Effect of pH on anomalous co-deposition and current efficiency during electrodeposition of Ni-Zn-P alloys

Cu/Ni/Au multilayers by electrochemistry: A crucial system in electronics - A critical review

“…those that can be deposited individually and those that can be only codeposited. The former group consists of metals that are much nobler than Ni, like Ag [54][55][56][57] and Cu [58][59][60][61][62][63][64][65][66][67][68]; metals that have similar standard potentials, such as Co [69][70][71][72][73][74][75][76] and Sn [77][78][79][80][81][82][83][84][85]; and metals that are more cathodic, like Cr [86,87], Zn [88][89][90][91][92][93][94][95][96][97][98][99][100] and Mn [101]…”

“…To avoid this precipitation, sodium citrate and ammonium chloride are usually added to the deposition bath[90]. Deposition of Ni-Zn alloys is possible in both acidic[91][92][93]96] and basic[89,90] baths. The anomalous deposition of Zn and Ni ions is reported to happen in baths with pH below 9[90].…”

“…Deposition of Ni-Zn alloys is possible in both acidic[91][92][93]96] and basic[89,90] baths. The anomalous deposition of Zn and Ni ions is reported to happen in baths with pH below 9[90]. The addition of Zn into the Ni bath hinders the reduction of Ni and its co-deposition (more than 7 wt.%) in the fcc structure of Ni highly decreases the coating's grain size[92].The pH of the bath has important effects on the composite and morphology of the deposits.…”

“…The addition of Zn into the Ni bath hinders the reduction of Ni and its co-deposition (more than 7 wt.%) in the fcc structure of Ni highly decreases the coating's grain size[92].The pH of the bath has important effects on the composite and morphology of the deposits. For example, increasing the pH from 8 to 11 increased the deposition of Ni, hence decreased the co-deposition content of Zn, changed the dark deposits to shiny ones, shifted the corrosion potential to more anodic values, and decreased the corrosion current density[90]. Moreover, flower-like, spherical, and dendritic morphologies are obtained depending on the pH of the deposition bath[94].…”

“…Moreover, flower-like, spherical, and dendritic morphologies are obtained depending on the pH of the deposition bath[94]. However, Ni-Zn coatings usually present a cracked surface due to the inclusion of the hcp Zn into the fcc Ni[90,91]. They have also a lower corrosion resistance compared to Ni films due to the formation of corrosion cells between Zn and Ni[97].…”