Corrosion Behavior of Ni-P Coated Steel Strips

Abstract

In addition to high hardness, Ni-P coatings obtained by the electroless method are widely used due to their high corrosion resistance. The corrosion resistance depends on the content of phosphorus in the coating. Various phosphorus contents result from changes in pH in the process of obtaining layers. The layers obtained in different working conditions were tested for electrochemical corrosion. Tests were conducted on a potentiostat PGP 201. There were plotted and analyzed the anodic polarization Tafel curves for different phosphorus contents, pH conditions and timeexposure in the coating bath. Analyzing the anodic polarization curves it is noticed that low phosphorus sample shows an almost continuous corrosion process while samples with high phosphorus content have slow corrosion in the 3.5% NaCl testing medium.