Application of Microwave Energy for Synthesis and Sintering of Al2O3-TiC Ceramics

Using microwave energy in ceramic processing can provide both energy and time saving and improve products. In this paper, the use of high power microwave energy for the synthesis and sintering of Al2O3-TiC ceramic composites were described. The microwave synthesis and sintering experiments were conducted in a 2.4 KW, 2.45 GHz multimode commercial microwave furnace with atmosphere control capabilities. Microwave combustion synthesis of both Al2O3-TiC powders and compact samples from the TiO2+C+Al+ Al2O3 mixtures were achieved successfully. The powder combustion under microwave could be achieved in less than 3 minutes which was 60 times faster than conventional combustion. For the compact combustion, the addition of 0-40wt % Al2O3 product phase as a diluent was used to lowering combustion temperature and decreasing the reaction rate. From the preliminary sintering results, the highest microwave sintering temperature was attained at 1500 oC. The microwave sintered Al2O3-TiC sample had a tendency to obtain a nearly full densification at lower sintering temperature compared to the conventional heating process. The gas generating problem at high temperature was eliminated due to fast sintering process and short dwelling time presented in microwave process. The specially-designed SiC susceptor was used to control the highly exothermic reaction during synthesis which helps achieve the appropriate microstructure. It was also employed during sintering to achieve efficient heating and uniform temperature distribution. 1