This relates to a process for manufacturing a recovery annealed coated steel substrate for packaging applications and a packaging steel product produced thereby.

The present invention is to provide a chrome-plated part having a corrosion resistance in normal and specific circumstances and not requiring additional treatments after chrome plating, and to provide a manufacturing method of such a chrome-plated part. The chrome-plated part 1 includes: a substrate 2; a bright nickel plating layer 5b formed over the substrate 2; a noble potential nickel plating layer 5a formed on the bright nickel plating layer 5b. An electric potential difference between the bright nickel plating layer 5b and the noble potential nickel plating layer 5a is within a range from 40 mV to 150 mV. The chrome-plated part 1 further includes: a trivalent chrome plating layer 6 formed on the noble potential nickel plating layer 5a and having at least any one of a microporous structure and a microcrack structure.

The invention consists of a chromium electroplating solution comprising a chromium electroplating solution comprising: (1) a water soluble trivalent chromium salt; (2) at least one complexant for trivalent chromium ions; (3) a source of hydrogen ions sufficient to create a pH of from 2.8-4.2; (4) a pH buffering compound; and (5) a sulfur-containing organic compound. The chromium electroplating solution is usable in a method for producing an adherent metallic coating on a decorative article, such coating having enhanced resistance to corrosion in environments containing calcium chloride.

The invention consists of a chromium electroplating solution comprising a chromium electroplating solution comprising: (1) a water soluble trivalent chromium salt; (2) at least one complexant for trivalent chromium ions; (3) a source of hydrogen ions sufficient to create a pH of from 2.8-4.2; (4) a pH buffering compound; and (5) a sulfur-containing organic compound. The chromium electroplating solution is usable in a method for producing an adherent metallic coating on a decorative article, such coating having enhanced resistance to corrosion in environments containing calcium chloride.

A method of adjusting and controlling the color of trivalent chromium deposits is provided. The method includes the steps of: (a) measuring the color of a trivalent chromium deposit standard; (b) adding one or more color enhancing additives to a trivalent chromium electrolyte; (c) contacting the substrate with the trivalent chromium electrolyte containing the one or more color enhancing additives to deposit trivalent chromium on the substrate; (d) measuring the color of the color-enhanced trivalent chromium deposit; (e) comparing the color of the color-enhanced chromium deposit to that of the standard; and (f) if necessary, adjusting the amount of the one or more color enhancing additives added to the trivalent chromium electrolyte if the color of the color-enhanced chromium deposit is outside of a desired optical variation from that of the standard color-enhanced chromium deposit. The color of the trivalent chromium deposit may be measured using a spectrophotometer.

A method of adjusting and controlling the color of trivalent chromium deposits is provided. The method includes the steps of: (a) measuring the color of a trivalent chromium deposit standard; (b) adding one or more color enhancing additives to a trivalent chromium electrolyte; (c) contacting the substrate with the trivalent chromium electrolyte containing the one or more color enhancing additives to deposit trivalent chromium on the substrate; (d) measuring the color of the color-enhanced trivalent chromium deposit; (e) comparing the color of the color-enhanced chromium deposit to that of the standard; and (f) if necessary, adjusting the amount of the one or more color enhancing additives added to the trivalent chromium electrolyte if the color of the color-enhanced chromium deposit is outside of a desired optical variation from that of the standard color-enhanced chromium deposit. The color of the trivalent chromium deposit may be measured using a spectrophotometer.

A method for the production of a metal strip coated with a coating. The coating containing chromium metal and chromium oxide and is electrolytically deposited from an electrolyte solution that contains a trivalent chromium compound onto the metal strip by bringing the metal strip, which is connected as the cathode, into contact with the electrolyte solution. An effective deposition of the coating with a high chromium oxide portion is achieved by successively passing the metal strip at a predefined strip travel speed through a plurality of electrolysis tanks arranged successively in a strip travel direction. The first electrolysis tank is set to a low current density; a second electrolysis tank, which follows in the strip travel direction, is set to a medium current density; and a last electrolysis tank is set to a high current density, where the low current density is greater than 20 A/dm.sup.2.

A method for the production of a metal strip coated with a coating. The coating containing chromium metal and chromium oxide and is electrolytically deposited from an electrolyte solution that contains a trivalent chromium compound onto the metal strip by bringing the metal strip, which is connected as the cathode, into contact with the electrolyte solution. An effective deposition of the coating with a high chromium oxide portion is achieved by successively passing the metal strip at a predefined strip travel speed through a plurality of electrolysis tanks arranged successively in a strip travel direction. The first electrolysis tank is set to a low current density; a second electrolysis tank, which follows in the strip travel direction, is set to a medium current density; and a last electrolysis tank is set to a high current density, where the low current density is greater than 20 A/dm.sup.2.

A method for galvanic application of a surface coating, in particular a chromium coating, to a body, for example a machine component. Before the galvanic application of the surface coating, a layer of a compound that can be oxidized by an electrolyte solution that is used, preferably a polyhydroxy compound with a viscosity of at least 1000 mPas at 25° C., is applied to the body. A method for galvanic application of a surface coating, in particular a chromium coating, to a body, for example a machine component, wherein the surface coating is carried out in a closed reactor in an at least two-stage, preferably three-stage process, is also disclosed. An electrolyte solution contained in the reactor at a temperature T1 for carrying out a subsequent process stage is substituted by an electrolyte solution at a temperature T2≠T1. A device for carrying out this method is also disclosed.

A method for galvanic application of a surface coating, in particular a chromium coating, to a body, for example a machine component. Before the galvanic application of the surface coating, a layer of a compound that can be oxidized by an electrolyte solution that is used, preferably a polyhydroxy compound with a viscosity of at least 1000 mPas at 25° C., is applied to the body. A method for galvanic application of a surface coating, in particular a chromium coating, to a body, for example a machine component, wherein the surface coating is carried out in a closed reactor in an at least two-stage, preferably three-stage process, is also disclosed. An electrolyte solution contained in the reactor at a temperature T1 for carrying out a subsequent process stage is substituted by an electrolyte solution at a temperature T2≠T1. A device for carrying out this method is also disclosed.