A Study of Electroless Nickel-Boron Coating Process

An electroless nickel-boron coating method has been developed that attempts to overcome the problems that are generally associated with the process of applying coatings. The problems include irregular film deposits and brittleness. The method is versatile and is applied for coatings on a number of substrates, including brass, copper, mild steel and stainless steel AISI 316L. Growth rates of 14 to 22 microns per hour are possible. The deposited coating thickness varied with the amount of complexing agent added to the solution, sodium borohydride concentration and to thebath temperature. When the deposits are annealed at 400 °C, transformations of amorphous nickelboron deposits to crystalline nickel and NiiB are obtained. The boron content in coated film varied from 1.26% to 4.15 %.