High Efficiency Sintering of Ceramics Using a Domestic Microwave Oven

Abstract

Microwave sintering is a process in which objective materials absorb microwaves and heat themselves from the inside. When microwave energy is effectively absorbed by the material, energy consumption for the sintering can be reduced. In this work, a domestic microwave oven (multimode cavity, 2.45 GHz) was employed for sintering ceramics. However, it is difficult to absorb microwaves effectively for long waves. Therefore, a method of efficiently absorbing the microwaves is needed. In general, dielectric loss of ceramics is low at room temperature, but high at high temperatures. A material with high dielectric loss at room temperature was used as a susceptor. The present investigation describes optimization of the heating system set up for the sintering of ZnO. Microwave processing resulted in a reduction of sintering time. A comparative study of ZnO using microwaves and by conventional heating was done using scanning electron microscopy (SEM) observation. The density and average grain size of microwave and conventionally sintered specimens at 1100°C were similar.