Measure and evaluate the hardness of the electrodeposited Nickel-Phosphorous (Ni-P) thin film coating on carbon steel alloy for automotive applications

In this research work, the electrodeposition of Nickel-Phosphorous (Ni-P) coating on carbon steel alloy for higher surface hardness has been investigated. Nickel phosphorus (Ni–P) with 11–12 wt% phosphorous was electrodeposited onto AISI 1045 steel substrate with direct current and solutions of phosphorous and phosphoric acid, nickel sulphate and nickel chloride. The effect of current density as a plating parameter was investigated. It appeared that by increasing the current density by 50, 100 and 150 mA/cm ² it is possible to obtain greater phosphorous content in Ni-P alloy coating. FESEM, XRD, EDS, scratch adhesion and micro hardness methods were employed to investigate the surface morphology, micro structure, composition and mechanical characteristics of Ni-P alloy coating. The structure became amorphous when the P content ranged from 11 to 12 wt%. Ni–P alloys with different phosphorous content were exposed to heat treatment at 300, 400 and 500 °C for 1 h in a hot air oven. The changes in mechanical characteristics were investigated.