Abstract: A novel aluminum alloy surface pretreatment process with fluoride-free and ammonium-free formula was developed. Through the two-step process of pretreatment etching-neutralizing, the aluminum alloy surface was smooth and had excellent sand finishing, the aluminum consumption was less than 2.0%. The sand finishing performance of the new process was better than that in the traditional alkaline-etching process, and was close to the traditional acid-etching process. The aluminum consumption of the new process was reduced by 71% compared with the traditional alkaline-etching process, and was close to the traditional acid-etching process. The process duration was 23% and 31% faster than the traditional alkaline-etching process and traditional acid-etching process, respectively. The optimum composition of the formula was: Na₂CO₃ (80 g·L^-1), NaOH (8 g·L^-1), Na₂SO₄ (25 g·L^-1), Na₃PO₄ (20 g·L^-1), SDS (0.6 g·L^-1) and glycerol (5 g·L^-1). The process was operated at 55℃ for 10 min. This process achieved following functions in one-step: degreasing, sand-finishing, surface mechanical lines-eliminating. This novel process has the advantages of lower pollution and water consumption, shorter process and higher efficiency, which is environment friendly and energy efficient.

Key words: aluminum alloy, surface pretreatment, fluoride-free and ammonium-free, aluminum consumption, sand finishing, surface, corrosion, environment

摘要： 针对铝合金表面预处理过程存在污染严重、水耗高等问题，研究开发无氟无铵铝合金表面预处理新工艺。考察了碱性药剂配方组成及浓度、温度和时间对铝耗和铝合金表面形貌的影响，并通过正交实验确定了新工艺的优化方案。研究结果表明，经过“预处理-中和”两个步骤，铝合金表面平整、起砂细腻，铝耗仅为 2.0%。新工艺起砂效果优于传统碱蚀工艺，与传统酸蚀工艺细腻砂面相近。新工艺铝耗比传统碱蚀工艺降低约71%，与传统酸蚀工艺相近。新工艺操作时间比传统碱蚀工艺和酸蚀工艺分别缩短了23%和31%。最佳药剂配方为Na₂CO₃（80 g·L^-1）， NaOH（8 g·L^-1），Na₂SO₄（25 g·L^-1）， Na₃PO₄（20 g·L^-1）， SDS（0.6 g·L^-1）， 甘油（5 g·L^-1）。 最佳操作条件为55℃和10 min。新工艺不仅从工艺源头消除了氟和氨氮污染，还实现了除油-起砂-去机械纹等多功能一体化集成。具有低污染、低铝耗、低水耗、短流程、高效率等优点，兼具环境友好和资源节约等优势。

关键词: 铝合金, 表面预处理, 无氟无铵, 铝耗, 起砂, 表面, 腐蚀, 环境