Corrosion-Electrochemical Behavior of Al-Nano-Al2O3 Metal Matrix Composites in an Aqueous 0.5 M NaCl Solution

The corrosion-electrochemical behavior of aluminum-aluminum nanooxide nanocomposites formed during the direct chemical interaction of molten aluminum with titanium nanooxide in molten alkali metal chlorides is studied at temperatures above 700 degrees C. Aluminum nanooxide crystals in the alpha-Al2O3 modification uniformly distributed over the metal matrix volume are detected by electron microscopy and X-ray diffraction. The corrosion rate in a 0.5 M NaCl solution determined by a gravimetric method decreases by 3-4 times during the transition from the initial aluminum to Al-Al2O3 composites, the character of corrosion changes from pitting to uniform, and the corrosion resistance class increases from 3 (resistant) to 2 (very resistant). This behavior is caused by the formation of a denser single-phase hydroxide coating on the surface of the composite as compared to a two-phase loose coating on aluminum. The corrosion potential does not depend on the introduction of aluminum oxide nanoparticles into the aluminum matrix.