Effect of Varying Cathode–Anode Parameters on Performance of Mild Steel Cathodically Protected by the Aluminum Anode in 0.5 m NaCl Environment

This work investigates the effect of varying cathode–anode parameters on the performance of mild steel cathodically protected by the aluminum anode in 0.5 M NaCl environment. The study aimed to assess the corrosion protection efficacy of the cathodic protection system and identify optimal parameters for maximizing protection while minimizing energy consumption. Impressed current system was employed to drive the aluminum electrons from the anode to the cathode to achieve cathodic protection of the mild steel cathode. Using Optical Electron Microscope, Scanning Electron Microscope with an electron diffraction spectrometer, and X-ray diffraction, the cathodically treated mild steel samples were characterized. The rate of mild steel corrosion was determined by adopting the potentiodynamic polarization method together with the weight loss method in a 0.5 M NaCl environment. Certain parameters including the working voltage, exposure time and electrode separation distance were also used to analyze the optimal features of the cathodic protection during the experiment. The findings demonstrated that, across the distances and exposure times, an aluminum anode operating at working voltages of 3 and 4 V in a 0.5 M NaCl environment provided sacrificial protection for the mild steel (cathode). The working voltage of 4 V yielded the best cathodic protection in 0.5 M NaCl at 5 cm for 15 min. Furthermore, at a working voltage of 5 V, efficient protection of the mild steel was achieved only at electrodes separation distances above 15 cm, while overprotection of the cathode which could possibly cause cathodic disbondment was observed at electrodes separation distances of 5 cm, 10 cm and 15 cm. The results of this experiment have practical implications for the development and improvement of cathodic protection systems for mild steel structures in environments with high levels of chloride. This highlights the significance of considering cathode–anode parameters to effectively reduce corrosion and ensure the long-term structural stability in the maritime industry and sub-sea operations.