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

FIELD: electrochemistry.

SUBSTANCE: invention relates to electrochemistry and specifically to a method of producing a decorative gradient coating. To obtain a coloured gradient coating with more than two colour transitions for each created colour, the voltage region of the created gradient U_start, U_end and calculating the stress of the defect area of the gradient — colour skip areas U_def1, U_def2 according to the formula U_def1,2=(U_end – U_start)/k, where U_start is lowest voltage used when creating gradient at initial stage of anodizing, U_end is highest voltage used when creating gradient at final stage of anodizing, U_def1 is lowest voltage at which a defect area in the gradient is observed, U_def2 is highest voltage at which a defect area in the gradient is observed, k is coefficient used to calculate the skip area — defect for gradients with colour transitions more than two times k=1;1.3, then the product is degreased, a preliminary oxide film is formed, created by anodizing at the initial stage of forming a gradient at voltage U_start, and the decorative coloured gradient coating is obtained by anodizing, which is carried out by smoothly removing the article from the electrolyte with simultaneous increase in the voltage value, at that, when U_def1 is reached and up to U_def2, holding the created colour until the current density drops to 0.1 A/dm² and changing the level of immersion of the article in the electrolyte, and after reaching U_def2, the previous holding parameters are used and the article is gradually removed from the electrolyte.

EFFECT: obtaining gradient interference films with and without colour skipping, characterized by high quality of porous oxide due to elimination of defects.

1 cl, 2 dwg, 2 tbl, 1 ex