Patent ID: 9689081
Date: 2017-06-27
CPC Classifications: C25D

Claim:
1. An electroplating bath for deposition of a dark chromium layer on a workpiece, the electroplating bath comprising: (A) trivalent chromium ions; (B) carboxylate ions; (C) at least one pH buffer substance; and (D) at least one coloring agent, wherein the at least one coloring agent comprises a coloring agent selected from: 2-Amino-4-methanesulfinyl-butyric acid, 1,1-Dioxo-1,2-dihydro-1lambda*6*-benzo[d]isothiazol-3-one, Prop-2-yne-1-sulfonic acid, Methanesulfinylmethane, and 2-(1,1,3-Trioxo-1,3-dihydro-1lambda*6*-benzo[d]isothiazol-2-yl)-ethanesulfonic acid, and wherein the at least one coloring agent optionally further comprises at least one coloring agent selected from sulphur containing compounds having the general Formula (II): wherein ═X represents ═O, or a free electron pair; R R R r is an integer from 0 to 4 or; R R or salts, tautomeric forms, betaine structures thereof; and (E) ferrous ions.