碲化鉛熱電模組接點之材料研究

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Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/83246

Title:	碲化鉛熱電模組接點之材料研究
Authors:	王毓謙;Wang, Yu-Chien
Contributors:	化學工程與材料工程學系
Keywords:	碲化鉛;熱電;接點;無電鍍;擴散阻障層;推力測試
Date:	2020-08-17
Issue Date:	2020-09-02 15:13:54 (UTC+8)
Publisher:	國立中央大學
Abstract:	由於人類對於能源的需求大增，以及石化燃料蘊藏量的有限性，開發並應用其他領域的替代性能源的重要性不言而喻。在再生能源領域中，能回收廢熱進行發電的熱電模組為近年來備受重視的開發項目。由碲化鉛熱電材料所構成的中溫熱電模組，在200-600度C的溫度範圍內具有相當優異的熱電表現。然而由於其元件應用溫度高，封裝熱電模組的所需條件對於模組來說更為嚴苛，常因劇烈的界面反應致使模組之熱電表現下降，甚至整體模組失效。本研究藉由應用無電鍍銀/鈷磷/鎳磷複合層作為擴散阻障層鍍於碲化鉛基材表面，並選用商用之銀銅鋅錫高溫銲膏，將碲化鉛與銅基板和鎳基板以630度C，10 分鐘的條件進行硬銲接合，探討此無電鍍複合層對於界面反應的改善以及接點之推力強度的增加，並進一步以400度C、2 天之熱時效測試，評估此無電鍍複合層在中溫熱電模組工作溫度的可靠度。由實驗結果可知，碲化鉛直接與銅、鎳基板以銀銅鋅錫銲膏進行接合的接點，界面反應較為劇烈，於接點之截面皆觀察到連續裂縫生成，而經熱時效測試後，更由於基材的嚴重消耗導致接點強度極低。引入無電鍍銀/鈷磷/鎳磷複合層後，消弭了無鍍層之接點的劇烈界面反應，且對於推力強度的提升有所貢獻。經熱時效測試後，亦維持良好界面與推力強度，表現出此擴散阻障層之可靠度。因此可推論，在碲化鉛熱電接點中引入此無電鍍銀/鈷磷/鎳磷複合層，不僅能作為有效的擴散阻障層之外，同時提升了系統的機械性質，在熱時效測試後亦能有優良的表現。;Due to the highly increasing demand for energy and the limited reserves of fossil fuels, it is very important to develop alternative energies of other fields. In the field of renewable energy, the development of thermoelectric modules, which can transfer waste heat into electricity, has gained much attention in recent decades. Mid-temperature thermoelectric modules consisting of lead telluride (PbTe) thermoelectric alloys are known for the high thermoelectric performance in the temperature range of 200 to 600 oC. However, because the bonding temperature is higher than the working temperature, it leads to serious interfacial reactions in the joints, which affects the efficiency and even causes the failure of thermoelectric modules. In this study, electroless Ag/Co-P/Ni-P composite layer was applied to PbTe thermoelectric material as diffusion barrier layer, and commercial AgCuZnSn brazing paste was used to braze PbTe with Cu and Ni electrodes in the condition of 630 oC for 10 minutes. By investigating the improvement of severe interfacial reactions in joints and the increase of shear strength, the reliability of the composite layer could be assessed. Severe interfacial reactions occurred between PbTe bulk and brazing paste, which led to continuous crack at the interface; in further thermal aging test at 400 oC for 2 days, the serious consumption of PbTe bulk caused even harsher interfacial reactions and thus critically deteriorated the mechanical strength of joints. With the insertion of the composite layer, the drastic interfacial reaction was avoided, and the shear strength was also improved. Besides, the results of thermal aging test also presented good reliability in maintaining interfaces and shear strength. These results provided that the electroless Ag/Co-P/Ni-P composite layer in the joints of PbTe not only presented effective diffusion barrier layer ability but also enhanced the mechanical strength, even after thermal aging test.
Appears in Collections:	[National Central University Department of Chemical & Materials Engineering] Electronic Thesis & Dissertation

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