Multiple Roughness Characteristics of Chemically Deposited Ni-P-W Coatings

This paper presents an experimental study of multiple roughness characteristics of Ni-P-W coatings on a mild steel substrate. The different roughness parameters considered are centre line average roughness (Ra), root mean square roughness (Rq), skewness (Rsk), kurtosis (Rku) and mean line peak spacing (Rsm). The aim of the present study is to optimize the coating process parameters based on Taguchi method and Grey relational analysis in order to obtain the particular bath composition which may be used to deposit Ni-P-W coatings with optimum roughness characteristics. Experiments are carried out based on the L27 Taguchi orthogonal designusing the combination of three process parameters, namely, concentration of tungsten ion, concentration of reducing agent and concentration of nickel source. It is observed that concentration of tungsten ion has the most significant influence in controlling roughness characteristics of Ni-P-W coating. The surface morphology, composition and phase structure of coatings are also studied with the help of scanning electron microscopy, energy dispersive X-ray analysis and X-ray diffraction analysis respectively