Establishing relationships between bath composition and the properties of amorphous Ni–Mo alloys obtained by electrodeposition

Abstract

In this study, the Response Surface Methodology (RSM) was used as an optimization tool along with a complete 3² factorial experimental design with 4 central points to determine the significant factors on the electrodeposition process of Ni-Mo alloys and support establishing relationships between the independent variables and the properties of the coatings. Specifically, the influence of the concentrations of nickel sulfate and sodium molybdate on different electroplating responses was evaluated. The models proposed in this work were validated with experiments performed within the level considered for both entry variables; no experimental combination of any level was considered for this purpose. Coatings with a high Mo percentage and distinct morphologies were produced. XRD diffractograms indicated that they were all amorphous. Variations in nickel sulfate (Ni) and sodium molybdate (Mo) concentrations in the bath produced coatings with different properties. The optimal bath condition found for Mo at% was constituted by a Ni:Mo concentration ratio of 7.5:5, producing a film with 29 at% of Mo. The optimal Ni:Mo for CE% and Rp was 10:3; highest CE% and Rp were 47% and 19,314 Ω/cm², respectively. The films produced in this work can be applied as anticorrosive coatings