Preparation and properties of cathodic plasma electrolysis Ni-P coatings

Cathodic plasma electrolysis (CPE) is an emerging surface engineering technology in the recent years. In present work CPE was successfully used for deposition Ni-P coatings on carbon steel. The deposition experimental results show that CPE possesses high coating deposition rate, faster than 4 mu m/min. SEM observations unveil the bonding between Ni-P coating and substrate is metallurgical. XRD diagram analysis indicates that the phases of as-deposited Ni-P coating are Ni and Ni3P, transformed from amorphous to crystallized state. The corrosion resistances of CPE and electroless plating (EP) coating have also been discussed by polarization curves in 3.5% NaCl solution at room temperature. Scratch tester was applied to study film-substrate adhesion of CPE Ni-P coating comparing with EP Ni-P coating.