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

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