Preparation and protection study of silver coating on copper wave tube

Purpose In marine environments, sulfurized silver-coated copper-based waveguides often suffer from severe galvanic corrosion due to local defects, which seriously affects the functionality of the waveguide. To prevent the waveguide from corrosion, this work prepared a silver coating on copper substrate using cyanide free electroplating technology, sequencely treated the coating by benzotriazole (BTA), methylbenzotriazole (TTA) and their BTA-TTA composite corrosion inhibitor system to substitute traditional silver plating sulfurization treatment. This study aims to achieve high corrosion resistance while maintaining communication performance through the application of a chromium-free passivation treatment to copper waveguides. Design/methodology/approach Current-time curves, X-ray diffraction patterns, Raman patterns, scanning electron microscopy, potentiodynamic polarization curves and AC impedance spectroscopy were used to evaluate the protection effect, which was further elucidated by density functional theory. Findings The results show that hydrophobic methyl group of TTA enhances the barrier properties of the film, while BTA provides more film-forming sites. Together, they constitute a multi-layer cross-linked composite film structure, thus achieving long-lasting anti-corrosion and anti-discoloration properties. Research limitations/implications Under this synergistic mechanism, the micro-pores on the surface of the coating can be covered by the inhibitor, which can greatly reduce the effect of galvanic corrosion on the coating. Originality/value Based on the mechanistic analysis of corrosion inhibitor adsorption on silver-plated copper layers, this paper provides important research insights for the industrial protection of waveguide components in deep-sea environments.