The material characteristic analysis of silicon nitride ceramics sintered by 2 8 GHz millimeter-wave heating method

摘要

We study the application of the millimeter wave heating method to the silicon nitride, which includes Yb{sub}2O{sub}3 and Al{sub}2O{sub}3 as an additive. The sintered bodies showed excellent mechanical properties such as high Vickers hardness and fracture toughness at room and high temperatures, proving effectiveness of the millimeter wave heating method. It thinks because the millimeter wave heating method promotes crystallization of additive layer at the grain boundary. In this study, we calculated Young's modulus from the Surface wave velocity that measured by a scanning acoustic microscope, and compared with the result from three-point bending test. The acoustic microscope can measure a partial difference because it uses local information, and non-destruction is effective too. Moreover, were examined about the behavior under the high temperature condition by the TG analysis and the EDX analysis.