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B95鋁合金在鈰鹽溶液中形成轉(zhuǎn)化膜的電極反應(yīng)機(jī)理
發(fā)布人：上海艾荔艾金屬材料有限公司www.bt990.com.cn
更新時間：2015-08-26
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(jī)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。
B95鋁合金在鈰鹽溶液中形成轉(zhuǎn)化膜的電極反應(yīng)機(jī)理Electrode reaction mechanism of conversion coating forming
process of B95 aluminium alloy in cerium(Ⅲ) salt solution
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(jī)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(dá)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(dá)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。
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.
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