Electrodeposition of Ni-Mo and Fe-Mo alloys from sulfate-citrate acid solutions

Abstract

This paper reports on a study of the electrodeposition of Ni-Mo and Fe-Mo alloys on Pt electrodes in a sodium citrate solution at pH 4.0. The alloys were subjected to cyclic voltammetry at different ion concentration ratios to identify their behavior. The electrodeposited coatings were analyzed by SEM, EDX and XRD. The results of the cyclic voltammetry tests indicated the presence of dissolution peaks only with high Ni or Fe ion concentrations. The SEM analysis revealed that the two alloys had dissimilar morphologies and the Ni-Mo alloys were homogeneous and thick. The Mo and O contents were higher in the Ni-Mo than in the Fe-Mo alloys. Anomalous deposition was found to occur in the co-deposition of Ni and Mo.

Characterisation of electrodeposited nanocrystalline Ni?Mo alloys

“…about 200 mV smaller than the potential for which the cathodic current starts to increase (curves 2a and b). This behaviour confirms that the cathodic process starts with hydrogen evolution before the onset of metal deposition [7,13]. We previously showed, through steady-state and impedance investigation, that the deposition of Ni-Mo alloys starts with hydrogen evolution resulting from citrate reduction of the alcohol function, through a mixed oxide layer.…”

“…The electrodeposition of Ni-Mo alloys has been extensively investigated [3][4][5][6][7]. These alloys, such as the commercial alloy Hastelloy B, exhibit exceptional corrosion resistance in highly corrosive media such as nonaerated concentrated hydrochloric solutions [8].…”

“…According to literature and previous investigations, the best complexing agent is sodium citrate together with ammonia [3,7]. The important plating parameters are the ratio of molybdate/nickel species concentrations, the sodium citrate and ammonia (pH) concentrations and the current density.…”

Electrodeposition and Characterization of Alloys and Composite Materials

“…The model of Mo-Ni alloy deposition is described by following reduction reactions [30]: [33]. It was later shown for the Mo-Ni-O powder electrodeposition [34] that this mechanism is only partially correct and that among metallic Ni and Mo, the MoO 3 phase is also deposited. Taking into account that NiO, MoO 3 , and MoNi 4 phases were detected in as-deposited samples by transmission electron microscopy (TEM), it is obvious that the mechanism of alloy deposition similar to the one presented by Eqs.…”

Influência Da Remediação Eletrocinética N0 Aumento Do Ciclo De Vida De Catalisadores Desativados Por Processo FCC

“…Uma vez que o processo de remediação permite a formação de um ciclo de regeneração tanto do catalisador, quanto do resíduo gerado, que é constituído pelos metais removidos do catalisador e o eletrólito suporte. Este resíduo pode após remediação ser direcionado a um segundo reator, de leito particulado (PONTE,1998), onde é feita a recuperação dos metais de forma seletiva por eletrodeposição, uma vez que o citrato de sódio, por ser complexante de V e Ni, favorece tanto o processo de remoção (reator eletrocinético-RE) como de eletrodeposição (reator de leito fluidizado-RLF) (SANCHES et al , 2003).…”