In the present work, tungsten carbide (WC) particulate of average size 10 mm were electrocodeposited in the nickel metal matrix, to form metal matrix composite (MMC) coating over the EN8 steel substrate. The electrodeposition of Ni-WC particulate composite coating was carried out using the Watt's bath under the influence of varying current density and duty cycle. It was found that current density of 0.02 A/ cm 2 was sufficient to start the codeposition kinetics. But, good quality of electrodeposition was obtained at a current density of 0.04 A/cm 2 . The WC particulate entrapment and distribution of WC particles in Ni matrix according the variation in experimental parameters has been reported. The dense and compact microstructure was obtained at a current density of 0.04 A/cm 2 and duty cycle of 30%. Microhardness and corrosion resistance properties of composite coating were also evaluated and reported.
INTRODUCTIONSurface modification, with the formation=deposition of overlaying layer of metal matrix composite (MMC), provides enhanced mechanical, tribological, and corrosion resistance properties. During the last few decades, researchers have attempted to improve those properties through electrocodeposition of hard particles such as Al 2 O 3 [1-4], TiO 2 [5, 6], SiC [7-9], ZrO 2 [10, 11], WS 2 [12], and Si 3 N 4 [13,14] in different metal matrixes (Ni, Cr, Co, etc.). Nickel is a most suitable metal, among all metal matrixes due to its good chemical compatibility with the other metal and alloys [18]. Moreover, it imparts very good corrosion resistance property to the coated surface. Tungsten carbide is a hard ceramic having high thermal stability and good dispersion properties which lead to high wear and thermal resistance properties of the coating. Deposition of electrically nonconductive tungsten carbide particles alone is very difficult, as it produces obstruction to obtain dense interface of metal-carbide during the electrodeposition process, but it can be easily codeposited with a transition group of elements. Although there are a number of surface coating techniques available, but the electrodeposition process has drawn significant attention because it is a nonthermal process, technologically feasible, easily controllable, economically superior technique to produce a MMC. It is based on the uniform entrapment of second-phase hard particles within the metal matrix.Although many research papers have been reported in the area of WC composite coating through direct current