New Insights on the Water-Oxygen Corrosion Behavior and Mechanism of ZrB2: DFT/AIMD Calculations and Experimental Analysis

Abstract

ZrB2 is considered the most promising antioxidant material in the aerospace and nuclear energy fields. However, the research on the mechanism of water-oxygen corrosion at the atomic scale is still insufficient, which may limit its practical application. In this work, the adsorption mechanism and co-adsorption behavior of O2 and H2O on ZrB2(0001) surface were studied by density functional theory (DFT) calculations. The adsorption energy and electronic structure indicated that the adsorption of O2 on ZrB2(0001) surface is stronger than that of H2O. The co-adsorption results showed that the O atoms adsorbed on the surface can promote the spontaneous dissociation of H2O, generating OH groups or H2 on the surface. The Ab initio molecular dynamics (AIMD) calculations further revealed the dynamic interaction mechanism of H2O/O2 co-adsorption on the surface. The results showed that the hydrogen bond interaction promotes the dissociation of H2O, generating Zr-O bonds, Zr-H bonds, and OH groups. Hydrogen bond interaction drives the H atom transfer behavior in H2O, accompanied by the generation of new H2O and H2 on the surface. Finally, the water-oxygen corrosion experiment of ZrB2 was carried out. The results indicated that water vapor may promote the oxidation and hydrogenation corrosion of ZrB2 by destroying the protective oxide scale. The generation of H2 was detected in the corrosion products. This work not only helps to understand the oxidation and hydrogenation mechanisms of ZrB2 under the coexistence of H2O/O2, but also provides an important theoretical basis for the safety protection of ZrB2.

Keywords: ZrB2, Surface, Density functional theory, Ab initio calculation, Hydrogen release