Surface coverage determination of iron-phosphate coatings on steel using voltammetric anodic dissolution technique

Jovan Popic, Bore Jegdic, Jelena Bajat, Miodrag Mitric, Vesna Miskovic-Stankovic
2013 Journal of the Serbian Chemical Society  
In this study, the effect of deposition time and concentration of NaNO 2 in the phosphate bath on the surface morphology of iron-phosphate coatings on low carbon steel was investigated using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The composition of ironphosphate coatings was determined using energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD), while surface coverage was evaluated by the voltammetric anodic dissolution (VAD) technique in the
more » ... chnique in the borate solution. The addition of NaNO 2 to the phosphate bath significantly increased the surface coverage since better packed crystals of smaller size, which favour the phosphate nucleation, were obtained. It was also shown that prolonged deposition time increased the surface coverage, coating roughness and crystal size in the lateral direction, altering also the crystal shape from large platelets non-uniformly distributed on the steel surface during the initial time to betterpacked laminated and needle-like structures during prolonged exposure.
doi:10.2298/jsc120706096p fatcat:ow5v6quaafgdhorgwapa67ckpi