Deposition of electroless Ni–P graded coatings and evaluation of their corrosion resistance

Electroless Ni–P coatings provide high hardness and excellent resistance to wear and abrasion. The present work aims to study the formation of electroless Ni–P graded coatings, with varying nickel and phosphorus contents of the individual layers and to evaluate their corrosion resistance by polarization and electrochemical impedance spectroscopic studies. The possibility of preparing electroless Ni–P graded coatings by sequential immersion in three different plating baths is discussed. The study reveals that electroless Ni–P graded coatings offer better corrosion resistance than non-graded Ni–P coatings.