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 MoO42 and Co2+ 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 MoO42- 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 MoO42- or Co2+ ions concentration had different effects on the deposition rate, the structure and the quality of electroless Ni-Mo-P and Ni-Co-P deposits.