凝固參數對於方向性成長之結構參數影響分析

Experimental Analysis of the Effect of the Solidification Parameters on the Structure Parameters of the Directional Solidification

趙隆山(Long-Sun Chao) ； 趙國傑(Kuo-Kung Chao) ； 陳毓儒(Yu-Ru Chen)

《鑄造工程學刊》 34卷3期 (2008/09) Pp. 45-58

https://doi.org/10.29809/JTFS.200809.0005

摘要

一般的鑄造過程是不易控制其凝固結構之形態，最多只能改變其晶粒大小，而方向性凝固與單晶成長屬於高難度之鑄造技術，需使用適當的鑄造機制來控制凝固結構形態。其中，以單晶之製程是最困難的技術，方向性成長則次之，而方向性成長是單晶製程之基礎。本文使用兩種不同材料之鑄件外模搭配不同的加熱模式，來探討於方向性凝固時，凝固參數與結構參數間的相互關係。於實驗研究中，以錫鉛合金為測試材料，採用光學顯微鏡觀察鑄件之顯微結構，利用熱偶線與溫測擷取系統，量測鑄件軸向溫度分佈，然後計算其結構與凝固參數，而鑄件之凝固參數為冷卻曲率、溫度梯度和成長速率，枝狀晶的結構參數為主枝狀晶臂間距λ1與二次枝狀晶臂間距λ2。除利用光學顯微鏡觀察微結構外，並進一步量測其導電率，同時與濕砂模鑄件的導電率作比較分析，以驗證不同長晶結構之電導性差異。

關鍵字

方向性凝固 ； 錫鉛合金 ； 凝固參數 ； 結構參數 ； 導電率

並列摘要

The morphology of solidification microstructure is difficult to control in a casting process, in which only the grain size can be easily changed. To perform advanced casting techniques such as directional solidification and the growth of single crystal, a proper casting mechanism is needed to control solidifying microstructure. Among these solidification processes, the growth of single crystal is the most difficult one and directional solidification is the second. The fabricating technique of single crystal is based on that of directional solidification. In this paper, two kinds of casting mold with different heating methods were used to investigate the relationship between the solidification parameters and the structure parameters in the directional solidification. In the experimental study, a tin-lead alloy was the testing material, an optical microscope was utilized to observe the solidifying microstructure and thermal couples were used to measure the temperatures along the axial direction of cylindrical casting. The solidification parameters are cooling rate, temperature gradient and growth rate and the structure parameters are primary arm spacing and secondary arm spacing. Except using an optical microscope to observe the microstructure, the electric conductivity was also measured and its values were compared with that from the green-sand-mold casting. The result can be used to verify that different material structures lead to different electrical conductivities

並列關鍵字

Directional Solidification ； Tin-Lead Alloy ； Solidification Parameter ； Structure Parameter and Electric Conductivity