Influence of process parameters on microhardness of electroless Ni-B coatings

Abstract

Electroless Ni-B coatings have found large applications due to their high hardness and wear resistance. The present paper tries to investigate the influence of coating process parameters on the microhardness of electroless Ni-B coating with the help of Taguchi analysis. Four parameters, namely, bath temperature, concentration of reducing agent, concentration of nickel source, and annealing temperature, are considered and fitted into an L27 orthogonal array to find out the optimized condition for improved hardness of the coating. The optimized condition is found to yield about 19 improvement in hardness of the coating compared to the initial condition. The significance of the process parameters and their interactions on the hardness of Ni-B coating is studied with the help of analysis of variance, which revealed that annealing temperature and concentration of reducing agent have significant influence over the hardness characteristics of electroless Ni-B coating. The compositional, microstructural, and phase structure analyses are conducted with the help of energy-dispersive X-ray analysis, scanning electron microscope, and X-ray diffraction analyzer, respectively. © 2012 Suman Kalyan Das and Prasanta Sahoo.