Abstract: A piston ring for internal combustion engines is provided, having a surface comprising a wear protection layer of iron or an iron alloy applied to the surface, wherein the wear protection layer has cracks and the cracks have an average density of 10-160 cracks per mm of the wear protection layer, wherein the iron or iron alloy have incorporated therein 0.2-15% by weight, based on the total weight of the wear protection layer, of carbon particles and 0.2-15% by weight, based on the total weight of the wear protection layer, of solid particles other than carbon particles. Furthermore, a method for manufacturing a piston ring is provided.

Abstract: A coated piston ring having a base body of chromium steel with more than 10 wt.-% chromium and having an inner circumferential surface, a first flank surface, a second flank surface and an outer circumferential surface. The first flank surface comprises a nitride diffusion layer with a layer thickness of from 5-300 ?m, a nitride connecting layer with a layer thickness of from 0.5-15 ?m on the nitride diffusion layer, and an oxide layer with a layer thickness of from 0.05-3 ?m on the nitride connecting layer. The second flank surface comprises the nitride diffusion layer, and the outer circumferential surface comprises the nitride diffusion layer and a chromium solid particle layer with 0.1-30 vol.-% solid particles, relative to the total volume of the chromium solid particle layer on the nitride diffusion layer.

Abstract: The present invention relates to an apparatus with a structured hard chrome layer electrodeposited onto a work-piece, the structured hard chrome layer being cup-shaped and/or labyrinth-like and/or column-shaped. The structured hard chrome layer can be electrodeposited from an electrolyte onto the work-piece, said electrolyte containing (a) a Cr (VI) compound in an amount corresponding to 50 g/l to 600 g/l of chromic acid anhydride; (b) 0.5 g/l to 10 g/l of sulphuric acid; (c) 1 g/l to 20 g/l of aliphatic sulphonic acid, comprising 1 to 6 carbon atoms; and (d) 10 g/l to 200 g/l of at least one compound forming a dense cathode film, said compound being selected from among ammonium molybdate, alkali molybdate and alkaline earth molybdate, ammonium vanadate, alkali vanadate and alkaline earth vanadate, ammonium zirconate, alkali zirconate and alkaline earth zirconate.

Abstract: A method for producing a structured hard chromium layer, during which chromium from an electrolyte is deposited onto a workpiece, which contains: a) a Cr(VI) compound in a quantity corresponding to between 50 and 300 g/l of chromic anhydride; b) 0.5 g/l to 10 g/l sulfuric acid, and; c) 5 g/l to 15 g/l aliphatic sulfonic acid having 1 to 6 carbon atoms. The electrolyte comprises substantially no compounds from the group consisting of ammonium molybdate, alkaline molybdate, alkaline earth molybdate, ammonium vanadate, alkaline vanadate and alkaline earth vanadate, ammonium zirconate, alkaline zirconate and alkaline earth zirconate, and is processed with a cathodic efficiency of 12% or less. A method for producing a coating, to a structured hard chromium layer, a coating and an electrolyte.

Abstract: A method of producing a structured hard chrome layer is described, wherein chromium is deposited from an electrolyte onto a workpiece, said electrolyte containing: (a) a Cr (VI) compound in an amount corresponding to 50 g/l to 600 g/l of chromic acid anhydride (b) 0.5 g/l to 10 g/l of sulphuric acid; (c) 1 g/l to 20 g/l of aliphatic sulphonic acid, comprising 1 to 6 carbon atoms, and (d) 10 g/l to 200 g/l of at least one compound forming a dense cathode film, said compound being selected from among ammonium molybdate, alkali molybdate and alkaline earth molybdate, ammonium vanadate, alkali vanadate and alkaline earth vanadate, ammonium zirconate, alkali zirconate and alkaline earth zirconate. Further, the application relates to a structured hard chrome layer obtained according to said method and to an electrolyte for carrying out said method.

Abstract: A method of producing a structured hard chrome layer is described, wherein chromium is deposited from an electrolyte onto a workpiece, said electrolyte containing: (a) a Cr (VI) compound in an amount corresponding to 50 g/l to 600 g/l of chromic acid anhydride (b) 0.5 g/l to 10 g/l of sulphuric acid; (c) 1 g/l to 20 g/l of aliphatic sulphonic acid, comprising 1 to 6 carbon atoms, and (d) 10 g/l to 200 g/l of at least one compound forming a dense cathode film, said compound being selected from among ammonium molybdate, alkali molybdate and alkaline earth molybdate, ammonium vanadate, alkali vanadate and alkaline earth vanadate, ammonium zirconate, alkali zirconate and alkaline earth zirconate. Further, the application relates to a structured hard chrome layer obtained according to said method and to an electrolyte for carrying out said method.

Abstract: A method for producing a structured hard chromium layer, during which chromium from an electrolyte is deposited onto a workpiece, which contains: a) a Cr(VI) compound in a quantity corresponding to between 50 and 300 g/l of chromic anhydride; b) 0.5 g/l to 10 g/l sulfuric acid, and; c) 5 g/l to 15 g/l aliphatic sulfonic acid having 1 to 6 carbon atoms. The electrolyte comprises substantially no compounds from the group consisting of ammonium molybdate, alkaline molybdate, alkaline earth molybdate, ammonium vanadate, alkaline vanadate and alkaline earth vanadate, ammonium zirconate, alkaline zirconate and alkaline earth zirconate, and is processed with a cathodic efficiency of 12% or less. A method for producing a coating, to a structured hard chromium layer, a coating and an electrolyte.

Abstract: A method of producing a structured hard chrome layer is described, wherein chromium is deposited from an electrolyte onto a workpiece, said electrolyte containing: (a) a Cr (VI) compound in an amount corresponding to 50 g/l to 600 g/l of chromic acid anhydride (b) 0.5 g/l to 10 g/l of sulphuric acid; (c) 1 g/l to 20 g/l of aliphatic sulphonic acid, comprising 1 to 6 carbon atoms, and (d) 10 g/l to 200 g/l of at least one compound forming a dense cathode film, said compound being selected from among ammonium molybdate, alkali molybdate and alkaline earth molybdate, ammonium vanadate, alkali vanadate and alkali ne earth vanadate, ammonium zirconate, alkali zirconate and alkaline earth zirconate. Further, the application relates to a structured hard chrome layer obtained according to said method and to an electrolyte for carrying out said method.