電化學阻抗研究金屬塗層之腐蝕現象

Electrochemical Impedance Study on the Corrosion Phenomenon of Organic Coated Metals

呂良崟(Liang-Yin Lu)

指導教授 ： 尹庚鳴

元智大學/工程學院/化學工程與材料科學學系/碩士(1997年)

摘要

為了解高分子塗層如何保護金屬底材不被各種接觸環境所腐蝕破壞，以及觀察高分子塗層在溶液中被破壞與劣化的進行。實驗選擇環氧樹脂當作保護金屬的高分子抑制膜來進行實驗。實驗的試片是以旋轉塗佈的方法將環氧樹脂被覆在金屬底材上製作而成。試片經烘焙後浸置在各種不同的溶液中，並以電化學阻抗法（Electrochemical Impedance Spectroscopy）測試塗層在溶液中的破壞情形。

實驗結果經由 EIS的 Nyquist圖（Z* vs. Z*）及Bode圖（ |Z| vs. log f 與 phase angle vs. log f ）兩個基本解析圖呈現出金屬/塗層隨時間的破壞情形。觀察長期的記錄塗層隨時間的變動，從巨觀來看，塗層的破壞是一遞減的趨勢。但是從微觀看，塗層的破壞不是一絕對遞減的趨勢，而是有一波動現象。此波動現象是來自於金屬/塗層界面上的反應造成的，可能是金屬腐蝕產物累積於塗層孔洞中或金屬底材上的反應。

為了詳加了解金屬/塗層破壞的情況，可以構建一個等效電路圖來模擬真實的金屬/塗層系統在浸置環境中破壞的進行。觀察等效電路圖上每個參數隨時間的變動情形，可以更加詳細的了解到每個時段支配著金屬/塗層腐蝕進行時變化最大的是那一個參數、最重要的是那一個參數。另外，也可以利用SEM觀看塗層表面的微細變化，與EIS的Nyquist圖及Bode圖做一比較對照。

關鍵字

電化學阻抗頻譜 ； 有機塗層

並列摘要

To understand how the polymer protect the metal substrate from corrosive environments, and to observe the process that the polymer was damaged, this experiment chosed epoxy resins as a polymer film to protect the metal. The sample were made by spin coating. The sample put to different solutions and to observe the decaying phenomena in the solution by the method of Electrochemical Impedance Spectroscopy（EIS）.

The experimental results were analyzed by two basic charts, Nyquist chart （Z* vs. Z*）and Bode chart（ |Z| vs. log f and phase angle vs. log f ）, generally, there was a decreasing tendency. However, there was a undulating phenomenon day by day. The cause of this phenomenon is due to the reaction on the metal/coating interface. The corrosion products of metal accumulate in the holes of coating and on the metal substrate surface.

To study the corrosion parameters, we could construct an equivalent circuit to simulate the real decaying process of the metal/coating system in the corrosive environment. To follow the time dependence of the equivalent circuit one could find the most important parameter that control the corrosion process in each period of time. Furthermore, we used SEM to observe the minute changes on the surface of coating and compare it with the Nyquist chart and Bode chart of EIS.

並列關鍵字

Electrochemical Impedance Spectroscopy ； Organic Coatings

參考文獻

3. Denny A Jones, 〝Principles and Prevention on Corrosion〞,Prentice Hall, 1997

4. J. Ross Macdonald, 〝Impedance Spectroscopy〞, John Wiley & Sons, 1987

5. Douglas C. Giancoli, 〝Physics for Scientists and Engineers〞,

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