Microstructural evolution and mechanical properties of in situ nano Ta 4 HfC 5 reinforced SiBCN composite ceramics
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ISSN 2226-4108 CN 10-1154/TQ
Research Article
Microstructural evolution and mechanical properties of in situ nano Ta4HfC5 reinforced SiBCN composite ceramics Bingzhu WANGa,b, Daxin LIa,b,*, Zhihua YANGa,b,c, Dechang JIAa,b,c,*, Jingyi GUANa,b, Hao PENGa,b, Delong CAIa,b, Peigang HEa,b, Xiaoming DUANa,b, Yu ZHOUa,b, Tao ZHANGd, Chenguang GAOd a
Institute for Advanced Ceramics, School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China b Key Laboratory of Advanced Structural-Functional Integration Materials & Green Manufacturing Technology, Harbin Institute of Technology, Harbin 150001, China c State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China d Beijing Institute of Control Engineering, Beijing 100080, China Received: March 11, 2020; Revised: June 25, 2020; Accepted: July 16, 2020 © The Author(s) 2020.
Abstract: The in situ nano Ta4HfC5 reinforced SiBCN–Ta4HfC5 composite 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–Ta4HfC5 were 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 Ta4HfC5 was obtained by adopting a second-step ball-milling. After reactive hot-pressing sintering, amorphous SiBCN has crystallized to 3CSiC, 6HSiC, and turbostratic BN(C) phases and Ta4HfC5 retained the form of the nanostructure. With the in situ generations of 2.5 wt% Ta4HfC5, Ta4HfC5 is preferentially distributed within the turbostratic BN(C); however, as Ta4HfC5 content further raised to 10 wt%, it mainly distributed in the grain-boundary of BN(C) and SiC. The introduction of Ta4HfC5 nanocrystals can effectively improve the flexural strength and fracture toughness of SiBCN ceramics, reaching to 344.1 MPa and 4.52 MPam1/2, 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. Keywords: Ta4HfC5; SiBCN; microstructure evolution; mechanical properties
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Introduction
With the development of aerospace technology, more
* Corresponding authors. E-mail: D. Li, [email protected]; D. Jia,[email protected]
stringent property requirements are put forward for advanced structural-functional integration of ceramic materials. Among many high-temperature structural materials, SiBCN non-oxide ceramics have attracted considerable attention due to their light-weight, high specific strength, excellent thermal stability, and resistance to thermal shock, oxidation, and ablation [1–3]. Polymer/precursor derived ceramics (PDCs), one of
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J Adv Ceram 2020, 9(6): 0–0
the very first routes to prepare SiBCN materials, remain amorphous nature at least up to 1400 ℃, and
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