Effect of AlN particles on the corrosion behavior of Al/AlNp composites

The corrosion behavior of Al/AlNP composites has been examined by using potentiodynamic polarization technique in 3.5wt% NaCl solution with the pH value of 5, 8.6, and 11.6 respectively. Electrochemical impedance spectra (EIS) measurements have also been carried out to assess the long-term effects of AlN particles. It has been found that Al/AlNP composites show the increased susceptibility to pitting attack compared with the unreinforced Al, which is attributed to the micro-galvanic action between AlN particles and the matrix Al. The micro-galvanic action mainly arises as a result of hydrolysis of AlN particles. In addition, EIS measurements reveal that the corrosion mechanism of Al/AlNP composites changes a lot with increasing immersion time, which is controlled by diffusion process at last.