Effects of WC and Sintering Processes on Thermal Properties of Cu-WC Composites
| Autor: | Li-Chih Chen, 陳力誌 |
|---|---|
| Rok vydání: | 2011 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 99 Thermal management has received much attention with increasing complexity of modern electronics and the development in green energy products such as LEDs and gasoline-electric hybrid engines. Besides the existing thermal modules, e.g. water cooling, heat pipes, and vapor chambers for high power electronics products, bulk metal matrix materials that bear excellent thermal properties are also increasingly important. The current research uses copper as matrix. Different contents of tungsten carbide are milled together with copper using high energy planetary ball mill. The mixtures are sintered through three different processes: sintering under reducing atmosphere, vacuum hot press, and hot isostatic pressing. Effects of tungsten carbides and manufacturing processes on the hardness, coefficients of thermal expansion (CTE), electric conductivity, and thermal conductivity are discussed. Result shows that copper and tungsten carbide barely wet each other. Density over 99.5% of theoretical value can only be achieved through hot isostatic pressing. When tungsten carbide content increases from 0% to 15%, both the electrical conductivity and CTE value of composite decreases drastically from 103.7%IACS and 18.3x10-6/℃ of sintered copper to 60.2%IACS and 12.9x10-6/℃, respectively. Thermal conductivity then decreases from 360.3W/m•K to 263.3W/m•K. On the other hand, the hardness increases from 50.6Hv to 83.4Hv as expected. Both tungsten carbide content and degrees of densification are shown to affect the properties of Cu-WC composites. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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