Effect of hydrolysis of AlN particulates on the corrosion behavior of Al/AlNp composites

The effect of hydrolysis of AlN particulates on corrosion behavior of Al/AlNp composites immersed in NaOH ethanol solution with the water content of 0-90 vol.% has been analyzed with potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Polarization curves revealed that both the anodic and the cathodic reaction contribute to the corrosion process of Al/AlNp composites, in which hydrolysis of AlN particulates increases the susceptibility of the composites to pit initiation and breakdown of surface film. The impedance spectrum of the composites is found to consist of two capacitive loops, which are well analyzed by the proposed circuit model. Two capacitive loops are correspondent with the anodic and the cathodic reaction, respectively. Based on the comparison among the parameters values for the circuit model, it is believed that hydrolysis of AlN particles affects corrosion behavior of Al/AlNp composites by accelerating both the anodic and the cathodic reaction.