CONTROLLED METHOD FOR DEPOSITION OF CHROME LAYER OR CHROME ALLOY ON AT LEAST ONE SUBSTRATE Russian patent published in 2022 - IPC C25D3/06 

FIELD: electroplating technology

SUBSTANCE: invention relates to the field of electroplating technology. The method includes the steps of (a) providing an aqueous spinning bath, and the bath contains trivalent chromium ions, bromide ions, alkali metal cations in a total amount of 0 to 1 mol /L based on the total volume of the spinning bath, and the bath has a target pH in the range from 4.1 to 7.0, (b) providing at least one said substrate and at least one anode, (c) immersing at least one said substrate in an aqueous spinning bath and supplying a direct electric current so that a chromium layer or chromium alloy is deposited on the cathode substrate, wherein during or after step (c) the pH of the spinning bath is lower than the target pH, (d) addition of NH₄OH and / or NH₃ during or after step (c) to the spinning bath so that the target pH of the spinning bath is restored, with the average thickness of the chromium or chromium alloy deposited in step (c) being 1 μm or more.

EFFECT: obtaining a chromium layer or a layer of a chromium alloy with an average roughness of less than 0.5 microns, excellent hardness and wear resistance during long-term operation of the spinning bath.

16 cl, 2 dwg, 2 tbl, 2 ex