【作者】 杨燕；

【导师】 温广武；

【作者基本信息】 哈尔滨工业大学 ， 材料学， 2011， 硕士

【摘要】 航天透波材料因其特殊的使用场合而要求具有优良的综合性能。传统的树脂如酚醛树脂、环氧树脂等耐高温性能不足,在透波材料领域中使用受限,有机硅树脂因其具有优良的耐热性和介电性能而备受关注。有机硅树脂作为透波复合材料的基体在俄罗斯已经被成功应用于战术导弹、航天飞机中。已有研究表明,在有机硅树脂中引入B元素,使之形成Si-O-B键桥可以进一步提高其耐热性能。本文使B(OH)3与聚甲基乙氧基硅氧烷(PMES)反应制备了SiBOCH体系的有机硅树脂,通过红外分析法证实了B以Si-O-B形式成功地连接到了硅氧烷结构中,通过TG分析了其耐热性能。以这种自制的有机硅树脂为基体,采用介电性能优异的石英纤维(布)做增强体,以寻求制备复合材料的最佳工艺方法为主线,借助于三点弯曲测试、SEM分析、FT-IR分析、TG分析等手段,研究了不同工艺下几种主要因素对复合材料组织和性能的影响。纤维布增强有机硅树脂复合材料的研究中显示,石英纤维表面浸润剂的去除对提高复合材料的弯曲性能有很大意义。偶联剂在纤维与基体界面处形成化学键合而表现出比热处理、酸刻蚀物理方法更有效果,其中偶联剂KH550比KH560更为合适。随着温度的升高,复合材料中因为水分、乙醇的挥发,Si-C键裂解产生CO2、H2O,Si-O键断裂生成小分子环体而使材料有较大失重,弯曲性能逐渐下降,350℃之后幅度更大。复合材料中含胶量为40%时,纤维周围树脂基体包覆较好,室温弯曲性能比含胶量为20%、60%的分别高出136%和221%。超声波振动能促进硅树脂中的Si-O-Si键的裂解,导致复合材料弯曲性能下降。制备工艺中浸泡反应法比真空辅助浸渍法和预浸料法优异,但纤维布的线密度比较大,影响了树脂胶液的浸渍效果,材料性能提升有限。将单向石英纤维采用缠绕法制备复合材料,室温弯曲强度能达到纤维布所得复合材料的最高值的2.08倍。在固化时采用热压方式,能有效提高固化交联程度,降低材料的气孔率、减小材料变形,复合材料的弯曲强度明显优于无压固化方式,室温下均值为248.0MPa,最高能达到259.9MPa,比无压固化的高出52.6%,350℃时均值为142.4Mpa,尚可比后者高出58.4%。更多还原

【Abstract】 Wave-transparent materials which have been extensive used in aerospace field requires excellent performance because of their special occasion. The use of traditional resins such as phenolic and epoxy as wave-transparent materials is limited, because their mechanical properties decreased severely as the temperature increased. However, organic silicone resin, whose heat resistance and dielectric properties are excellent have attracted much attention. In Russia, this resin has been used successfully in the tactical missile and space shuttles as the matrix of composites. It has been shown that, the Boron element added in silicone resin, forming Si-O-B bridge can improve its heat resistance further.The SiBOCH silicone resin can be prepared by the chemical reaction of B(OH)3 and poly-methyl ethoxy siloxane (PMES). The FT-IR analysis showed that the B element has been successfully connected to the silicon-oxygen alkane structure as Si-O-B bond. Meanwhile , its thermal properties has also been analyzed by TG.This paper is to seek an optimal preparation method of the composites with this prepared silicone resin as matrix and quartz fiber (cloth) who has good dielectric properties as reinforcement. The mechanical properties and microstructures were analyzed by three point method, SEM, FT-IR and TG-DTA.In the research of fiber cloth reinforce silicone resin composites, it shows that, the removal of the fiber sizing has a significant effect on the flexural strength of composites. Coupling agent used in the interface between fiber and matrix to form a chemical combination, can improve mechanical properties more effectively than method of heat treatment and acid etching, which are physical treatment. In addition, the coupling agent KH550 is more appropriate than KH560. With the increase of temperature, water and ethanol in the composites volatilize, the cleavage of Si-C bond can generate CO2 and H2O , Si-O bond break and small molecule ring body were produced, all of these lead to a greater weight loss and a drop of the flexural properties , especially after 350℃. When the resin content of the composite is 40% (mass fraction), the resin matrix can cover the fiber better, so at room temperature its flexural strength can be 1.36 and 2.21 times higher than the content is 20% and 60% respectively. Ultrasonic vibration can promote the cleavage of Si-O-Si bond in silicone resin, which results in the flexural strength decrease. Among the several methods of fabrication, soaking-reaction mothd can perform better than vacuum-assisted impregnation and prepreg one. However the linear density of the fiber is relatively large, affecting the impregnation of resin glue. As a result, the improvement of strength is limited.Use unidirectional quartz fiber to fabricate composites by filament winding process, the flexural strength at room temperature can be 2.08 times as high as fiber cloth reinforced composites. The hot-pressing way used in the curing step, can improve the crosslinking effectively, lower the porosity of the material, reducing deformation. Consequently, the flexural strength of the composite is superior to pressureless way. At room temperature, it is 248.0 MPa on average, with a peak of 259.9MPa, which can be 0.526 times higher than the pressureless one. At 350℃, the flexural strength is 142.4Mpa, this can also be 0.584 times higher than the latter.更多还原