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采用化学镀在45~#钢表面制备了低磷的Ni-P镀层并研究其组成、状态和在10%的HCl溶液中的全浸泡腐蚀行为.结果表明,低磷镀层表面均匀致密;镀层中磷含量为3.75%,呈晶态结构;与基体结合良好,结合力达95 N;腐蚀液温度为60℃时,低磷镀层的腐蚀率随着腐蚀时间的延长而增加;腐蚀2 h后镀层表面仍均匀致密,胞状组织明显;4 h后表面粘附的颗粒增多,在表面存在的缺陷周围首先出现了腐蚀裂纹,并沿着胞状物界面向四周扩展,腐蚀液的渗入增大了接触面积;8 h后腐蚀裂纹沿着界面扩展至整个镀层表面;10 h后大量镀层被腐蚀掉,镀层对基体已基本起不到保护作用.
The electroless Ni-P coating with low phosphorus content was prepared on the surface of 45 ~ # steel and its composition, state and total immersion corrosion in 10% HCl solution were investigated. The results showed that the surface of the low phosphorus coating was uniform and compact. Phosphorus content of 3.75%, was crystalline structure; good combination with the substrate, the binding force of 95 N; etching solution temperature of 60 ℃, the corrosion rate of low phosphorus coating with the corrosion time increases; corrosion 2 h after plating The surface is still uniform and dense, and the cellular structure is obvious. After 4 h, the number of particles adhering to the surface increases. Corrosion cracks appear first around the defects existing on the surface and extend to the periphery along the cell interface. The penetration of the etching solution increases the contact area After 8 h, the corrosion cracks extended to the entire coating surface along the interface. After 10 h, a large amount of coating was eroded away, and the coating had no protective effect on the substrate.