多壁碳纳米管长度对导热硅脂导热性能的影响

Influences of Multi-walled Carbon Nanotubes Length on Thermal Properties of Thermal Grease

本文以多壁碳纳米管为添加材料用于改善导热硅脂的导热性能,分别研究了碳纳米管长度和碳管表面改性对硅脂热性能的影响。结果表明碳管长度对硅脂的热性能有明显影响,硅脂的导热性能会随着添加的MWCNT长度的增加而降低,只有当MWCNT的长度小于一定值后,才能有效提高硅脂的导热性能,否则可能会产生相反的效果。碳管表面的功能化处理能提高硅脂的导热性能。透射电子显微镜分析表明,经过表面改性的MWCNT表面发生明显变化,功能团的附着使得碳管之间的分散性增强,从而使添加了改性后的MWCNT/硅脂导热系数增大,热阻降低。

In the present work,multi-walled carbon nanotubes(MWCNTs) are used as additives for enhancing the thermal conductivity of the widely-used silicon grease as thermal interface materials(TIMs).The effects of the MWCNTs length and surface treatment on the silicon grease conductivity are studied.The results show that the MWCNT length has strong influences on the thermal performance of the grease with MWCNT additives.The equivalent thermal conductivity of the composite layer of the grease and the solid surfaces increases as the MWCNT length decreases.Only the length of MWCNTs is short enough,their addition can improve the thermal performance of the common silicon grease.Surface treatment on MWCNTs can improve the thermal performance of the grease.Through transmission electron microscope(TEM) observation it is found that after the modification of the short MWCNTs the MWCNT entanglement phenomenon in the mother silicon grease is weakened and the MWCNTs are dispersed more uniformly.