Obtaining of the Ni-P Coatings on Steel Strips

Abstract

The Ni-P coatings on steel strips were obtained by electroless method. Experiments were performed at three pHs, respectively: 6.6; 5.11 and 4.32 with immersion times 5 and 12 minutes at 80 - 85°C. Deposits were caractherized by energy-dispersive analysis (EDS), scanning electron microscopy (SEM) and optical microscopy. The chemical composition shows an increased of phosphorus content at the pH descrease, so at the pH-6.6 the phosphorus content in the coating is 4.74 wt% and at pH-4.32 is 12.42 wt% P. Regardless of the pH value is observed was some chemical dishomogeneity of layers the more pronounced with as the pH value is higher. Alongside Ni and P the layers can contain small amounts of oxygen and other elements coming from the nickel bath impurities and from working environment. Also it shows the surface morphology in correlation with the deposition process parameters and surface defects possible.

Behavior on Plastic Deformation of Thin Steel Strips Coated with Electroless Ni-P

“…Almost any surface can be covered: metallic or non-metallic, including polymers (plastics), ceramics. The performances of this type of coverage have led to their use in various industrial fields: cellulose and paper production, plastics, food, petroleum-petrochemical, textile, automotive, aeronautical, electronic, nuclear industry [6,7]. Deposits obtained by the chemical method are mainly used in applications that require significantly improved characteristics for the deposited layer, the most important being uniformity of thickness, hardness, high resistance to wear and corrosion [8].…”