First-Principles Study on the Effect of Pure and Oxidized Transition-Metal Buffers on Adhesion at the Alumina/Zinc Interface

In view of improving the performance of anticorrosive zinc coatings, we report a first-principles density functional theory study on the effect of a metal buffer on the adhesion characteristics at the weakly interacting alumina/zinc interface. With results obtained for metals across the first-transition series (M = Cr, Fe, Ni) we show that such buffers may enhance considerably the interface strength, the effect being particularly well pronounced for Cr. Moreover, relying on a series of model MO x oxide buffers (x = 1, 3/2, 2), we demonstrate that buffer oxidation is in most cases detrimental to adhesion. Systematic analysis of the interfacial bonds enables one to ascribe the predicted beneficial effect of metallic buffers to the formation of strong interfacial metal–oxygen and metal–zinc bonds. Reduction of the number of such bonds upon buffer oxidation drives the decrease of interface adhesion. If the oxidation of buffers composed of more reactive metals cannot be avoided, late-transition elements may be more promising candidates for practical applications.