Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7887057 | Ceramics International | 2018 | 6 Pages |
Abstract
Boron nitride/silicon nitride (BN/Si3N4) composite ceramics were fabricated via the in-situ nitridation of boron (B) and silicon (Si) powders in forming gas (95%N2/5%H2) at 1390â¯Â°C. The effect of the B content on the phase composition, microstructure, density/porosity, machinability as well as mechanical properties of nitridized BN/Si3N4 composite ceramics was investigated. The addition of B slightly increased the nitridation degree of the Si and B powders mixture, and improved the ratio of the β-Si3N4 phase significantly at low B contents. B powders may have acted as a nucleating agent to promote the formation of β-Si3N4 crystals. A core-shell Si3N4/BN structure was revealed by the TEM technique, and the number of BN layers increased with the increase of the B content. The in-situ BN formed by the nitridation of B played a similar role with the BN directly added in enhancing the machinability of the BN/Si3N4 composite ceramics. The method of the in-situ nitridation of B is also effective to prepare SiC fiber-reforced BN/Si3N4 ceramic matrix composites.
Keywords
Related Topics
Physical Sciences and Engineering
Materials Science
Ceramics and Composites
Authors
Xueyuan Tang, Yongwei Li, Xuan Cheng, Ying Zhang,