A hybrid coating of organometallic complex with a silane coupling compound to protect galvannealed (GA) steel from white rust without sacrificing weldability

Abstract

A unique organic-metallic hybrid coating has been formulated to impede white rust formation on galvannealed (GA) steel strips without hindering weldability. With an optimal concentration ratio of methacrylate silane coupling agent to a titanium (IV) lactate metal complex on the surface of zinc were creating of a network-type nanostructure. Controlling the dry film thickness and curing at 120 °C for 60 s with a chemical roll coater produced a thin film coating (<∼2 μm). Spectroscopic instruments like scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), dynamic contact resistance measurement, and electrochemical impedance spectroscopy (EIS) were used to investigate the coating's surface microstructure, interfacial bonding, anticorrosion, and electrical conductivity characteristics for weldability. The welding properties were tested using the AWS D8.9 standard, and the material was subjected to a simulated salt spray test under ASTM B117 to evaluate anti-corrosion (white rust formation). It was observed that ‘Silane’ to ‘Titania complex’ at a ratio of 0.02 in the formulation was providing excellent performance in terms of anti-corrosion and weldability. This coating has the potential to replace the traditionally used harmful chromate passivation coating over zinc and zinc alloy surfaces in the entire steel industries.