Fabrication of Co−Ni−P film with excellent wear and corrosion resistance by electroplating with supercritical CO2 emulsion

To avoid the defects caused by the hydrogen evolution and improve the corrosion and wear properties of the electroplated films in the traditional aqueous bath electrodeposition, a supercritical carbon dioxide (Sc-CO₂) emulsion was proposed to electrodeposite ternary nanocrystalline Co?Ni?P alloy films. Microstructure, corrosive and tribological properties of the Co?Ni?P films were investigated and compared with the ones electroplated by conventional method. The results show that the Co?Ni?P films produced with Sc-CO₂ assisted electrodeposition exhibit a more compact microstructure. The preferred orientation plane of hcp (110) for the Co?Ni?P films produced in conventional aqueous bath is changed to be hcp (100) for the one prepared in emulsified Sc-CO₂ bath. The microhardness, corrosion resistance and tribological properties of the Co?Ni?P films are substantially improved with the assistance of Sc-CO₂ in the electrodeposition bath.