Effects of CVD BN Coatings on Flexural Properties of Si3N4/SiBN Composites by Precursor Infiltration Pyrolysis
MA Xin1,2, QIU Haipeng1,2, LIANG Yanyuan1,2, LIU Shanhua1,2, WANG Xiaomeng1,2, ZHAO Yuliang1,2, CHEN Mingwei1,2, XIE Weijie1,2
1 AVIC Composite Technology Center, AVIC Manufacturing Technology Institute, Beijing 101300, China 2 National Key Laboratory of Advanced Composites, Beijing 101300, China
Abstract: Continuous Si3N4 ceramic fiber is the candidate as reinforcement in the ceramic matrix composites for high temperature microwave transpa-rent application own to its high thermal stability, mechanical and dielectric properties. Continuous Si3N4 ceramic fiber reinforced SiBN ceramic matrix composites were prepared by precursor infiltration pyrolysis (PIP). The effects of CVD BN on the flexural properties of Si3N4/SiBN composites were investigated. The results show a uniform and dense BN coating was obtained. The BN-coated Si3N4/SiBN composites exhibits toughness fracture characteristic own the fine interfacial bonding between fiber and matrix. When the thickness of BN coating is 200 nm, the fle-xural strength and fracture toughness of the Si3N4/SiBN composites were 182.3 MPa and 17.3 MPa·m1/2 respectively, which are 59.6% and 94.4% higher than those of the uncoated composites.
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