The Origin of High Thermal Conductivity and Ultralow Thermal Expansion in Copper鈥揋raphite Composites

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• 作者：Izabela Firkowska ; Andr茅 Boden ; Benji Boerner ; Stephanie Reich
• 刊名：Nano Letters
• 出版年：2015
• 出版时间：July 8, 2015
• 年：2015
• 卷：15
• 期：7
• 页码：4745-4751
• 全文大小：379K
• ISSN：1530-6992

文摘

We developed a nanocomposite with highly aligned graphite platelets in a copper matrix. Spark plasma sintering ensured an excellent copper鈥揼raphite interface for transmitting heat and stress. The resulting composite has superior thermal conductivity (500 W m^鈥? K^鈥?, 140% of copper), which is in excellent agreement with modeling based on the effective medium approximation. The thermal expansion perpendicular to the graphite platelets drops dramatically from 鈭?0 ppm K^鈥? for graphite and copper separately to 2 ppm K^鈥? for the combined structure. We show that this originates from the layered, highly anisotropic structure of graphite combined with residual stress under ambient conditions, that is, strain-engineering of the thermal expansion. Combining excellent thermal conductivity with ultralow thermal expansion results in ideal materials for heat sinks and other devices for thermal management.