(中國鋼研科技集團有限公司 先進金屬材料涂鍍國家工程實驗室，北京 100081)
摘 要: 采用電化學(xué)阻抗譜(EIS)研究B95鋁合金在10 mmol/L CeCl3溶液中轉(zhuǎn)化膜的形成過程，在建立稀土轉(zhuǎn)化膜成膜過程三階段機理基礎(chǔ)上，采用電化學(xué)阻抗譜(EIS)技術(shù)研究溶液中氧含量、H2O2、pH值等各種條件變化對轉(zhuǎn)化膜形成過程的影響。結(jié)果表明：O2參與的反應(yīng)不是Ce轉(zhuǎn)化膜形成速度的決定步驟，添加H2O2加快Ce轉(zhuǎn)化膜形成速度，特別是形成過程的第一階段；微陰極區(qū)氧主要按二電子途徑還原，使局部pH上升，當(dāng)pH達到或超過8.05時，Ce(Ⅲ)水合氫氧化物/氧化物開始沉積；Ce(Ⅲ)轉(zhuǎn)化膜達到穩(wěn)定平衡階段，部分Ce(OH)3會被氧還原的中間產(chǎn)物H2O2氧化成CeO2；在中性或弱酸性溶液中，提高溶液的pH值對最終成膜有利。
關(guān)鍵字: B95鋁合金；交流阻抗；Ce轉(zhuǎn)化膜；電極反應(yīng)；成膜過程
（National Engineering Laboratory for Advanced Coatings Technology of Metal Materials,
China Iron and Steel Research Institute Group, Beijing 100081, China）
Abstract:The electrochemical impedance spectroscope (EIS) was used to study the conversion coating forming process of B95 aluminum alloy in 10 mmol/L CeCl3 solution. The formation process of rare earth (RE) conversion coating can be divided into three stages. Based on the three stages formation mechanism of the rare earth conversion coatings, the influences of O2 concentration, oxidant, pH etc on the formation process of conversion film were investigated. The result shows that the reaction caused by the O2 participation is not determinate step of the Ce conversion coating formation, the addition of H2O2 speeds up the formation of Ce conversion coating, especially in the first stage. The two electric ways of cathodic reaction are formed by the conversion coating on B95 aluminum alloy in CeCl3 solution, which reasonably explains the local pH rise in micro cathode area, Ce(Ⅲ) hydrous hydroxide/oxide begins to deposit when the pH reaches or exceeds 8.05. Part Ce(OH)3 can be oxidized into CeO2 by the intermediate products of H2O2 when Ce(Ⅲ) conversion coating achieves stable equilibrium. In neutral or subacidity solution, improving the pH of solution will beneficial to the final formation of the coating.
Key words: B95 aluminium alloys; electrochemical impedance spectroscope (EIS); Ce conversion coating; electrode reaction; coating forming process
