Localized corrosion of alpha-brasses (15-20 zinc) in NaCI- solutions studied with local probe techniques

摘要

Brass is a family of Cu-Zn alloys widely used in many areas, especially for marine applications. The exposure to salt water and cycles of dry- and wet periods are common for marine environments. When exposed to ambient atmosphere, alpha-brasses around 20 wt. % zinc or more form immediately a protective layer consisting predominantly of zinc oxide (ZnO), whereas in aggressive solutions, such as those containing sodium chloride (NaCI), the passive layer consists predominantly of copper oxide (CU2O). Corrosion of brasses is commonly known as dealloying of zinc, i.e., dezincification. However, it has been reported that the dissolution of both zinc and copper occurs, although copper is promptly deposited back to the surface, creating a copper rich surface layer.