Formation mechanism of Si3N4 in reaction-bonded Si3N4-SiC composites. Issue 15 (15th November 2016)

• Record Type: Journal Article
• Authors: Long, Menglong; Li, Yong; Qin, Haixia; Xue, Wendong; Chen, Junhong; Sun, Jialin; Vasant Kumar, R.
• Is Part Of: Ceramics international. Volume 42:Issue 15(2016)
• Page Start: 16448
• Page End: 16452
• Publication Date: 2016-11-15
• Subjects: Silicon nitridation -- Formation mechanism -- Thermodynamics -- SiO(g) -- Si3N4-SiC; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2016.05.118
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: The formation mechanism and thermodynamics of Si3 N4 in reaction-bonded Si3 N4 -SiC materials were analyzed. There are two kinds of Si3 N4, fibroid α-Si3 N4 and columnar β-Si3 N4, which are formed by different processes in Si3 N4 -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 Si3 N4, 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 Si3 N4 in situ. SiO(g) reacts with nitrogen forming Si3 N4 at both central and peripheral sections of block. The non-uniform distribution of Si3 N4 and uneven microstructure is caused by the generation process, indicating that it is unavoidable in Si3 N4 -SiC composites.