关键词: 氮化硅基陶瓷, 微波烧结, 调控策略, 微波功率

Abstract: Microwave sintering technology was widely used in preparation of ceramic materials. However, the silicon nitride based ceramic materials sintered by microwave had problems such as poor performance consistency and large power fluctuations during heating processes. Therefore, the distribution characteristics of electric field and temperature field were compared in microwave sintering chambers with or without loads and different sample placement methods according to simulation. The influences of microwave power on the distribution of electric field and temperature field were analyzed, and the principle of microwave sintering power selection was proposed. The influences of heating rate and matching power on mechanics properties of ceramics in different temperature ranges were compared through experimental results. The results show that adding loads and arranging samples tightly in microwave field are beneficial for improving the uniformity of the electric field. The experimental results indicate that the Si3N4-based ceramic materials with the best mechanics properties may be obtained by selecting heating rates of 80 ℃/min, 50 ℃/min and 25 ℃/min at 0~800 ℃, 800~1400 ℃ and 1400~1650 ℃ respectively, and matching powers of 1600 W, 1800 W and 2200 W are selected for each temperature range. The Vickers hardness reaches(18.278±0.233)GPa, and the fracture toughness reaches(8.588±0.165)MPa·m1/2. Compared with the uniform heating processes, the hardness increases by 14.8%, the toughness increases by 22.5%, and the consistency of ceramic material properties may be improved effectively with the regulation strategy herein.

Key words: Si3N4-based ceramics, microwave sintering, control strategy, microwave power