1. Effects of silicon addition on the microstructure and properties of B4C–SiC composite prepared with polycarbosilane-coated B4C powder.
- Author
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Du, Xianwu, Wang, Yang, Zhang, Zhixiao, Zhang, Fan, Wang, Weimin, and Fu, Zhengyi
- Subjects
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MICROSTRUCTURE , *SILICON , *CARBIDES , *COMPOSITE materials , *MICROFABRICATION , *MECHANICAL behavior of materials , *CERAMIC materials - Abstract
Dense, fine grained B 4 C–SiC composites were successfully fabricated with the hot-pressing pyrolyzed mixtures of polycarbosilane-coated B 4 C powder and the Si additive at 1950 °C for 1 h under 30 MPa. The addition of Si not only improved the densification process due to the formation of liquid phase Si, but also greatly enhanced the mechanical properties of B 4 C ceramics. However, the added Si showed no significant effect on fracture toughness. The improvement in mechanical properties was attributed to the decrease of porosity and the elimination of free carbon derived from polycarbosilane and B 4 C powder. The introduction of Si improved the microstructure homogeneity and further refined the layer structure of in-situ SiC grains. The flexural strength, Vickers hardness, and fracture toughness of the sample prepared with 11.4 wt% Si, respectively, reached 389 MPa, 33.2 GPa, and 5.64 MPa m 1/2 . [ABSTRACT FROM AUTHOR]
- Published
- 2015
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