A method of producing a metal strip coated with a coating, said coating containing chromium metal and chromium oxide and being electrolytically deposited from an electrolyte solution that contains a trivalent chromium compound and at least one salt for increasing conductivity and at least one acid or one base for setting a desired pH value, onto the metal strip by bringing the metal strip into electrolytically effective contact with the electrolyte solution during an electrolysis time. The metal strip is successively passed at a predefined strip travel speed in a strip travel direction through a plurality of electrolysis tanks successively arranged in the strip travel direction. At least the first electrolysis tank, as viewed in the strip travel direction, or a front group of electrolysis tanks is filled with a first electrolyte solution and the last electrolysis tank, as viewed in the strip travel direction, or a rear group of electrolysis tanks is filled with a second electrolyte solution. The second electrolyte solution contains no additional components apart from the trivalent chromium compound as well as the at least one salt and the at least one acid or base and is especially free of organic complexing agents and free of buffering agents.

A method for producing a metal strip coated with a coating that contains 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 efficient deposition of coating with a high proportion of chromium oxide is obtained by successively passing the metal strip through a plurality of electrolysis tanks. The electrolyte solution in at least the last electrolysis tank, as viewed in the strip travel direction, or in a rear group of electrolysis tanks has an average temperature of at most 40° C., and the electrolysis time, during which the metal strip is in electrolytically effective contact with the electrolyte solution in the last electrolysis tank or in the rear group of electrolysis tanks is less than 2.0 seconds.

A method for producing a metal strip coated with a coating that contains 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 efficient deposition of coating with a high proportion of chromium oxide is obtained by successively passing the metal strip through a plurality of electrolysis tanks. The electrolyte solution in at least the last electrolysis tank, as viewed in the strip travel direction, or in a rear group of electrolysis tanks has an average temperature of at most 40° C., and the electrolysis time, during which the metal strip is in electrolytically effective contact with the electrolyte solution in the last electrolysis tank or in the rear group of electrolysis tanks is less than 2.0 seconds.

It is determined whether an imaginary component at a predetermined frequency of an alternating current impedance is equal to or more than a preliminarily set film-formable value or not. The metallic coating is formed in a state where the substrate is pressed by the solid electrolyte membrane when the imaginary component is equal to or more than the film-formable value in the determining. The metallic coating is formed in a state where the pressing of the substrate by the solid electrolyte membrane is released to separate the solid electrolyte membrane from the substrate, the solid electrolyte membrane is re-tensioned with a constant tensile force, and subsequently, the substrate is pressed by the re-tensioned solid electrolyte membrane when the imaginary component is smaller than the film-formable value in the determining.

A belt conveyer 7 includes a metal belt-shaped conveyer main body 9 and a metal clip 8 held on the conveyer main body 9, and clamps an end part on one side of a work 14 by the spring force of the metal clip 8. A roller conveyer 6 includes multiple conveying rollers 10 that rotate in synch with the belt conveyer 7 and supports the work 14 from below where an end part on the other side of the work 14 clamped by the belt conveyer 7 is placed on the plurality of conveying rollers. The work 14 is conveyed in a horizontal position and is subjected to plating, with the end part on the one side of the work 14 clamped by the belt conveyer 7 and end part on the other side of the work 14 placed on the roller conveyer 6.

A belt conveyer 7 includes a metal belt-shaped conveyer main body 9 and a metal clip 8 held on the conveyer main body 9, and clamps an end part on one side of a work 14 by the spring force of the metal clip 8. A roller conveyer 6 includes multiple conveying rollers 10 that rotate in synch with the belt conveyer 7 and supports the work 14 from below where an end part on the other side of the work 14 clamped by the belt conveyer 7 is placed on the plurality of conveying rollers. The work 14 is conveyed in a horizontal position and is subjected to plating, with the end part on the one side of the work 14 clamped by the belt conveyer 7 and end part on the other side of the work 14 placed on the roller conveyer 6.

A plant for immersion treatment of vehicle bodies may include: at least one skid configured to support a body; at least one process liquid tank; and/or a conveyor line configured to convey the at least one skid above the at least one process liquid tank. The at least one skid may include base and support parts. The support part may be supported on the base part using a rotatable shaft, so that the support part is rotatable between a first position, in which the body is not immersed in the at least one process liquid tank, and a second position for immersing the body in the at least one process liquid tank. The at least one skid may include a toothed wheel connected to the rotatable shaft for controlled rotation. The at least one skid may include a controllable locking/unlocking device configured to lock/unlock free rotation of the rotatable shaft.

A plating apparatus includes a plating tank and a plating unit. The plating unit includes a partition wall allowing the plating solution to pass through but not allowing the plating object to pass through, and defines inside thereof a plating object passage through which the plating object passes, an injector which injects the plating solution upward, a mixing portion in which the plating solution and the plating object are mixed, an anode outside the plating object passage, a cathode inside the plating object passage with a hollow region through which a fluid mixture of the plating solution and the plating object passes upward, a first shielding wall which guides the fluid mixture downward, and a second shielding wall outside the first shielding wall. A lower end of the first shielding wall is lower than an upper end of the second shielding wall.

A method of producing a metal strip coated with a coating, said coating containing chromium metal and chromium oxide and being electrolytically deposited from an electrolyte solution that contains a trivalent chromium compound and at least one salt for increasing conductivity and at least one acid or one base for setting a desired pH value, onto the metal strip by bringing the metal strip into electrolytically effective contact with the electrolyte solution during an electrolysis time. The metal strip is successively passed at a predefined strip travel speed in a strip travel direction through a plurality of electrolysis tanks successively arranged in the strip travel direction. At least the first electrolysis tank, as viewed in the strip travel direction, or a front group of electrolysis tanks is filled with a first electrolyte solution and the last electrolysis tank, as viewed in the strip travel direction, or a rear group of electrolysis tanks is filled with a second electrolyte solution. The second electrolyte solution contains no additional components apart from the trivalent chromium compound as well as the at least one salt and the at least one acid or base and is especially free of organic complexing agents and free of buffering agents.

A method of producing a metal strip coated with a coating, said coating containing chromium metal and chromium oxide and being electrolytically deposited from an electrolyte solution that contains a trivalent chromium compound and at least one salt for increasing conductivity and at least one acid or one base for setting a desired pH value, onto the metal strip by bringing the metal strip into electrolytically effective contact with the electrolyte solution during an electrolysis time. The metal strip is successively passed at a predefined strip travel speed in a strip travel direction through a plurality of electrolysis tanks successively arranged in the strip travel direction. At least the first electrolysis tank, as viewed in the strip travel direction, or a front group of electrolysis tanks is filled with a first electrolyte solution and the last electrolysis tank, as viewed in the strip travel direction, or a rear group of electrolysis tanks is filled with a second electrolyte solution. The second electrolyte solution contains no additional components apart from the trivalent chromium compound as well as the at least one salt and the at least one acid or base and is especially free of organic complexing agents and free of buffering agents.