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Detailed Program
Paper Number : EF-I06
Time Frame : 17:20~17:45
Presentation Date : Friday, 28, November
Session Name : Electric Field Assisted Sintering
Session Chair 1# : Young-Hwan Han
Session Chair 2# : Koji Morita
Milliwave Sintering of Silicon Carbide with Carbon additives
Tetsuo UCHIKOSHI
National Institute for Materials Science
Microwave heating is one of the new sintering processes in which the materials absorb the electromagnetic energy of microwave and transform it into heat. The use of microwave radiation for sintering of ceramics has been recently proposed as a newly focused scientific approach. Microwave sintering has a lot of advantages, for example, selective heating, self-heating, rapid and volumetric heating. Especially, microwave sintering is one of the effective methods for the sintering of dielectric materials because their loss tangent (tan ¥ä) is quite large. Many researchers have reported the effect of the microwave sintering on the properties in the dielectric ceramics such as PZT and BaTiO3, etc. ¡°Selective heating¡± is a distinct characteristic that has not been seen in any other heating process: The material with the highest loss tangent is selectively heated if two or more materials with different dielectric losses exist in a compact. In this study, we utilized the milliwave of 28 GHz for densifying hard-to-sinter SiC by coating the SiC particles with high loss tangent carbon additives.
The effect of carbon addition on the densification of SiC specimens sintered by milliwave sintering (M.S.) and conventional sintering (C.S.) is shown in Fig.1. The microstructures of the selected specimens of different sintering conditions are shown in Fig. 2. Dense SiC body with the theoretical density of >97% was obtained by the milliwave sintering at 1800C. On the other hand, the relative density of the conventionally-sintered body was lower than 80%. It is probable that the carbon surrounding the SiC particles was heated up higher than 1800C by the selective heating absorbing the milliwave. Consequently, the local heating promote the sintering between the SiC particles. The density of SiC sintered by microwave heating depended on the carbon contents.
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