基于固体聚硅氧烷的前驱体浸渍裂解法(PIP)制备C/SiOC复合材料及其微结构与力学性能研究

以熔融的MK树脂(聚甲基倍半硅氧烷)为前驱体, 采用改进的前驱体浸渍裂解法(PIP)制备了致密的C/SiOC复合材料。为了降低MK树脂的固化温度, 选择有机磺酸作为交联剂, 并采用红外光谱分析仪(FT-IR)和热重分析-差热分析仪(TG-DTA)研究了MK树脂的固化机理和陶瓷化行为。研究表明: MK树脂的陶瓷产率高达85wt%, 其裂解得到的SiOC陶瓷自由碳含量低于3wt%, 有利于提高陶瓷的高温稳定性。经过8次PIP制备的C/SiOC复合材料的密度可达1.82 g/cm ³。对得到的C/SiOC复合材料进行三点弯曲测试, 其弯曲强度为(312±25) MPa, 表现出明显的非脆性断裂行为。

C/SiOC Composites by a Modified PIP Using Solid Polysiloxane: Fabrication,Microstructure and Mechanical Properties

A modified polymer infiltration and pyrolysis method (PIP) was developed to enhance the densification of C/SiOC composites, using molten MK resin (polymethylsilsesquioxane) as precursor. Organic sulfonic acid was added as cross-linking agent to lower the curing temperature. The cross-linking mechanism and ceramization behavior of MK resin was studied. A high ceramic yield of about 85wt% and low free carbon content below 3wt% are achieved, with excellent high-temperature stability of the derived SiOC. The modified PIP approach presents a high densification efficiency. After only 8 PIP cycles, the final C/SiOC composites possess a density of about 1.81 g/cm ³. Compared with those composites fabricated by conventional PIP process, the C/SiOC composites prepared by modified PIP process show a much denser microstructure with much more improved densification efficiency. Bending strength of the as-fabricated C/SiOC composites is of (312±25) MPa, showing obvious non-brittle fracture behavior.