Role of Ni addition in Corrosion Behavior of Model Interface between Rust Layer and Steel Matrix on Weathering Steel

摘要

In order to clarify the improvement mechanism of corrosion resistance for Ni-containing weathering steels, the pH of electrolyte permeating through rust layers formed by the cyclic corrosion test was measured. In addition, a model interface between rust layers and steel matrix was fabricated, and the corrosion behavior of steels under rust layers during the cyclic corrosion test was analyzed. The pH of electrolytes permeating through rust layers increased and the Cl~- concentration decreased by Ni addition to the weathering steels. This is one of the reasons that Ni-containing weathering steels have a higher corrosion resistance than conventional weathering steels. Ni addition induced the formation of Fe_3O_4 at the interface between rust layer and steel matrix. It appears that the formation of Fe_3O_4 increases the pH of electrolyte permeating through rust layers.