Abstract
The rotating cylinder electrode (RCE) is one rig constructed and designed to study the behaviour of the material under the effect of flow. The behaviour of hot and cold rolled UNS S32205 duplex stainless steel (DSS) in erosion-corrosion (EC) conditions were studied to monitor the material loss and surface degradation. The impact is highlighted and explained with the aim to offer better understanding regarding degradation phenomena. Mine water solution containing silica sand particles (SiO2) was the environment of interest for this study. Both gravimetric and electrochemical methods (potentiodynamic polarisation (PP) and open circuit potential (OCP)) were adopted for the erosion-corrosion behaviour of the alloys. The cold rolled material displayed better resistance to erosion-corrosion at all speed tested in comparison with hot rolled material. The surface morphology for both materials revealed erosion dominating the erosion-corrosion process with minimal evidence of pitting. The hardness of cold rolled sample showed higher hardness as compared to hot rolled due to the impingement by sand particle hence better resistance to erosion-corrosion. The wear corrosion mechanism displayed grooving on the material surface especially at a higher speed. The effect of particles in wear mechanism play an important role. The electrochemical results showed increasing corrosion rate as the rotating speed of the electrode increased. The higher pH of mine water solution resulted in the passivation of the sample. The analysis trend was not surprising as the vulnerability of the surface layer increased with increasing velocity under the subjected conditions. Aggressive conditions and sand concentration are good enough to prove relation between wear rate and corrosion rate. The environmental impact was not aggressive enough to create much interferences hence the surface deterioration was not severe in all analysis.
M.Ing. (Chemical Engineering Technology)