The effects of pulse electrodeposition parameters on morphology, hardness and wear behavior of nano-structure Cr–WC composite coatings

Electrodeposition of nano-structured Cr–WC had been carried out from a trivalent chromium bath using a square shaped pulse current. The average size of WC particles was 70 nm. The effect of pulse electroplating parameters such as current density and duty cycle on the amount of incorporated WC particles and morphology of the coatings was investigated. The structure and morphology of the coatings were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. In addition, the hardness and tribological behavior of the coatings were investigated by micro hardness and pin on disk methods, respectively. The results showed that with decreasing duty cycle, the volume percentage, hardness and wear resistance of coating increased. Also, by increasing the current density up to 15 A/dm2, the both of volume percentage and hardness will increase. An increase in current density up to 20 A/dm2, had an inverse results. Finally the optimum wear resistance was achieved at the current density of 8 A/dm2, duty cycle of 50%.

► The wear resistance of Cr–WC nano-composite is enhanced by increasing current density. ► The duty cycle decreases the WC particles and wear resistance of the coating. ► The best coating of Cr–WC is occurred at 8 A/dm2 and duty cycle of 50%.