Electroless deposition of ternary Ni-W-P alloys from sulphate and chloride based baths

The present investigation focuses on the preparation of ternary electroless Ni-W-P alloy deposits using sulphate (B1) and chloride (B2) based baths. The characteristics of the deposits were studied using XRD, SEM, XPS and atomic force microscopy (AFM) techniques. XRD patterns showed that the tungsten influences the structure and grain size of the deposits produced using B1 and B2 based baths. EDX analysis showed that a drastic reduction of phosphorus content owing to the addition of tungsten in both types of deposits. XPS studies showed that W content was approximately 2 at.-% and in the coatings deposited using B1 baths the elemental form of tungsten is twice that in the coatings deposited using B2 baths, From SEM analysis coarse nodular structure was found for the deposits obtained using B1 baths. It was also found from AFM images that the roughness values of ternary deposits using B2 baths were lower than those using B1 baths. Heat treatment at different temperatures on the deposits showed a higher increase in hardness in the coatings from B2 baths.