https://scholars.lib.ntu.edu.tw/handle/123456789/60152
Title: | Sn-Zn近共晶合金之鑄造性分析及電鍍鎳對於抗彎性質之研究 | Authors: | 李建良 Li, Jian-Liang |
Keywords: | Sn-Zn近共晶合金;抗彎性質;鍍鎳;Sn-Zn near eutectic alloy;the resistance of bending;Ni electrodeposting | Issue Date: | 2005 | Abstract: | 本研究係針對Sn-Zn近共晶合金(Sn-8.8Zn、Sn-8.4Zn及Sn-7.5Zn)來研究其鑄造性,並設計Sn-Zn合金在不同凝固速度下,其顯微組織之差異,最後在表面電鍍鎳,探討其對Sn-Zn近共晶合金抗彎性質之影響。研究結果顯示,Sn-8.8Zn合金凝固收縮量約11.1%,而本實驗鑄件之最佳冒口尺寸(Dr = 70mm,Hr = 80mm),冒口頸尺寸(Dn = 35mm,Hn = 10mm),冒口模數:冒口頸模數:鑄件模數比為8:5:7。 在不同的凝固冷卻速度下,Sn-8.8Zn及Sn-8.4Zn之顯微組織中的初晶Zn隨凝固時間之增加會由小、短的形狀逐漸變為粗、大,而Sn-7.5Zn合金在不同的凝固冷卻速度下,其顯微組織皆無初晶Zn析出,惟,凝固冷卻速度越慢,共晶Zn之析出量有減少的趨勢。 因Zn相對於Sn而言,其電位較高,故較易被鍍液腐蝕,因此較薄鍍鎳層(25μm)在初晶Zn之位置,會有鍍層中斷或鍍層厚度不均勻之現象,但隨著鍍鎳層厚度增加,鍍鎳層厚度不均勻的現象會逐漸減低。 在相同的試驗壓力條件下,高溫壓彎之試片彎曲角度明顯比常溫壓彎之試片大。而在初晶Zn減少、鍍鎳層厚度增加之情形下,試片之抗彎性皆會因此而有明顯提高之趨勢,故,以Sn-7.5 Zn、鍍鎳層75μm試片之整體效益最佳。 This study investigated the casting properties of Sn-Zn near eutectic alloy and the different microstructures with different solidification cooling rates. Then investigate the effect of Ni electrodepositing on the bending resistance of Sn-Zn near eutectic alloy. The results indicate the solidification shrinkage of Sn-8.8Zn alloy is 11.1%, and the best riser size(Dr=70 mm, Hr=80 mm), riser neck size (Dr=70 mm, Hr=80 mm)for this casting. The modulus of riser:the modulus of riser neck:the modulus of casting is 8:5:7. As solidifying times increases , the primary Zn shape of the microstructure of Sn-8.8Zn and Sn-8.4Zn alloys is form short to coarse . A result indicate that the Ni coating layer exhibits interruption or discontinuous at the primary Zn phase that exposed to the substrate surface.But this discontinuity phenomenon decreases gradually as thickness of plating increase. At the same load and loading cycles, the bending angles in high temperature(160℃)is more bigger than in room temperature. At the primary Zn decreasing and the Ni coating layer increases , the bending resistance of Sn-Zn near eutectic alloy is much better. Then, the best specimen is Sn-7.5Zn alloy and 75μm Ni coating layer. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/61099 | Other Identifiers: | zh-TW |
Appears in Collections: | 機械工程學系 |
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ntu-94-R92522701-1.pdf | 23.53 kB | Adobe PDF | View/Open |
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