HUANG Juntong, ZHANG Meng, LI Xibao, HU Zhihui, FENG Zhijun, LIU Mingqiang, LUO Junming
(School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063, Jiangxi, China)
Abstract: In order to solve the problems of Si3N4 bonded SiC composites, i.e., incomplete nitridation resulted in "black heart" / "sandwich" and the strength needed to be improved, in this work, the catalytic nitriding process of silicon powder with the catalyst of Fe, Co and Ni was firstly investigated. Then the effect of Co catalyst on the physical properties and microstructure characteristics of Si3N4 bonded SiC composites were investigated. The results showed that the catalysts of Fe, Co and Ni effectively promoted the nitridation of Si powder and the formation of Si3N4 fibers, and reduced the reaction temperature. After nitridation sintering at 1400 °C, the as-prepared Si3N4-SiC composites had the highest strength of 60.2 MPa when the Co content was 0.5wt.%, 88.7% higher than that without Co. It may result from the formation of a fiber network structure, thus strengthening the SiC matrix.
Key words: catalyze; nitridation reaction; Si3N4 bonded SiC composites; fiber reinforcement.