铝合金表面无铬环保型化学转化膜工艺

Process of Chrome-free Chemical Conversion Film on Aluminum Alloy

采用单因素试验方法，以磷酸盐化学转化膜膜重及其在3．5％NaCI溶液经全浸腐蚀试验的失重率作为转化膜性能评价指标，确定了以M03为添加剂的铝合金磷酸盐化学转化处理液的最佳配方和工艺参数：ZnO8g／L，H3P0420mL／L，NaF0．8g／L，Y2O3 0．02g／L，处理温度为（40±2）℃，处理时间为8～10min，pH=（3．0±2）。采用模拟大气腐蚀及全浸泡试验研究了经不同转化处理的铝合金试样涂漆后转化膜与涂层间的结合力。结果表明，在相同的试验条件下，稀土促进生成的磷酸盐化学转化膜与有机涂层间的结合力优于磷酸一铬酸盐转化膜。

Take the weight of phosphate conversion coating and the rate of weight loss in 3. 5 % NaC1 solution as evaluation indexes, orthogonal experiment was used to determine the optimal formula and technological parameters of phosphate conversion processing solution with Y2O3 as additive. The parameters are as follows： ZnO 8 g/L, H2 PO3 20 mL/L, NaF 0. 8 g/L, Y2O3 0.02 g/L, temperature = （40±2） ℃, time=8--10 min, pH = （3.0±2）. The phosphate conversion films formed under the technological conditions has good corrosion resistance. The binding force between the conversion films which were differently processed on aluminum alloy samples after painting and the organic coating was studied by simulated atmospheric corrosion and full immersion test. The results show that under the same experimental conditions, the bonding force between the phosphate conversion film generated with Y2O3 as additive and the organic coating is superior to that of phosphate-chromate conversion film.