Measurements of the Thermal Conductivity and Electrical Conductivity of Carbon Nanofibers

(1)测量了不同制造条件下单根碳纤维的导热系数。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，材料的导热系数大大增加，当热处理温度从700℃变化到3000℃时，导热系数可达几百倍。阐明了热处理温度对单根碳纤维横截面微观结构的影响。(2)测量了不同堆积密度下填充碳纤维的导热系数和热扩散率。填充碳纤维的导热系数在很大程度上取决于填充密度。阐明了热导率与填充密度之间的关系，并用…测量了填充碳纤维的导电率。(3)在微电子机械系统(MEMS)的帮助下，用于碳纤维的探头已经微型化，适用于纳米级样品的测量。成功地制作了热丝部分宽10 0 nm、厚4 0 nm、长6μm的纳米薄膜探头。已经证实，该纳米探头可用于测量直径在几十纳米的碳纳米管的导热系数。(4)利用国家先进工业科学技术研究所操纵扫描电子显微镜内的局部聚焦电子束照射，将碳纳米管的一端成功地固定在纳米探头的中心部分，制成T型纳米传感器。(5)在测量单个碳纳米管的导热系数之前，必须知道铂纳米膜的导热系数和导电率，并对这些值进行了准确的测量。利用变温液氮恒温器在100-320K范围内测量了不同直径的单根碳纳米管的导热系数，证实了碳纳米管在300K附近具有约2000W/mK的渐近值。(7)对碳纳米纤维和纳米管导热系数的测量结果进行了不确定度分析。证实了本方法的适用性，并对实测值发表了一些新的认识。较少

(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