Potential of Combretum glutinosum leaf extract as corrosion inhibitor for Al-Si-Mg alloy in artificial seawater environment

This study investigates the inhibition potential of Combretum glutinosum leaf extract on the corrosion resistance of Al-7%Si-0.3%Mg (A356) in artificial seawater environment (static), using weight loss and potentiodynamic polarization methods. The corrosion rates were studied at different concentration of Combretum glutinosum, 0.4, 0.8, 1.2, 1.6 and 2.0v/v at room temperature (27oC). The experimental results revealed that Combretum glutinosum in 3.5% NaCl environment reduced the corrosion rates of the alloy at the different concentrations studied. The minimum inhibition efficiency was obtained at 0.4v/v inhibitor concentration with 33.07% after 30 days exposure time. Moreover, the optimum inhibition efficiency was achieved at 1.6v/v concentration with 83.46% after 30 days exposure time. The potentiodynamic polarization results also showed that Combretum glutinosum served as an effective inhibitor for the alloy within the temperature and concentration ranges considered with a maximum of 88.15% inhibition efficiency. The results obtained from weight loss and potentiodynamic polarization methods were in a good agreement. Microstructural observation of the samples revealed the effect of inhibitor on the test samples.Keywords: Al-Si-Mg alloy, corrosion inhibitor, Combretum glutinosum, Potentiodynamic