促进剂对锌镍系磷化膜表面形貌及耐蚀性的影响

The effect of accelerators on the surface morphology and corrosion resistance of zinc nickel phosphating films

通过对钢铁件进行磷化处理,可以有效改善钢铁件表面的物理化学性能,为了获得耐蚀性能优异的磷化膜,需要选择合适的促进剂。在一定的条件下,通过向磷化液中加入硝基胍、亚硝酸钠、钼酸钠3种物质作为磷化促进剂,在30CrMnSi钢表面制备磷化膜。采用扫描电子显微镜、腐蚀电化学测试,硫酸铜点滴试验,中性盐雾实验,接触角试验等手段对磷化膜的性能进行了表征,对比了促进剂添加前后的效果以及促进剂种类对中温锌镍系的膜层耐蚀性能的影响。结果表明:在磷化液中添加促进剂时,磷化膜的微观结构变得更加致密,硫酸铜点滴时间都有所延长,自腐蚀电位更正,自腐蚀电流密度较小,在盐雾环境中都有一定的耐腐蚀性,都能起到增强磷化膜的耐腐蚀性能。通过比较得出当硝基胍为促进剂时,磷化膜的耐腐蚀性能最佳。

By phosphating steel parts,the physical and chemical properties of the surface can be effectively improved.In order to obtain a phosphating film with excellent corrosion resistance,it is necessary to choose appropriate accelerators.Under certain conditions,nitroguanidine,sodium nitrite and sodium molybdate were added to the phosphating solution as phosphating accelerators to prepare phosphating films on the surface of 30CrMnSi steel.The performance of phosphating films was characterized by scanning electron microscope,corrosion electrochemical test,copper(II)sulfate dropping test,neutral salt spray test,contact angle test,etc.The effects before and after addition of accelerator,as well as the effect of accelerator types on the corrosion resistance of zinc nickel film layers at medium temperature were compared.The results show that when accelerator is added to the phosphating solution,the microstructure of the phosphating film becomes more compact,the dropping time of copper(II)sulfate is prolonged,the self-corrosion potential is more positive,the self-corrosion current density is smaller,and the corrosion resistance of the phosphating film is enhanced in salt spray environment.Through comparison,it is concluded that when nitroguanidine is the accelerator,the corrosion resistance of the phosphating film is the best.