臺灣博碩士論文加值系統

本研究旨在探討熱處理對A356鋁合金及Al/SiC複合材料熱傳導率之改良，使用材料包括為重力鑄造與高壓鑄造之A356鋁合金，以及以擠壓鑄造法將A356鋁溶湯滲入80%體積分率之SiC胚體所製成之Al/SiC複合材料。採用之熱處理溫度範圍為200℃~600℃，時間為半小時。熱處理後使用OM、SEM/EDX進行微觀結構分析，並以XRD分析試片之晶格常數變化，以及分析熱處理對密度、導電率及熱傳導率之影響。
實驗結果顯示，200~600℃/0.5 h 熱處理條件中，350℃/0.5 h 者對析出A356鋁合金Pri-α基地相固溶合金元素之效果最明顯，能使壓鑄A356合金之熱傳導率由128.6 W/mK增加至159.9 W/mK，提升熱傳導率之效果最佳，為最適之「析出熱處理」條件；而經580℃/0.5 h熱處理後A356合金鑄件密度由2.61g/cm3提升至2.81g/cm3，效果最明顯，為最適之「提升密度」條件。綜合上述熱處理效果，擇定580℃/0.5 h+350℃/0.5 h二段式熱處理作為改善A356鋁合金及Al/SiC複合材料熱傳導率之最適條件。
對Al/SiC複合材料而言，由於採用持溫持壓之擠壓鑄造法，獲得充分緻密化之複合材料，金相觀察顯示A356鋁合金與SiC胚體充分密合，經量測其密度為3.08 g/cm3，已接近100%理論填充密度，而熱傳導率高達197.7 W/mK，高於一般市售Al/SiC複合材料者(SiC體積分率約60~70%，熱傳導率約160~180 W/mK)。由於Al/SiC複材已充分緻密化，故580℃/0.5h之熱處理對Al/SiC複材密度提升效果不大。至於熱處理對Al/SiC複合材料熱傳導率之影響方面，由於A356鋁合金在複材中所佔比例不高(僅20%)，因此雖經350℃/0.5h之「析出熱處理」，但對複材之熱傳導率並未有可察覺之改善效果。

The purpose of this study is to investigate the improvement of thermal conductivity of A356 Al alloy and Al/SiC composites by heat treatment. The materials used include A356 Al alloy for gravity casting and high pressure casting, and 80% Volume fraction SiC made Al/SiC composite material. The heat treatment temperature range is 200℃~ 600℃, the time is half an hour. After heat treatment, the microstructure was analyzed by OM and SEM / EDX. The changes of the lattice constant were analyzed by XRD, and analyzed the effects of heat treatment on density, electrical conductivity and thermal conductivity.
The experimental results show that in the heat treatment conditions of 200-600℃/0.5h, the effect of precipitating the soluted alloying elements in the Pri-α matrix of A356 Al alloy is the most obvious at 350℃/0.5 h, and the thermal conductivity of die casting A356 Al Alloy increased from 128.6 W/mK to 159.9 W/mK, effect of increasing thermal conductivity was the best, which was the optimum "precipitation heat treatment" condition; while the density of A356 Al alloy after heat treatment at 580℃/0.5 h increased from 2.61 g/cm3 to 2.81 g/cm3, the effect is the most obvious, which was the most optimum "improving density" condition. Based on the above heat treatment results, the two-step heat treatment of 580℃/0.5h + 350℃/0.5h was selected as the optimum condition to improve the thermal conductivity of A356 Al alloy and Al/SiC composite.
For Al/SiC composite, due to the use ofholding temperature and holding pressure squeeze casting method, to obtain fully densified composite material, metallographic showed that A356 Al alloy and sintered SiC fully adhered, the measured density is 3.08 g/cm3, which is close to the theoretical packing density of 100%, the thermal conductivity is as high as 197.7 W / mK, which is higher than that of commercially available Al/SiC composites (SiC volume fraction was about 60-70% and thermal conductivity was about 160-180 W / mK). As the Al/SiC composite material has been fully densified, the heat treatment at 580℃/0.5h has just little effect on the Al/SiC composite density increase. As for the heat treatment on the thermal conductivity of Al/SiC composites, because A356 Al alloy in the proportion of composite is not high (only 20%), so after 350℃/0.5h "precipitation heat treatment", the effect of improving the thermal conductivity on the composite is not perceptible.

摘要 i
目錄 vi
表目錄 viii
圖目錄 ix
第一章導論 10
1.1 研究背景與動機 10
1.2 研究目的與方法概述 11
第二章文獻回顧 12
2.1.鋁合金 12
2.1.1鋁合金簡介 12
2.1.2鋁合金分類 12
2.1.3鋁合金之熱處理 14
2.1.4 A356鑄造鋁合金簡介 14
2.2.金屬之導電/導熱性 15
2.2.1導電性 15
2.2.2導熱性 18
2.2.3導電率/熱傳導率之關係 19
2.3 鋁合金之導電/導熱性質 20
2.3.1鋁合金之導電/熱傳導率簡介 20
2.3.2合金元素添加對鋁合金熱傳導率之影響 20
2.3.3熱處理對鋁合金熱傳導率之影響 22
2.4 Al/SiC複合材料 23
2.4.1金屬/陶瓷複合材料簡介 23
2.4.2擠壓鑄造法製成Al/SiC複合材料 23
2.4.3擠壓鑄造法原理與特色 25
第三章實驗步驟 27
3.1 實驗設計 27
3.2 鋁合金製備 27
3.3 Al/SiC複材製備 28
3.4 熱處理 29
3.5性質量測 30
3.5.1 金相分析 30
3.5.2 導電率測試 31
3.5.3 XRD晶格常數分析 31
3.5.4 熱傳導率測試 31
3.5.5 鋁合金及Al/SiC複材密度量測 32
第四章結果與討論 34
4.1 熱處理對鋁合金顯微組織與性質之影響 34
4.1.1金相分析 34
4.1.2密度量測 38
4.1.3 導電/熱傳導率量測 39
4.1.4 XRD晶格常數分析 42
4.1.5二段式熱處理對鋁合金導電/熱傳導率之影響 44
4.2 Al/SiC複材性質分析 45
4.2.1金相分析 45
4.2.2密度分析 46
4.2.3熱傳導率分析 47
第五章結論 50
參考文獻 52

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