The present experimental investigation deals with the deposition of electroless Ni-P-W coating on mild steel substrate and optimization of tribological parameters for better tribological behaviour like minimization of wear depth and coefficient of friction. Three tribological test parameters, namely, load, speed, and time, are optimized for minimum friction and wear of the coating. Friction and wear tests are carried out in a multitribotester using block on roller configuration under dry conditions. Taguchi based grey relational analysis is employed for optimization of this multiple response problem using L27 orthogonal array. Analysis of variance shows that load, speed, time, and interaction between load and speed have significant influence on controlling the friction and wear behavior of Ni-P-W coating. It is observed that wear mechanism is mild adhesive in nature. The structural morphology, composition, and phase structure of the coating are studied with the help of scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and X-ray diffraction analysis (XRD), respectively. 1. Introduction Most of the engineering components undergo rubbing action due to which wear takes place on the surface of the components and become useless after a certain period. Life and performance of these engineering components can be extended by applying hard coatings over the surface of the components. The thickness of coatings ranged between 10 and 500？μm and their rates of deposition can provide the required product quality at relatively low capital and operating costs. Among the various metallic coating procedures based on aqueous solutions, most metals are electroplated since electroplating is technically straightforward and less expensive than electroless (autocatalytic) deposition. On the other hand, electroless deposition is of industrial importance mainly for copper, nickel, and some nickel based alloys. Industrial use of electroless deposition method continues to increase due to its good anticorrosion, antifriction, and wear protection properties. Electroless method has several advantages over electroplating technique, except for the life of the bath. The advantages include the quality of the deposit, namely, the physical and mechanical properties. In this process, a sharp edge receives the same thickness of deposit as a blind hole does and it offers extremely bright deposits, which are comparable with electroplated ones. The desirable properties can be varied by choosing different pH, temperature, and composition of the bath. Electroless nickel
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