionally Graded Materials


High order step wise functionally graded materials Al2O3-Ti are fabricated. These materials combine the high fracture toughness of Ti phase and the relatively low density of Al2O3 and stand for candidate materials for harsh mechanical and thermal environments. The techniques of powder technology are utilized to fabricate these materials that composed of five graded layers of Al2O3-Ti phases. Al2O3 increasing linearly across these layers (0, 25, 50, 75 and 100wt% respectively).The green specimens are composed of Al2O3-TiH2 layers and the sintered specimens are composed of graded Al2O3-Ti. Spark Plasma Sintering technique is utilized for sintering of the graded green specimens. The best sintering conditions is found at 1500°C for 30 minute of sintering that gives apparent density of 4.25 g/cm3, porosity of 1.28% and diametric expansion of 1.58%. Optical microscopy shows gradual transition of phases at the interface of the graded layers