文献类型：期刊文献

英文题名：Nanostructured sic ceramics prepared by a new process - Crystallization of interfacial glass

作者：Zhang, Zongtao[1]; Zhu, Yihua[1]; Hu, Liming[1]

机构：[1]E CHINA UNIV CHEM TECHNOL,NATL ENGN RES CTR ULTRAFINE POWDERS,SHANGHAI 200237,PEOPLES R CHINA

年份：1996

卷号：7

期号：4

起止页码：453

外文期刊名：NANOSTRUCTURED MATERIALS

收录：;EI(收录号：1996333221591);WOS:【SCI-EXPANDED(收录号:WOS:A1996UN69500007)】；

语种：英文

外文关键词：Annealing - Ceramic materials - Chemical variables control - Crystallization - Densification - Glass - Grain size and shape - Hot pressing - Infiltration - Phase transitions - Plastic flow - Silicon carbide

摘要：Large bulk and fully dense SiC based nanoceramics with average grain size of 50 nm and 20-30 wt.% nanometer sized alpha-Sialon, AlxSi3-xO6 and alpha-SiO2 interfacial phases were prepared by a new process, crystallization of interfacial glass, using LMAS glass-coated SiC powder as starting material. The process involves two major steps: densification by hot pressing, and crystallization of interfacial glass by annealing treatment. The densification was controlled by interfacial glass content, hot pressing temperature, and hot pressing pressure; density 99.8% theoretical being reached for SiC/30 wt.% glass nanoceramics hot-pressed at 1520 degrees C and 22 MPa for 30 min. The crystallization was complete and nearly all the interfacial glass was transformed into nanocrystalline phases after 800 degrees C and 900 degrees C for 5 h annealing treatments. Plastic flow and rearrangement of particles and interfacial glass infiltration are densification Mechanisms. A large number of nanometer sized SiC powder particles serve as nucleating agents, e.g. hetero-nucleation, and are responsible for interfacial glass crystallization. A characteristic of the present process is that there is no SiC grain growth during densification and interfacial glass crystallization.