Performance Evaluation Effect of Aluminum Anode on Mild Steel in 0.5M NaCl Solution

Abstract

This study examined the performance of mild steel cathodically protected in 0.5M NaCl environment using aluminum anodes. Mild steel sheet of (40 mm x 20 mm x 1 mm) was used and aluminium plate of (30 mm x 20 mm x 1 mm) were prepared as aluminium anodes. The initial surface preparation was performed with finer grades of emery papers of different grit sizes. They were properly cleaned with acetone, prickled and kept in a desiccators for twenty four hours. The prepared samples were then connected to the direct current via a rectifier at varying applied potential of 3, 4, and 5 V and cathode-anode distance of 5-30 cm regulated between 5-15 minutes. The corrosion properties of the resulting samples were examined in 0.5M NaCl using VERSASTAT 4 potentiostat with linear polarization technique. The structural properties were characterized using scanning electron microscope equipped with an energy dispersive spectrometer. The results showed that the protection of the mild steel in the electrolyte varied with the applied voltages and anode-cathode distance. From the potentiodynamic polarization test, the corrosion rate of the mild steel was 0.003 mm/year and the corrosion potential were-577.844 mV. The results gotten from the cathodic protection experiment showed that at 4 V and a distance of 5cm for 15 mins, the aluminum anode was giving the best protection of 0.005g weight increase. It also showed that at 5 V and 5cm for 5 mins, cathodic disbondment started occurring due to over protection caused by closer cathode-anode distances and over-potential.