改性先驱体制备C/SiC复合材料性能研究

采用交联剂对聚碳硅烷(PCS)先驱体进行改性,以改性先驱体配置溶液制备了C/SiC复合材料。在制备过程中,由于改性先驱体较高的陶瓷产率,缩短了复合材料基体致密化周期,气孔率降低到7.2%,密度提升到2.01 g/m~3。在改善试样显微结构的同时,改性先驱体能够明显提升C/SiC复合材料力学性能,弯曲强度提高到459.4 MPa,断裂韧性提升到13.6MPa·m~(1/2),相比单组分PCS先驱体分别提高了51.9%和32.0%。烧蚀性能考核表明,试样的线烧蚀率和质量烧蚀率分别为8.3×10~(-3) mm/s和4.3×10~(-3) g/s,相比单组分PCS制备的试样分别降低了85.7%和73.1%。通过对试样内部显微结构和考核后形貌进行分析,结果表明试样力学和烧蚀性能的提升主要得益于致密化的基体以及基体对纤维很好的保护作用。

Properties of C/SiC composites prepared by modified precursor

A crosslinking agent is used to modify the polycarbosilane (PCS) precursor. The modified precursor is used to fabricate C/SiC composites. Because of the relative high ceramic yield of the modified precursor, the densification time of C/SiC composite was reduced, while the porosity of samples was decreased by 7.2% and the density was increased by 2.01g/m3. With the improvement of the inner microstructure of C/SiC, the modified precursor can also improve the mechanical properties of C/SiC. The bending strength was increased by 459.4MPa and the fracture toughness was increased by 13.6 MPa·m1/2, which were increased by 51.9% and 32.0% respectively in comparison with samples fabricated by the single component PCS precursor. The performance test results of ablation show that the mass ablative rate and the linear ablative rate are 8.3×10-3mm/s and 4.3×10-3g/s respectively, which have been reduced 85.7% and 73.1% respectively in comparison with samples fabricated by the single component PCS precursor. The analysis results of the surface morphology and the inner microstructure of C/SiC indicate that the improvement of mechanical and ablation properties benefit by the dense matrix and the matrix protection for the fiber.