Abstract
Using liquid poly(methylvinyl)borosilazanes (PMVBSZ) as precursor, carbon fiber reinforced SiBCN matrix composites (Cf/SiBCN) were fabricated by a modified polymer infiltration and pyrolysis (PIP) process. With dicumyl peroxide added as cross-linking agent, the PMVBSZ could be solidified at a low temperature of 120 °C, leading to a high ceramic yield of ~70%. The cross-linking mechanism and ceramization processes of the precursor were investigated in detail. Moreover, a modified infiltration technology was developed, which improved the efficiency and protected the precursor against moist air during PIP. Consequently, the obtained Cf/SiBCN composites had an oxygen content of around 1.22 wt%. Benefiting from the high ceramic yield and high efficiency of the modified PIP, Cf/SiBCN composites with an open porosity of ~10% and uniform microstructure were obtained after only 7 cycles of PIP. The flexural strength and fracture toughness of the derived Cf/SiBCN composites were 371 MPa and 12.9 MPa·m1/2, respectively. This work provides a potential route for the fabrication of high performance Cf/SiBCN composites.
Highlights
Silicoboron carbonitride (SiBCN) ceramics have attracted great attention due to their excellent thermal stability [1,2], high temperature mechanicalJ Adv Ceram 2018, 7(3): 266–275 strengthen them such as incorporation of fibers, whiskers, and/or particles are necessary [10]
With dicumyl peroxide (DCP) added as cross-linking agent, the PMVBSZ becomes a transparent and foam-free solid (Fig. 2(b))
This reveals that DCP effectively promotes crosslinking of PMVBSZ
Summary
Silicoboron carbonitride (SiBCN) ceramics have attracted great attention due to their excellent thermal stability (up to 2000 °C) [1,2], high temperature mechanical. Lee et al [15] reported the obtained Cf/SiBCN composites based on above precursor have a relative density of 89% and an average bending strength of 255 MPa. the introduction of SiC filler particulates into the matrix can further improve the thermal stability of Cf/SiBCN composites [16]. It was reported that the Cf/SiBCN composites with SiC filler particulates could retain 96% of its room-temperature strength and possess non-brittle fracture behavior even after heating at 1700 °C for 10 h in Ar. Using sodium borohydride as boron source, Zhao et al [17] synthesized liquid soluble SiBCN ceramic precursor with a ceramic yield of 75.6% and a low viscosity of 65 mPa·s, which can efficiently prepare ceramic matrix composites. A modified infiltration technology was developed to improve the efficiency and protect the precursor against moist air during PIP for the fabrication of Cf/SiBCN composites
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