Estudo de revestimentos metálicos depositados por aspersão térmica contra a corrosão marinha

Abstract

Thermally sprayed metallic coatings for corrosion protection have a wide industrial applicability, because besides offering cathodic protection or by substrate barrier, it is also easily applied on large surfaces. Arc Spraying and Flame Spraying process are commonly used on a large scale in industry, but provide coatings that can exhibit many discontinuities, such as pores, oxides and cracks. In this context, the main objective of this work was to compare the microstructural and electrochemical characteristics of six different anodic coatings of aluminum (Al) and zinc (Zn) deposited on carbon steel substrate, in order to determine its corrosion resistance in synthetic marine water and to select the best coating for industrial scale application.For this, measurements of thickness, hardness, roughness, pore and oxide content, corrosion potential monitoring and anodic potentiodynamic polarization were performed. Thus, Al test samples were produced by the FS and AS processes (process comparison) and Zn test samples by the FS process (materials comparison), by varying the parameter compressed air pressure. The results indicated that the coating that presented the best protection characteristics against corrosion was sprayed zinc by the conventional flame process.