碳纳米管增强铝基复合材料的制备与性能研究

发布时间：2018-01-31 05:42

  本文关键词： 碳纳米管 铝基复合材料 粉末热轧 粉末冶金 力学性能 热膨胀系数 预球磨　出处：《合肥工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：碳纳米管作为一维碳族材料,其具有的优异的力学、电学、热学等性能而被广泛关注,同时它还具备高强度、高模量等特性作为优良的复合材料增强相。利用碳纳米管来增强铝基体复合材料,探究复合材料的制备方法并对其相关性能进行研究,对深入展开碳纳米管对铝基复合材料性能的改善,具有重要的价值和意义。本文通过粉末热轧的工艺方法制备了碳纳米管增强铝基复合材料,利用连续热轧的工艺,避免传统粉末冶金工艺过程中间歇操作的不足,可以实现复合材料连续成型。研究了碳纳米管的含量、结构和复合粉体的球磨时间、转速以及烧结温度对碳纳米管增强铝基复合材料的影响。研究结果表明,轧制变形能减少复合材料内部的组织间隙,改变铝基体的晶粒取向,实现碳纳米管在铝基体中均匀分散。随着碳纳米管含量的增加,复合材料的密度和相对密度都不断减小,复合材料的拉伸强度和硬度均是呈先上升后下降的变化趋势,当碳纳米管质量分数含量为1.5%时,其拉伸强度和硬度达到最大值,分别为298.23 MPa和93.33 HB,与相同工艺下制备的纯铝基体相比分别提高了约33.4%和15.4%。随着温度的升高,复合材料的热膨胀系数逐渐增大,热扩散系数逐渐降低；随着碳纳米管含量的增加,复合材料的热膨胀系数和热扩散系数均是逐渐降低。当温度为200℃,碳纳米管的质量分数为2%的情况下,复合材料的热膨胀系数为17.84×10-6K,与纯铝基体相比,下降了17.14%；复合材料的热扩散系数为37.036 mm2/s,相比与纯铝,降低了14.39%。利用预先球磨分散碳纳米管与粉末冶金相结合的工艺,制备了碳纳米管增强铝基复合材料,研究了不同球磨转速、球磨时间下的碳纳米管的长径比对复合材料的影响。研究结果表明,对碳纳米管进行预球磨处理能起到有效分散作用,随着预球磨处理碳纳米管的时间不断增加,复合材料的拉伸强度和硬度均呈先增加后降低的变化趋势,当预球磨时间为150 min时,复合材料的拉伸强度能达到243.35 MPa,硬度达到82.70 HB。当预球磨碳纳米管的转速为400 r/min时,用于增强复合材料的拉伸强度最佳,能达到279.73 MPa,复合材料的硬度能有78.64HB。
[Abstract]:Carbon nanotubes (CNTs), as one-dimensional carbon group materials, have attracted much attention due to their excellent mechanical, electrical, thermal and other properties. At the same time, they also have high strength. Carbon nanotubes (CNTs) were used to reinforce aluminum matrix composites. The preparation methods of composites were investigated and the related properties were studied. It is of great value and significance for further developing carbon nanotubes to improve the properties of aluminum matrix composites. In this paper, carbon nanotubes reinforced aluminum matrix composites were prepared by hot powder rolling. Continuous hot rolling was used to avoid the shortage of batch operation in the traditional powder metallurgy process, and the continuous forming of composite materials could be realized. The content, structure and milling time of composite powder were studied. The effect of rotating speed and sintering temperature on carbon nanotube reinforced aluminum matrix composites. The results show that rolling deformation can reduce the microstructure gap and change the grain orientation of aluminum matrix. Carbon nanotubes were dispersed uniformly in aluminum matrix. With the increase of carbon nanotube content, the density and relative density of composites decreased. The tensile strength and hardness of the composites increased first and then decreased. When the content of carbon nanotubes was 1.5, the tensile strength and hardness reached the maximum. It was 298.23 MPa and 93.33 HB. compared with the pure aluminum matrix prepared by the same technology, it increased about 33.4% and 15.44, respectively, with the increase of temperature. The thermal expansion coefficient of the composites increases and the thermal diffusion coefficient decreases gradually. With the increase of carbon nanotube content, the thermal expansion coefficient and thermal diffusion coefficient of the composites decrease gradually. When the temperature is 200 鈩，

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