Investigation of the Effect of MoO42− and Co2+ up on Electroless Ni–Mo–P and Ni–Co–P Alloys in Acidic Solution Using Tyrosine as Stabilizer: Characterization and Electrochemical Study

The deposition rate, composition, morphology, and structure of electroless deposits Ni–Mo–P and Ni–Co–P plated at different concentrations of MoO 4 2 - and Co 2 + from acidic tyrosine baths were conducted in this study. Electrochemical study of electroless Ni–Co–P coating was investigated. The deposition rate and the composition of Ni–Mo–P and Ni–Co–P coatings were determined using gravimetric and EDX method which depends on the corresponding ions concentration in the plating bath. The MoO 4 2 - ion played rather an inhibitor role of electroless Ni–Mo–P coating even at low concentration in the plating bath. SEM was used to analyze the morphology of electroless alloys, whereas XRD was used to investigate the structure evolution. The Ni–P, Ni–Mo–P and Ni–Co–P deposits were characterized by distinct morphology depending on P, Mo and Co content in the coatings, whereas, the structure of each alloy depended only on P and Co contents in Ni–Co–P coating. Either MoO 4 2 - or Co 2 + ions concentration had different effects on the deposition rate, the structure and the quality of electroless Ni–Mo–P and Ni–Co–P deposits.