鎂的添加對鋅鋁合金微組織、熱物及耐蝕性影響之研究

Investigation into the effects of Mg addition in the Al-Zn alloy on the microstructure, thermal properties and corrosion resistance

吳俊毅(Jiun-Yi Wu)

指導教授 ： 王惠森

義守大學/理工學院/材料科學與工程學系/碩士(2016年)

摘要

為了探討Mg的添加量對熱浸鍍5%Al-Zn微結構、耐蝕特性、熱物性質及機械性質之影響，本研究以5%Al-Zn為基礎，利用特製的模具模擬產線鍍鋅冷卻速率(約18 oC/s)，製作出添加不同Mg含量的Zn-5% Al-X%Mg合金(X=0-2 wt.%)試片。隨後透過微結構、耐蝕特性、熱物性質及機械性質等綜合評估提供最佳之添加比例。
　　從實驗結果顯示，在微組織方面，在特定冷卻速率下，Zn-5% Al-X%Mg其組成包含3大結構:Primary Zn、Binary二元相為: Zn- Al、Ternary三元相為: Zn-Al-MgZn2；隨Mg的增加，Primary Zn及Binary含量隨之降低，顆粒逐漸變小，但Ternary數量及大小卻會增加。
　　熱物性質方面，透過高溫示差掃描量熱儀(Differential Scanning Calorimetry, DSC)升溫及降溫檢測及相圖比對分析，本研究已確認不同比率Mg添加之相變化的溫度、熔點及液化溫度，特別是2%Mg添加可提供最低的液化溫度，有利於製程上品質及成本上的控管；而耐蝕特性方面，無論是電化學測試或鹽霧測試，2%Mg添加可提供較低的腐蝕速率及有較多的亮區(Zn(OH)2)，同時在機械性質方面，2%Mg添加提供了一定的硬度。因此綜合以上評估，對於2%Mg添加可視之為最佳的添加比例。

關鍵字

Mg添加 ； 熱浸鍍5%Al-Zn ； 微組織 ； 耐蝕性質 ； 熱物性質 ； 機械性質

並列摘要

To investigate the effects of Mg additions in the hot dipping 5%Al-Zn on the microstructure and various properties, in this study, 5%Al-Zn, which was designed as a base material, using a special copper mold, simulating a cooling rate (18 oC/s) of hot-dipped galvanized production line, to produce various Mg additions of Zn-5% Al-X%Mg (X=0-2 wt.%) alloys. After then, through comprehensive evaluation of the microstructure, corrosion resistance, thermal and mechanical properties, to find the best composition of Zn-5% Al-X%Mg alloy.
　　Experimental results shown, regarding to microstructure, under a certain cooling rate, Zn-5% Al-X%Mg alloys consists of three major structures, including: Primary Zn, Binary Zn-Al phases, Ternary Zn-Al-MgZn2 phases. As Mg content was increased, Primary Zn and Binary contents gradually decreased, and grain size of the both structures gradually decreased. But the content of Ternary phases and grain size increased.
　　From the view point of thermal properties, through the comparison the results of Differential Scanning Calorimetry (DSC) test under the heating and cooling process and phase diagram analysis, the phase transformation temperature, melting point and liquation temperature of Zn-5% Al-X%Mg alloys were defined. Especially, for the 2%Mg additions, it provide lowest a liquidation temperature, which is beneficially to production quality and cost control. Regarding to the corrosion resistance, whether electrochemical or salt spray test, 2%Mg additions can provide the slowest corrosion rate and have more bright areas (Zn(OH)2). Also it provides an acceptable hardness. Therefore, in this study, 2%Mg addition in Zn-5% Al alloy can be considered the optimal composition of the Zn-5% Al-X%Mg alloy.

並列關鍵字

Hot-galvanized ； Mg additions ； microstructure ； corrosion resistance ； thermal property ； mechanical property

參考文獻

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