Eight kind pretreatment progresses were proposed as pretreatment of 6063 diecast aluminium alloy, surface morphologies of untreated or treated were observed by optical microscope. The polarization curves and electrochemical impedance spectroscopy for the conversion coatings obtained after different pretreatments were measured in a 3.5% (mass fraction) NaC1 solution. A optimal pretreatment progress was obtained as following:polishing from 180# to 1000# by grit emery papers →alkaline cleaning with 100g/LNaOH + 40g/LNa3PO4 + 15 g/LNa2SiO3for 2 rain at 60℃ →acid cleaning with 20% HNO3 + 10% H3PO4 + 5% HF for 1 rain at room temperature →surface activation with 10g/LNaOH for 30 second→washed three time with distilled water and dries. The morphology of the surface of A1 alloy obtained after pretreatment, uncoated or coated in Ce (NO3) 3 and KMnO4 chemical conversion solution were studied by scanning electron microscopy (SEM) and elemental composition of Ce-Mn conversion coating were studied by energy-dispersive spectroscopy (EDS), respectively. The results showed that the clean surface and welldistributed cathodic points is a necessary step for producing Ce-Mn conversion coating on the surface of A1 alloy in following immersion in Ce ( NO3 ) 3 and KM-nO4 bath. Otherwise, a complete and optimal corrosion resistance conversion coating could not be formed after pretreatment.%采用光学显微镜分析6063轧制铝合金经8种前处理工艺处理后对表面形貌和转化成膜效果的影响；选择了其中四种具有代表性的转化膜，在3．5％NaCl溶液中的进行极化曲线和交流阻抗研究，较佳前处理工艺为，水磨砂纸逐级打磨至1000#→在强碱性溶液（100g／LNaOH＋40g／LN％P04＋15g／LNa2Si03）中60℃，超声去油处理2分钟→混合酸溶液（20％HN03＋10％H3P04＋5％HF）浸泡1分钟→10g／LNaOH溶液中浸渍30秒，每步间用蒸馏水清洗三次，采用扫描电子显微镜（SEM）和能谱（EDS）分析了4种前处理工艺对成膜前后表面的形貌和成分影响，表明铝合金经前处理后表面洁净，阴极点适当暴露却均匀分布。生成的Ce－Mn转化膜完整，耐腐蚀能力强。
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