Chromium-Free Ti/Zr Passivation for Metal Surfaces

The patent removes chromium compounds from the anticorrosion treatment formulation entirely, extracting the harmful substance while maintaining the protective function through alternative active ingredients (fluoro complexes of titanium, zirconium, hafnium, silicon, and boron combined with metal cations), thereby eliminating toxicological hazards while preserving corrosion protection

The patent combines multiple components into a single aqueous formulation: fluoro complexes of metal elements (titanium, zirconium, hafnium, silicon, boron) with specific metal cations (cobalt, magnesium, zinc, nickel, tin, iron, aluminum, copper) in controlled ratios, creating a synergistic chromium-free system that achieves effective corrosion protection without toxicological hazards

The patent optimizes the fluoride-to-metal molar ratio parameter within a specific range (1:1 to 1:6) to balance complexation capacity and passivation effectiveness. By controlling this critical parameter, the formulation achieves adequate complexation of metal ions while maintaining sufficient free fluoride for effective passivation of the metal surface, resolving the contradiction between increased fluoride content and passivation effectiveness

The patent creates a dynamic equilibrium in the aqueous formulation where fluoride ions continuously complex with metal cations while simultaneously providing passivation at the metal surface. The controlled molar ratio allows the system to dynamically balance between forming stable complexes and maintaining active passivating species, ensuring both complexation capacity and passivation effectiveness coexist