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研究生：	陳泓志 Chen, Hung-Chih
論文名稱：	方向性凝固之實驗與界面熱傳分析 Experimental Study and Metal-Mold Heat Transfer Analysis of Directional Solidification
指導教授：	趙隆山 Chao, Long-Sun
學位類別：	碩士 Master
系所名稱：	工學院 - 工程科學系 Department of Engineering Science
論文出版年：	2012
畢業學年度：	100
語文別：	中文
論文頁數：	154
中文關鍵詞：	界面熱傳係數、巨觀及微觀金相組織、溫度場
外文關鍵詞：	interfacial heat transfer coefficients, macro and micro structures, temperature field
相關次數：	點閱：163 下載：0
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一般鑄造過程中不易控制其凝固結構之型態，最多只能改變其晶粒大小，而方向性凝固之方法可使得鑄件的微結構沿著某一固定方向成長。而在金屬凝固過程中，溫度與濃度場的變化則是會影響材料的顯微結構，其中微結構的控制更是改善機械性質與物理特性的關鍵所在。
由於鑄件與模具間的界面熱傳性質的不確定性會影響分析的結果，因此本文利用Beck逆運算法與實驗溫測數據來求得在鑄件四周沿軸向與徑向之界面熱傳係數，再利用此界面熱傳係數來進行溫度場的模擬。
在本研究之方向性凝固實驗中，使用錫鉛(Sn-90wt％ Pb)合金針對不同的模具、冷激銅盒、加熱器溫度、冷激銅盒溫度及載台下降速率來進行方向性凝固，並觀察其凝固的巨觀及微觀金相組織、量取冷卻曲線、估算溫度梯度及分析鑄件離開加熱區時間，來了解鑄件晶粒尺寸與晶體成長之束縛控制的情形，以及溫度場的分佈。
利用Beck逆運算得到界面熱傳係數去估算凝固過程溫度變化，與實驗結果比較到達液相線與共晶溫度的時間是差不多的，可將此方法用來預測界面熱傳係數並估算溫度場。

In the general casting process, it is difficulty to control the morphology of solidifying microstructures, in which only the grain size can be easily changed. The scheme of directional solidification can make the microstructures grow along a fixed direction. In a solidification process of metal, the temperature and concentration fields will affect the microstructures of materials, the control of which is the key point of improving the mechanical and physical properties.
The uncertainty of the heat transfer condition between the mold and casting will influence the analysis results. Consequently, the Beck inverse method and the temperature-measured data of a solidification experiment are used to calculate the interfacial heat transfer coefficients, which are then employed to numerically analyze the temperature field of the solidification process.
In the thesis, the Sn-90wt%Pb alloy is used as the testing material for the experimental study of directional solidification. Three sets of directional solidification experiments with different mold materials, heater temperatures, copper chills and water temperatures and descending speeds of the platform are investigated. After the solidification, the macro and micro structures are observed. The effects of these three sets on cooling curves, temperature gradients, grown rate, grain size, the constraint of dendrite grown, and temperature distributions are also analyzed.
The Beck inverse scheme is employed to predict the interfacial heat transfer coefficients. With the coefficients, the temperature distributions during the directional solidification are computed, which are compared with the experimental ones. From the comparison results, it can be found that the computed arrival times of liquidus and eutectic temperatures are similar to those taken from the experiments. Accordingly, it is feasible to utilize the methods built in the research to predict the interfacial heat transfer coefficients and to solve the temperature fields of the directional solidification processes.

摘要.............................................Ι
Abstract........................................II
致謝.............................................III
目錄..........................IV
表目錄..........................VII
圖目錄..........................VIII
第一章	緒論..........................1
1-1	研究動機..........................1
1-2	文獻回顧..........................2
第二章 方向性凝固基礎理論分析..........................5
2-1 凝固過程..........................5
2-1-1成核階段( Nucleation )..........................5
2-1-2晶粒成長與侵犯階段( Growth and Impingement )............6
2-1-3晶粒成長型態..........................7
2-2方向性凝固模式..........................8
第三章  實驗設備與方法..........................10
  3-1實驗流程..........................10
3-2實驗參數..........................11
3-3鑄造之實驗設備..........................12
   3-3-1 熱電偶點焊與氫氧焰氣焊設備..........................12
3-3-2 溶解爐..........................12
3-3-3 方向性凝固載台與冷激端設備..........................13
  3-3-4 加熱及溫度控制設備..........................14
3-3-5 鑄件外模..........................14
      3-3-6溫度擷取設備..........................15
  3-3-7 恆溫循環水槽..........................15
3-3-8 方向性凝固實驗之機構設計..........................16
   3-4觀察金相顯微組織之實驗..........................16
3-4-1 金相觀察之實驗設備..........................17
3-4-2 金相顯微組織的觀察..........................18
3-5實驗數據整理與計算..........................21
第四章 數值分析..........................23
4-1 數學模式之基本假設..........................23
4-2 差分方程式..........................23
4-3 界面熱傳係數之計算..........................25
 4-4 Beck逆運算法..........................26
4-5 Beck逆運算法的處理模式..........................27
   4-6潛熱釋放之計算方法..........................30
第五章  結果與討論..........................33
5-1 金相觀察..........................33
5-1-1 鑄件的巨觀金相觀察..........................34
5-1-2 鑄件的微觀金相觀察..........................36
 5-1-2-1橫截面晶粒數分析..........................36
5-1-2-2縱截面之成長方向分析..........................37
   5-2 界面熱傳係數..........................38
5-2-1 軸向界面熱傳係數..........................39
5-2-2 徑向界面熱傳係數..........................41
 5-3 鑄件的溫度量測與數值比較..........................43
      5-3-1 冷卻曲線之分析與數值比較.........................43
5-3-2 溫度梯度之分析與數值比較..........................44
   5-4 鑄件各位置離開加熱區時間和凝固時間的實驗與數值比較......45
第六章 結論..........................47
參考文獻..........................50
附錄A 晶粒數之取樣方式..........................138
附錄B 溫度場之差分方程式推導..........................139
附錄C 錫鉛合金之潛熱式推導..........................152

                                    

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