Corrosion electrochemical behavior of metal matrix composites “Al-nano-Al₂O₃” IN 0.5M NaCl aqueous solution

The corrosion-electrochemical behavior of nanocomposites of the “aluminum-nano-aluminum oxide” system, formed by direct chemical interaction of molten aluminum with titanium nanooxide in an environment of molten alkali metal chlorides at temperatures above 700^оC, has been studied. Nanoalumina crystals in the α-Al₂O₃ modification, uniformly distributed throughout the volume of the metal matrix, were detected by means of electron microscopy and X-ray diffraction. The corrosion rate in 0.5M NaCl, determined by the gravimetric method, decreases by 3–4 times when moving from initial aluminum to Al-Al₂O₃ composites, while the nature of corrosion changes from pitting to uniform and the corrosion resistance class from 3 (resistant) to 2 (very persistent). This is due to the formation of a denser single-phase hydroxide coating on the surface of the composite compared to a two-phase loose coating on aluminum. The corrosion potential is not affected by the incorporation of aluminum oxide nanoparticles into the aluminum matrix.