Disclosed is an electrolyte for the electrolytic deposition of chromium as a metal, comprising (a) a chromium (III) salt and (b) metallic chromium, the use of the electrolyte for producing chromium layers on rotationally symmetrical components, in particular gravure printing cylinders, and methods, in which this electrolyte is used.

An object comprising a chromium-based coating on a substrate is disclosed. The chromium is electroplated from an aqueous electroplating bath comprising trivalent chromium cations, wherein the chromium-based coating comprises: a first chromium-containing layer, on the substrate, having a thickness of at least 100 nm, and a Vickers microhardness value of 700-1000 HV; a second chromium-containing layer, on the first chromium-containing layer, having a Vickers microhardness value that is at least 1.3 times higher than the Vickers microhardness value of the first chromium-containing layer, and a crystal size of 8-35 nm; and wherein the chromium-based coating exhibits a critical scratch load value (L.sub.c2) of at least 60 N in the adhesion test according to ASTM C1624-05 (2015; point 11.11.4.4), and wherein the chromium-based coating does not contain chromium carbide. Further is disclosed a method for its production.

Materials and methods for precious metal recovery are disclosed. Usable leaching solutions are preferably aqueous based and include appropriate materials in sufficient quantities to solubilize and stabilize precious metal. Such materials typically include oxidant material. Some or all of the oxidant material can be, in some instances, generated in-situ. The leaching solution is typically contacted with a substrate having a target precious metal, thereby solubilizing precious metal to form a stable, pregnant solution. The precious metal can then be recovered from the pregnant solution. In some instances, components of the leaching solution can be regenerated and reused in subsequent leaching.

The present invention relates to a very specific electroplating bath for depositing a black chromium layer, a respective method thereof, and a respective substrate with said black chromium layer thereon. The substrate comprising said black chromium layer is excellently suited for decorative purposes.

The present invention relates to a very specific electroplating bath for depositing a black chromium layer, a respective method thereof, and a respective substrate with said black chromium layer thereon. The substrate comprising said black chromium layer is excellently suited for decorative purposes.

An object comprising a chromium-based coating on a substrate is disclosed. The chromium is electroplated from an aqueous electroplating bath comprising trivalent chromium cations, wherein the chromium-based coating comprises at least one chromium-containing layer, the chromium-based coating does not contain macrocracks, wherein a macrocrack is a crack that extends from the outer surface of the chromium-based coating, through the chromium-based coating, to the substrate, the chromium-based coating has a Vickers microhardness value of 800-1100 HV, and the chromium-based coating exhibits a critical scratch load value (L.sub.C2) of at least 80 N in the adhesion test according to ASTM C1624-05 (2015; point 11.11.4.4). Further is disclosed a method for its production.

The present invention relates to a method for electrodepositing a dark chromium layer on a substrate and a substrate having at least one side fully covered with a dark chromium layer. The method includes utilizing an aqueous trivalent chromium electroplating bath comprising colloidal particles and a step of treating the substrate with a rinse liquid having a temperature of 50° C. or more.

The present invention relates to a method for electrodepositing a dark chromium layer on a substrate and a substrate having at least one side fully covered with a dark chromium layer. The method includes utilizing an aqueous trivalent chromium electroplating bath comprising colloidal particles and a step of treating the substrate with a rinse liquid having a temperature of 50° C. or more.

An electrolyte solution for chrome plating from trivalent chromium is prepared by dissolving in an aqueous medium a trivalent chromium salt (e.g., chromium (III) chloride or chromium (III) sulfate), dissolving an oxalate compound (e.g., sodium oxalate, potassium oxalate, or oxalic acid), dissolving a metal salt (e.g., aluminum sulfate or aluminum chloride), dissolving an alkali metal sulfate (e.g., sodium sulfate or potassium sulfate), and dissolving an alkali metal halide (e.g., sodium fluoride or potassium fluoride). A substrate is chrome plated from trivalent chromium using the electrolyte solution by passing a current between a cathode and an anode through the electrolyte solution to deposit chromium on the substrate.

An aqueous trivalent chromium electrolyte comprising trivalent chromium ions and amino acids that allow for producing a dark colored hue in the trivalent chromium coating which is plated on a substrate. The amino acids described herein comprise a cationic side chain and are at least essentially free of sulfur. The cationic side chain of the amino acid further comprises nitrogen. When used in the trivalent chromium electrolyte, these amino acids allow for producing significantly darker trivalent chromium deposits. The trivalent chromium electrolyte is used in a method for producing the desired dark colored hue in the trivalent chromium coating that is produced on a substrate using electrodeposition.