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
• • 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
  • C25D3/567—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of platinum group metals
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C5/00—Alloys based on noble metals
  • C22C5/04—Alloys based on a platinum group metal
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D21/00—Processes for servicing or operating cells for electrolytic coating
• • 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
  • C25D3/12—Electroplating: Baths therefor from solutions of nickel or cobalt
  • C25D3/14—Electroplating: Baths therefor from solutions of nickel or cobalt from baths containing acetylenic or heterocyclic compounds
  • C25D3/18—Heterocyclic compounds
• • 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
  • C25D3/50—Electroplating: Baths therefor from solutions of platinum group metals
• • 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
• • 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

Definitions

• the invention relates to an electrolyte bath for the deposition of binary palladium-tin alloys, a composition for such an electrolyte bath, the use of such an electrolyte bath, a method for coating with such an electrolyte bath, a coating and an article coated with the coating.
• cyanide baths are disclosed.
• cyanide baths are highly toxic, and the use of cyanides should be avoided.
• GB1468580 discloses a sulfite bath for the deposition of palladium and palladium alloys.
• the bath contains between 1 and 200 g/l of sulfite.
• the color of the deposit of palladium alloys from sulfite electrolyte baths is often darker.
• sulfite electrolyte baths often have stability problems.
• US 2003047460 discloses palladium and palladium alloy baths, where palladium is added as a special ethylenediamine complex.
• the pH of the bath is acidic and ranges between 3 and 5. Only thin-layer palladium alloys can be deposited from these electrolytic baths.
• the object is therefore to provide an electrolyte bath from which a crack-free coating with a high layer thickness can be deposited, which is more cost-effective in particular compared to pure palladium and which has high abrasion resistance and good corrosion resistance, wherein the coating is particularly shiny and has a light color, preferably of L* ⁇ 82 in the CIELAB color space.
• an electrolyte bath for the cathodic deposition of a binary Pd/Sn alloy with at least 70 wt.% Pd and at most 30 wt.% Sn, wherein the electrolyte bath is present as an aqueous solution with pH 7.0 to pH 9.0, preferably pH 7.5 to pH 8.0, containing ammonium ions, and containing 0.5 g/l to 10 g/l Pd ions, 1 g/l to 20 g/l Sn ions, at least one wetting agent, at least one complexing agent and at least one brightening agent.
• a binary palladium-tin alloy can be deposited from such an electrolyte bath, which is abrasion-resistant and exhibits good corrosion resistance.
• a coating deposited from the electrolyte bath according to the invention is just as corrosion-resistant as a pure palladium coating of the same layer thickness.
• the electrolyte bath is also suitable for producing coatings with high layer thicknesses. Good adhesion is achieved.
• the coating is not brittle and does not exhibit cracking. Due to the alloying with tin, which is more cost-effective than palladium, the deposited coating is more cost-effective to produce than a pure palladium coating.
• the coating is glossy and has a light color with L* ⁇ 82 in the CIELAB color space.
• 0.5 g/l to 10 g/l Pd ions correspond to 0.0047 mol/l to 0.0940 mol/l Pd ions
• 1 g/l to 20 g/l Sn ions correspond to 0.0084 mol/l to 0.1685 mol/l Sn ions.
• the pH value can be adjusted with ammonia water, simplifying bath operation.
• An electrolyte bath with 5 g/l to 7 g/l Pd ions is particularly suitable.
• the Pd ions are present in divalent form, with the Pd ions being present in particular in the form of palladium chloride, palladium tetramine sulfate, palladium diaminodinitrite, palladium diaminodichloride.
• an electrolyte bath containing 3 g/l to 6 g/l Sn ions is preferred.
• wetting agents may be included, in particular alkyl ether sulfonates, alkyl ether phosphates, or preferably fatty alcohol alkoxylates.
• complexing and chelating agents known in the chemical industry can be used as complexing agents.
• examples include phosphonates, gluconates, citrates, nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), ethylene glycol bis(aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA), and ethylenediaminedisuccinic acid (EDDS).
• NTA nitrilotriacetic acid
• EDTA ethylenediaminetetraacetic acid
• EGTA ethylene glycol bis(aminoethyl ether)-N,N,N',N'-tetraacetic acid
• EDDS ethylenediaminedisuccinic acid
• the brightening agent is advantageously a brightening agent from the group of substituted aromatic N-heterocycles, or from a mixture of substituted aromatic N-heterocycles.
• It may also contain a tension reducer, particularly saccharin or an organic sulfonate.
• conducting salts and/or pH stabilizers may be included, in particular ammonium, sodium or potassium phosphate, oxalate, pyrophosphate, sulfate, nitrate, chloride, citrate, tartrate or succinate.
• the electrolyte bath should be a clear solution, particularly free of precipitates.
• concentration of the metal salts, wetting agents, brightening agents, and additional ingredients should be selected so that the electrolyte solution is clear and remains clear throughout the coating process.
• the resulting coating is particularly glossy, adheres well, is crack-free, and is abrasion- and corrosion-resistant.
• a particularly advantageous composition of an electrolyte bath comprises 6 g/l Pd ions from palladium diaminodichloride, 4 g/l Sn ions from tin pyrophosphate, 60 g/l ammonium sulfate, 80 g/l ammonium dihydrogen phosphate, 4 g/l betaine as a wetting agent, 30 g/l nitrilotriacetic acid, 0.2 g/l fatty alcohol ethoxylate as a further wetting agent, 2 g/l saccharin as a voltage reducer, 4 ml/l of a mixture of substituted aromatic N-heterocycles, for example pyridine or pyrimidine derivatives, as a brightening agent, wherein the pH is adjusted to 8.0 with ammonia water.
• the invention further relates to the use of a previously described electrolyte bath for the electroplating of an object with an electrically conductive surface, wherein a binary Pd/Sn alloy containing at least 70 wt.% Pd and at most 30 wt.% Sn is cathodically deposited.
• the alloy therefore consists exclusively of 70 wt.% to ⁇ 100 wt.% Pd and >0 wt.% to 30 wt.% Sn.
• alloys with 73 to 77 wt.% palladium and 23 to 27 wt.% tin exhibit maximum abrasion resistance.
• the invention further relates to a method for producing a coating using a previously described electrolyte bath.
• This method can involve immersing the object to be coated in the electrolyte bath and applying a voltage to the electrodes, with a current density between 0.01 A/ dm2 and 5 A/ dm2 being set.
• the object is connected as the cathode.
• the method can be carried out particularly advantageously if the bath is maintained at a temperature of 25°C to 65°C.
• a current density of 0.05 to 0.5 A/dm 2 is particularly suitable.
• the invention further relates to a coating, in particular produced or producible using a method described above, wherein the coating consists of a binary alloy comprising at least 70 wt.% Pd and at most 30 wt.% Sn, in particular 73 to 77 wt.% Pd and 23 to 27 wt.% Sn.
• the coating advantageously has a whiteness of L* ⁇ 82 in the CIELAB color space.
• the coating can be used as the outermost final layer because it has high abrasion resistance and a particularly elegant appearance.
• the coating can also be applied as an intermediate layer in a multi-layer coating system.
• the coating is particularly well-suited as a diffusion barrier layer in a multi-layer coating system.
• a diffusion barrier layer can prevent the diffusion of copper ions from the copper underlayer commonly used in fashion jewelry into the outermost final layer, thus preventing tarnishing of the final layer.
• a coating with a thickness of 0.1 to 5 ⁇ m, and especially 2 ⁇ m, is particularly suitable as a corrosion protection layer.
• an article in particular a costume jewelry or decorative article, is also coated with a coating described above.
• Such an item especially a piece of costume jewelry, exhibits good durability even with prolonged and frequent use.
• the coating eliminates the need for nickel-containing coatings, making such an item particularly physiologically compatible.
• an adhesive gold layer can be arranged directly over the coating.
• Such an adhesive gold layer can have a thickness of 0.05 to 0.3 ⁇ m.
• Fig. 2 shows the abrasion resistance of the alloys in the Taber Abraser test.
• the abrasion resistance does not behave linearly with the alloy composition as expected. This is evident from Fig. 2 and Table 2.
• the deposited coating exhibits maximum abrasion resistance at a palladium alloy concentration of approximately 75 wt.%.
• Such an alloy can be obtained by deposition from an electrolyte bath containing 6 g/l Pd ions and 4 g/l Sn ions.
• a brass jewelry blank was coated with an exemplary electrolytic bath.

Landscapes

• 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)

Applications Claiming Priority (1)

Publications (2)

Family

ID=95065842

Family Applications (1)

Country Status (3)

Citations (3)

Family Cites Families (6)

• 2024
  • 2024-03-28 AT ATA50274/2024A patent/AT528141A1/de unknown
• 2025
  • 2025-03-26 EP EP25166353.0A patent/EP4624636A3/fr active Pending
  • 2025-03-26 CN CN202510365626.0A patent/CN120719350A/zh active Pending

Patent Citations (3)

Also Published As

Similar Documents

Legal Events