Aplicação da nitretação a plasma na redução da corrosão em pinos anódicos de cubas eletrolíticas de produção de alumínio

Abstract

The anodic stubs low carbon steel are constituent parts of Soderberg anodes of the electrolytic cells , which are used in the production of primary aluminum , acting as an element of mechanical support of the anode block and as a conductor of continuous electric current between the electrolytic cells , which interconnected form a direct current circuit in series . The wear caused by corrosion is the main parameter to determine its end of life which modifying its geometry, impacts on increasing electric losses at the anode. The plasma nitriding process is a surface treatment widely used for improving the fatigue, wear and corrosion resistance of the steels. This study is the characterization of an anodic stub post-working regime, without surface treatment and plasma nitriding with and without post-oxidation applied to new anodic stub through techniques of optical and scanning electron microscopy (SEM), hardness and X-ray diffraction, as well as the study of the effect of nitriding with and without post-oxidation in reducing corrosion of the anodic stub during labor by dimensional analysis. The results show the change in microstructure of the steel stub during labor regime and potential reduction in wear rate in treated stubs, especially for the nitriding stub with post-oxidation.