LaPO_4涂层对C纤维增强SiBCN陶瓷基复合材料性能的影响

Effects of LaPO_4 Coating on Properties of Carbon Fiber Reinforced SiBCN Ceramic Matrix Composites

使用水热法在二维编织的连续C纤维(Cf)表面沉积一种新型的LaPO_4涂层,并通过树脂转移模塑(RTM)和聚合物浸渍裂解(PIP)工艺制备Cf/LaPO_4/SiBCN陶瓷基复合材料(CMCs)。经微观组织表征,纤维束表面较为均匀地沉积了一层厚度约500nm的LaPO_4涂层,且涂层在高温裂解过程中并未和纤维及基体发生明显的化学反应及元素迁移。同时制备Cf/SiBCN,Cf/PyC/SiBCN和Cf/BN/SiBCN复合材料,与Cf/LaPO_4/SiBCN复合材料在抗弯强度、断裂韧度及抗氧化性能等方面进行对比。结果表明:制备所得Cf/LaPO_4/SiBCN复合材料相对其他材料的断裂韧度提升了30%以上;在1350℃/50h长时氧化过程中质量损失最小、纤维几乎完整保留,抗氧化性能明显提升。综上,LaPO_4涂层相比上述其他涂层进一步增强了C纤维增强的SiBCN陶瓷基复合材料在高温下的综合性能,提升了材料的高温应用潜力。

A novel lanthanum monazite（LaPO4）coating was applied on two-dimensional woven continuous carbon fibers by a simple hydrothermal method.Then a Cf/LaPO4/SiBCN ceramic matrix composite（CMCs）was fabricated via subsequent RTM（resin transfer moulding） PIP（polymer impregnation and pyrolysis）technology.Microstructure observation shows that most of the carbon fibers are coated uniformly with a layer of lanthanum monazite with the thickness of 500 nm and there is no obvious chemical contamination between the coating and fiber/matrix during high temperature pyrolysis process.Cf/SiBCN,Cf/PyC/SiBCN and Cf/BN/SiBCN composites were also made to be compared with Cf/LaPO4/SiBCN composites in three-point bending test,fracture toughness test and oxidation test.The results show that Cf/LaPO4/SiBCN composites obtain at least 30%improvement in fracture toughness;in 1350℃/50 hoxidation test,Cf/LaPO4/SiBCN composites have the lowest mass loss and the fibers are protected effectively by the coatings,demonstrating the significant increasing in oxidation resistance.Overall,compared with other mentioned coatings,the lanthanum monazite coating enhances much more the high temperature performance of the carbon fiber reinforced SiBCN ceramic matrix composites and promotes the high temperature application potential of the composites.