Study on the electrochemical behavior and fluoride film formation of high-purity 70/30 copper–zinc alloy in NaF solution

Abstract

The threshold concentrations of Cu²⁺ and Zn²⁺ required for the formation of fluoride-containing corrosion product films on copper-zinc alloy are calculated using the dissolution-ionization-diffusion-deposition model of the Cu-Zn-F system proposed in this work. Based on the model, the mechanism underlying dezincification of copper-zinc alloy and negligible formation of metallic fluoride on surface, even in saturated NaF solution, is explained. Furthermore, fluoride-containing films are successfully fabricated on the alloy surface with the addition of certain concentration of Cu²⁺ and Zn²⁺, as calculated from the model. This work provides a promising approach for designing the corrosion product film via immersion.