Effect of Pulse Current Density Variation on Cu-Zn Alloys Electrodeposited in Pyrophosphate-Based Baths

Abstract In this study, a steel substrate was coated with Cu-Zn alloy using the electrodeposition method. A pyrophosphate-based electrolyte was preferred and the properties of Cu-Zn coatings deposited at different pulse current (PC) density values were investigated. From the results, it was revealed that the coating properties were significantly affected below and above the PC density value of 20 mA/cm 2 , and it can be stated that this value is a critical for the properties of Cu-Zn alloy coatings. From the X-ray diffraction results, it was found that only the α phase was present in the structure up to 20 mA/cm 2 PC density value, while the α and β ′ phases were found to coexist at higher current density values. As the PC density increased, the Zn content of the Cu-Zn coatings increased from 7% to 56%, while the surface morphology showed a coarser grain structure with relatively lateral voids. While the corrosion current slightly increased with rising Zn content due to higher PC density, it eventually decreased at higher current densities, likely due to Zn-induced passive film formation.