Federal-mogul Burscheid Gmbh

Rudolf Linde

Stefan Durdoth

Steffen Hoppe

Ralf Lammers

Klaus Staschko

Hans-Albert Michel

Stefan Duerdoth

Stefan Dürdoth

Walter Stumpf

Wolfgang Stuckert

A piston ring () has a running surface () and a flank surface () which are coated. The uppermost layer of the running surface () is a hydrogen-containing or a hydrogen-free DLC layer, and the uppermost layer of at least one flank surface () is a chromium layer. A method of producing a piston ring () includes forming a DLC layer as the uppermost layer of the running surface (), and forming a chromium layer as the uppermost layer of at least one flank surface ().

Piston ring

A structured chromium solids particles layer with a network of cracks in which solids particles are embedded, wherein the crack density is 10-250 per mm, the particle size of the solids particles lies in the range of from 0.01-10 &#x3bc;m, the proportion of solids particles in the overall layer is 1-30 vol.-% and the chromium solids particles layer has a microstructure with depressions in the surface of the layer, wherein the proportion of the surface area accounted for by the depressions is 5-80%. A method for producing the structured chromium solids particles layer on a workpiece includes introducing the workpiece into an electrolyte containing a Cr(VI) compound and electrolytically depositing a chromium layer at a current density of 20-100 A/dmand a current yield of 12% or less and then reversing the current direction wherein the solid particles are embedded within the network of cracks.

Structured chrome solid particle layer and method for the production thereof

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.

Production of structured hard chrome layers

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.

Production of a structured hard chromium layer and production of a coating

A method of producing a structured hard chrome layer is described, wherein chromium is deposited from an electrolyte onto a workpiece, said electrolyte containing: Further, the application relates to a structured hard chrome layer obtained according to said method and to an electrolyte for carrying out said method.

In an electrodeposited hard-chromium coat, particularly for a piston ring, which is substantially formed of an electrolyte containing hexavalent chromium, wherein there are cracks in the coat and diamond particles are embedded in these cracks, the diamond particles have a size ranging from 0.25 to 0.5 &mgr;m.

Hard-chrome plated layer

A cast-iron piston ring for a piston of an internal combustion engine includes a ring composed of cast-iron and having a circumferential surface; a nitrided layer covering the entire circumferential surface of the ring, the nitrided layer including a diffusion layer and a connection layer disposed above the diffusion layer in which the diffusion layer and the connection layer both cover the entire circumferential surface of the ring; and a metal layer which is electrodeposited onto the connection layer, which is composed of a metal having a hardness which is less than that of the connection layer, and which has a thickness of less than 5 &mgr;m.

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Wermelskirchen, Germany

Rudolf Linde