Ca^(2+)和臭氧对A3碳钢表面磷化膜的影响

Influence of Ca^(2+) and Dissolved Ozone in Phosphating Solution on Phosphate Coating on A3 Carbon Steel

在低温磷化条件下,在磷化液中加入Ca^(2+)并以臭氧作为促进剂,在A3碳钢表面制备了磷化膜。通过SEM、XRD、EDS、FT-IR以及腐蚀电化学测试等手段对磷化膜进行表征,研究了Ca^(2+)和臭氧对磷化膜的结构和性能的影响。结果表明,在磷化液中添加Ca^(2+)所得磷化膜的质量随着Ca^(2+)浓度的提高而减小,添加Ca^(2+)可细化磷化膜的晶粒、提高磷化膜的致密度和耐蚀性能;溶解在磷化液中的臭氧具有细化磷化膜晶粒和促进晶粒生长的作用,能大幅提高磷化膜晶粒的形核率和磷化膜的主体形成速度。当磷化液的pH=2.70、Ca^(2+)浓度为1.8 g/L、臭氧含量为2.50 mg/L时,磷化膜的质量为5.46 g/m^2,其耐硫酸铜点滴腐蚀时间超过122 s,在5%NaCl溶液中的腐蚀电流为0.50μA/cm^2。

Phosphate coating on the surface of A3 carbon steel was prepared through the addition of Ca^2＋ and ozone as an accelerator of phosphating treatment at low temperature,and was characterized by SEM,XRD,EDS,FT-IR and corrosion electrochemical testing.The effects of Ca^2＋ and dissolved ozone in phosphating solution on the structure and performance of phosphate coating were investigated. The results show that the coating mass decreases with increasing the Ca^2＋ concentration in phosphating solution.Ca^2＋ can reduce the crystal size of coating and increase the density and corrosion resistance of coating.The dissolved ozone in phosphating solution can reduce the crystal size of coating and promote the growth of crystal,so the nucleation and formation rates are increased and the corrosion resistance of coating is improved.When pH=2.70,concentration of Ca^2＋ and ozone were 1.8 g/L and 2.50 mg/L respectively,the mass of phosphate coating was 5.46 g/m^2,the corrosion-resistance time of coating with CuSO4 dripping was122 s,and the corrosion current of phosphating sample was 0.50μA/cm^2 in 5%NaCl solution.