摻混鑽石粉末及膨脹石墨之矽膠複合材料之熱性質研究

Investigation on the thermal properties of silicone composites filled with expanded graphite and diamond powder

譚至良

指導教授 ： 戴念華

國立清華大學/工學院/材料科學工程學系/碩士(2012年)

摘要

近年來在電子元件邁向微縮化及微/奈機電系統的整合下，奈米尺度下的熱管理儼然成為一項非常重要的研究課題。傳統上，碳材料普遍具有較優異的熱傳導能力，因此，被廣泛應用在複合材料領域中，以提升高分子基材的熱傳導特性及其他相關性質。
有鑑於此，本研究使用化學插層法製備的膨脹石墨以及市售的鑽石粉作為補強材，並以矽膠作為高分子基材。實驗中使用三軸滾輪機製備膨脹石墨/矽膠複合材料試片；以正己烷當作溶劑使鑽石粉有效地分散在矽膠基材中，並且透過電磁攪拌的方式製備鑽石/矽膠複合材料試片；最後，結合以上兩種製程製備膨脹石墨/鑽石/矽膠複合材料試片。在實驗設計上，本研究分別填入不同維度及粒徑大小的補強材於高分子基材中，透過雷射閃光法量測複合材料之熱擴散係數，進而計算出其熱傳導值，並探討其對熱傳導機制的影響；其次，以四點探針量測系統及熱重分析儀鑑定複合材料之電絕緣性及熱穩定性；最後，再輔以場發射掃描式電子顯微鏡觀察複合材料斷面之表面形貌。
在本研究中，將膨脹石墨與粒徑尺寸為150-180 μm之鑽石粉末分別以3 wt% 與50 wt% 共同填充於矽膠中，可以得到本實驗最高的熱傳導值為2.41 W/m∙K。

關鍵字

鑽石 ； 膨脹石墨 ； 矽膠 ； 熱傳導係數 ； 電絕緣

並列摘要

Recently, due to the rapid developments in miniaturization of electronic devices and integrated micro/nano-electro-mechanical systems (MEMs/NEMs), thermal managements in nanoscale have become a critical issue. Traditionally, the carbon-based materials are regarded as the potential candidates due to the high thermal conductivity. Therefore, they are extensively applied to the field of composites for enhancing the thermal conductivity and other properties of polymers.
In this study, we used expanded graphite (EG) prepared by using chemical intercalation method and commercial diamond powder (DP) as reinforcements, silicone as polymer matrix. First, we fabricated EG/Silicone composite specimens by three-roll mill. Second, we used hexane as solvent to disperse DP uniformly in silicone, and fabricated DP/Silicone composite specimens by electrical-magnetic stirring. Finally, we combined above-mentioned methods to fabricate EG/DP/Silicone composites specimens. In experimental design, we filled different dimension degree and grain size of reinforcements in Silicone. We measured the thermal diffusivities of composites by laser flash method, in order to calculate the thermal conductivities of composites. The effects on the mechanisms of heat conduction were also discussed. In the other hand, we used four-point probe analysis system and thermogravimetric analysis to characterize the electric insulativity and thermal stability, respectively. Finally, we observed the morphology of crossection of composites by field emission scanning electron microscope.
In this study, we used expanded graphite and diamond powder with particle size between 150-180 μm as filler filled into silicone together with 3 wt% and 50 wt%, respectively. In this case, we can obtain the highest thermal conductivity, 2.41 W/m∙K.

參考文獻

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