EP0909839B1 - Galvanic hard chromium layer - Google Patents

Galvanic hard chromium layer Download PDF

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Publication number
EP0909839B1
EP0909839B1 EP98118677A EP98118677A EP0909839B1 EP 0909839 B1 EP0909839 B1 EP 0909839B1 EP 98118677 A EP98118677 A EP 98118677A EP 98118677 A EP98118677 A EP 98118677A EP 0909839 B1 EP0909839 B1 EP 0909839B1
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Prior art keywords
hard chromium
deposited
layer
solid particles
layers
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EP98118677A
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German (de)
French (fr)
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EP0909839A1 (en
Inventor
Rudolf Linde
Ulrich Dipl.-Ing. Buran
Hans-Jochem Dr. Neuhäuser
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Federal Mogul Burscheid GmbH
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Federal Mogul Burscheid GmbH
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D15/00—Electrolytic or electrophoretic production of coatings containing embedded materials, e.g. particles, whiskers, wires
    • C25D15/02—Combined electrolytic and electrophoretic processes with charged materials
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/10—Electroplating with more than one layer of the same or of different metals
    • C25D5/12—Electroplating with more than one layer of the same or of different metals at least one layer being of nickel or chromium
    • C25D5/14—Electroplating with more than one layer of the same or of different metals at least one layer being of nickel or chromium two or more layers being of nickel or chromium, e.g. duplex or triplex layers
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/18—Electroplating using modulated, pulsed or reversing current
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/60—Electroplating characterised by the structure or texture of the layers
    • C25D5/615—Microstructure of the layers, e.g. mixed structure
    • C25D5/617—Crystalline layers
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/60—Electroplating characterised by the structure or texture of the layers
    • C25D5/625—Discontinuous layers, e.g. microcracked layers

Definitions

  • the invention relates to a galvanic hard chrome layer with a partial or through the entire layer thickness by anodic circuit widened crack network, with solid particles embedded in the cracks.
  • hard chrome layers are made of micro-crack-forming Chromium plating electrolyte with solid particles dispersed therein using separated from pulsating current, with the cathodic circuit of the Workpiece itself in the forming chrome layer in addition to the cracks in the Chromium matrix itself store the solid particles.
  • the invention is based on the object of a galvanic hard chrome layer Preamble of claim 1 with respect to their strength properties to improve.
  • this object is achieved by the features of patent claim 1 and by a production method according to claim 9.
  • the chromium is deposited from the electrolyte on the cathodically connected workpiece with pulsating direct current with current densities between 5 and 250 A / dm 2 , so that layers of hard chromium with different crystallization forms are deposited in the chrome layer in accordance with the current density.
  • the workpiece is switched anodically, so that the crack network in hard chrome expands and fills with the solid particles.
  • At least two or more superimposed layers of hard chrome are deposited on the workpiece, in which solids are embedded by anodic switching.
  • total layer thicknesses preferably about 0.005 to 1.0 mm
  • the thickness of the individual layers is then 0.0005 to 0.5 mm.
  • the chrome can also be alloyed.
  • Preferred alloy metals are molybdenum, Tungsten and / or vanadium, the production as known per se, the Alloy elements are dissolved in the chromium plating electrolyte as salts and can be galvanically deposited together with the chrome.
  • the alloy elements are preferred in amounts of 0.1 to 30 percent by weight in the chrome layer available.
  • all layers of a chrome layer can consist of a chrome alloy or any layer of a separate alloy consist.
  • the invention also relates to the use defined in claim 8.
  • the running surfaces of piston rings for internal combustion engines were coated with the chrome layer according to the invention and the piston rings were examined in test bench runs.
  • the piston rings coated according to the invention were usable even under extreme temperature and wear loads with a considerably longer service life than the previously known piston rings provided with chromium plating layers.
  • the layers have improved technological properties in the composite.
  • the invention thus a chrome or chrome alloy layer with im Crack network created and encapsulated solid particles, which compared to the chromium interlayers known from EP PS 0217 126 has improved technological properties.
  • the layer has surface coating of piston rings Use of hard materials as solid particles a much longer Lifetime in motor operation.
  • the piston rings provided with the layer according to the invention can be used under extreme temperature and wear loads.
  • the layer according to the invention can be used in the same way as a coating for similar machine parts subjected to high temperatures and / or wear.
  • the production of the layers according to the invention is hardly more expensive than the layers known from EP PS 0217 126.
  • the invention is explained in more detail on the basis of two exemplary embodiments with a cross-section recording.
  • the starting point is a chrome plating electrolyte
  • the starting point is a chrome plating electrolyte 250 g / l CrO 3 chromic acid 2.5 g / l H 2 SO 4 sulfuric acid 20 g / l Al 2 O 3 Aluminum oxide as dispersed hard-packed particles
  • the cross-sectional image shows the cross-section through the deposited chrome layer in 500 times magnification with 18 layers of chrome layers lying on top of each other.
  • the layer (2) of hard chromium with pulsating direct current is first deposited on the substrate (1) in step 1 in process step 1.
  • the layer (3) was formed with constant direct current in process stage 2.
  • the crack network (4) of the layer (3) reaching into the layer (2) was repeated a total of 18 times, so that an entire layer with 18 layers was made Alternation of layers 2 and 3 arises.
  • a chromium plating electrolyte as in example 1 is assumed, to which 220 g / l (NH 4 ) 6 Mo 7 O 2 4 4 H 2 O (ammonium molybdate) are added to produce a chromium molybdenum alloy layer.
  • the deposited chromium-molybdenum alloy contains 2.4% by weight of molybdenum.
  • the deposition conditions of the layer are the same as in exemplary embodiment 1.
  • the deposited layer shows approximately the same cross-sectional image as the cross-sectional image of the layer from exemplary embodiment 1.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electroplating Methods And Accessories (AREA)
  • Physical Vapour Deposition (AREA)
  • Electroplating And Plating Baths Therefor (AREA)
  • Pistons, Piston Rings, And Cylinders (AREA)

Description

Die Erfindung betrifft eine galvanische Hartchromschicht mit einem sich teilweise oder durch die gesamte Schichtdicke erstreckendem durch anodische Schaltung aufgeweitetem Rißnetzwerk, mit in den Rissen eingelagerten Feststoffpartikeln.The invention relates to a galvanic hard chrome layer with a partial or through the entire layer thickness by anodic circuit widened crack network, with solid particles embedded in the cracks.

Nach der EP PS 0217 126 ist es bekannt, in die Risse des Rißnetzwerkes von galvanisch abgeschiedenen Hartchromschichten Feststoffpartikel einzulagern, die vor allem zur Erhöhung der Verschleißfestigkeit aus Hartstoffpartikeln bestehen. Im Prinzip können in die Risse jedoch Feststoffpartikel aus Festschmierstoffen, duktilen Metallen, organischen Thermoplasten und / oder Feststoffen zur Verbesserung der Gleiteigenschaften der Chromschicht, Duktilität, der Korrosionsbeständigkeit oder zur Einfärbung eingelagert sein.
Zur Herstellung werden mikrorißbildende Verchromungselektrolyte mit darin dispergieren Feststoffpartikeln verwendet, so daß beim Galvanisieren unter mehrfacher Stromumkehr bei kathodischer Schaltung des Werkstückes sich der Chromüberzug bildet und bei anodischer Schaltung des Werkstückes sich die Mikrorisse aufweiten und mit den Feststoffpartikeln füllen. Bei der nachfolgenden Stromumkehr werden durch Chromabscheidung die Risse verschlossen und die eingelagerten Feststoffpartikel in den Rissen eingekapselt.According to EP PS 0217 126, it is known to embed solid particles in the cracks of the crack network of electrodeposited hard chrome layers, which particles consist primarily of hard material particles to increase wear resistance. In principle, however, solid particles of solid lubricants, ductile metals, organic thermoplastics and / or solids can be embedded in the cracks to improve the sliding properties of the chrome layer, ductility, corrosion resistance or for coloring.
For the manufacture, micro-cracking chromium plating electrolytes with solid particles dispersed therein are used, so that the chrome plating is formed during electroplating under multiple current reversal with cathodic switching of the workpiece, and when the workpiece is anodically switched, the micro-cracks expand and fill with the solid particles. In the subsequent reversal of the current, the cracks are closed by chromium deposition and the embedded solid particles are encapsulated in the cracks.

Nach der EP PA 0668 375 werden Hartchromschichten aus mikrorissbildenden Verchromungselektrolyten mit darin dispergierten Feststoffpartikeln unter Verwendung von pulsierendem Strom abgeschieden, wobei unter kathodischer Schaltung des Werkstückes sich in die bildende Chromschicht außer in den Rissen auch in die Chrommatrix selbst die Feststoffpartikel einlagern.According to EP PA 0668 375, hard chrome layers are made of micro-crack-forming Chromium plating electrolyte with solid particles dispersed therein using separated from pulsating current, with the cathodic circuit of the Workpiece itself in the forming chrome layer in addition to the cracks in the Chromium matrix itself store the solid particles.

Die aus der EP PS 0127 126 bekannten Chromschichten, mit in den Rissen eingelagerten Hartstoffpartikeln, haben sich vor allem als Laufflächenbeschichtungen von Kolbenringen und ähnlichem, auf reibenden Verschleiß bei hohen Temperaturen belasteten Maschinenteilen, bewährt.
Je nach Bauart und Leistungstyp der Verbrennungskraftmaschine sind die Kolbenringe unterschiedlich extremen Belastungen ausgesetzt.The chrome layers known from EP PS 0127 126, with hard material particles embedded in the cracks, have proven themselves above all as tread coatings on piston rings and the like, machine parts subjected to high temperatures at high temperatures.
Depending on the design and performance type of the internal combustion engine, the piston rings are exposed to different extreme loads.

Der Erfindung liegt die Aufgabe zugrunde, eine galvanische Hartchromschicht gemäß Oberbegriff des Patentanspruches 1 in Bezug auf ihre Festigkeitseigenschaften weiter zu verbessern.The invention is based on the object of a galvanic hard chrome layer Preamble of claim 1 with respect to their strength properties to improve.

Erfindungsgemäß wird diese Aufgabe durch die Merkmale des Patentanspruches 1 und durch ein Herstellungsverfahren gemäß Anspruch 9 gelöst. Und zwar wird zur Herstellung mindestens einer Lage Hartchrom das Chrom aus dem Elektrolyten am kathodisch geschalteten Werkstück mit pulsierendem Gleichstrom mit Stromdichten zwischen 5 und 250 A/dm2 abgeschieden, so daß in der Chromlage entsprechend der Stromdichte Lagen Hartchrom mit unterschiedlicher Kristallisationsform abgeschieden werden. Nach einer Abscheidungsphase einer Lage wird das Werkstück anodisch geschaltet, so daß sich das Rißnetzwerk im Hartchrom aufweitet und mit den Feststoffpartikeln füllt. Entsprechend der Wiederholung des Vorgangs werden mindestens zwei bzw. mehrere übereinanderliegende Lagen Hartchrom am Werkstück abgeschieden, in die durch anodische Schaltung Feststoffe eingelagert werden. Bei Gesamtschichtdicken von bevorzugten etwa 0,005 bis 1,0 mm liegt die Dicke der einzelnen Lagen dann bei 0,0005 bis 0,5 mm.According to the invention, this object is achieved by the features of patent claim 1 and by a production method according to claim 9. To produce at least one layer of hard chrome, the chromium is deposited from the electrolyte on the cathodically connected workpiece with pulsating direct current with current densities between 5 and 250 A / dm 2 , so that layers of hard chromium with different crystallization forms are deposited in the chrome layer in accordance with the current density. After a layer has been deposited, the workpiece is switched anodically, so that the crack network in hard chrome expands and fills with the solid particles. Corresponding to the repetition of the process, at least two or more superimposed layers of hard chrome are deposited on the workpiece, in which solids are embedded by anodic switching. With total layer thicknesses of preferably about 0.005 to 1.0 mm, the thickness of the individual layers is then 0.0005 to 0.5 mm.

Zusätzlich kann das Chrom legiert sein. Bevorzugte Legierungsmetalle sind Molybdän, Wolfram und / oder Vanadium, wobei zur Herstellung wie an sich bekannt, die Legierungselemente in den Verchromungselektrolyten als Salze gelöst sind und zusammen mit dem Chrom galvanisch abgeschieden werden. Die Legierungselemente sind bevorzugt in Mengen von 0,1 bis 30 Gewichtsprozente in der Chromschicht vorhanden. Im Sinne der Erfindung können alle Lagen einer Chromschicht einheitlich aus einer Chromlegierung oder aber auch jede Lage aus einer gesonderten Legierung bestehen. Die Erfindung betrifft auch die in Anspruch 8 definierte Verwendung. The chrome can also be alloyed. Preferred alloy metals are molybdenum, Tungsten and / or vanadium, the production as known per se, the Alloy elements are dissolved in the chromium plating electrolyte as salts and can be galvanically deposited together with the chrome. The alloy elements are preferred in amounts of 0.1 to 30 percent by weight in the chrome layer available. In the sense of the invention, all layers of a chrome layer can consist of a chrome alloy or any layer of a separate alloy consist. The invention also relates to the use defined in claim 8.

Mit der erfindungsgemäßen Chromschicht wurden die Laufflächen von Kolbenringen für Verbrennungskraftmaschinen beschichtet und die Kolbenringe wurden in Prüfstandsläufen untersucht. Die erfindungsgemäß beschichteten Kolbenringe waren auch bei extremen Temperatur- und Verschleißbelastungen mit wesentlich längerer Lebensdauer einsatzfähig als die bisher bekannten mit Chromeinlagerungschichten versehenen Kolbenringe.
Offensichtlich besitzen die Schichten aufgrund der Zusammensetzung aus Chrom mit Lagen unterschiedlicher Kristallisationsform, verbesserte technologische Eigenschaften im Verbund. Die Legierung des Chroms, vor allem mit den Metallen Molybdän, Vanadium und Wolfram ergibt dann eine weitere Verbesserung.The running surfaces of piston rings for internal combustion engines were coated with the chrome layer according to the invention and the piston rings were examined in test bench runs. The piston rings coated according to the invention were usable even under extreme temperature and wear loads with a considerably longer service life than the previously known piston rings provided with chromium plating layers.
Obviously, due to the composition of chromium with layers of different crystallization forms, the layers have improved technological properties in the composite. The alloy of chromium, especially with the metals molybdenum, vanadium and tungsten, results in a further improvement.

Durch die Erfindung ist somit eine Chrom- bzw. Chromlegierungsschicht mit im Rißnetzwerk eingelagerten und eingekapselten Feststoffpartikeln geschaffen, welche gegenüber den aus der EP PS 0217 126 bekannten Chromeinlagerungsschichten verbesserte technologische Eigenschaften besitzt. Insbesondere als Oberflächenbeschichtung von Kolbenringen weist die Schicht insbesondere bei Verwendung von Hartstoffen als Feststoffpartikel eine wesentlich verlängerte Lebensdauer im motorischen Betrieb auf.The invention thus a chrome or chrome alloy layer with im Crack network created and encapsulated solid particles, which compared to the chromium interlayers known from EP PS 0217 126 has improved technological properties. Especially as In particular, the layer has surface coating of piston rings Use of hard materials as solid particles a much longer Lifetime in motor operation.

Die mit der erfindungsgemäßen Schicht versehenen Kolbenringe sind unter extremen Temperatur- und Verschleißbelastungen einsetzbar. Die erfindungsgemäße Schicht ist in gleicher Weise als Beschichtung für ähnliche, auf hohe Temperatur und / oder verschleißbelastete Maschinenteile einsetzbar.
Die Herstellung der erfindungsgemäßen Schichten ist vergleichsweise zu den aus der EP PS 0217 126 bekannten Schichten kaum aufwendiger.
Die Erfindung wird anhand von zwei Ausführungsbeispielen mit einer Querschliffaufnahme näher erläutert.The piston rings provided with the layer according to the invention can be used under extreme temperature and wear loads. The layer according to the invention can be used in the same way as a coating for similar machine parts subjected to high temperatures and / or wear.
The production of the layers according to the invention is hardly more expensive than the layers known from EP PS 0217 126.
The invention is explained in more detail on the basis of two exemplary embodiments with a cross-section recording.

Beispiel 1:Example 1:

Ausgegangen wird von einem Verchromungselektrolyten mit The starting point is a chrome plating electrolyte

Beispiel 1:Example 1:

Ausgegangen wird von einem Verchromungselektrolyten mit 250 g/l CrO3 Chromsäure 2,5 g/l H2SO4 Schwefelsäure 20 g/l Al2O3 Aluminiumoxid als dispergierte Feststollpartikel The starting point is a chrome plating electrolyte 250 g / l CrO 3 chromic acid 2.5 g / l H 2 SO 4 sulfuric acid 20 g / l Al 2 O 3 Aluminum oxide as dispersed hard-packed particles

Die Verchromung erfolgt bei 55 C° in 3 Stufen.

  • 1. Zum Verchromen wird das Werkstück in einer ersten Stufe kathodisch geschaltet und während 20 Minuten einem pulsierendem Gleichstrom mit einer Stromdichte zwischen 120 A/dm2 und 20 A/dm2 ausgesetzt. Der Wechsel der Stromdichte erfolgt nach 0,05 Sekunden, so daß das Werkstück insgesamt jeweils 12000 Zyklen Stromdichten von 120 A/dm2 und 20 A/dm2 ausgesetzt ist.
  • 2. Anschließend wird in einer zweiten Stufe das Werkstück unter kathodischer Schaltung mit einer Chromschicht während 30 Minuten bei einer konstanten Stromdichte von 65 A/dm2 versehen.
  • 3. In einer dritten Stufe wird umgepolt und durch anodische Schaltung des Werkstückes bei einer Stromdichte von 65 A/dm2 während einer Minute, wird das Rißnetzwerk der vorher abgeschiedenen Chromschichten aufgeweitet und mit Feststoffpartikeln gefüllt.
    • The chrome plating takes place in three stages at 55 ° C.
  • 1. For chrome plating, the workpiece is switched cathodically in a first stage and exposed to a pulsating direct current with a current density between 120 A / dm 2 and 20 A / dm 2 for 20 minutes. The current density changes after 0.05 seconds, so that the workpiece is exposed to a total of 12,000 cycles of current densities of 120 A / dm 2 and 20 A / dm 2 .
  • 2. Then, in a second stage, the workpiece is provided with a chrome layer under cathodic circuit for 30 minutes at a constant current density of 65 A / dm 2 .
  • 3. In a third stage, the polarity is reversed and by anodic switching of the workpiece at a current density of 65 A / dm 2 for one minute, the crack network of the previously deposited chrome layers is expanded and filled with solid particles.

    • Es ist nach dieser Zeit eine Schicht mit einer Schichtdicke von 0,05 mm erzeugt, so daß der gesamte Abscheidungsvorgang neunmal wiederholt wird, um eine gewünschte Schichtdicke von 0,5 mm zu erhalten.After this time, a layer with a layer thickness of 0.05 mm is produced, see above that the entire deposition process is repeated nine times to achieve a desired one Obtain layer thickness of 0.5 mm.

    Das Querschnittsbild zeigt den Querschnitt durch die abgeschiedene Chromschicht in 500 facher Vergrößerung mit 18 Lagen aufeinanderliegender Chromschichten.
    Auf das Substrat (1) ist zunächst in Stufe 1 die Lage (2) Hartchrom mit pulsierendem Gleichstrom in der Verfahrensstufe 1 abgeschieden. Die Lage (3) entstand bei konstantem Gleichstrom in Verfahrensstufe 2. Anschließend wurde in der Verfahrensstufe 3 das bis in die Lage (2) reichende Rißnetzwerk (4) der Lage (3) insgesamt 18 mal wiederholt, so daß eine Gesamtschicht mit 18 Lagen aus Abwechslung der Lagen 2 und 3 entsteht.    The cross-sectional image shows the cross-section through the deposited chrome layer in 500 times magnification with 18 layers of chrome layers lying on top of each other.
    The layer (2) of hard chromium with pulsating direct current is first deposited on the substrate (1) in step 1 in process step 1. The layer (3) was formed with constant direct current in process stage 2. Subsequently, in process stage 3, the crack network (4) of the layer (3) reaching into the layer (2) was repeated a total of 18 times, so that an entire layer with 18 layers was made Alternation of layers 2 and 3 arises.

    Beispiel 2:Example 2:

    Im Ausführungsbeispiel 2 wird von einem Verchromungselektrolyten wie im Beispiel 1 ausgegangen, dem zur Herstellung einer Chrommolybdänlegierungsschicht 220 g/l (N H4)6 Mo7 O2 4 4 H2O (Ammoniummolybdat) zugesetzt sind. Die abgeschiedene Chrom-Molybdänlegierung enthält 2,4 Gew. % Molybdän.
    Die Abscheidungsbedingungen der Schicht sind die gleichen wie im Ausführungsbeispiel 1. Die abgeschiedene Schicht zeigt in etwa ein gleiches Querschnittsbild wie das Querschnittsbild der Schicht aus Ausführungsbeispiel 1.    In embodiment 2, a chromium plating electrolyte as in example 1 is assumed, to which 220 g / l (NH 4 ) 6 Mo 7 O 2 4 4 H 2 O (ammonium molybdate) are added to produce a chromium molybdenum alloy layer. The deposited chromium-molybdenum alloy contains 2.4% by weight of molybdenum.
    The deposition conditions of the layer are the same as in exemplary embodiment 1. The deposited layer shows approximately the same cross-sectional image as the cross-sectional image of the layer from exemplary embodiment 1.

    Claims (9)

    1. Electrolytically deposited hard chromium coating having a crack network extending partially or completely through the entire coating thickness, and widened anodically, with solid particles incorporated in the cracks, characterised in that the hard chromium coating consists of at least two layers of hard chromium, and the layers have different crystalline forms, one layer (3) being deposited using constant direct current and containing the crack network (4) with the incorporated solid particles, and in that at least one layer (2) is deposited using pulsating direct current, so that the solid particles are encapsulated.
    2. Electrolytically deposited hard chromium coating according to patent claim 1, characterised in that the layers (2) of hard chromium which are deposited using a pulsating direct current are deposited with current densities of between 5 and 250 A/dm2.
    3. Electrolytically deposited hard chromium coating according to one of patent claims 1 to 2, characterised in that the thickness of the entire hard chromium coating is 0.005 to 1.0 mm.
    4. Electrolytically deposited hard chromium coating according to one of patent claims 1 to 3, characterised in that the thickness of the individual layers of hard chromium (2, 3) is between 0.0005 and 0.5 mm.
    5. Electrolytically deposited hard chromium coating according to one of patent claims 1 to 4, characterised in that the hard chromium is alloyed with metals which are simultaneously deposited from the chrome-plating electrolyte during plating.
    6. Electrolytically deposited hard chromium coating according to one of patent claims 1 to 5, characterised in that the chromium contains 0.1 to 30% by weight molybdenum, vanadium and/or tungsten.
    7. Electrolytically deposited hard chromium coating according to one of patent claims 1 to 6, characterised in that the individual layers of hard chromium contain different alloy elements.
    8. Use of the electrolytically deposited hard chromium coating according to one of patent claims 1 to 7 as a surface coating for piston rings of internal combustion engines.
    9. Method of producing an electrolytically deposited hard chromium coating according to one of patent claims 1 to 7, characterised in that in a first stage the workpiece (1) is connected as a cathode and, using pulsating direct current, a first layer (2) of hard chromium is deposited from a sulphuric chrome-plating electrolyte with solid particles dispersed in it, in that in a second stage, the hard chromium layer (3) is deposited on layer (2) using constant direct current, in that in a third stage, with the workpiece (1) connected as an anode, the crack network (4) of layer (3) is widened and filled with solid particles, and in that the deposition of hard chromium layers (2) and (3) of method stages 1 and 2 as well as the widening of the crack network (4) and filling with solid particles according to method stage 3 are repeated until the desired total coating thickness is reached.
    EP98118677A 1997-10-16 1998-10-02 Galvanic hard chromium layer Expired - Lifetime EP0909839B1 (en)

    Applications Claiming Priority (2)

    Application Number Priority Date Filing Date Title
    DE19745811 1997-10-16
    DE19745811A DE19745811C2 (en) 1997-10-16 1997-10-16 Electroplated hard chrome layer, use and method for the production thereof

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    Publication Number Publication Date
    EP0909839A1 EP0909839A1 (en) 1999-04-21
    EP0909839B1 true EP0909839B1 (en) 2002-12-11

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    DE (2) DE19745811C2 (en)
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    Publication number Priority date Publication date Assignee Title
    DE19931829A1 (en) 1999-07-08 2001-01-18 Federal Mogul Burscheid Gmbh Galvanic hard chrome layer
    WO2001048267A1 (en) * 1999-12-27 2001-07-05 Nippon Piston Ring Co., Ltd. Sliding member
    DE102005023627B4 (en) * 2005-05-21 2010-05-06 Federal-Mogul Burscheid Gmbh Steel Kolbe ring
    DE102007038188B4 (en) * 2007-08-13 2018-11-15 Federal-Mogul Burscheid Gmbh Wear-resistant coated piston ring and method for its production
    DE102007050811A1 (en) 2007-10-24 2009-04-30 Robert Bosch Gmbh Wear protection layer and method for its production
    DE102015105761A1 (en) * 2015-04-15 2016-10-20 HDO Druckguss- und Oberflächentechnik GmbH Component with applied chromium layer with tungsten content and molybdenum content and method for producing such a component by means of ternary deposition
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    DE19745811C2 (en) 2002-06-13
    ES2184184T3 (en) 2003-04-01
    DE19745811A1 (en) 1999-04-22
    EP0909839A1 (en) 1999-04-21

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