METHOD FOR SINGLE TONE COLORING OF PRODUCT(S) FROM TITANIUM, TANTALUM, NIOBIUM, HAFNIUM, TUNGSTEN ALLOYS Russian patent published in 2023 - IPC C25D11/22 

FIELD: electroplating.

SUBSTANCE: invention can be used to obtain a monotonous oxide film on the surface of products by anodizing. The method includes formation of an anodic oxide film by electrochemical method, while determining the dependence of the current density on the voltage value, drawing up a graph calculated and applicable to the complete coverage of the surface of the product by dipping and anodizing first the first part of the product, then the second part of the product not covered with a film, while the minimum distance between the fastening of the anode terminal with the product and the part of the product immersed in the electrolyte must be at least 5 mm, and for coatings formed at a final colour-forming voltage value from 51 V to 120 V, a preliminary oxide film is applied, which is formed at a lower voltage value, at the final colour-forming voltage from 51 V to 75 V, the difference between the two voltages is 15 V, from 76 V to 95 V, the difference is 25 V, from 96 V to 120 V, the difference is 40 V, and the current density is selected in according to the voltage on the graph, which corresponds to the desired colour.

EFFECT: invention provides controlled uniform formation of a decorative coating, characterized by colour saturation and purity on the entire surface of the product(s); the method reduces the probability of defects, such as uneven structure of porous oxide cells, colour smudges, arson, embrittlement, in particular colour smudges ascending to the anode terminal at the air-electrolyte interface.

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