Authors: Bingzhu Wang, Daxin Li, Zhihua Yang, Dechang Jia, Jingyi Guan, Hao Peng, Delong Cai, Peigang He, Xiaoming Duan, Yu Zhou, Tao Zhang, Chenguang Gao
Published: 2020-11-27
DOI: 10.1007/s40145-020-0410-9
Source: Full article
AbstractThein situnano Ta4HfC5reinforced SiBCN-Ta4HfC5composite ceramics were prepared by a combination of two-step mechanical alloying and reactive hot-pressing sintering. The microstructural evolution and mechanical properties of the resulting SiBCN-Ta4HfC5were studied. After the first-step milling of 30 h, the raw materials of TaC and HfC underwent crushing, cold sintering, and short-range interdiffusion to finally obtain the high pure nano Ta4HfC5. A hybrid structure of amorphous SiBCN and nano Ta4HfC5was obtained by adopting a second-step ball-milling. After reactive hot-pressing sintering, amorphous SiBCN has crystallized to 3C-SiC, 6H-SiC, and turbostratic BN(C) phases and Ta4HfC5retained the form of the nanostructure. With thein situgenerations of 2.5 wt% Ta4HfC5, Ta4HfC5is preferentially distributed within the turbostratic BN(C); however, as Ta4HfC5content further raised to 10 wt%, it mainly distributed in the grain-boundary of BN(C) and SiC. The introduction of Ta4HfC5nanocrystals can effectively improve the flexural strength and fracture toughness of SiBCN ceramics, reaching to 344.1 MPa and 4.52 MPa·m1/2, respectively. This work has solved the problems of uneven distribution of ultra-high temperature phases in the ceramic matrix, which is beneficial to the real applications of SiBCN ceramics.