Measurements of the Thermal Conductivity and Electrical Conductivity of Carbon Nanofibers

(1)对不同制造条件下单个碳纤维的导热系数进行了测量。阐明了热处理温度对导热系数的影响。测量结果表明，随着热处理温度的升高，导热系数大幅度提高，从700℃升高到3000℃，导热系数可达数百倍。阐明了热处理温度对单个碳纤维横截面表面微观结构的影响。(2)对不同填充密度下碳纤维的导热系数和热扩散系数进行了测试。填料碳纤维的导热性能在很大程度上取决于填料密度。阐明了碳纤维的导热系数与填充密度之间的关系，并进一步准确地测定了碳纤维填充后的电导率。(3)在微机电系统（MEMS）的帮助下，用于碳纤维的探针已经实现了微小型化，可以用于纳米尺度样品的测量。成功制备了热丝部分宽100 nm、厚40 nm、长6 μm的纳米膜探针。实验结果表明，该纳米探针可用于测量直径为几十纳米的碳纳米管的导热系数。(4)在国家先进工业科学技术研究院的操作扫描电镜内，利用局部聚焦电子束辐照，成功地将碳纳米管的一端附着在纳米探针的中心部分，制成了t型纳米传感器。(5)在测量单个碳纳米管的热导率之前，必须知道铂纳米膜的热导率和电导率，并且这些值已经准确测量。目前纳米膜的两个测量值都小于体积值的一半。(6)利用变温液氮低温恒温器，在100-320 K范围内测量了不同直径纳米管的导热系数。在300 K附近，碳纳米管的渐近值约为2000 W/mK。(7)对碳纳米纤维和纳米管的热导率测量进行了不确定度分析。本方法的适用性得到了证实，并发表了一些关于测量值的新知识。少

(1)Measurements of the thermal conductivity of individual carbon fibers under different manufacturing conditions have been carried out. The effects of heat treatment temperature on the thermal conductivity have been clarified. The measured results show that the thermal conductivity greatly increases as the heat treatment temperature increases, and even up to several hundred times when the temperature is changed from 700℃ to 3000℃. The effects of heat treatment temperature on the microstructure of the cross-sectional surface of individual carbon fibers have been clarified.(2)Measurements of the thermal conductivity and thermal diffusivity of packed carbon fibers at the different packed densities have been carried out. The thermal conductivity of the packed carbon fibers depends greatly on the packed density. The relationship between the thermal conductivity and the packed density has been clarified, and further the electrical conductivity of the packed carbon fibers has been measured ac … More curately.(3)With the help of Micro-Electro-Mechanical Systems (MEMS), the probe used for carbon fibers has been microminiaturized to be applicable for measurements of the nanoscale samples. The nanofilm probe with 100 nm wide, 40 nm thick, and 6 μm long in the part of hot wire has been micro fabricated successfully. It has been confirmed that this nanoprobe can be used to measure the thermal conductivity of a carbon nanotube with its diameter at the dozens of nanometers.(4)By using local focused electron beam irradiation inside a manipulation SEM of the National Institute of Advanced Industrial Science and Technology, one end of the carbon nanotube has been successfully attached to the center part of the nanoprobe to make a T-type nanosensor.(5)Before measuring the thermal conductivity of individual carbon nanotubes, the thermal conductivity and electrical conductivity of the platinum nanofilm must be known and these values have been measured accurately. The both of present measured values for the nanofilm are found to be less than half of the bulk values.(6)Using the variable temperature liquid nitrogen cryostat, the thermal conductivity of individual nanotubes with different diameters has been measured in the range of 100-320 K. It has been confirmed that the carbon nanotube has an asymptotic value of about 2000 W/mK near 300 K.(7)Uncertainty analysis for the measurements of the thermal conductivity of carbon nanofiber and nanotube has been performed. The applicability of the present method has been confirmed and some new knowledge on the measured values has been published. Less