臺灣博碩士論文加值系統

摘要本研究主要藉由不同熱處理條件探討鋁鈧合金的顯微組織對其腐蝕行為之影響。實驗中採用的測試溶液為3.5％NaCl並以HCl或NaOH調整其酸鹼值；熱處理則有A：480℃×24hr固溶處理＋水冷、B：480℃×24hr固溶處理＋人工時效100℃×6hr和C：480℃×24hr固溶處理＋人工時效100℃×24hr三種條件。Al-Sc合金熱處理後顯微組織顯示：經過480℃×24hr固溶處理後，Al-Sc合金可達成均質化效果，晶界上無明顯析出相出現，晶粒尺寸約為50μm，硬度值只有86.1Hv。Al-Sc合金析出物數量與分布情況，由時效時間長短控制。經過480℃×24hr固溶處理＋人工時效100℃×24hr後，Al-Sc合金晶粒尺寸約為10μm，析出勿分布均勻，應是析出物細化晶粒的效果，微硬度值206.8Hv。經過熱處理的Al-Sc合金電化學試驗結果顯示：A組Al-Sc合金因晶界上無明顯析出物產生，使氫離子和氯離子容易侵蝕晶界，造成沿晶腐蝕嚴重。B組Al-Sc合金在100℃×6hr時效後，因析出物較少而造成腐蝕反應較為集中，腐蝕電位傾向活性(約-960mVSCE)。C組Al-Sc合金腐蝕電位則較為貴重(約-790mVSCE)，其因析出物Al3Sc細小且均勻緻密分布，容易使材料表面產生陰極保護現象，導致C組Al-Sc合金有較低的腐蝕電流密度較A組穩定。

AbstractThe corrosion behavior of aluminum alloys alloyed with Sc after different heat treatment has been reported in a 3.5% NaCl aqueous solution by using electrochemical method. The surface morphology of the corroded samples was investigated by a scanning electron microscope. Experimental results showed that micro harduess of the Al-Sc alloy was 206.8Hv after a precipitation heat treatment (homogenized at 480℃ for 24h and aged at 100℃ for 24h), due to the presence of Al3Sc precipitates. The precipitates are also affect the corrosion behavior of the alloy. Electrochemical measurement results indicated that the Al-Sc alloy after precipitation heat treatment possesses the most noble corrosion potential. However, the Al-Sc alloy after homogenization possess uniform chemical compositions in the matrix and manifest the lowest corrosion rate.

目錄中文摘要………………………………………………………………. Ⅰ 英文摘要………………………………………………………………..Ⅱ 目錄……………………………………………………………………..Ⅳ 表目錄…………………………………………………………...…..... Ⅶ 圖目錄…………………………………………………………………..Ⅷ 第一章、 緒論…………………………….…………………………...1 1-1前言..……………………………………………………....1 1-2背景..………………………………………………………2 1-3研究目的..…………………………………………………3 1-4文獻參考..…………………………………………………5 1-4-1添加合金元素Sc對鋁合金之影響………..……….....5 1-4-2鍛造用鋁合金簡介…..………………………………...6 1-4-3鋁合金之電化學腐蝕影響..…………………………...8 1-4-4鋁及鋁合金的腐蝕類型..………….………………....10 第二章、 理論分析…………………………………………………..15 2-1鋁合金析出強化…………………………………………15 2-1-1析出硬化之熱處理過程……………………………...15 2-2 鋁的電化學腐蝕………………………………………...17 2-3電化學定義..…………………………………………......18 2-4腐蝕電化學量測…………………………………………19 2-4-1 Tafel外推法………………………….……….………19 2-4-2循環極化法………………………….………….…….21 2-4-3酸鹼 pH值之測定………………….….…………….22 2-4-4電位-pH圖……….……………………….………......22 2-4-5活化支配之腐蝕與其速度之求法……………..…….23 第三章、 實驗方法與步驟………………………………………......24 3-1實驗材料……………………..……………………….….24 3-2實驗設備……………………………………………..…..24 3-3試片製備………………………………………………....24 3-4 Al-Sc合金電化學腐蝕性質與酸鹼環境腐蝕試驗.…….25 第四章、 結果與討論…………………………………………..........27 4-1熱處理對鋁鈧合金顯微組織之影響……………………27 4-2 Al-Sc合金在中性3.5％NaCl溶液之電化學試驗….…..29 4-2-1極化曲線的變化………………………………….…..29 4-2-2在中性3.5％氯化鈉溶液中的腐蝕破損分析…….…30 4-3 Al-Sc合金在不同pH值3.5％NaCl 溶液中電化學實 驗…………………………………………………………32 4-3-1 Al-Sc合金在酸性氯化鈉溶液的極化曲線……….…32 4-3-2 Al-Sc合金在鹼性氯化鈉溶液的極化曲線…….……34 4-3-3 Al-Sc合金在不同pH值氯化鈉溶液中的腐蝕破損 分析..…………………………………………………35 第五章、 結論…………………………………………………..........39 參考文獻…..……………………………………………………………41 附錄…………..…………………………………………………………47

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