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
  • C25D5/10—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
• • 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
  • C25D3/56—Electroplating: Baths therefor from solutions of alloys
• • 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
  • C25D5/34—Pretreatment of metallic surfaces to be electroplated
  • C25D5/36—Pretreatment of metallic surfaces to be electroplated of iron or steel
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12181—Composite powder [e.g., coated, etc.]

Definitions

• the present invention is based on an aluminum / magnesium alloy coated workpieces, as well as a method for their Production.
• the deposition of aluminum, magnesium or aluminum / magnesium alloys on workpieces made of base metal is a proven way to protect these workpieces from corrosion. she are simultaneously provided with a decorative coating.
• the protective metal layer is predominantly galvanic on the workpiece deposited. By the deposited metal layer, the corrosion resistance of the workpiece significantly improved. It turns out, however, that the Corrosion resistance of the workpiece from the adhesion of the applied Protective layer on the workpiece depends. In case of insufficient adhesion of the Protective layer on the workpiece, the protective layer is easily removed, for. For example Screwing one with a surface layer of aluminum, magnesium or an aluminum / magnesium alloy provided screw as a workpiece in a second workpiece. As a result, corrosion occurs at these points, in particular Contact corrosion on. This corrosion inevitably leads to the destruction of the Workpiece. A long-term prevention of corrosion is therefore not guaranteed.
• EP 1 141 447 B1 electrolytes for coating of Workpieces with layers of aluminum / magnesium alloys revealed. Such a coating is particularly necessary when compounds with Magnesium parts are to be produced because the corrosion products of the magnesium metal alkaline and attack the aluminum surface coatings. By using aluminum / magnesium alloys, the contact corrosion is here avoided and causes a long-term stability of the coating. It is proposed steel fasteners for contact with magnesium components, especially in the automotive industry with aluminum / magnesium alloys to coat. In EP 1 141 447 B1 no metallic Interlayers between the workpiece and the corrosion-reducing Layer of an aluminum / magnesium alloy are arranged disclosed.
• the above-described corrosion occurs increasingly at high pH values, so that in both cases mentioned above the destruction of the surface layer of the fastener or component, the corrosion rate increases at high pH.
• the technical object of the present invention is coated To provide workpieces that have improved corrosion resistance, especially in the alkaline range and in combination with others Materials show a reduced corrosion, especially when the coated workpieces as fasteners for fastening components be used.
• a coated workpiece comprising a substrate, an applied on the substrate metallic intermediate layer and an applied on the intermediate layer Layer containing an aluminum / magnesium alloy.
• the surface of the substrate electrically conductive. This can preferably be achieved by a coating of the Substrates made with graphite.
• the substrate contains a metal and / or a metal alloy.
• the substrate may be a metallized substrate, wherein the Substrate may be metallized over the entire surface or part of the surface.
• Preferred substrates contain plastics.
• the substrate may further contain ingredients selected from the Group iron, steel, iron alloy, non-ferrous metals, zinc die casting, die-cast aluminum, Titanium, titanium as alloy, magnesium, magnesium die casting or mixtures thereof, wherein the aforementioned metals preferably present as an alloying ingredient in the substrate.
• the metallic intermediate layer preferably contains iron, iron and nickel, tin and nickel, nickel, cobalt, copper, chromium, molybdenum, vanadium or alloys of the aforementioned metals.
• the metallic intermediate layer preferably has a layer thickness from 0.1 ⁇ m to 30 ⁇ m.
• the Layer thickness of the metallic intermediate layer 0.5 microns to 20 microns, more preferably 1 ⁇ m to 10 ⁇ m and most preferably 1.5 ⁇ m to 8 ⁇ m
• an aluminum / magnesium alloy preferably contains 0.5 to 70 % By weight of magnesium. In a further preferred embodiment, 1 to 50 % By weight, more preferably from 2 to 40% by weight, in a further preferred embodiment 3 to 30% by weight, preferably 4 to 25% by weight, and most preferably 5 to 20 wt.% Magnesium in the aluminum / magnesium alloy.
• the layer contains an aluminum / magnesium alloy a layer thickness of 0.1 .mu.m to 100 .mu.m.
• the layer thickness is 0.5 microns to 70 microns, farther preferably 1 .mu.m to 50 .mu.m, preferably 2 .mu.m to 40 .mu.m, more preferably 3 .mu.m to 30 microns, more preferably 4 microns to 28 microns and most preferably 5 microns to 25 ⁇ m.
• the layer containing the aluminum / magnesium alloy is preferably the surface layer of the coated workpiece. alternative may still at least one layer on the layer containing the aluminum / magnesium alloy be applied, preferably a passivation is.
• the coated workpiece is preferably a rack product, a Bulk goods or an endless product, wherein the coated workpiece is preferably a wire, a sheet metal, a bolt, a nut, a concrete anchorage, a fastener or a machine component is.
• the coated workpiece in the automotive industry in the transmission, engine and Used body area. It can be an oil pan or a transmission oil pan be.
• the metallic intermediate layer is made an aqueous solution or a non-aqueous solution.
• the metallic intermediate layer chemically deposited.
• the metallic intermediate layer may consist of a aqueous electrolytes are electrodeposited.
• Possible electrolytes are solutions of metal salts of iron, cobalt, nickel, copper or Tin. These may be in the form of halides, sulfates, sulfonates or fluoroborates.
• the electrolytes may contain other additives such.
• the metallic intermediate layer is electrodeposited from a non-aqueous electrolyte.
• Possible Electrolytes contain compounds of molybdenum or vanadium or all other aforementioned metals, which may contain the intermediate layer.
• the metals are preferably in the form of halides which are reacted with ethers, in particular diethyl ether and / or acetylacetonate (acac) can be complexed.
• the layer containing an aluminum / magnesium alloy is deposited from an anhydrous electrolyte.
• the layer containing an aluminum / magnesium alloy is electrodeposited from an anhydrous electrolyte.
• the electrolyte used may be any electrolyte which is familiar to the person skilled in the art.
• the electrolyte contains organoaluminum compounds of the general formulas (I) and (II) M [(R 1 ) 3 Al- (H-Al (R 2 ) 2 ) n -R 3 ] Al (R 4 ) 3 wherein n is 0 or 1, M is sodium or potassium and R 1 , R 2 , R 3 , R 4 may be the same or different, wherein R 1 , R 2 , R 3 , R 4 is a C 1 to C 4 Alkyl group and a halogen-free, aprotic solvent is used as a solvent for the electrolyte.
• the electrolyte used may be a mixture of the complexes K [AlEt 4 ], Na [AlEt 4 ] and AlEt 3 .
• the molar ratio of the complexes to AlEt 3 is preferably 1: 0.5 to 1: 3 and more preferably 1: 2.
• the electrolytic deposition of the layer containing an aluminum / magnesium alloy on the workpiece is using a soluble Aluminum and a likewise soluble magnesium anode or using an anode made of an aluminum / magnesium alloy.
• the electrolytic coating is preferably at a temperature performed from 80 to 105 ° C.
• a temperature of the galvanizing bath is preferred from 91 to 100 ° C
• the substrate is before in step a) the metallic intermediate layer is applied, one the electrical Current-conducting layer applied.
• the electric current conducting layer can be used with any method be applied to the substrate, which is known in the art.
• the electric current conducting layer by metallization applied to the substrate.
• Fastening means When the coated workpiece of the present invention is referred to as Fastening means is used, unexpectedly no impairment occurs of the coated workpiece. Although a surface layer of a Aluminum / magnesium alloy is very hard, brittle and less ductile, it sticks still very strong after and during use as a fastener on the coated workpiece. Furthermore, the coating used consisting of the intermediate layer and the surface layer so elastic that it has not changed adversely after use as a fastener. If the coated workpiece is e.g. screwed as a screw in a component unexpectedly replenishes the surface treatment of the workpiece. This then leads to a further reduction in the stress of the coated Workpiece. Because no destruction of the metallic intermediate layer as well the surface layer containing an aluminum / magnesium alloy occurs, The coated workpiece is safe even after and during its use protected against corrosion, especially against contact corrosion.
• a sheet metal of size 100 x 25 x 1 mm steel St37 is made with a nickel intermediate layer provided with a thickness of about 1 micron.
• the nickel layer is out an aqueous nickel sulfamate electrolytically deposited.
• following is a layer of an aluminum / magnesium alloy with a Magnesium content of 20 wt .-% and a layer thickness of 12 microns by galvanic Deposition from a non-aqueous electrolyte on the nickel layer deposited.
• the coated sheet is lengthwise at an angle of Bent 180 °, wherein the applied metal layers in the region of the bending edge stay intact.
• a sheet metal of size 100 x 25 x 1 mm steel St37 is made with a layer of an aluminum / magnesium alloy with a magnesium content of 20% by weight and a layer thickness of 12 microns by electrodeposition of a provided with non-aqueous electrolyte.
• the thus coated sheet becomes the length bent at an angle of 180 °, wherein at the bending edge parts of the coating tear open and sometimes flake off in the form of the finest needles.
• Five screws of size M6 x 55 are made with an aluminum / magnesium alloy with a magnesium content of 15 wt .-% and a layer thickness of 16 ⁇ m by electrodeposition from a non-aqueous electrolyte Mistake.
• the nickel layer is made of an aqueous Nickel sulfamate electrolytically deposited.
• the following will be on the nickel layer is an aluminum / magnesium alloy with a magnesium content of 15 wt .-% and a layer thickness of 16 microns by electrodeposition applied from a non-aqueous electrolyte.
• Screws of size M5 x 5 are in a drum with an aluminum / magnesium alloy with a magnesium content of 10 wt .-% and a average layer thickness of 14 microns from a non-aqueous electrolyte galvanically coated.
• the nickel layer is made of an aqueous nickel sulfamate electrolyte applied galvanically. The following is on the nickel layer in a drum, a layer of an aluminum / magnesium alloy with a magnesium content of 10% by weight and an average layer thickness of 15 microns of a non-aqueous electrolyte applied electroplated.
• Each three equally coated screws are in a housing until it stops made of an aluminum / magnesium alloy with a screw diameter screwed in matching bag nut.
• the following is the corrosion behavior examined in a salt spray chamber. It turns out that the Housing in which the screws are screwed with an intermediate layer of nickel were only significantly later corroded. The case with the Screws without nickel interlayer show first at an earlier time Corrosion phenomena.
• the metallic interlayer significantly improves the corrosion resistance conditionally.
• Coated workpieces comprising a substrate, one on the Substrate applied metallic intermediate layer and one on the intermediate layer coated layer containing an aluminum / magnesium alloy show a superior property profile that matches the workpieces of the prior art Do not have technology.

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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)
• Other Surface Treatments For Metallic Materials (AREA)
• Laminated Bodies (AREA)
• Electroplating And Plating Baths Therefor (AREA)

Priority Applications (8)

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Publications (1)

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Citations (4)

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• 2003
  • 2003-10-18 EP EP03023454A patent/EP1524336A1/de not_active Withdrawn
• 2004
  • 2004-09-09 US US10/576,284 patent/US20070212563A1/en not_active Abandoned
  • 2004-09-09 KR KR1020067007417A patent/KR20060097016A/ko not_active Application Discontinuation
  • 2004-09-09 CN CNA2004800307029A patent/CN1871375A/zh active Pending
  • 2004-09-09 JP JP2006534735A patent/JP2007509233A/ja not_active Abandoned
  • 2004-09-09 WO PCT/EP2004/052097 patent/WO2005035835A2/de active Application Filing
  • 2004-09-09 EP EP04766747A patent/EP1675974A2/de not_active Withdrawn
  • 2004-09-09 RU RU2006117025/02A patent/RU2353714C2/ru not_active IP Right Cessation

Patent Citations (4)

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