硅溶胶水热处理及添加B2O3微粉改性碳/碳复合材料的抗氧化性能

OXIDATION RESISTANCE OF CARBON/CARBON COMPOSITES MODIFIED BY SILICA SOL HYDROTHERMAL TREATMENT WITH B_2O_3 POWDER ADDED

以正硅酸乙酯为原料,采用一种新颖的硅溶胶及添加B2O3微粉-水热处理,并经800℃煅烧30min,对碳纤维增强碳(carbon fiber reinforced carbon,C/C)复合材料基体进行改性。研究了水热处理温度、时间、B2O3微粉的添加等工艺因素对改性C/C复合材料的结构及抗氧化性能的影响。采用X射线衍射仪、扫描电子显微镜和能量色散谱仪对改性C/C复合材料的表面物相组成、显微结构和微区化学元素组成进行了表征。结果表明:硅溶胶-热处理法提供了一条较好的C/C复合材料基体抗氧化改性的途径;复合材料的抗氧化性能随着水热温度的升高呈现先降低,后提高的趋势;适当延长反应时间,能提高复合材料的抗氧化性能;添加B2O3微粉的硅溶胶改性后的C/C复合材料的抗氧化性能明显提高,改性后的样品在500℃经5h氧化后,没有产生质量损失。

The matrix in carbon fiber reinforced carbon （C/C） composites was modified by a novel silica sol with and without the addition of B2O3 powder and bydrothermal treatment method using tetraethyl orthosilicate as raw material and calcined at 800℃ for 30 min. The influences of hydrothermal treatment temperature, time and addition of B2O3 powder on the microstructure and oxidation resistance of the as-modified C/C composites were investigated. The as-modified C/C composites thermally treated by the silica sol-gel were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. The results show that the silica sol-thermal treatment provides an effective route to improve the oxidation resistance of C/C composites. The oxidation resistance of C/C composites tends to first decrease and then increase with the increase of thermal treatment temperature. The oxidation resistance of C/C composites is improved by an increase in the thermal treatment time and the addition of B2O3 powder into the silica sol. Almost no mass loss of the sample by the silica sol with B2O3 powder-thermal treatment was observed after oxidation at 500℃ for 5 h.