METHOD FOR GRADIENT COLOURING OF FULL SURFACE OF ARTICLE MADE FROM ALLOYS OF TITANIUM, TANTALUM, ZIRCONIUM, NIOBIUM, HAFNIUM, TUNGSTEN OR PART THEREOF Russian patent published in 2024 - IPC C25D11/02 

FIELD: electrochemistry.

SUBSTANCE: method involves creating graphs 1, 2 of the dependence of experimentally detected current density values on voltage for the formation of a preliminary oxide film and a gradient coating, degreasing the article, formation of a preliminary single-colour oxide film by anodizing in a potentiostatic mode with a colour corresponding to the minimum voltage U_min used to create a colour gradient, as well as current density selected according to graph 1 relative to supplied voltage U_min, and then held until current density drops to 0.1 A/dm², gradient coating is formed by smooth dipping into electrolyte with simultaneous reduction of voltage value from highest U_max to lowest value in gradient U_min at current density selected according to graph 2 relative to voltage corresponding to colour created at highest voltage in gradient U_max, wherein it is first necessary to immerse and anodize a section of the article, which must be coated with a colour corresponding to the highest voltage in the gradient U_max, and further dipping and voltage change occur at current density drop to 0.2–0.3 A/dm².

EFFECT: obtaining an interference gradient film characterized by high quality due to elimination of defects caused by non-uniform distribution of current density (j), its too high or low value, overheating of the anode and electrolyte with increase in the voltage value, abrupt immersion of the anode into the electrolyte.

1 cl, 2 dwg, 1 tbl