Mechanical property improvements in Nicalon SiC fibre reinforced silicon nitride ceramics by oxide coating of Si3N4 starting powders
- 作者：Demir ; Adem ; Tatli ; Zafer
- 关键词：A. Ceramic matrix composites (CMCs) ; B. Fibre/matrix bond ; B. Mechanical properties ; E. Sintering ; Oxide coating
- 刊名：Composites Part A ; Applied Science and Manufacturing (Incorporating Composites and Composites Manufacturing)
- 出版年：2004
- 期刊代码：17_1359835x
- 类别：ms
- 出版时间：December, 2004
- 卷：35
- 期：12
- 页码：1433-1440
- 文件大小：438 K
摘要
Ceramic matrix composites are attractive as candidate materials for high-temperature applications offering some advantages compared to monolithic ceramics and high-temperature metal alloys. SiC fibre reinforced silicon nitride is one such composite system. However, the processing route is critical to the production of a reliable composite. In this study, silicon nitride matrix densification was improved and sintering temperature was lowered by coating of Si3N4 particles with oxides deposited from hydrolysed metal alkoxides. The solution containing oxide coated Si3N4 powders was used as a slurry to infiltrate Nicalon SiC fibre tows. Following previous studies, the fibres were heat-treated in carbon monoxide to improve mechanical and surface properties. Infiltrated green bodies were hot-pressed at elevated temperatures to produce dense composites. The results showed that particle coating accelerated densification kinetics, eliminated pores and reduced the required hot-pressing temperature. There was also less fibre degradation as a result of the lower temperature of densification. Bending strength and fracture toughness of the composites were measured and fractography was conducted using scanning electron microscope. Composites manufactured using coated Si3N4 powders showed improved properties, specifically matrix stiffening and delayed crack initiation under load.