【作者】 陈盛洪；

【导师】 陈贵清；

【作者基本信息】 哈尔滨工业大学 ， 材料学， 2008， 硕士

【摘要】 细编穿刺织物具有良好的整体结构和较高的纤维体积含量,是制作高性能防热隔热用C/C复合材料的优良基材。本文研究了从室温到1200℃材料热膨胀性能和热扩散性能随温度的变化规律,数值模拟了0°/90°正交铺设和0°/90°/±45°铺设材料的热物理性能,分析了材料热膨胀性能和热扩散性能的影响因素,研究了材料热物理性能与材料结构之间的相互关系。本文的主要研究内容及结果如下:热膨胀性能的实验结果表明:从室温至1200℃,0°/90°正交铺设和0°/90°/±45°铺设材料xy向的热膨胀系数均高于z向的,由于材料中的孔洞和间隙的作用,热膨胀系数先随着温度的升高急剧降低,然后随着温度的升高总体上呈上升的趋势。0°/90°/±45°铺设材料的结构整体性强,所以材料的热膨胀系数先随温度的升高而降低,降低的趋势较激烈,然后随温度的升高而增大,增大的趋势较平稳。模拟了0°/90°正交铺设和0°/90°/±45°铺设材料热膨胀性能,模拟误差均在20%以内,说明了模型的合理性。基体和纤维的相对含量决定了材料最终的热膨胀系数,所以纤维束椭圆横截面模拟得到的z向和xy向热膨胀系数比相应的方形横截面的大;材料随着纤维体积分数的增大,z向和xy向的热膨胀系数减小;材料的z向和xy向热膨胀系数随着铺设方式的不同,产生规律性的变化。热扩散性能的实验结果表明:0°/90°正交铺设和0°/90°/±45°铺设材料xy向的热扩散系数和热导率大于z向的,热扩散系数和热导率均随着温度的升高不断下降,这是由材料的显微结构变化引起的,材料的z向和xy向热扩散系数随温度升高差别逐渐变小,材料的比热随温度升高而增大。0°/90°/±45°铺设材料的结构整体性强,材料z向和xy向的热扩散系数随温度的升高差别逐渐变小,差别变小的趋势比0°/90°正交铺设的明显。模拟了0°/90°正交铺设和0°/90°/±45°铺设材料热扩散性能,模拟的边界条件和实验不一致使模拟出现误差,误差均在-20%之内。纤维束椭圆横截面形状相对方形横截面的来说,热扩散系数和比热增大,导致热导率也增大;材料热扩散系数和比热随着纤维的体积分数增加而减小,热导率减小。更多还原

【Abstract】 Fine weave pierced fabric has good overall structure and high fiber volume fraction. It’s an excellent basic material to produce high-performance thermal insulation C/C composite. This paper studies the law of coefficients of thermal expansion (CTEs) and thermal diffusibility with temperature changes from room temperature to 1200℃, the numerical simulation on the thermal physical properties of the 0°/90°cross-ply and 0°/90°/±45°paving composites, the influence factor of composite coefficients of thermal expansion and thermal diffusibility, the interrelationship between composite thermal physical properties and structure. The main research and the results are as follows:The experiment results of CTEs show that xy-direction’s of 0°/90°cross-ply and 0°/90°/±45°paving composites CTEs are higher than z-directional from the room temperature to 1200℃. Because of the holes, cracks and gaps in the material, firstly CTEs sharply lower as the temperature increase, then CTEs trend upward with increasing temperature on the whole. 0°/90°/±45°paving composites are stronger structural integrity, CTEs change more intense with the increase of temperature firstly, then change more smoothly with the increase of temperature.CTEs are simulated on 0°/90°cross-ply and 0°/90°/±45°paving composites. The simulation error is in 20 percent, this explains that the models are rationality. The relative content of matrix and fiber decides the composite CTEs, so the simulated xy-directional and z-directional CTEs of the elliptical cross-section model are higher than the corresponding square-section’s. With the increase of fiber volume fraction, composite xy-directional and z-directional CTEs reduce. The xy-directional and z-directional CTEs change regularly with the paving of the different ways.The experiment results of thermal diffusibility show that xy-directional of 0°/90°cross-ply and 0°/90°/±45°paving composites thermal diffusion coefficients and thermal conductivities are higher than z-directional. Because of the microstructure changes, they go lower as the temperature increased. The differences of thermal diffusion coefficients between xy-directional of 0°/90° cross-ply and 0°/90°/±45°paving composites become smaller and smaller. The specific heat goes greater as the temperature increased. 0°/90°/±45°paving composites are stronger structural integrity, xy-directional and z-directional thermal conductivities become closer and closer as the temperature increased.Thermal diffusivity properties are simulated on 0°/90°cross-ply and 0°/90°/±45°paving composites. The inconsistencies of boundary conditions between simulations and experiments appear errors. Compared the elliptical cross-section model with the square cross-section, thermal diffusion coefficients increase, specific heat increases, thermal conductivities increase. With the increase of fiber volume fraction, composite coefficients of thermal diffusion and thermal conductivities decrease, heat specific decreases.更多还原