WO2015177315A1 - Procédé pour la fabrication de substrats revêtus de chrome-oxyde de chrome et substrats revêtus produits de cette manière - Google Patents

Procédé pour la fabrication de substrats revêtus de chrome-oxyde de chrome et substrats revêtus produits de cette manière Download PDF

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Publication number
WO2015177315A1
WO2015177315A1 PCT/EP2015/061333 EP2015061333W WO2015177315A1 WO 2015177315 A1 WO2015177315 A1 WO 2015177315A1 EP 2015061333 W EP2015061333 W EP 2015061333W WO 2015177315 A1 WO2015177315 A1 WO 2015177315A1
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Prior art keywords
chromium
coating
electrolyte
chromium oxide
metal
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PCT/EP2015/061333
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English (en)
Inventor
Jacques Hubert Olga Joseph Wijenberg
Adrianus Jacobus Wittebrood
Michiel STEEGH
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Tata Steel Ijmuiden B.V.
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Application filed by Tata Steel Ijmuiden B.V. filed Critical Tata Steel Ijmuiden B.V.
Priority to RSP20191121 priority Critical patent/RS59292B1/sr
Priority to EP15726901.0A priority patent/EP3146091B1/fr
Priority to ES15726901T priority patent/ES2744566T3/es
Publication of WO2015177315A1 publication Critical patent/WO2015177315A1/fr

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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
    • 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
    • C25D5/10—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
    • C25D5/48—After-treatment of electroplated surfaces
    • C25D5/50—After-treatment of electroplated surfaces by heat-treatment
    • C25D5/505—After-treatment of electroplated surfaces by heat-treatment of electroplated tin coatings, e.g. by melting
    • 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
    • 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
    • C25D5/627—Electroplating characterised by the visual appearance of the layers, e.g. colour, brightness or mat appearance
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D9/00—Electrolytic coating other than with metals
    • C25D9/04—Electrolytic coating other than with metals with inorganic materials
    • C25D9/08—Electrolytic coating other than with metals with inorganic materials by cathodic processes
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D3/00—Electroplating: Baths therefor
    • C25D3/02—Electroplating: Baths therefor from solutions
    • C25D3/04—Electroplating: Baths therefor from solutions of chromium
    • C25D3/06—Electroplating: Baths therefor from solutions of chromium from solutions of trivalent chromium
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D9/00—Electrolytic coating other than with metals
    • C25D9/04—Electrolytic coating other than with metals with inorganic materials
    • C25D9/08—Electrolytic coating other than with metals with inorganic materials by cathodic processes
    • C25D9/10—Electrolytic coating other than with metals with inorganic materials by cathodic processes on iron or steel

Definitions

  • the present invention relates to a method for manufacturing chromium- chromium oxide coated substrates and to the chromium-chromium oxide substrates thus produced.
  • the present invention further relates to the use of the chromium-chromium oxide coated substrates in packaging applications.
  • Electrodeposition is the process of depositing a metallic coating on a substrate by passing an electrical current through an electrolyte solution that contains the metal to be deposited.
  • trivalent chromium electrolytes one major concern is the possible oxidation of trivalent chromium to hexavalent chromium at the anode.
  • water also some Cr(III) might be oxidised unintentionally to Cr(VI) at the anode, because the electrode potentials for the oxidation of water to oxygen and the oxidation of Cr(III) to Cr(VI) are very close.
  • US2010/0108532 discloses a process for plating chromium from a trivalent chromium plating bath.
  • the electrolyte comprises a chromium metal added as basic chromium sulphate, sodium sulphate, boric acid and maleic acid.
  • the electrolyte further comprises manganese ions to reduce the formation of excessive amounts of hexavalent chromium. Although the formation of excessive amounts of hexavalent chromium is avoided, hexavalent chromium is nevertheless still produced.
  • EP0747510 describes a method for depositing chromium oxides from a trivalent chromium solution that is free from added buffer. Due to the absence of a buffer the pH increases in the cathode film, which in turn allows for the direct formation of chromium oxide on the cathode. According to EP0747510, the formation of hexavalent chromium at the anode may be prevented or reduced by selecting a suitable anode, e.g. platinum, platinised-titanium, nickel- chromium or carbon, and by employing a depolariser such as potassium bromide.
  • the trivalent chromium electrolyte solution employed in EP0747510 also contains potassium chloride, which is converted into chlorine during the eiectrodeposition process. Chlorine gas is potentially harmful to the environment and to the workers and is therefore undesirable.
  • the first aspect of the invention relates to a method for manufacturing a chromium metal - chromium oxide coated substrate by electrolytically depositing a plurality of chromium metal - chromium oxide coating layers on an electrically conductive substrate from an electrolyte solution that comprises a trivalent chromium compound and a chelating agent, wherein the electrolyte solution is free of chloride ions and of a boric acid buffering agent, the electrically conductive substrate acts as a cathode and an anode comprising a catalytic coating of iridium oxide or a mixed metal oxide or a hydrogen gas diffusion anode is chosen for reducing or eliminating the oxidation of Cr(III)-ions to Cr(VI)-ions, wherein during the deposition of a chromium metal - chromium oxide layer hydrogen bubbles are formed at the strip surface, and wherein between the deposition of the chromium metal - chromium oxide layers, the hydrogen bubbles are removed from the surface of the
  • This invention relates to the deposition of multiple chromium and chromium oxide layers (Cr-CrOx) from a trivalent chromium electrolyte by means of electrolysis in a strip plating line.
  • Cr-CrOx chromium and chromium oxide layers
  • a layer of chromium is first deposited and then a CrOx layer is produced on top in a second process step.
  • Cr and CrOx are formed simultaneously (i.e. in one step), indicated as a Cr-CrOx layer.
  • Chromium oxide is distributed throughout the chromium-chromium oxide coating obtained from the one-step deposition process according to the invention.
  • each single layer contains CrOx distributed throughout each chromium-chromium oxide layer.
  • the degree of porosity is reduced by depositing a plurality (> 1) of Cr- CrOx coating layers on top of each other on one or on both sides of the electrically conductive substrate.
  • Each single Cr-CrOx layer is deposited in a single step, and multiple single layers are deposited in subsequent plating cells or even in subsequent plating lines, or by going through a single cell or plating line more than once.
  • the hydrogen bubbles must be removed from the surface of the strip.
  • the substrate with this one or more layers is understood to be the strip. The bubbles adhere to the outer surface of the coated substrate and from this surface the bubbles need to be removed before the next Cr-CrOx layer is deposited.
  • a buffering agent is a weak acid or base used to maintain the acidity (pH) of a solution near a chosen value after the addition of another acid or base. That is, the function of a buffering agent is to prevent a rapid change in pH when acids or bases are added to the solution.
  • Boric acid is a buffering agent.
  • the hydrogen bubbles are removed from the surface of the strip by the strip exiting and re-entering the electrolyte, or by using a pulse plate rectifier or by a mechanical action such as a shaking action or a brushing action.
  • the bubbles are removed and the next Cr-CrOx coating layers is then deposited onto a surface from which the bubbles have been removed.
  • the product coated on one or both sides with multiple single layers of Cr-CrOx coating layers passes all the performance tests for a packaging application if the steel substrate with the Cr- CrOx coating layer is provided with a polymer coating. Its performance is comparable to or even better than the conventional (Cr(VI)-based !) ECCS material with a polymer coating.
  • the deposition of CrOx is driven by the increase of the surface pH due to the reduction of H + (more formally: H 3 0 + ) to H 2 (g) at the strip surface (being the cathode). This means that hydrogen bubbles form at the strip surface. The majority of these bubbles are dislodged during the plating process, but a minority adheres to the substrate for a time sufficient to cause underplating at those spots leading to porosity of the chromium and chromium oxide layer (Cr- CrOx).
  • This substrate with only a single layer of chromium and chromium oxide (Cr-CrOx) passes all the performance tests for a packaging application where the steel substrate with the Cr-CrOx coating layer is provided with a polymer coating.
  • So bubbles will form at random spots, and not preferably at a porosity.
  • the resulting layer after two or more layers have been deposited i.e. a plurality, which is 2 layers or more
  • the catalytic coating material platinum, irid ium oxide or a mixed metal oxide
  • the boric acid buffering agent was initially omitted from the trivalent chromium based electrolyte so that chromium oxide would preferentially form on the cathode, i.e. in preference to chromium metal .
  • the absence of the boric acid buffering agent in the electrolyte has the effect that the anode becomes very acidic:
  • the electrodepositon of the chromium-chromium oxide coating was carried out in the presence of the electrolyte of the invention, i.e. an electrolyte without chloride ions and without a boric acid buffering agent, a sulphate containing conductivity enhancing salt and an anode comprising a catalytic coating of platinum, a significant amount of hexavalent chromium was observed at the anode. Surprisingly, it was found that the formation of hexavalent chromium was avoided when the catalytic coating of platinum was replaced by a catalytic coating of irid ium oxide or mixed metal oxide.
  • the omission of boric acid from the electrolyte and the selection of an iridium oxide or mixed metal oxide coated anode has the further advantage that it is not necessary to provide the electrolyte with additives, e.g. Mn 2+ ions, in order to suppress or avoid the formation of hexavalent chromium.
  • the present inventors discovered that for the production of ECCS via trivalent Cr chemistry only one simple electrolyte without a buffer is required. Even though this simple electrolyte does not contain a buffer it was found by the present inventors that surprisingly also Cr metal is deposited from this electrolyte due to partial reduction of Cr oxide into Cr metal. This discovery simplifies the overall ECCS production enormously, because an electrolyte with a buffer for depositing Cr metal is not required as is wrongfully assumed by US6004488, but only one simple electrolyte without a buffer, which also solves the problem of contamination of this electrolyte with a buffer.
  • the electrolyte comprises a conductivity enhancing salt, preferably an alkali metal sulphate, more preferably potassium sulphate.
  • a conductivity enhancing salt preferably an alkali metal sulphate, more preferably potassium sulphate.
  • the inventors found that conductivity enhancing salts based on alkali metal sulphates were suitable replacements for conductivity enhancing salts based on chlorides in that good electrolyte conductivity was still obtained, albeit to a lesser degree.
  • An additional advantage is that the use of such electrolytes in combination with iridium oxide or mixed metal oxide anode coatings avoids the formation of harmful by-products such as hexavalent chromium and chlorine. It was found that electrolytes that contained potassium sulphate as the conductivity enhancing salt were very suitable for increasing the conductivity of the electrolyte.
  • Chloride free-lithium, sodium or ammonium salts are also very suitable for increasing the conductivity of the electrolyte.
  • Sodium sulphate is particularly preferred since the solubility of sodium sulphate is much higher than the solubility of potassium sulphate.
  • a higher salt concentration increases the kinematic viscosity of the electrolyte and enables the use of lower currents for depositing chromium- chromium oxide coatings. By lowering the current density, the risk of unwanted side reactions, e.g. oxidation of Cr(III) to Cr(VI), is reduced and the working lifetime of the catalytic coating may be extended.
  • the chelating agent comprises an alkali metal cation and a carboxylate.
  • the benefit of using an alkali metal cation is that its presence greatly enhances the conductivity of the electrolyte. Potassium or sodium cations are particularly preferred for this purpose, since compared to other alkali metal cations, they afford the greatest conductivity enhancement.
  • Chelating agents comprising carboxylate anions, preferably having between 1 and 6 carbon atoms, were used to improve the coating characteristics of the chromium-chromium oxide coating. Suitable carboxylate anions include oxalate, malate, acetate and formate, with formate being most preferred since very good coating characteristics are obtained.
  • the above carboxylate anions are weak chelating agents and may be used alone or in combination. These weak chelating agents destabilise the very stable hexa-aqua complex, where L represents the chelating agent ligand : Cr(H 2 0)
  • the electrolyte comprises sodium sulphate it is preferred to use sodium formate, for instance instead of potassium formate, since this simplifies the electrolyte composition.
  • the electrolyte solution is free of a buffering agent. It has been found that the absence of a buffering agent in the electrolyte enables chromium oxide to be deposited in preference to chromium metal. Further, the omission of a boric acid buffering agent from the electrolyte means that the oxidation of Cr(III) to Cr(VI) is prevented or at least suppressed when the electrolyte comprises an alkali metal sulphate as the conductivity enhancing salt. By omitting the buffer from the electrolyte the surface pH at the cathode increases to between 6.5 and 11.5 such that chromium oxide will be deposited in addition to chromium metal.
  • the trivalent chromium compound comprises basic chromium(III) sulphate.
  • Basic chromium sulphate is very suitable as an alternative to chloride containing chromium compounds such as chromium(III) chloride.
  • basic chromium sulphate in the electrolyte instead of a chloride containing chromium compound, the risk of producing chlorine gas at the anode is avoided.
  • Other preferred trivalent chromium salts comprise chromium(III) formate, chromium(III) oxalate, chromium(III) acetate, chromium(III) potassium oxalate and chromium(III) nitrate.
  • the above salts, including basic chromium(III) sulphate may be provided alone or in combination.
  • the mixed metal oxide comprises oxides of iridium and tantalum.
  • the anode is provided with an electro-catalytic coating based on platinum.
  • electro-catalytic coatings comprising a mixture of iridium oxide and tantalum oxide did not cause hexavalent chromium to form at the anode when the anode was immersed in the chloride-free trivalent chromium based electrolyte.
  • the electrolyte solution is free of a depolariser, preferably potassium bromide.
  • a depolariser preferably potassium bromide.
  • the presence of a depolariser such as bromide in a trivalent chromium based electrolyte suppresses the oxidation of Cr(III) to Cr(VI).
  • the inventors found that despite the absence of a depolariser in the electrolyte, no hexavalent chromium was formed at the anode (platinum coated) when the electrolyte was a chloride trivalent chromium based electrolyte. Instead, it was found that the depolariser suppresses chlorine formation.
  • the inventors also found that when the trivalent chromium based electrolyte of the invention comprised a depolariser and a sulphate based conductivity enhancing salt, a significant amount of hexavalent chromium was formed at the platinum coated anode. Moreover, it was found that bromine gas was formed when the depolariser comprised potassium bromide. Bromine gas is potentially harmful to the environment and to the workers and is therefore undesirable. The inventors discovered that in order to avoid hexavalent chromium formation, it is not necessary to provide a depolariser, e.g.
  • the pH of the electrolyte solution is adjusted to between pH 2.6 and pH 3.4, preferably to between pH 2.8 and pH 3.0. It was found that pH of the electrolyte influences the composition, the surface appearance, e.g. colour, and the surface morphology of the chromium-chromium oxide coating. With respect to the effect of pH on the composition of the chromium-chromium oxide coating, it was found that the amount of chromium metal deposited at the cathode could be increased by providing a trivalent chromium based electrolyte having a pH between pH 2.6 and 3.0. On the other hand, if the pH of the electrolyte is adjusted to above pH 3.0, chromium oxide is deposited in preference to chromium metal.
  • the surface pH has an effect on the surface appearance of the deposited coating.
  • the surface appearance of the chromium-chromium oxide coating changed from grey to a brownish colour as the electrolyte pH was increased.
  • This has been attributed to the composition of the chromium-chromium oxide coating containing more chromium metal (grey) at low pH and more chromium oxide (brown) at higher pH .
  • surface appearance it is preferred to provide an electrolyte having a pH between 2.6 and 3.0 so as to obtain a chromium-chromium oxide coating that is predominantly grey in colour.
  • the electrolyte pH also has a direct impact on the surface morphology of the chromium-chromium oxide coating.
  • the use of an electrolyte having a pH above 3.0 resulted in a chromium-chromium oxide coating having a relatively open and coarse structure.
  • the pH was between 2.6 and 3.0, preferably between 2.8 and 3.0
  • the obtained chromium-chromium oxide coating was characterised by a more compact coating structure that exhibited reduced porosity relative to coatings deposited at a pH above 3.0. From a surface morphology perspective, it is preferred to provide an electrolyte having a pH between 2.8 and 3.0 since a greater improvement in the passivation properties of the coating can be obtained in view of the reduced porosity of such coatings.
  • the electrolyte pH influences the rate at which the chromium-chromium oxide coating is deposited on the substrate.
  • the deposition of chromium oxide at the cathode occurs at a pH between 6.5 and 11.5 and is driven by the reduction of H + (H 3 0 + ) to H 2 (g).
  • H + H 3 0 +
  • H 2 H 2
  • an electrolyte with a pH of at least 3.4.
  • an electrolyte pH of at least 2.8 is preferred.
  • the temperature of the electrolyte solution also influences the deposition reaction and the surface appearance of the chromium-chromium oxide coating. It was found that an electrolyte solution having a temperature between 30 C and 70 C is very suitable for depositing a chromium-chromium oxide coating with a good surface appearance. Preferably the temperature of the electrolyte solution is between 40°C and 60°C since this leads to a more efficient deposition reaction. Within this temperature range, the electrolyte solution exhibits good conductivity, meaning that less power is required to deposit the chromium- chromium oxide coating.
  • the electrically conductive substrate is provided by electrolytically depositing a tin coating on one or both sides of a steel substrate and subjecting the tin coated steel to a diffusion annealing treatment to form an iron-tin alloy on the steel.
  • the steel substrate comprises a recrystalisation annealed single reduced steel or a double reduced steel that was subjected to a recrystalisation annealing treatment between a first rolling treatment and a second rolling treatment.
  • the tin coating may be provided onto one or both sides of the steel substrate in a tin electroplating step, wherein the tin coating weight is at most 1000 mg/m 2 and preferably between at least 100 and/or at most 600 mg/m 2 of the substrate surface.
  • the tin layer is converted into an iron- tin alloy that contains at least 80 weight percent (wt.%) of FeSn (50 at.% iron and 50 at.% tin).
  • This substrate may then be cooled rapidly in an inert, non-oxidising cooling medium, while keeping the coated substrate in a reducing or inert gas atmosphere prior to cooling, so as to obtain a robust, stable surface oxide.
  • the FeSn alloy layer provides corrosion protection to the underlying steel substrate. This is partly achieved by shielding the substrate, as the FeSn alloy layer is very dense and has a very low porosity. Moreover, the FeSn alloy itself is very corrosion resistant by nature.
  • the electrically conductive substrate comprises blackplate or tinplate. It was found that the method of the invention is very suitable for depositing the chromium-chromium oxide coating onto blackplate (also known as uncoated steel) and tinplate, which are both commonly used in the packaging industry.
  • an organic coating is provided on one or both sides of the chromium metal - chromium oxide coated substrate. It was found that organic coatings could be readily applied on to the chromium-chromium oxide coating, which itself acts a passivation layer to protect the electrically conductive substrate. In the case of tinplate or of a steel substrate provided with an FeSn layer, the chromium-chromium oxide coating is provided to passivate the tin surface in order to prevent or at least reduce the growth of tin oxides, which over time, may cause an applied organic coating to delaminate from the substrate. The chromium-chromium oxide coating also exhibited good adhesion to the electrically conductive substrate and to the subsequently applied organic coating.
  • the organic coating may be provided as a lacquer or as a thermoplastic polymer coating.
  • the thermoplastic polymer coating is a polymer coating system that comprises one or more layers of thermoplastic resins such as polyesters or polyolefins, but can also include acrylic resins, polyamides, polyvinyl chloride, fluorocarbon resins, polycarbonates, styrene type resins, ABS resins, chlorinated polyethers, ionomers, urethane resins and functionalised polymers.
  • Polyester is a polymer composed of dicarboxylic acid and glycol.
  • suitable dicarboxylic acids include therephthalic acid, isophthalic acid, naphthalene dicarboxylic acid and cyclohexane dicarboxylic acid.
  • suitable glycols include ethylene glycol, propane diol, butane diol, hexane diol, cyclohexane diol, cyclohexane dimethanol, neopentyl glycol etc. More than two kinds of dicarboxylic acid or glycol may be used together.
  • Polyolefins include for example polymers or copolymers of ethylene, propylene, 1-butene, 1-pentene, 1-hexene or 1-octene.
  • Acrylic resins include for example polymers or copolymers of acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester or acrylamide.
  • Polyamide resins include for example so-called Nylon 6, Nylon 66, Nylon 46, Nylon 610 and Nylon 11.
  • Polyvinyl chloride includes homopolymers and copolymers, for example with ethylene or vinyl acetate.
  • Fluorocarbon resins include for example tetrafluorinated polyethylene, trifluorinated monochlorinated polyethylene, hexafluorinated ethylene- propylene resin, polyvinyl fluoride and polyvinylidene fluoride.
  • Functionalised polymers for instance by maleic anhydride grafting include for example modified polyethylenes, modified polypropylenes, modified ethylene acrylate copolymers and modified ethylene vinyl acetates.
  • thermoplastic polymer coating systems have shown to provide excellent performance in can-making and use of the can, such as shelf-life.
  • the second aspect of the invention relates to a chromium metal - chromium oxide coated substrate produced according to the first aspect of the invention.
  • Chromium carbide was present in the chromium-chromium oxide coating in the chromium metal layer adjacent to the cathode (it was not found in the chromium oxide layer). It is understood that the anion of the chelating agent, e.g. formate, may be the source of the carbide. It is believed that the presence of chromium carbide in the chromium metal promotes growth in the upwards direction relative to the substrate.
  • Organic carbon was predominantly found in the chromium oxide layer, but was also found in the chromium metal layer, more specifically, between the grains of chromium metal in the chromium metal layer. Chromium carbide could be found at these grain boundaries.
  • Chromium sulphate was also found in the chromium-chromium oxide coating. More specifically, sulphate was present in the chromium oxide layer, which indicates that sulphur is incorporated into (bound to) the chromium oxide layer during its formation.
  • the third aspect of the invention relates to the use of the chromium metal - chromium oxide coated substrate in packaging applications.
  • a packaging steel sample (consisting of a commonly used low carbon steel grade and temper) was cleaned in a commercial alkaline cleaner (Chela Clean KC- 25 supplied by Foster Chemicals), rinsed in de-ionised water, pickled in a 5 % sulphuric acid solution at 25°C for 10 s, and rinsed again.
  • the sample was plated with a tin coating (600 mg/m 2 ) from an MSA (Methane Sulphonic Acid) bath that is commonly used for the production of tinplate in a continuous plating line.
  • MSA Metal Sulphonic Acid
  • the tin plated steel sample was annealed in a reducing gas atmosphere, using HNX containing 5 % H 2 (g). The sample was then heated from room temperature to 600 °C at a heating rate of 100 °C/s. Immediately after the sample had reached its peak temperature of 600 °C, the sample was cooled down in 1 s to a temperature of 80 °C by means of a water quench.
  • the iron-tin alloy layer that was formed contained more than 90 % of the FeSn alloy phase.
  • the steel sample with the FeSn alloy layer was provided in a rectangular plating cell with grooves along the side walls for holding the sample and the anodes.
  • the chromium-chromium oxide coating was deposited from an electrolyte containing 120 g/l basic chromium sulphate, 80 g/l potassium sulphate and 51 g/l potassium formate.
  • This electrolyte solution was free from chlorides, a buffering agent, e.g. boric acid, and a depolariser such as potassium bromide.
  • the pH of this electrolyte was approximately 3.85.
  • the temperature of the electrolyte solution was 50°C.
  • the chromium-chromium oxide coating was deposited from an electrolyte for depositing a Cr-CrOx layer consisting of an aqueous solution of chromium (III) sulphate, sodium sulphate and sodium formate and optionally sulphuric acid, the aqueous electrolyte having a pH at 25 °C of between 2.5 and 3.5, preferably at least 2.7 and/or at most 3.1.
  • the electrolyte contains between 80 and 200 g-l "1 of chromium (III) sulphate, preferably between 80 and 160 g-l "1 of chromium (III) sulphate, between 80 and 320 g-l "1 sodium sulphate, preferably between 80 and 320 g-l "1 sodium sulphate, and between 30 and 80 g-l "1 sodium formate.
  • the pH of the electrolyte was stepwise adjusted from pH 3.85 to 3.4, 3.2, 3.0, 2.8 and 2.6 respectively by adding sulphuric acid (98 wt%).
  • the electrolysis time was determined for depositing a total Cr coating weight of ⁇ 60 mg/m 2 , as determined by X-ray fluorescence (XRF) analysis using a SPECTRO XEPOS XRF spectrometer with a Si-Drift Detector.
  • XRF X-ray fluorescence
  • the current density was determined at a fixed electrolysis time of 1 s.
  • the colour of the chromium-chromium oxide coating was determined using a Minolta CM-2002 spectrophotometer according to the well known CIELab system.
  • the CIELab system uses three colour values L*, a* and b* for describing colours, which are calculated from the so-called tristimulus values X, Y and Z.
  • the a* value represents the green-red chromatic axis in the CIELab colour space.
  • the b* value represents the blue-yellow chromatic axis.
  • Table 1 The results of the deposition experiments and the colour measurements are shown in Table 1.
  • EDX Energy Dispersive X- ray
  • the obtained EDX spectra showed that the amount of oxygen in the chromium-chromium oxide coating increased with increasing pH, indicating that chromium oxide is deposited preferentially over chromium metal as the electrolyte becomes less acid.
  • the EDX spectra also revealed the presence of chromium sulphate in the chromium-chromium oxide coating.
  • X-ray photoelectron spectroscopy was also used to characterise the samples (Table 2).
  • XPS spectra and depth profiles were recorded on a Kratos Axis Ultra using Mg Ka X-rays of 1253.6 eV. The measured spot size was 700 ⁇ x 300 ⁇ .
  • the depth profiles were recorded using 4 keV Ar+ ions creating a sputter crater of 3 mm x 3 mm.
  • the sputter rate was calibrated using a BCR standard of 30 nm Ta 2 0 5 on Ta and was 2.15 nm/min.
  • the sputter rate for Cr-species is expected to be similar to Ta 2 0 5 .
  • the porosity of the coatings was also measured by integrating the atomic percentage (as determined by XPS) of Sn + Fe/Cr over the outermost 3.2 nm of the coating.
  • the thickness of the 2-layer coating in Table 2 is twice that of the single layer coating, but the reduction in degree of porosity is independent of the thickness of the two layers. Consequently, in a practical case, the total thickness of the one layer coating and the two layer coating will be similar.
  • the total thickness of the layer consisting of a plurality of single layers is preferably between 20 and 150 mg/m 2 as expressed in Cr-total, more preferably between 25 and 100 mg/m 2 as expressed in Cr-total, even more preferably at least 40 and/or at most 85 mg/m 2 .
  • the thickness of the coating layer is expressed in mg/m 2 as expressed in Cr-total. This is therefore also a measure for the coating weight as expressed in Cr-total.
  • the thickness of a coating layer of 100 mg/m 2 as expressed in Cr-total is therefore 14 nm.
  • Each electrolyte contained 120 g/l basic chromium sulphate.
  • the electro-active surface area of the anode was 122 mm x 10 mm.
  • the anodic current density was 60 A/dm 2 .
  • the ambient air above the solution was analysed by means of chlorine 0.2/a Drager-tubes®.
  • the Cr(VI) concentration in the Cr(III) electrolyte was analysed by means of Differential Pulse Polarography (DPP). The results of the investigation after 5 h electrolysis are shown in Table 3.
  • the conductivity enhancing salt comprises sulphates instead of chlorides
  • significant amounts of hexavalent chromium are formed at the anode when the anode comprises a catalytic coating of platinum (cf. Test no.3 and no.4) .
  • the presence of bromide in a sulphate containing electrolyte can be seen to even increase the formation of hexavalent chromium .
  • the catalytic coating of platinum was replaced by a catalytic coating of a mixed metal oxide of tantalum oxide and irid ium oxide, no hexavalent chromium was formed at the anode (Test no.5 and no.6).
  • chromium-chromium oxide coatings that were (i) deposited according to the method of the present invention (one-step process) or (ii) deposited in accordance with the method of EP0747510 (two-step process). It was found that the use of a one-step or a two-step deposition process influenced the composition of the deposited chromium-chromium oxide coating. Specifically, chromium-chromium oxide coatings obtained from a two-step process contained less chromium oxide than chromium-chromium oxide coatings obtained from a one-step process.

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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)
  • Inorganic Chemistry (AREA)
  • Electroplating And Plating Baths Therefor (AREA)
  • Electroplating Methods And Accessories (AREA)

Abstract

La présente invention concerne un procédé pour la fabrication d'un substrat revêtu de chrome métallique-oxyde de chrome par dépôt électrolytique d'une pluralité de couches de revêtement de chrome métallique-oxyde de chrome sur un substrat électroconducteur à partir d'une solution électrolytique qui comprend un composé du chrome trivalent et un agent chélatant, la solution électrolytique étant exempte d'ions chlorure et d'un agent tampon à base d'acide borique, le substrat électroconducteur servant de cathode et une anode comprenant un revêtement catalytique d'oxyde d'iridium ou d'un oxyde métallique mixte ou une anode de diffusion d'hydrogène gazeux étant choisie pour réduire ou éliminer l'oxydation d'ions Cr(III) en ions Cr(VI), des bulles d'hydrogène, pendant le dépôt d'une couche de chrome métallique-oxyde de chrome, étant formées à la surface de la bande et, entre le dépôt de couches de chrome métallique-oxyde de chrome, les bulles d'hydrogène étant enlevées de la surface de la bande.
PCT/EP2015/061333 2014-05-21 2015-05-21 Procédé pour la fabrication de substrats revêtus de chrome-oxyde de chrome et substrats revêtus produits de cette manière WO2015177315A1 (fr)

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RSP20191121 RS59292B1 (sr) 2014-05-21 2015-05-21 Postupak za proizvodnju supstrata obloženih hromom-hrom oksidom
EP15726901.0A EP3146091B1 (fr) 2014-05-21 2015-05-21 Procédé de fabrication de substrats revêtus d'oxyde chromium-chromium
ES15726901T ES2744566T3 (es) 2014-05-21 2015-05-21 Procedimiento para fabricar sustratos recubiertos con cromo-óxido de cromo

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EP14169277.2 2014-05-21

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WO2018185154A1 (fr) * 2017-04-04 2018-10-11 Atotech Deutschland Gmbh Procédé de dépôt électrolytique d'une couche de chrome ou d'alliage de chrome sur au moins un substrat
EP3666931A1 (fr) 2018-12-13 2020-06-17 ThyssenKrupp Rasselstein GmbH Procédé de fabrication d'une bande métallique ayant un revêtement de chrome et d'oxyde de chrome avec un électrolyte à base de chromium trivalent
EP3722464A1 (fr) 2019-04-09 2020-10-14 ThyssenKrupp Rasselstein GmbH Procédé de passivation de la surface d'une tôle noire ou d'une tôle blanche et système d'électrolyse permettant la mise en oeuvre dudit procédé
CN111793809A (zh) * 2019-04-09 2020-10-20 蒂森克虏拉塞斯坦有限公司 制造涂有涂层的金属带的方法和执行方法的电解系统
WO2022013387A1 (fr) * 2020-07-15 2022-01-20 Tata Steel Nederland Technology B.V. Procédé d'électrodéposition d'une couche de chrome fonctionnelle ou décorative à partir d'un électrolyte au chrome trivalent
US20220136121A1 (en) * 2019-02-25 2022-05-05 Tata Steel Ijmuiden B.V. Method for manufacturing chromium oxide coated tinplate
US11396713B2 (en) 2018-12-13 2022-07-26 Thyssenkrupp Rasselstein Gmbh Method for the production of a metal strip coated with a coating of chromium and chromium oxide using an electrolyte solution with a trivalent chromium compound
EP4159896A2 (fr) 2021-10-04 2023-04-05 ThyssenKrupp Rasselstein GmbH Procédé de passivation de la surface d'une tôle étamée et système d'électrolyse destiné à la mise en uvre du procédé
EP4219795A4 (fr) * 2020-12-21 2024-01-31 JFE Steel Corporation Feuille d'acier traitée en surface et son procédé de production
EP4212650A4 (fr) * 2020-12-21 2024-01-31 JFE Steel Corporation Feuille d'acier traitée en surface et son procédé de production

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EP4083268A1 (fr) * 2021-04-30 2022-11-02 Atotech Deutschland GmbH & Co. KG Composition d'électrodéposition pour le dépôt d'une couche de chrome ou d'alliage de chrome sur un substrat

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WO2013143928A1 (fr) * 2012-03-30 2013-10-03 Tata Steel Ijmuiden Bv Substrat revêtu pour applications d'emballage et procédé de production dudit substrat revêtu

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EP0035667A1 (fr) * 1980-03-10 1981-09-16 International Business Machines Corporation Solution et bain galvanoplastique, à base de chrome trivalent
EP0079768A1 (fr) * 1981-11-18 1983-05-25 International Business Machines Corporation Dépôt électrolytique de chrome et de ses alliages
US5476578A (en) * 1994-01-10 1995-12-19 Electroplating Technologies, Ltd. Apparatus for electroplating
EP0747510A1 (fr) * 1995-06-06 1996-12-11 Atotech Usa, Inc. Revêtement d'oxyde de chrome à partir d'une solution de chrome trivalent
WO2013143928A1 (fr) * 2012-03-30 2013-10-03 Tata Steel Ijmuiden Bv Substrat revêtu pour applications d'emballage et procédé de production dudit substrat revêtu

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CN110446802A (zh) * 2017-04-04 2019-11-12 安美特德国有限公司 在至少一个基底上电解沉积铬或铬合金层的方法
EP4170071A1 (fr) * 2017-04-04 2023-04-26 Atotech Deutschland GmbH & Co. KG Procédé de dépôt électrolytique d'une couche de chrome ou d'alliage de chrome sur au moins un substrat
WO2018185154A1 (fr) * 2017-04-04 2018-10-11 Atotech Deutschland Gmbh Procédé de dépôt électrolytique d'une couche de chrome ou d'alliage de chrome sur au moins un substrat
CN110446802B (zh) * 2017-04-04 2023-02-28 安美特德国有限公司 在至少一个基底上电解沉积铬或铬合金层的方法
US11274373B2 (en) 2018-12-13 2022-03-15 Thyssenkrupp Rasselstein Gmbh Method for the production of a metal strip coated with a coating of chromium and chromium oxide using an electrolyte solution with a trivalent chromium compound
EP3666931A1 (fr) 2018-12-13 2020-06-17 ThyssenKrupp Rasselstein GmbH Procédé de fabrication d'une bande métallique ayant un revêtement de chrome et d'oxyde de chrome avec un électrolyte à base de chromium trivalent
DE102018132075A1 (de) 2018-12-13 2020-06-18 thysenkrupp AG Verfahren zur Herstellung eines mit einer Beschichtung aus Chrom und Chromoxid beschichteten Metallbands auf Basis einer Elektrolytlösung mit einer dreiwertigen Chromverbindung
US11396713B2 (en) 2018-12-13 2022-07-26 Thyssenkrupp Rasselstein Gmbh Method for the production of a metal strip coated with a coating of chromium and chromium oxide using an electrolyte solution with a trivalent chromium compound
US20220136121A1 (en) * 2019-02-25 2022-05-05 Tata Steel Ijmuiden B.V. Method for manufacturing chromium oxide coated tinplate
DE102019109354A1 (de) * 2019-04-09 2020-10-15 Thyssenkrupp Rasselstein Gmbh Verfahren zur Passivierung der Oberfläche eines Schwarzblechs oder eines Weißblechs und Elektrolysesystem zur Durchführung des Verfahrens
JP2020172701A (ja) * 2019-04-09 2020-10-22 ティッセンクルップ ラッセルシュタイン ゲー エム ベー ハー ブラックプレート又はブリキの表面を不動態化するための方法及びその方法を実施するための電解システム
CN111793809A (zh) * 2019-04-09 2020-10-20 蒂森克虏拉塞斯坦有限公司 制造涂有涂层的金属带的方法和执行方法的电解系统
US11401621B2 (en) * 2019-04-09 2022-08-02 Thyssenkrupp Rasselstein Gmbh Method of producing a metal strip coated with a coating of chromium and chromium oxide using an electrolyte solution with a trivalent chromium compound and electrolysis system for implementing the method
CN111793815A (zh) * 2019-04-09 2020-10-20 蒂森克虏拉塞斯坦有限公司 钝化黑钢板或镀锡钢板表面的方法和执行方法的电解系统
EP3722464A1 (fr) 2019-04-09 2020-10-14 ThyssenKrupp Rasselstein GmbH Procédé de passivation de la surface d'une tôle noire ou d'une tôle blanche et système d'électrolyse permettant la mise en oeuvre dudit procédé
CN111793809B (zh) * 2019-04-09 2023-08-08 蒂森克虏拉塞斯坦有限公司 制造涂有涂层的金属带的方法和执行方法的电解系统
WO2022013387A1 (fr) * 2020-07-15 2022-01-20 Tata Steel Nederland Technology B.V. Procédé d'électrodéposition d'une couche de chrome fonctionnelle ou décorative à partir d'un électrolyte au chrome trivalent
EP4219795A4 (fr) * 2020-12-21 2024-01-31 JFE Steel Corporation Feuille d'acier traitée en surface et son procédé de production
EP4212650A4 (fr) * 2020-12-21 2024-01-31 JFE Steel Corporation Feuille d'acier traitée en surface et son procédé de production
EP4159896A2 (fr) 2021-10-04 2023-04-05 ThyssenKrupp Rasselstein GmbH Procédé de passivation de la surface d'une tôle étamée et système d'électrolyse destiné à la mise en uvre du procédé
DE102021125696A1 (de) 2021-10-04 2023-04-06 Thyssenkrupp Rasselstein Gmbh Verfahren zur Passivierung der Oberfläche eines Weißblechs und Elektrolysesystem zur Durchführung des Verfahrens

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