Aplicação de complexos de CuII, NiII, ZnII e NbV com ligantes carboxilatos em banhos de eletrodeposição
Mariana Beatriz dos Reis Silva
Agradecimentos Primeiramente à Deus, por tudo. Ao Prof. Benedito pela orientação, confiança, oportunidade e dedicação dispensada durante este período. À minha irmã Ana, meus sobrinhos Matheus, Pedro e Thiago e ao meu cunhado Sérgio, pelo apoio, incentivo e carinho. Ao Paulo e à Regina Nessralla pelo incentivo, apoio e amizade. Ao IQSC e aos funcionários pelo suporte técnico. À FAPESP pela bolsa concedida A todos que, diretamente ou indiretamente, contribuíram para a realização deste trabalho.
... STRACT Cu(II), Ni(II), Zn(II) and Nb(V) coordination complexes were obtained with acetate, citrate and oxalate ions as ligands (ex-situ complexes) to be applied in electrodeposition baths. The aim is to use these complexes as metal sources without further addition of additives which are the coordinated ligands. As reference study, electroplating baths with sulfate salts of the metal ions in presence of the ligands were investigated in the metal:ligand ratio of 1:5 and 10:1; then, similar coordination complexes can be generate in solution (in-situ complexes). The ex-situ complexes were characterized by elemental analysis, infrared and UV-vis spectroscopies and cyclic voltammetry (in Pt). The electrolyses were performed in 1020 steel as substrate with one or two metal complexes present in the bath. Niobium electroplating baths with 1020 steel previously covered with Cu and/or Zn as substrates were also successfully performed. The deposits were analyzed by scanning electron microscopy (SEM), energy dispersive spectroscopy X-ray (EDS), diffuse reflectance, X-ray diffraction (XRD) and polarization curves (corrosion studies). The bath with 10:1 in-situ complexes provided deposits with poor morphologic aspects in relation to the deposits obtained from bath with 1:5 in-situ and ex-situ complexes. The morphologies of the deposits obtained from bath with the acetate complexes were dendritics and with low adherence. The bath with both citrate-and oxalate-complexes were smoothes, compacts, with good adherence and brightness. Different structural phases were observed in the deposits and the most of them provided protection against corrosion. It was concluded that coordinated ligands influence differently in the electrodeposition processes.