【摘要】 通过在重铬酸盐溶液中添加KF、H3BO3及混合稀土添加剂等成分,得到了适合于2A12铝合金表面无色导电氧化的化学氧化工艺。采用点滴法、中性盐雾试验和电化学测量方法评价了转化膜的耐蚀性,研究表明:Na2Cr2O7和KF含量、溶液pH值、温度、处理时间等对转化膜的外观、耐蚀性影响明显,混合稀土添加剂的影响尤为显著。在最佳工艺条件下所得转化膜可通过120h的中性盐雾试验,其表面电阻为40μΩ。通过化学氧化过程的电位-时间曲线分析,清楚了化学转化膜的形成过程。更多还原

【Abstract】 The technology of forming colourless conductive conversion coating on the surface of the 2A12 aluminium alloy is obtained, by adding ingredients such as KF?H₃PO₄?H₃BO₃ or K₃Fe（CN）₆ to the aqueous solution of dichromate. The relationship between corrosion resistance and the concentration of Na₂Cr₂O₇ is obtained to be parabola. The optimum concentration is 4 g/L when the time of corrosion resistance is 10.5 min. The relationship between corrosion resistance and the concentration of KF has the same tendency to Na₂Cr₂O₇ and the optimum concentration is 0.3～0.4 g/L.The salt spray results show that the conversion coatings formed in solution using mixed rare earth as additive can resist the corrosion for five periods, after seven periods, the surface of the film is slightly eroded. The SEM micrographs shows the microstructure differences of conversion films before and after salt spray. After salt spray testing, lots of corrosion products can be observed on the surface of the bare aluminium alloy; if the mixed rare earth was used as additive, almost no corrosion products were observed on the surface of the film.The contact resistance of the conversion coatings is measured by means of multi-ohm meter, almost 40 μΩ, fulfills the need of application.更多还原