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 3C-SiC, 6H-SiC, 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 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.
Highlights
IntroductionJ Adv Ceram 2020, 9(6): 739–748 the very first routes to prepare SiBCN materials, remain amorphous nature at least up to 1400 °C, and do not undergo microstructural changes at this temperature [3]
With the development of aerospace technology, morePolymer/precursor derived ceramics (PDCs), one of www.springer.com/journal/40145J Adv Ceram 2020, 9(6): 739–748 the very first routes to prepare SiBCN materials, remain amorphous nature at least up to 1400 °C, and do not undergo microstructural changes at this temperature [3]
The previous studies showed that the heterogeneous microstructure leading to poor mechanical properties of the SiBCN ceramics are needed to be further optimized for the real applications at high temperatures [9,10]
Summary
J Adv Ceram 2020, 9(6): 739–748 the very first routes to prepare SiBCN materials, remain amorphous nature at least up to 1400 °C, and do not undergo microstructural changes at this temperature [3]. The chemistry, microstructure, and properties of the PDCs SiBCN can be tailored effectively by controlling the initial reagent structure, chemical reaction, and processing parameters [4]. This method has some nonnegligible shortcomings that limit its wide applications. The previous studies showed that the heterogeneous microstructure leading to poor mechanical properties of the SiBCN ceramics are needed to be further optimized for the real applications at high temperatures [9,10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
