Improving Adhesion at the Alumina/Zinc Interface by Stainless Steel Buffers

Abstract

The weak interaction between zinc and alumina is responsible for a poor performance of anticorrosive galvanic zinc coatings on modern advanced high strength steels. In this context, we report a theoretical study on the effect of realistic multicomponent metal buffers on the adhesion strength of a model α-alumina(0001)|zinc interface. Relying on results of ab initio calculations on relevant individual oxide|oxide, oxide|metal, and metal|metal interfaces (separation and interface energies), we determine by Monte Carlo simulations the thermodynamically preferred sequence of components in a multicomponent buffer, as a function of buffer composition and oxygen conditions. We find that stainless steel buffers considerably enhance the overall strength of the alumina|zinc interface. Most importantly, we show that a partial oxidation of multicomponent buffers, which is unavoidable under realistic conditions, does not degrade their performance. This advantageous property relies on the separation of metal and oxide components in the buffer and on the resulting suppression of weakly interacting oxide|zinc and moderately strong alumina|metal interfaces. More generally, owing to the possibility of selective oxidation and component segregation, multicomponent buffers appear as promising solutions for adhesion improvement at weakly interacting metal|oxide interfaces.