Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5438685 | Ceramics International | 2016 | 5 Pages |
Abstract
The formation mechanism and thermodynamics of Si3N4 in reaction-bonded Si3N4-SiC materials were analyzed. There are two kinds of Si3N4, fibroid α-Si3N4 and columnar β-Si3N4, which are formed by different processes in Si3N4-SiC materials. Silicon reacts with oxygen, forming gaseous SiO and reducing oxygen partial pressure. SiO(g) diffuses from central to peripheral sections of blocks and reacts with nitrogen, thus forming Si3N4, mainly in peripheral sections. The reaction between silicon and oxygen causes the consumption of oxygen and leads to low oxygen partial pressure in the sintering system, which allows silicon to react with nitrogen directly generating Si3N4in situ. SiO(g) reacts with nitrogen forming Si3N4 at both central and peripheral sections of block. The non-uniform distribution of Si3N4 and uneven microstructure is caused by the generation process, indicating that it is unavoidable in Si3N4-SiC composites.
Keywords
Related Topics
Physical Sciences and Engineering
Materials Science
Ceramics and Composites
Authors
Menglong Long, Yong Li, Haixia Qin, Wendong Xue, Junhong Chen, Jialin Sun, R. Vasant Kumar,