Ni-P合金镀层在HCl溶液中的腐蚀行为

Corrosion Behavior of Ni-P Alloy Coating in HCl Solution

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.

A low phosphor containing coating was plated on surface of 45^# steel by electroless plating.The microstructure and corrosion behavior in 10%HCl solution of the low phosphor coating were investigated.The result shows that the coating exihibits an uniform and dense appearance,contains 3.75%P and is crystalline.The adhesive strength of the coating with the substrate steel is 95 N.The corrosion rate raises with increasing corrosion time.The surface of the coating keeps intact after immersion for 2 h,and becomes a cell-like morphology for 4 h.Corrosion cracks appear firstly around defects on the surface and extend along the cell boundaries.After immersion for 8 h,corrosive medium may penetrate through cracks to the substrate and finally destroy the coating for 10 h.