EP0147484A1 - Procédé pour obtenir un revêtement protecteur pour des surfaces soumises à l'usure mécanique et thermique et revêtement obtenu par le procédé - Google Patents

Procédé pour obtenir un revêtement protecteur pour des surfaces soumises à l'usure mécanique et thermique et revêtement obtenu par le procédé Download PDF

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Publication number
EP0147484A1
EP0147484A1 EP83113249A EP83113249A EP0147484A1 EP 0147484 A1 EP0147484 A1 EP 0147484A1 EP 83113249 A EP83113249 A EP 83113249A EP 83113249 A EP83113249 A EP 83113249A EP 0147484 A1 EP0147484 A1 EP 0147484A1
Authority
EP
European Patent Office
Prior art keywords
layer
lying
electro
deposition
fact
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP83113249A
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German (de)
English (en)
Other versions
EP0147484B1 (fr
Inventor
Paolo Filomeni
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
INDUSTRIALE Srl
Original Assignee
INDUSTRIALE Srl
Gilardini SpA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by INDUSTRIALE Srl, Gilardini SpA filed Critical INDUSTRIALE Srl
Priority to AT83113249T priority Critical patent/ATE48659T1/de
Priority to DE8383113249T priority patent/DE3380965D1/de
Priority to EP83113249A priority patent/EP0147484B1/fr
Publication of EP0147484A1 publication Critical patent/EP0147484A1/fr
Application granted granted Critical
Publication of EP0147484B1 publication Critical patent/EP0147484B1/fr
Expired legal-status Critical Current

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Classifications

    • 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
    • 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
    • C25D5/60—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
    • C25D5/623—Porosity of the layers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B77/00—Component parts, details or accessories, not otherwise provided for
    • F02B77/02—Surface coverings of combustion-gas-swept parts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
    • F05C2201/00—Metals
    • F05C2201/04—Heavy metals
    • F05C2201/0403—Refractory metals, e.g. V, W
    • F05C2201/0406—Chromium

Definitions

  • the present invention relates to a process for obtaining a protective coating for mechanical elements subjected to both thermal and mechanical wear, for example, subjected simultaneously to wear by sliding and friction and to oxidation, such as the surfaces of elements comprising the combustion chamber of a heat engine, for example, the cylinders, valve stems, piston crowns and, above all, piston rings.
  • the invention further relates to a protective coating obtained by the process.
  • Known electro-deposited coatings are principally obtained by means of coating a layer of chrome onto a base layer of nickel deposited on the surface to be protected.
  • the thickness of the coating thus obtained does not exceed about 0.45 mm because layers of greater thickness would not be economic given the long deposition times required and, above all, because they would be incoherent, therefore causing a rapid flaking of the protective layer.
  • the deposition processes are largely known, as are their operating parameters.
  • An object of the present invention is that of providing a process for obtaining a protective coating for surfaces subjected to wear, which will be free from the described disadvantages and in particular of greater thickness and resistance to chemical corrosion so as to be able effectively to protect the surfaces to which they are applied.
  • Another object of the present invention is that of providing such a protective coating by utilising electro-deposited coating layers.
  • the said objects are achieved by the present invention in that it relates to a process for obtaining a protective coating for surfaces subjected to wear by sliding and oxidation, in particular for surfaces of heat engines, characterised by the fact that it comprises:
  • the present invention further relates to a protective coating for covering the surfaces of heat engines subjected to thermal and mechanical wear, in particular for elements constituting a combustion chamber of a diesel engine and particularly for piston rings and sealing rings of the pistons of reciprocating engines, characterised by the fact that it comprises at least:
  • an element of a combustion chamber for a heat engine is generally indicated 1, this being constituted, in the illustrated example, by a sealing ring for a diesel engine piston.
  • the element l,of which, for simplicity, only an outer portion of the radial section is illustrated, has a surface 2, in the illustrated example the outer side surface, subjected to wear both by sliding and oxidation, being intended to form a sliding seal between piston and the side wall of the cylinder of an engine in operating conditions.
  • the surface 2 is provided with a protective coating 3 which acts to protect it both from mechanical wear and from thermal wear due to chemical and electro-chemical attack at high temperature by the combustion products.
  • the protective coating 3, in the illustrated example, comprises two superimposed layers, electro-deposited onto the surface 2; a first layer 4 of hard chrome, having a Vickers hardness of 536 Kg/mm2 and a thickness of 35 micron (0.035 mm ) deposited immediately in contact with the surface 2 of the element 1, which is made of cast iron; and a second layer 5 of hard chrome, having a Vickers hardness of 1073 Kg/mm 2 (1073 HV) and of thickness equal to 1.05mm , deposited over the layer 4.
  • the layer 4 is compacted, substantially free from cracks, micro-cracks and porosity, and adheres perfectly to the cast iron of the element 1.
  • the layer 5 is perfectly adherent to the layer 4, free from blow holes and cracks, well formed and having instead a plurality of micro-cracks 6 of very small dimensions (Figure 3) lying between about 5 and 30 micron, uniformly distributed in the layer 5 itself.
  • the protective coating 3 formed according to the invention can be applied to any surface subject to thermal and mechanical wear; and in the field of engines not only the piston rings, but also the valve stems and the cylinder sleeves, and the piston crowns or cavities can be covered with this coating.
  • the coating 3 can be made with a number of different variants, depending on technical requirements ---of-the various applications, and therefore the layer 4 can have a maximum thickness lying between 20 and 40 micron and a hardness lying between 400 and 600 HV, whilst the layer 5 can have a hardness equal to or greater than 1000 HV and a maximum thickness equal to about 1.2 mm.
  • the coating 3 further comprises a third electro-deposited layer for running-in made of hard chrome deposited over the layer 5, of a hardness lying between about 650 and 800 HV and having a thickness such as to be completely worn away,leaving the layer 5 exposed, during the running-in phase of the engine the elements of which have had the coating 3 applied thereto.
  • the coating 3 has the dual function of constituting a protective layer for the surface 2 with regard to oxidising and chemically aggressive agents in general, and constitutes a consumable anti-wear layer for the surface 2. According to the invention this dual function is performed separately by the two layers 4 and 5.
  • the layer 4 thanks to its high compactedness and excellent adhesion to the base material, whether it be cast iron or steel, guarantees the anti-corrosive and anti-oxiditive protection even in the presence of high temperatures (such as, for example, those in the combustion chambers of super-charged engines) and aggressive fuels such as heavy diesel having a high sulphur content. Thanks to its high thermal stability and to its capacity for rapid passivation, in fact, the chrome layer 4 prevents the formation of local electro-chemical corrosion pairs and the penetration of corrosive agents towards the base material.
  • the layer 5, serves to be slowly consumed during the operating life of the element 1 in such a way as to prevent direct sliding of the surface 2 and consequent possible gripping or seizure. Thanks to the great thickness (more than three times the normal thickness of electro-deposited chrome protective layers) it allows about three times the operating life of the element 1 permitting the maintenance intervals of the engines on which the elements provided with protective coatings 3 are fitted to be extended.
  • This layer 5, as well as its thickness, is represented by the presence of the micro-cracks 6.
  • the protective coating 3 previously described is obtained with the following process.
  • the layer 4 After having proceeded with an accurate cleaning of the element 1 to be coated, there is deposited on the surface 2, by means of electro-deposition treatment, the layer 4 by operating in an electrolytic vessel with lead anodes and cathodes constituted by the elements to be coated, in an electrolytic bath containing chrome in solution, preferably as CrO 3 , and chromic acid and with a voltage between the electrodes of between 4 and 10 volts.
  • the hardness and thickness of the layer 4 can instead be chosen in dependence on the single coating requirements, by varying in a known way the duration of the deposition operation and the percentage composition of chrome in the bath; these must however remain between the following values:
  • a washing operation is performed and then a second electro-deposition operation, this time utilising an aqueous electrolytic bath containing Cr0 3 and a mixture of acids based on sulphuric acid (H 2 S0 4 ) preferably mixed with hydrofluoric acid (HF) and possibly with other mineral acids.
  • H 2 S0 4 sulphuric acid
  • HF hydrofluoric acid
  • the chrome layer 5 is deposited after the layer 4, acting in vessels with lead anodes and cathodes constituted by the elements to be treated and a voltage between the electrodes of about 5-15 volts.
  • the hardness of the deposit which must be greater than or equal to about 1000 k g/mm 2 (Vickers) can be determined.
  • the maximum economic thickness of the layer 5 is of the order of 1.2 mm.
  • a further electro-deposition operation can subsequently be performed by depositing on the layer 5 a further hard chrome layer of Vickers hardness lying between 650 and 800 Kg/mm 2 by working with a cathode current density of about 30-40 Ampere and a speed of deposition equal to that used in the deposition phase of the layer 5.
  • This produces a layer having characteristics similar to those of the layer 5 but somewhat softer, which can be used as a running-in layer.
  • Micro-cracks 6 can also be obtained in this layer.

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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)
  • Crystallography & Structural Chemistry (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Electroplating Methods And Accessories (AREA)
  • Laminated Bodies (AREA)
  • Electronic Switches (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Physical Vapour Deposition (AREA)
EP83113249A 1983-12-30 1983-12-30 Procédé pour obtenir un revêtement protecteur pour des surfaces soumises à l'usure mécanique et thermique et revêtement obtenu par le procédé Expired EP0147484B1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
AT83113249T ATE48659T1 (de) 1983-12-30 1983-12-30 Verfahren zur herstellung einer schutzschicht fuer oberflaechen die mechanischem und thermischem verschleiss unterworfen sind.
DE8383113249T DE3380965D1 (de) 1983-12-30 1983-12-30 Verfahren zur herstellung einer schutzschicht fuer oberflaechen die mechanischem und thermischem verschleiss unterworfen sind.
EP83113249A EP0147484B1 (fr) 1983-12-30 1983-12-30 Procédé pour obtenir un revêtement protecteur pour des surfaces soumises à l'usure mécanique et thermique et revêtement obtenu par le procédé

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP83113249A EP0147484B1 (fr) 1983-12-30 1983-12-30 Procédé pour obtenir un revêtement protecteur pour des surfaces soumises à l'usure mécanique et thermique et revêtement obtenu par le procédé

Publications (2)

Publication Number Publication Date
EP0147484A1 true EP0147484A1 (fr) 1985-07-10
EP0147484B1 EP0147484B1 (fr) 1989-12-13

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Family Applications (1)

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EP83113249A Expired EP0147484B1 (fr) 1983-12-30 1983-12-30 Procédé pour obtenir un revêtement protecteur pour des surfaces soumises à l'usure mécanique et thermique et revêtement obtenu par le procédé

Country Status (3)

Country Link
EP (1) EP0147484B1 (fr)
AT (1) ATE48659T1 (fr)
DE (1) DE3380965D1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0972861A2 (fr) * 1998-06-26 2000-01-19 Nippon Piston Ring Co., Ltd. Couches de placage laminées avec une resistance à l'usure et à la fatigue superieure
EP1624092A1 (fr) * 2004-08-06 2006-02-08 Yamaha Hatsudoki Kabushiki Kaisha Pot d'échappement chromé
FR3032725A1 (fr) * 2015-02-12 2016-08-19 Snecma Procede de depot d'un revetement de protection contre l'erosion sur une piece metallique

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1301720A (fr) * 1961-09-26 1962-08-17 Procédé pour le dépôt électrolytique de chrome dur poreux sur l'aluminium ou ses alliages
DE1496809A1 (de) * 1966-05-05 1969-07-17 Goetzewerke Verfahren zum Verchromen insbesondere von Kolbenringen
DE1521079A1 (de) * 1963-12-04 1970-05-14 Volkswagenwerk Ag Verfahren zum Abscheiden von glaenzenden mikrorissigen Chromueberzuegen mittels Doppelverchromung

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1301720A (fr) * 1961-09-26 1962-08-17 Procédé pour le dépôt électrolytique de chrome dur poreux sur l'aluminium ou ses alliages
DE1521079A1 (de) * 1963-12-04 1970-05-14 Volkswagenwerk Ag Verfahren zum Abscheiden von glaenzenden mikrorissigen Chromueberzuegen mittels Doppelverchromung
DE1496809A1 (de) * 1966-05-05 1969-07-17 Goetzewerke Verfahren zum Verchromen insbesondere von Kolbenringen

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
CHEMICAL ABSTRACTS, vol. 92, 1980, page 504, no. 118542f, Columbus, Ohio, US; & JP - A - 79 117 335 (KOBE STEEL, LTD.) 12-09-1979 *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0972861A2 (fr) * 1998-06-26 2000-01-19 Nippon Piston Ring Co., Ltd. Couches de placage laminées avec une resistance à l'usure et à la fatigue superieure
EP0972861A3 (fr) * 1998-06-26 2000-05-24 Nippon Piston Ring Co., Ltd. Couches de placage laminées avec une resistance à l'usure et à la fatigue superieure
US6296951B1 (en) 1998-06-26 2001-10-02 Nippon Piston Ring Co., Ltd. Laminated chromium plating layers having superior wear resistance and fatigue strength
EP1624092A1 (fr) * 2004-08-06 2006-02-08 Yamaha Hatsudoki Kabushiki Kaisha Pot d'échappement chromé
US7726121B2 (en) 2004-08-06 2010-06-01 Yamaha Hatsudoki Kabushiki Kaisha Engine part
FR3032725A1 (fr) * 2015-02-12 2016-08-19 Snecma Procede de depot d'un revetement de protection contre l'erosion sur une piece metallique

Also Published As

Publication number Publication date
EP0147484B1 (fr) 1989-12-13
DE3380965D1 (de) 1990-01-18
ATE48659T1 (de) 1989-12-15

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