Psidium guajava Leaves as Corrosion Inhibitor of Al-6061

The anti-corrosion characteristic of the extract of Psidiumguajava leaves on aluminum in 3.5 wt% sodium chloride were examined using electrochemical measurement. The thermodynamic factors such as the free energy adsorption, change in enthalpy, and entropy was also analyzed. The adsorption isotherm was detail described to study the adsorption of the inhibitor on the aluminum surface with various concentrations of the inhibitor. The electrochemical measurement was done through the potentiodynamic polarization test. The results show that the inhibitor act as the mixed type inhibitor and its adsorption on the aluminum surface obeys Temkin adsorption isotherm. The study suggests that the use of Psidium guajava leaves extract for the food industrial application is eco-friendly and safe, especially in salt solution medium.

De-alloying Behavior of Mg–Al alloy in Sulphuric Acid and Acetic Acid Aqueous Solutions

The fabricated Mg–Al alloy consists of α-Mg phase and Mg–Mg17Al12 eutectic phase. The corrosion behavior of cast Mg–Al alloy in sulphuric acid (H2SO4) and acetic acid (HAc) aqueous solutions was investigated. The Mg–Al alloy shows general corrosion in H2SO4 solution, and the α-Mg dendrites revealed a slightly faster corrosion rate than that of the eutectics. In HAc solution, the alloy shows an obvious selective corrosion characteristic, with the α-Mg dendrites being corroded preferentially. Grain orientation plays an important role in corrosion behavior of the alloy in the HAc solutions.