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
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C13/00—Alloys based on tin
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C18/00—Alloys based on zinc
• • 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
  • C25D3/60—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of tin

Definitions

• the invention relates to galvanic electrolyte baths and their use.
• Higher requirements such as resistance to salt spray testing up to the first occurrence of red rust of up to 1000 hours, may be met by coating with zinc alloys containing nickel, cobalt or iron as the alloying component followed by chromating.
• the proportion of alloying elements may be less than 1% by weight, for example 0.4-0.6% by weight of Fe in the ZnFe system, up to 15% by weight, for example 12-15% by weight of Ni in the ZnNi system ( Zinc alloy process: properties and applications in the art , Dr. A. Jiménez, B. Kerle and H. Schmidt, Galvanotechnik 89 (1998) 4 ).
• Tin-zinc alloy layers can also be used as anti-corrosion layers for iron.
• values of up to 1000 hours are achieved with chromated SnZn layers until the first appearance of red rust.
• the most favorable alloy composition is 70% by weight of Sn and 30% by weight of Zn.
• the disadvantage seen is the low hardness of SnZn layers of only about 50 HV ( Tin-Zinc-Plating, E. Budmann and D. Stevens, Trans. IMF 76 (1998) 3 ).
• the invention therefore an object of the invention to find galvanic electrolyte baths for the deposition of alloy systems with particularly high corrosion resistance, which meet the future requirements in terms of corrosion protection.
• the above electrolytic baths can be used for electroplating a ternary tin-zinc-cobalt alloy layer consisting of 30 to 65% by weight of tin, 30 to 65% by weight of zinc and 0.1 to 15% by weight of cobalt.
• the alloy layer consists of 40 to 55 wt.% Tin, 45 to 55 wt.% Zinc and 1 to 5 wt.% Cobalt.
• the alloy layer can serve as a corrosion protection layer, as a solderable layer or as a decorative final layer. Furthermore, it can be used with a subsequent passivation as a corrosion protection layer on a ferrous material.
• ternary tin-zinc alloys according to the invention which consist of 30 to 65 wt.% Tin, 30 to 65 wt.% Zinc and 0.1 to 15 wt.% Cobalt, as a third alloy component, the requirements meet with regard to corrosion resistance excellent.
• the alloy layers are produced by electroplating, namely by electrolytic deposition from aqueous electrolytic electrolyte baths containing the alloy components in dissolved form.
• the tin-zinc ternary alloys can be deposited on substrates from alkaline or neutral galvanic electrolyte baths.
• An alkaline electrolyte is understood here to mean an electrolyte having a pH greater than 10.
• the neutral electrolyte is an electrolyte with a pH of 6 - 10.
• the alloy components are added to the aqueous electrolyte bath in the form of their respective medium soluble ionic compounds.
• Tin is preferably used as sulfate, chloride, sulfonate, oxalate or in the form of sodium or potassium stannate.
• Zinc is preferably added as sulfate, chloride, hydroxide, sulfonate or oxide.
• cobalt is preferably added as each of sulfate, chloride, hydroxide or carbonate.
• the galvanic electrolytes according to the invention for the production of ternary tin-zinc alloy layers may further contain customary and known additives and auxiliaries in electroplating.
• additives and auxiliaries may be alkalis for pH adjustment, such as sodium, potassium or ammonium hydroxide, or inorganic acids, such as hydrochloric acid, sulfuric acid, phosphoric acid, boric acid, alkali metal salts of these acids as buffer and / or conductive salts, organic acids such as hydroxycarboxylic acids and / or salts thereof, for example citric acid, complexing agents such as EDTA, wetting agents, brighteners, etc.
• citric acid complexing agents
• complexing agents such as EDTA
• wetting agents wetting agents
• brighteners etc.
• the ratio of the metals in the electrodeposited alloy layer can be influenced in a known manner by the ratio of the metals in the bath composition, by the nature and amount of the other bath components and by the deposition parameters.
• the substrate to be coated for example a component to be protected from corrosion from an iron material
• the substrate to be coated is immersed in a corresponding galvanic bath and wired as a cathode.
• Anodes can be used as counterelectrodes of insoluble or, preferably in the case of neutral electrolytes, soluble materials.
• Insoluble anodes are usually made of graphite or platinized titanium.
• Soluble anodes suitably consist of the metals of the alloy layer to be deposited, preferably in the desired composition.
• a temperature of about 20 - 70 ° C and a current density of about 0.1 - 5 A / dm 2 are considered, with deposition rates of about 0, 05 - 1 ⁇ m / minute.
• the galvanic deposition of the alloy takes place at temperatures between 40-70 ° C at current densities of 1 - 5 A / dm 2 with deposition rates of 0.15 - 0.3 microns / minute.
• As anodes graphite or platinized titanium can be used.
• organic acids and their salts organic acids and their salts, phosphonic acids, phosphonates, gluconates, glucoheptonic acids, glucoheptonates and ethylenediaminetetraacetic acid can be used.
• Suitable wetting agents and brighteners can be used in the appropriate media resistant surfactants, polyhydric alcohols and betaines.
• the alloy composition of the layer can be varied.
• an increase in the hydroxide content causes a reduction in the tin content and a corresponding increase in the other two metals in the layer.
• An increase in the amount of complexing agent causes a decrease in the zinc content and an increase in the tin content in the layer.
• these changes have virtually no influence.
• the galvanic deposition of the alloy is carried out at temperatures between 40-70 ° C at current densities of 0.5 - 3 A / dm 2 with deposition rates of 0.05 - 0.3 microns / minute.
• As anodes graphite or platinized titanium can be used. The use of soluble anodes is also possible.
• the ratio of the alloy composition can be varied by varying the coating parameters.
• the ternary tin-zinc alloys have very advantageous material properties, due to which they can be used both as an independent material, and in particular in the form of coatings on substrates in different ways.
• the ternary tin-zinc alloys have a particularly high corrosion resistance. Therefore, these alloys are particularly suitable as corrosion protection coatings on iron materials. Accordingly, the corresponding galvanic electrolytes can preferably be used to produce corrosion protection coatings on iron materials.
• coated iron sheets in combination with the usual passivation by chromating or chromitization readily achieve a resistance to the occurrence of red rust of over 3000 hours.
• the properties of the ternary tin-zinc alloy layers can be optimized depending on the choice of the third alloy element.
• Table 1 gives an overview of the influence of the third alloying element when either good corrosion resistance, hardness, abrasion or solderability are desired.
• the nickel and iron alloys are given as comparative examples. ⁇ b> ⁇ u> Table 1 ⁇ / u> ⁇ /b> corrosion hardness abrasion solderability SnZnNi + - + - SnZnFe - + - + SnZnCo + + - +
• the SnZnFe and SnZnCo alloy layers achieve the highest hardness values.
• the highest abrasion resistance is exhibited by SnZnNi layers.
• Such alloy layers can therefore be used advantageously as wear protection layers under mechanical stress.
• SnZnFe and SnZnCo layers are particularly easy to solder and are therefore excellently suited in electronics as solderable layers and as contact surfaces.
• Table 2 shows the corresponding data for exemplarily selected alloy systems.
• the ternary tin-zinc alloys can also be used as decorative end layers.
• the three alloy systems depending on the choice of the third alloy element, interesting and appealing, lying in the blue range colors.
• the above-mentioned layer composition can be obtained with this electrolyte at a temperature of 60 ° C and current densities of 1-2 A / dm 2 . In this case, about 0.2 microns alloy layer are built up per minute. The density of the alloy layer is 7.27 g / cm 3 .
• the above-mentioned layer composition can be obtained with this electrolyte at a temperature of 60 ° C and current densities of 0.5 - 1 A / dm 2 . 0.15 ⁇ m layer is built up per minute.
• the density of the alloy layer is 7.27 g / cm 3 .
• the above-mentioned layer composition can be obtained with this electrolyte at a temperature of 40 ° C and current densities of 1.5 A / dm 2 . In this case, about 0.4 microns alloy layer are built up per minute. The density of the alloy layer is 7.2 g / cm 3 .
• the above-mentioned layer composition can be obtained with this electrolyte at a temperature of 40 ° C and current densities of 1.5 A / dm 2 . In this case, about 0.4 microns alloy layer are built up per minute. The density of the alloy layer is 7.25 g / cm 3 .

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

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• 2000
  • 2000-09-16 DE DE10045991A patent/DE10045991A1/de not_active Ceased
• 2001
  • 2001-08-16 WO PCT/EP2001/009452 patent/WO2002022913A2/de active Application Filing
  • 2001-08-16 DE DE50114623T patent/DE50114623D1/de not_active Expired - Lifetime
  • 2001-08-16 CN CN01816986.4A patent/CN1239751C/zh not_active Expired - Fee Related
  • 2001-08-16 JP JP2002527347A patent/JP4817352B2/ja not_active Expired - Fee Related
  • 2001-08-16 US US10/380,212 patent/US20040091385A1/en not_active Abandoned
  • 2001-08-16 EP EP01969597A patent/EP1319093B1/de not_active Expired - Lifetime
• 2003
  • 2003-09-25 HK HK03106913.8A patent/HK1054576A1/xx not_active IP Right Cessation

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