【作者】 宋阳曦；

【导师】 张长瑞；

【作者基本信息】 国防科学技术大学 ， 材料科学与工程， 2010， 硕士

【摘要】 为了保证导弹制导系统的正常工作,导弹天线罩必须具备透波、防热和承载等多种功能。反辐射导弹作为专门攻击雷达的精确制导武器,还要求其天线罩具备宽频透波的特殊功能。本文以反辐射导弹为背景,针对宽频透波天线罩,通过材料体系选择和结构设计,制备了二维石英纤维织物增强石英基(2D SiO_2f/SiO₂)复合材料和二维石英纤维织物增强氮化物基(2D SiO_2f/Nitride)复合材料,较为系统地表征了材料的力学性能、介电性能和热物理性能,并深入研究了制备工艺、微观结构与材料性能之间的关系。采用溶胶凝胶工艺,通过浓缩硅溶胶并引入手糊成型工艺和模压工艺,实现了2D SiO_2f/SiO₂材料的的成型和制备。探讨了制备温度和纤维体积分数对材料微观结构与性能的影响。结果显示,800℃制备的复合材料具有良好的韧性以及较大的断裂功,其弯曲强度和弹性模量分别为97.0MPa、11.6GPa;900℃制备的复合材料同样显示出一定的韧性特征,其弯曲强度和弹性模量分别为72.3MPa、10.2GPa;而1000℃制备的复合材料,力学性能较差,其弯曲强度和弹性模量分别为46.2MPa、9.8GPa,石英纤维的微晶化是材料力学性能降低的主要原因。适当提高纤维体积分数,2D SiO_2f/SiO₂复合材料的力学性能提高,纤维体积分数的增大和界面结合的适当增强分别是材料弯曲性能和层间剪切性能提高的主要原因。但是纤维体积分数的增加要通过提高模压压力来实现,当模压压力过大时,纤维出现机械损伤,复合材料变脆、力学性能降低。模压压力为1.5MPa,2D SiO_2f/SiO₂复合材料的纤维体积分数为45%时,综合性能较好。当纤维体积分数从34%提高至45%时,材料的弯曲强度、层间剪切强度和弹性模量分别由50.2MPa、3.1MPa、8.3GPa提升至97.0MPa、9.1MPa、11.6GPa,;当纤维体积分数提高至48%时,纤维出现机械损伤,材料的弯曲强度、层间剪切强度和弹性模量分别下降为57.3MPa、5.7MPa、9.3GPa。纤维体积分数为40%和45%的2D SiO_2f/SiO₂复合材料,介电常数分别为2.64和2.61,损耗角正切分别为1.9×10^-3和1.6×10^-3,在2¹8GHz的频段内理论功率透过系数均大于75%,热导率分别为0.37W×m^-1×K^-1和0.35W×m^-1×K^-1,热膨胀系数分别为0.30×10^-6K^-1和0.32×10^-6K^-1。采用先驱体浸渍裂解（PIP）工艺,并引入模压工艺,制备出2D SiO_2f/Nitride复合材料。探讨了先驱体裂解温度和纤维体积分数对材料微观结构与性能的影响。结果显示,先驱体裂解温度升高,2D SiO_2f/Nitride复合材料力学性能明显降低。裂解温度从800℃提高到1000℃,弯曲强度和弹性模量分别为180.7MPa、20.3GPa下降至90.5MPa、14.5GPa。随着复合材料的纤维体积分数的提高,2D SiO_2f/Nitride复合材料的弯曲强度和弹性模量逐渐上升,而层间剪切强度基本保持稳定。当纤维体积分数从45%提高至55%时,材料的弯曲强度和弹性模量分别由119.1MPa、17.4GPa提升至180.7MPa、20.3GPa;材料的层间剪切强度稳定在13GPa左右。2D SiO_2f/Nitride复合材料的介电性能和热物理性能随纤维体积分数的变化规律与2D SiO_2f/SiO₂复合材料一致。纤维体积分数为45%⁵5%的2D SiO_2f/Nitride复合材料,介电常数处于2.92².82,损耗角正切处于3.5×10^-32.9×10^-3,在2¹8GHz的频段内理论功率透过系数大于70%,热导率处于0.82⁰.80W×m^-1×K^-1,热膨胀系数处于1.11×10^-61.05×10^-6K^-1。更多还原

【Abstract】 The radome must possess multifunctions of thermal protection, electromagnetic transparence and load bearing to meet the requirements of the homing guidance systems of the missile. As the precision guided werpon aiming at radars, broadband wave-transparent radome is especially required for the anti-radiation missile. In this dissertation, based on the anti-radiation missile and aiming at the broadband wave-transparent radome, the 2D SiO_2f/SiO₂ and 2D SiO_2f/Nitride composites were prepared after composites selection and structural design. The mechanical properites, dielectrical properites and thermal physical properties of the composites were characterized systematically, and the relationship between preparation process, microstructure and properties of the composites were studied.The 2D SiO_2f/SiO₂ composites were formed and prepared successfully via sol-gel process with the help of silica sol concentration, hand lay-up and molding process. The effects of sintering temperatures and fiber volume fraction on the microscopic structure and properties of the composites were investigated. The results show that composites prepared at 800℃show good toughness and high fracture energy, with the flexural strength and elastic modulus at 97.0MPa and 11.6GPa, respectively. Composites prepared at 900℃also show certain toughness, and the flexural strength and elastic modulus reach 72.3MPa and 10.2GPa, respectively. But composites prepared at 1000℃show poor mechanical properites, with the flexural strength and elastic modulus are 46.2MPa and 9.8GPa, respectively. The better mechanical properties are attributed to microcrystallization of the silica fiber. The composites exhibit better mechanical properties as the fiber volume fraction increases, and the better mechanical properties are attributed to the higher fiber volume fraction and strengthening of the fiber/matrix interfacial bonding, respectively. But fiber volume fraction are raised via elevating molding pressure, when the molding pressure are too high the fibers will be damaged seriously, the composites will become brittler and show poor mechanical properties as a result. The composites exhibit best mechanical properties when the molding pressure is 1.5MPa and the fiber volume fraction is 45%. When the fiber volume fraction increases from 34% to 45%, the flexural strength, interlaminar shear strength and elastic modulus of the composites increase from 50.2MPa, 3.1MPa and 8.3GPa to 97.0MPa, 9.1MPa and 11.6GPa, respectively. When the fiber volume fraction increases to 48%, bending strength, interlaminar shear strength and elastic modulus decreased to 57.3MPa, 5.7MPa and 9.3GPa. For composites with fiber volume fraction of 40% and 45%, the dielectric constant are 2.64 and 2.59, the loss tangent are 1.9×10^-3 and 1.6×10^-3, the theoretic power transmission coefficient are above 75% in the frequency range from 2 to 18 GHz, the thermal conductivity are 0.57 and 0.55W×m^-1×K^-1, while the coefficient of thermal expansion are 0.30×10^-6 and 0.33×10^-6K^-1, respectively.The 2D SiO_2f/Nitride composites were prepared via precursor infiltration and pyrolysis process with the introduction of molding process. The relationship between pyrolysis temperature, fiber volume fraction, structure and mechanical properties of the composites were studied. The results show that the mechanical properties of the composites decrease significantly as the pyrolysis temperature increases. As the pyrolysis temperature increases from 800℃to 1000℃, the flexural strength and elastic modulus of the composites decrease from 180.7MPa and 20.3GPa to 90.5MPa and 14.5GPa, respectively. With the increase of fiber volume fraction, the flexural strength and elastic modulus of the composites increase gradually, while the interlaminar shear strength remains stable. When the fiber volume fraction increases from 45% to 55%, the flexural strength and elastic modulus of the composites increase from 119.1MPa and 17.4GPa to 180.7MPa and 20.3GPa, respectively, while the interlaminar shear strength remains stable at around 13.0GPa. The dielectric properties and thermophysical properties of 2D SiO_2f/Nitride composites exhibited similar results with 2D SiO_2f/SiO₂ composites with the change of fiber volume fraction. For composites with fiber volume fraction between 45% and 55%, the dielectric constant are between 2.92 and 2.82, while the loss tangent are between 3.5×10^-3 and 2.9×10^-3, the theoretic power transmission coefficient are above 70% in the frequency range from 2 to 18 GHz, the thermal conductivity are between 0.82 and 0.80W×m^-1×K^-1, while the coefficient of thermal expansion are between 1.11×10^-6 and 1.05×10^-6K^-1.更多还原