OBTENÇÃO E CARACTERIZAÇÃO DE REVESTIMENTO A BASE DE NIÓBIO APLICADO EM AÇO CARBONO (SAE 1020)

Abstract

The constant search for materials that are increasingly resistant and long lasting against corrosion is well known. The mechanical problems and consequent economic losses caused by corrosive processes in various industrial sectors bring to light the need for investment in metal surface treatment methods. Carbon steel is a widely used metal in industries; however, it has a low corrosion resistance and goes through surface treatment processes before it is used. One of the most used process for increasing the corrosion resistance of carbon steel is phosphorylation, but the sludge resulting from this technique is damaging to the environment because it is extremely toxic. There are studies to find processes and materials that protect metals from corrosion and that are environmentally friendly. Niobium is an abundant metal in the Brazilian territory, and has been gaining space in research as a protector against corrosion, since it is extremely resistant. The goal of this study was to produce a niobium-based coating to be used in corrosion protection of carbon steel (SAE 1020) by varying the reactants and its molar ratio The coatings was produced by using the Pechini method with niobium and ammonium oxalate as a precursor of niobium and they were manually applied to the substrate with a 15 minute immersion period and a 5 minute run time. Subsequently, they were thermally treated in an oven at 450 ° C for about 1 hour. The coated plates were characterized using electrochemical and non-electrochemical techniques. The results of open circuit potential, electrochemical impedance spectroscopy and cathodic potentiodynamic polarization have shown resistance to corrosion of the base metal. The X-ray diffraction (XRD), scanning electron microscopy (SEM) and dispersive energy spectroscopy (DES) results have showed that the coating formed is homogeneous and has no defects such as cracks and bubbles in its structure.