ENHANCED TECHNIQUE FOR PRODUCTION OF GOLDEN BRONZE BY INTER-DIFFUSION OF TIN AND COPPER UNDER CONTROLLED CONDITIONS Russian patent published in 2018 - IPC C25D5/10 C25D5/50 C25D7/06 B32B15/01 A44C21/00 

FIELD: electrolytic methods.

SUBSTANCE: invention relates to methods for producing a metal article with an outer bronze layer having the appearance of golden or red bronze and can be used for making coins. Multilayer substrate is provided, comprising a core having an outer contact surface, a copper layer electrolytically applied to the outer contact surface of the core, a tin layer electrolytically applied to the copper layer, and an upper metal layer electrolytically applied to the tin layer and containing copper and / or zinc, and annealing the multilayer substrate to enable the diffusion of the tin layer into the copper layer and the upper metal layer and obtaining an annealed substrate containing a bronze outer layer formed as a result of inter-diffusion, having the appearance of golden bronze with tin content between 8-15 wt%. Outer contact surface of the core is made without nickel to prevent formation of tin and nickel containing intermetallic compounds near the outer contact surface during annealing. Thickness of the upper metal layer is 0.1-4 mcm in accordance with the thickness of the copper layer and the thickness of the tin layer to prevent tin droplets from forming during the annealing process as a result of inter-diffusion of the outer layer of bronze.

EFFECT: enabling production of improved articles having a decorative coating of bronze, having a yellow-golden colour, similar to a gold or red colour.

48 cl, 21 dwg, 4 ex