低密度碳粘接碳纤维复合材料(CBCF)抗氧化改性研究

以全氢聚硅氮烷(PHPS)为原料, 采用浸渍-热转化方法, 在低密度碳粘接碳纤维复合材料(CBCF)中短切碳纤维表面成功包覆硅氧氮(SiON)涂层。采用扫描电子显微镜(SEM)、能量色散X射线光谱(EDS)等分析测试手段对碳纤维表面的SiON涂层进行了形貌和物相分析, 结果表明: 涂层主要由Si、O、N元素组成, 在PHPS浓度为3wt%和5wt%条件下制备的涂层均匀、致密, 随着PHPS浓度的提高, 涂层厚度增加, 但易发生结块。当PHPS浓度为10wt%和20wt%时, 制备的SiON涂层出现结块并且存在裂纹。采用热重分析和等温氧化实验对纯CBCF和SiON涂层改性的CBCF复合材料抗氧化性能进行考核, 结果显示碳纤维表面包覆SiON涂层能够显著提高CBCF复合材料的抗氧化性, 随着PHPS浓度增大, 低密度CBCF复合材料抗氧化性能显著提高。

Modification of Oxidation Resistance for Low Density Carbon-bonded Carbon Fiber (CBCF) Composite

Perhydropolysilazane (PHPS) derived SiON coatings were deposited on surface of chopped carbon fiber in carbon-bonded carbon fiber (CBCF) composite by precursor infiltration-thermal (PIT) conversion method. Morphology and elemental analysis of SiON coating were investigated by SEM and EDS. The results show that the coatings are uniform, dense and mainly composed of Si, O and N elements. Meanwhile, the coating gets thicker with the increasing concentration of PHPS, but tends to agglomerate in the opening pores, especially when the concentration of PHPS reaches 10wt% and 20wt%, obvious agglomeration emerges in the opening pores. Meanwhile, cracks appear in the coating on the carbon fibre surface. Finally, oxidation resistance of CBCF composites treated by SiON coating was studied by TGA analysis and isothermal oxidation assessment. The results show that SiON coatings deposited on the carbon fiber surface in CBCF composite can remarkably enhance the oxidation resistance of CBCF, and the oxidation resistance increases with the increasing concentration of PHPS.