LY12铝合金表面稀土转化膜腐蚀行为的研究

Corrosion Behavior of Rare Earth Metals Conversion Coatings on LY12 Alloy

通过金相观察和X射线能谱分析 (EDS)研究了LY1 2铝合金表面两种稀土转化膜的腐蚀行为 ,在NaCl溶液中稀土转化膜的腐蚀以点腐蚀开始 ,点蚀处基体含Cu量高。根据Mansfeld点腐蚀模型等效电路提出了利用电化学阻抗谱 (EIS)研究稀土转化膜在NaCl溶液中腐蚀程度的新方法 ,转化膜在NaCl溶液中浸泡时间较短、腐蚀不太严重的情况下 ,等效电路中的Warburg阻抗W可以忽略 ,通过简化等效电路得出了计算转化膜表面点腐蚀百分率F的公式。

Corrosion behavior of two kinds of rare earth metal (REM) conversion coatings on LY12 alloy was examined by optical microscopy and energy dispersive spectroscopy. The corrosion of REM conversion coatings in NaCl solution is initiated by pitting whose substrate is concentrated with Cu. According to the equivalent circuit of pitting model illustrated by Mansfeld, a new method for measuring the pitting growth of REM conversion coatings was put forward by employing electrochemical impedance spectroscopy. Warburg impedance W could be ignored under the circumstance of short term exposing REM conversion coatings to NaCl solution. This leads to develop a formula for calculating the ratio of corrosion F on the surface of REM conversion coatings by simplifying the equivalent circuit.