Classifications

• • 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
  • C25D3/565—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of zinc
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
• • 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
• • 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

Definitions

• the present invention relates to an aqueous, alkaline electrolyte and a method for the deposition of zinc-containing layers
• the present invention relates to an aqueous, alkaline electrolyte and a method for the deposition of zinc-containing layers on surfaces of piece goods, in which the piece goods is introduced into the aqueous alkaline electrolyte.
• the invention furthermore relates to a piece goods provided with a zinc-containing layer and to the use of the zinc-containing layer as corrosion protection on metallic piece goods, in particular those made of iron and steel.
• a widely used and established method in the art is the application of a metallic coating to the metallic workpiece to be protected.
• workpieces made of iron and steel are often galvanized in order to protect them from corrosive environmental influences.
• the coating metal in the corrosive medium electrochemically nobler or base behave than the material base metal alone. If that is Coating metal behaves subordinate, it acts as a sacrificial anode in the corrosive medium in the sense of a cathodic protection against the base metal.
• the corrosion protection of zinc based on the fact that it is still less noble than the base metal and therefore initially attracts the corrosive attack exclusively on itself.
• zinc coatings are particularly suitable in the field of functional coatings.
• the zinc layer can be used with various chemical and physical
• Processes are applied, for example in the hot dip process, where alloys are common, but in particular by means of electrolytic
• Electrolytic compositions are described in numerous patents; In the following, only the essential electrolyte types are listed:
• Chloride electrolytes are almost exclusively in the Piece electroplating used for relatively fast and sometimes high-gloss galvanizing
• the electrodeposited zinc layer normally sacrifices itself so rapidly in corrosive media such as saline solutions, acids or alkalis to form massive, voluminous corrosion products, so that almost all of them themselves are sacrificed by an additional barrier layer, typically one
• the corrosion protection obtained is usually expressed in terms of two types of corrosion: the coating corrosion, ie the formation of zinc corrosion products, also known as “white corrosion", and the base metal corrosion, in the case of iron or steel also called “red rust”.
• the coating corrosion ie the formation of zinc corrosion products, also known as "white corrosion”
• the base metal corrosion in the case of iron or steel also called “red rust”.
• Common test methods are the neutral salt spray test DIN EN ISO 9227 or ASTM B1 17 as well as climate change tests such as VDA 233-102.
• the zinc + passivation system has reached a technical limit that can not be exceeded, but is sufficient for many applications.
• numerous zinc alloys co-deposits of zinc with one or more other metals
• zinc / cobalt and zinc / iron both with very low alloy contents of less than 1% Co or Fe
• zinc / nickel > 7% Ni
• zinc / nickel with a nickel content of 13-15% which is the current optimum in terms of corrosion protection, heat resistance and avoidance of contact corrosion with aluminum alloys, has meanwhile become established as the only zinc alloy system.
• this layer is widely used.
• the other zinc electroplated zinc electroplated alloys were completely or largely displaced by zinc / nickel.
• nickel has the disadvantage of being a strong allergen.
• zinc / nickel layers sometimes precipitate when the nickel content becomes too high, and this already starts at about 17% nickel.
• Such a layer is in Relative to the parent metal is no longer base, and therefore it loses its function as a sacrificial anode in the cathodic corrosion protection system.
• the object of the present invention is to provide a zinc-containing layer which, even without nickel, has the highest possible
• the necessarily resulting corrosion products should be as inconspicuous as possible, especially not white and voluminous as the typical zinc corrosion products.
• JP63176490A which describes a phosphatizable zinc / iron / manganese layer, but this is a process in one
• Sulphate electrolytes with very high current densities and belt speeds as is customary for electrolytic strip galvanizing.
• Sulphate electrolytes are not suitable for piece electroplating because they are optimized for the high speed and current densities (about a factor of 50-100 more than usual in piece electroplating) and moreover react very sensitively to different anode-cathode spacings. In addition, they are difficult or impossible to adjust with organic additives.
• strip galvanizing the anode-cathode distance is fixed and does not vary practically.
• the piece electroplating parts are coated, not just flat sheet metal, but finished molded or cast parts with z.T. sophisticated three-dimensional geometry. Therefore, the teaching described in JP63176490A is not useful for the present task.
• Zinc, iron and manganese are said to be in a wide range
• an aqueous, alkaline electrolyte for electrodeposition of a zinc, iron, manganese-containing layer on surfaces of metallic piece goods, in particular piece goods made of iron and / or steel characterized in that the electrolyte contains: Zinc ions in an amount of 4-60 g / l, preferably 4-45 g / l, more preferably 4-30 g / l, even more preferably 5-20 g / l, especially 7-10 g / l;
• Iron ions in an amount of 0.5-30 g / l, preferably 0.5-25 g / l, more preferably 0.6-25 g / l, even more preferably 0.7-10 g / 1, in particular from 1 to 3 g / l;
• Manganese ions in an amount of 0.1-15 g / l, preferably 0.1-10 g / l, more preferably 0.2-8 g / l, even more preferably 0.2-5 g / l in particular from 0.3 to 1 g / l.
• anions such as acetate, carbonate, chloride, silicate, sulfate, as counterions to the abovementioned cations and, together with the sodium and potassium ions, as conductive salts, and / or
• This layer can be passivated in trivalent or chromium-free conversion layers and, moreover, can still be provided with organic or inorganic topcoats.
• the electrolyte according to the invention has the following economic and ecological advantages:
• the electrolyte according to the invention does not contain nickel, which would like to be avoided as a strong allergen for reasons of occupational safety.
• the corrosion protection that can be generated with this electrolyte can compete with the zinc / nickel layers according to the prior art and thus represents a much better tolerated alternative.
• Zinc, iron and manganese are essential for humans and generally well tolerated.
• the electrolyte according to the invention is alkaline, preferably highly alkaline with a pH of more than 13, preferably 13.5-14.5, in particular about 14. Beyond that, however, pose no special dangers. Despite the increase in the alloying partners from one to two and the associated complexity of the electrolyte according to the invention is to operate with the same efficiency as an alkaline zinc / nickel bath.
• Suitable sources of zinc ions may be soluble zinc compounds such as zinc chloride, zinc sulfate or organic zinc compounds such as zinc methanesulfonate. Usually, zinc oxide or even metallic zinc is dissolved in the highly alkaline electrolyte and thus produces the necessary zincate ions.
• Suitable sources of iron ions can be soluble iron compounds such as iron chloride, iron sulfate, iron carbonate or organic
• Iron compounds such as iron acetate.
• Suitable sources of manganese ions may be soluble manganese compounds such as manganese chloride, manganese sulfate, manganese carbonate or potassium permanganate. The latter would be reduced in the bath mixture preferably with a little methanol to a soluble manganese compound.
• the electrolyte complexing agent in particular amines,
• Further optional constituents of the electrolyte are additives selected from the group consisting of brighteners, wetting agents and mixtures thereof. These include preferably benzylpyridinium carboxylate, nicotinic acid, N-methylpyridinium carboxylate and aldehydes.
• the anode is preferably made of steel, nickel, nickel-plated steel, platinum-plated titanium or another platinum-plated inert metal or mixed-oxide-coated titanium or another mixed metal-coated inert metal.
• the connected as a cathode metallic workpieces are attached to the frame or coated in a drum or other suitable for bulk cargo equipment.
• a method is also provided for the galvanic deposition of zinc-containing layers on surfaces of piece goods, in which the piece goods are introduced into an electrolyte, as described above, and zinc-containing layers are electrodeposited on the piece goods.
• the deposition is preferably carried out at a temperature of 20 to 40 ° C, more preferably at a temperature of 25 ° C.
• the current density in the deposition is preferably in a range of 0.1 to 20 A / dm ⁇ 2>, in particular from 0.5 to 3 A / dm ⁇ 2>.
• Another object of the present invention is a zinc-containing layer prepared by a method as described above.
• the zinc, iron, manganese-containing layer contains metallic zinc and iron as well as metallic and / or oxidic manganese.
• the weight fractions of the elements can be measured by energy dispersive X-ray spectroscopy, EDX.
• the weight fraction of the elements in a zinc, iron, manganese-containing layer deposited by the method according to the invention is usually in the following ranges:
• Zinc is usually in the range of 40% by weight to 96% by weight, preferably from 65% by weight to 92% by weight, more preferably from 77% by weight to 89% by weight, based in each case on the total weight of zinc, iron, manganese.
• the proportion by weight of iron is usually in the range from 4% by weight to 50% by weight, preferably from 8% by weight to 30% by weight, more preferably from 10% by weight to 20% by weight, based in each case on the total weight of zinc , Iron, manganese.
• the proportion by weight of manganese is usually in the range from 0.05% by weight to 10% by weight, preferably from 0.1% by weight to 5% by weight, more preferably from 0.5% by weight to 3% by weight, in each case based on the total weight of zinc, iron, manganese.
• the thickness of the zinc-containing layer may vary, for example, depending on the desired anti-corrosion properties. For the most Applications, it has proven to be favorable, the zinc-containing layer with a mean layer thickness of 3 ⁇ to 30 ⁇ , preferably from 5 ⁇ to 20 ⁇ , and in particular of 7 ⁇ ⁇ ⁇ 15 ⁇ adjust.
• Layer thickness can be Magnetinduktiv, by means of X-ray fluorescence on copper parts or by measuring a break in the
• Scanning electron microscope can be determined.
• the zinc, iron, manganese-containing layer with adapted passivation is zinc, iron, manganese-containing layer with adapted passivation
• Articles or articles which have a zinc, iron, manganese-containing layer according to the invention can therefore be permanently and thus particularly advantageously protected against corrosion.
• Articles or articles which have a zinc-containing layer according to the invention are also the subject of the present invention.
• a zinc, iron, manganese-containing layer prepared from an aqueous, alkaline electrolyte according to claim 1 as corrosion protection
• Potassium zincate electrolyte iron: 1 1, 8-12.5%, manganese: 0.2-2.0%, remainder zinc sodium zincate electrolyte: iron: 1 1, 9-12.5%, manganese: 0.2-2.0 %, Remainder zinc
• Both sheets were passivated in SurTec 680 Chromittechnik and dried.
• the dried sheets were annealed at 120 ° C for 24 hours to reduce corrosion protection in accordance with VDA requirements.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Mechanical Engineering (AREA)
• Electroplating And Plating Baths Therefor (AREA)
• Electroplating Methods And Accessories (AREA)

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• 2017
  • 2017-12-22 CN CN201780079887.XA patent/CN110291229B/zh active Active
  • 2017-12-22 EP EP17822685.8A patent/EP3559318A1/de active Pending
  • 2017-12-22 WO PCT/EP2017/084331 patent/WO2018115413A1/de unknown
  • 2017-12-22 JP JP2019533422A patent/JP7002548B2/ja active Active
  • 2017-12-22 US US16/472,217 patent/US11578419B2/en active Active

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