微纳石墨烯粉体导热性能的测量与研究

发布时间：2018-05-23 12:42

  本文选题：石墨烯粉末 + 瞬态电热技术　； 参考：《青岛理工大学》2016年硕士论文

【摘要】：石墨烯是碳材料界的新兴材料,具有优异的导热性能,有效测量并深入研究其热物性意义重大。由于微尺度下石墨烯尺寸较小,无法运用传统热物性测量方法加以测量,且目前关于粉末形态的石墨烯热传输特性研究尚浅。另外,在粉末材料面内方向导热系数的确定上,多数测量方法中存在一定的局限性。本文采用瞬态电热技术测量了微尺度下石墨烯粉末面内方向的热扩散率并推导出相应的本征导热系数,有效避免了测量时的厚度局限问题。借助导热系数测试仪(基于改良的瞬态平面热源法)测量了石墨烯粉末垂直于面内方向的导热系数,分析了含水率、密度、预热温度对石墨烯粉末导热系数的影响,揭示了相应的导热机理,为石墨烯粉末的热应用提供了科学依据。采用瞬态电热技术测量了密度为0.24 g/cm~3的5-6层纯石墨烯粉末面内方向的热扩散率,其值为0.86×10~(-5)-1.52×10~(-5) m~2 s~(-1),相应的本征导热系数为13.5-23.8W/(m·K)。基于改良的瞬态平面热源法测得了石墨烯粉末垂直于面内方向的导热系数为18.8 W/(m·K)。使用导热仪研究了含水率对石墨烯粉末导热性能的影响。实验结果显示石墨烯粉末的导热系数随含水率的增加而显著增加,当含水率达到92.3%时,混合物(石墨烯与水)的导热系数提高了60%。通过保持体积不变,不断增加质量的方法改变石墨烯粉末样品密度。使用导热仪测量了不同密度下石墨烯粉末导热系数的变化情况,发现其导热系数与密度成正比。在密度从0.02g/cm~3增加到0.22g/cm~3时,导热系数总体提升了8.09%。为研究预热温度对石墨烯导热系数的影响,依次对密度恒定为0.045 g/cm~3的石墨烯粉末样品在50℃-300℃(11个温度点逐渐递增)的温度条件下分别进行预热,结果表明不同预热温度处理后,冷却到室温的各样品导热系数的值无明显变化,与室温22℃下的值基本相同。即在50℃-300℃的加热温度范围内冷却到室温后的石墨烯粉末的导热系数不受预热温度的影响。
[Abstract]:Graphene is a new material in the field of carbon materials, which has excellent thermal conductivity. It is of great significance to effectively measure and study the thermal properties of graphene. Because of the small size of graphene in microscale, it can not be measured by traditional thermal physical property measurement method, and the study on the thermal transfer characteristics of graphene powder morphology is still shallow. In addition, there are some limitations in the determination of in-plane thermal conductivity of powder materials. In this paper, the in-plane thermal diffusivity of graphene powder is measured by transient electrothermal technique and the corresponding intrinsic thermal conductivity is derived, which effectively avoids the thickness limitation problem in the measurement. The thermal conductivity of graphene powder perpendicular to the plane was measured by means of a thermal conductivity tester (based on the improved transient plane heat source method). The effects of moisture content, density and preheating temperature on the thermal conductivity of graphene powder were analyzed. The heat conduction mechanism is revealed, which provides a scientific basis for the thermal application of graphene powder. The in-plane thermal diffusivity of 5-6 layers of pure graphene powder with density of 0.24 g/cm~3 has been measured by transient electrothermal technique. Its value is 0.86 脳 10 ~ (-5) ~ (-5) -1.52 脳 10 ~ (10) ~ (-5) m ~ (2) 路s ~ (-1) ~ (-1), and the corresponding intrinsic thermal conductivity is 13.5-23.8W/(m ~ (-1). Based on the improved transient plane heat source method, the thermal conductivity of graphene powder perpendicular to the in-plane direction is measured to be 18.8 W / m KN. The effect of moisture content on thermal conductivity of graphene powder was studied by means of thermal conductivity instrument. The experimental results show that the thermal conductivity of graphene powder increases significantly with the increase of moisture content. When the moisture content reaches 92.3, the thermal conductivity of the mixture (graphene and water) increases by 60%. The density of graphene powder samples was changed by keeping the volume constant and increasing the mass. The thermal conductivity of graphene powder under different densities was measured by means of a thermal conductivity meter, and it was found that the thermal conductivity was proportional to the density. When the density increased from 0.02g/cm~3 to 0.22g / cm ~ 3, the thermal conductivity increased by 8.09g / cm ~ 3. In order to study the effect of preheating temperature on the thermal conductivity of graphene, the graphene powder samples with constant density of 0.045 g/cm~3 were preheated at 50 鈩，

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