臭氧复合钼酸铵促进剂对金属铝磷化的影响

Effects of ozone-ammonium molybdate compound accelerant on phosphating of metallic aluminium

利用臭氧的强氧化性和环境友好性,研究将其用作铝材磷化过程中的氧化促进剂。采用SEM、极化曲线等测试手段,确定了磷化液的最佳配比为：ρ（Zn^2＋）=5.0 g/L、ρ（PO4^3-）=20 g/L、ρ（F-）=1.5 g/L、ρ（钼酸铵）=1.0 g/L、ρ（臭氧）=0.5~0.9 mg/L,pH控制在3.5~3.7。在此条件下加入臭氧复合钼酸铵促进剂,制得磷化膜的主要成分为Zn3（PO4）2.4H2O,并含少量锌,膜质量可达4.95 g/m2。在质量分数为3%的氯化钠溶液中测定磷化膜的电极化曲线,其腐蚀电位相对于其他条件下形成的磷化膜发生正移,腐蚀电流密度仅为3.0μA/cm2,说明磷化膜的耐腐蚀性能好。

Ozone was used as oxidizing accelerant in phosphating of metallic aluminium based on its strong oxidizing property and environmental friendliness. The best mix ratio of phosphating solution components was confirmed by SEM and polarization as follows ：ρ（Zn^2＋）=5.0 g/L、ρ（PO4^3-）=20 g/L、ρ（F-）=1.5 g/L、ρ（ ammonium molybdate } = 1.0 g/L, p （ozone} = 0. 5 -0. 9 mg/L,and pH was at 3.5 -3.7. Under above conditions, the phosphating film was prepared while adding ozone-ammonium molybdate compound accelerant. Main ingredient of the prepared phosphating film was Zn3 （ PO4 ） 2 · 4H2 O, in which a small amount of zinc was contained and the film weight could reach 4.95 g/m2. Polarization curve of phosphating film was measured in NaC1 solution with the mass fraction of 3%. Its corrosion potential had a positive shift comparing with that of the phosphating films formed under other conditions and the corrosion current density was only 3.0 μA/cm2. Thus showed it had a good corrosion resistance.