Electroless nickel deposition on mild steel by using a new bath formulation and its characterization

Abstract

A new bath formulation has been developed to prepare the Ni-P deposits on mild steel substrates.The alkaline hath formulation contains NiCl₂ as a Ni source and sodium hypophosphite as reducing agent. The Ni-P alloy with higher phosphorus content was obtained by using this new bath formulation. The uniform deposits of Ni-P (1.98-12.5) were obtained. The change in rate of deposition with time, temperature and pH was studied. The effect of concentration of nickel and reducing agent on the deposition was investigated. The samples obtained were characterized by using SEM, XRD, DSC and ICP-OES techniques. The Ni-P deposits were amorphous in nature and upon heat treatment in between 300 to 450°C, it changes to crystalline Ni₃-P phase. The phosphorus content of the deposits increases with the deposition time and highest P content is obtained on the samples prepared at 3 h time.