Efeitos da deposição de revestimentos de nióbio na taxa de corrosão do aço DOMEX 700

Abstract

DOMEX 700 is a high strength, low-alloy steel used in structural design, heavy machinery and agricultural machinery. The corrosion resistance of these steels has been the subject of research in order to allow its use in corrosive environments. In this work, Plasma Magnetron Sputtering was employed to deposit niobium coatings using argon, oxygen and nitrogen as working gas, and later remelted in the process of autogenous TIG welding on the sample with O2 working gas. The effects on the corrosion rate were analyzed in H2SO4 0,1 M solution, because its influence on the corrosion resistance of niobium has already been demonstrated, as well as the formation of stable niobium oxides in aqueous solution, by measuring the open circuit potential and carrying out the polarization techniques. The corrosion rate was determined for the base metal and the coated samples. The results indicated that the niobium coatings reduced the protection rate of DOMEX 700 steel by at least 82%, however there was a dilution of the coatings after polarization. The coating with subsequent remelting reduced by 98% and indicated promising results to improve the adhesion of coatings to allow a possible industrial application.