采用常规性能分析、傅里叶变换红外光谱分析、差示扫描量热分析、热重分析、凝胶渗透色谱分析等对模压高碳酚醛树脂进行表征,通过模压成型分别制备了碳纤维和高硅氧纤维增强模压高碳酚醛树脂复合材料,测试了不同成型压力下两种复合材料的力学性能和耐烧蚀性能,最后通过超声无损检测方法对复合材料密实度进行表征.结果表明,模压高碳酚醛树脂苯环上以邻位取代为主,其游离酚和游离醛含量较低,180℃的凝胶时间低于50 s,适用于较高温度下的快速模压成型工艺;该树脂分子量小,对纤维的浸润性好,适宜的固化温度为(190±5)℃,900℃的残炭率可达67.13%.随成型压力增加,碳纤维和高硅氧纤维增强复合材料的拉伸和弯曲性能均逐渐提高,但当成型压力大于45 MPa后,增加趋势变缓;当成型压力为45 MPa时,两种复合材料具有最好的耐烧蚀性能,其中碳纤维增强复合材料的线烧蚀率和质量烧蚀率分别为0.0068 mm/s和0.0559 g/s,高硅氧纤维增强复合材料的线烧蚀率和质量烧蚀率分别为0.1164 mm/s和0.0708 g/s.通过超声无损检测方法可以初步判断碳纤维增强复合材料的密实度.%High char-yield phenolic resin was analyzed by general performances analysis,FTIR,DSC,TG and GPC etc.. Car-bon fiber and high silica fiber reinforced the resin based composites were prepared respectively through compression molding,the mechanical and ablation resistant properties of the two composites at different molding pressure were tested,finally the compactness of the two composites were analyzed by ultrasonic nondestructive testing (UNDT). The result show that,the substitution on benzene ring of the resin is mostly ortho-substituted,the free phenol content and free formaldehyde content are low,the gelation time at 180℃ is less than 50 s,which indicates that the resin can be used for the rapid compression molding at high temperature. The resin has low molecular weight and good soakage for fiber,its appropriate curing temperature is (190±5)℃ and the char-yield at 900℃can reach 67.13%. With the increase of molding pressure,the tensile and flexural properties of the two composites increase,but when the molding pressure is higher than 45 MPa,the increase trends become slow. When the molding pressure is 45 MPa,the ablation resistant properties of the two composites are best,the linear ablation rate and the mass ablation rate of the carbon fiber reinforced composite is 0.006 8 mm/s and 0.055 9 g/s respectively,those of high silica fiber reinforced composite is 0.116 4 mm/s and 0.070 8 g/s respectively. The compactness of the carbon fiber reinforced composite can be determined through UNDT preliminarily.
展开▼
