Wear properties of nickel coating film plated from emulsion with dense carbon dioxide

The microstructure and wear behavior of nickel coating film was investigated under dry conditions using a pin-on-plate type reciprocating diamond scratch tester. The nickel coating film was produced on brass substrate by an electroplating reaction that was carried out in an emulsion of dense carbon dioxide (CO2) and an electroplating solution with nonionic surfactants. The microstructures of nickel coating film and wear characteristics were investigated by surface analysis using optical microscope, roughness tester and SEM. The wear tests were done under unlubricated condition at room temperature. The produced nickel coating films have a higher uniformity, a smaller grain size, and a significantly higher Vickers hardness (680 Hv) demonstrated very good friction and wear resistance properties. The results also showed that this nickel coating film plated from emulsion with dense CO2 has better wear stability than that of nickel coating film produced with conventional electroplating system.