METHOD FOR MAKING COATINGS ON SURFACES OF INTERNAL CAVITIES OF PRODUCTS FROM ALLOYS OF VALVE GROUP METALS Russian patent published in 2023 - IPC C25D11/02 C25D11/18 

FIELD: mechanical engineering.

SUBSTANCE: method includes electrolytic oxidation inside the cavities with a duration of 30-60 min with the flow of electrolyte solutions through them and changing the direction of their flow to the opposite after half the treatment time, whereas before oxidation, an elastic compressible compensator is installed in the cavity of the product and the electrolyte is frozen, then by heating the walls of the product the frozen electrolyte near them is partially defrosted, further oxidation is carried out with the electrolyte flowing in the gaps between the surfaces of the cavity and the ice of the frozen electrolyte when fresh electrolyte is pumped into the cavity through the counter electrode during the first half of the oxidation duration and the spent electrolyte is pumped out of the cavity through the counter electrode during the second half of the oxidation duration at an average temperature of the solution flowing into the cavity, 2-5°C and its consumption of 0.1-2.0 l per minute per 1 dm² of the cavity surfaces, and after oxidation, the coatings obtained as a result of it are filled by boiling distilled water in the cavity for 40-60 minutes, filling the cavity halfway and resetting the product once so that the surfaces of the cavity are exposed to water and steam for 50% of the boiling time.

EFFECT: obtaining high-quality coatings, in which the ratio of the minimum and maximum values of thickness and breakdown voltage within one product is at least 0.85.

1 cl, 2 tbl, 4 dwg, 2 ex