Study on the Adsorption Behavior and Pitting Mechanism of Nb and S on the TiN Surface in High-Strength Anti-seismic Rebar

In this study, the corrosion experiments combined with first-principles calculations were used to study the adsorption behavior and pitting corrosion mechanism of Nb and S on the TiN surface. The results of SEM indicated that Nb and S were obviously enriched on the TiN surface, and the enrichment of S was stronger than that of Nb. The results of segregation energy indicated that Nb and S tended to segregate on the surface of Fe (110) and TiN (100), and the segregation of S was stronger than that of Nb. The results of adsorption energy indicated that the vacancy points and top points on the TiN (100) surface were the most stable for Nb and S, respectively, and the adsorption stability of S on the TiN (100) surface was stronger than that of Nb. The results of co-adsorption energy indicated that both Nb and S promoted the mutual adsorption on the TiN (100) surface, the co-adsorption stability of top adsorbed S on the TiN (100) surface with pre-adsorbed Nb was stronger than that of vacancy adsorbed Nb on the TiN (100) surface with pre-adsorbed S, and this co-adsorption effect was effective within a certain distance. These findings will be helpful to understand the pitting corrosion mechanism of rebar matrix induced by TiN.