锌-铁系蓝色磷化工艺参数对膜外观及耐蚀性能的影响

Effect of Blue Phosphating Parameters of Zn-Fe Series on Appearance and Corrosion Resistance of Phosphating Coatings

为了提高磷化膜的装饰效果,替代钢铁室温发蓝工艺,开发了一种能在室温下获得蓝色磷化膜的磷化工艺。用目测法和硫酸铜点滴试验研究了溶液pH值、温度、磷化时间等因素对磷化膜外观和耐蚀性的影响;用电化学法考察了蓝色磷化膜在3.5%NaCl溶液中的电化学行为,分别采用扫描电镜(SEM)和能谱仪(EDS)观察分析了蓝色磷化膜的微观形貌和组成成分。结果表明:在pH值2.5～3.0,温度23～31℃,时间15min条件下所获蓝色磷化膜有较好的耐蚀性,其耐硫酸铜点滴时间56s;能使Q235钢基体自腐蚀电位提高0.3V,并且使基体由阳极活性溶解态转变成钝化态。

In order to improve the decorative effect of phosphating coatings and find substitutes for oxidation technology of steel at room temperature,a new phosphating process was de-veloped,which could be used to obtain blue phosphating coating on the surface of steel.The influences of pH value,temperature of phosphating solution and phosphating time on the appearance and corrosion resistance of phosphating coating were studied by eye examinations and copper sulfate dropping tests.Electrochemi-cal behavior of the blue phosphating coating in 3.5% NaCl solu-tion was evaluated by using electrochemical techniques.The mor-phology and composition of the blue phosphating coating were an-alyzed by means of scanning electron microscopy and energy dis-persive spectrometry.Results show that the blue phosphating coating obtained from the phosphating solution with a pH value of 2.5-3.0 and temperature of 23 ～ 31 ℃ after 15 minutes of phosphating has excellent corrosion resistance,and has a life of 56 seconds for resisting copper sulfate dropping.It was able to in-crease the corrosion potential of Q235 steel matrix by 0.3 V,fa-cilitating transformation of the steel matrix from active dissolved state to passivated state.