WEI Hongkang 1, XIE Zhipeng 1,2, WANG Chang’an 1,2, ZHAO Lin 1,OU YANG Ruifeng 1, DENG Xiangyu 1
(1.Jingdezhen Ceramic Institute, College of Materials Science and Engineering, Jingdezhen 333403, Jiangxi, China; 2. Tsinghua University,
State Key Laboratory of New Ceramics & Fine Processing, Beijing, 100084, China)
Abstract: The density and mechanical properties of B4C ceramics can be significantly improved with the introduction of Si additive. In this study, CNTs were added into B4C-16wt.%Si powders. (SiC,CNTs)/B4C ceramic matrix composites were prepared at 1600 oC by spark plasma sintering. The effects of CNTs additions on the mechanical properties and sintering behavior of the composites were studied. Phase transition,microstructures and the strengthening and toughening mechanism of the composites were analyzed. The results indicate that silicon powders react with boron carbide powders to form a new phase of SiC. A spot of CNTs is beneficial to improve the relative density and mechanical properties of the composites. For the specimen with 1.5 wt.% CNTs, flexural strength of 541 MPa, vickers hardness of 39.5 GPa and fracture toughness of 6.4 MPa∙m1/2 are obtained. The increased mechanical properties of the composites are mainly attributed to the increase of the relative density, the pulling out and bridging of CNTs.
Key words: boron carbide; silicon; carbon nanotubes; SPS; mechanical properties