基于高固相含量溶胶制备三维编织碳纤维增强莫来石复合材料（英文）

Preparation of three-dimensional braided carbon fiber reinforced mullite composites from a sol with high solid content

以固相含量为20%(质量分数)、Al2O3/SiO2质量比为2:1的Al2O3-SiO2溶胶为原料,制备三维编织碳纤维增强莫来石(3D C/mullite)复合材料。分析溶胶的特性与莫来石化行为,发现溶胶经1300°C热处理基本实现完全莫来石化,凝胶粉呈现出较好的烧结收缩特性。通过溶胶"真空浸渍-干燥-热处理"路线制备出3D C/mullite复合材料,即使总孔隙率为26.0%,复合材料仍获得良好的力学性能,弯曲强度和断裂韧性分别为241.2MPa和10.9 MPa?m1/2。表征复合材料在1200、1400和1600°C下的抗氧化性能。由于基体的进一步致密化,3D C/mullite复合材料在1600°C下氧化30 min后,仅有微小的质量损失,力学性能几乎没有变化。

To prepare the three-dimensional braided carbon fiber reinforced mullite （3D C/mullite） composites, an Al2O3-SiO2 solwith a solid content of 20% （mass fraction） and an Al2O3/SiO2 mass ratio of 2：1 was selected as the raw material. Characteristics andmullitization of the sol were analyzed throughly. It is found that the formation of mullite is basically completed at 1300℃ and thegel powders exhibit favorable sintering shrinkage. The 3D C/mullite composites without interfacial coating were fabricated throughthe route of vacuum impregnation-drying-heat treatment. Satisfied mechanical properties with a flexural strength of 241.2 MPa anda fracture toughness of 10.9 MPa·m1/2are obtained although the total porosity reaches 26.0%. Oxidation resistances of the compositesat 1200, 1400 and 1600 ℃ were investigated. Due to the further densification of matrix, the 3D C/mullite composites show tiny massloss and their mechanical properties are well retained after oxidation at 1600 ℃ for 30 min.