EP4127273A1 - Procédé galvanique pour l'électrodéposition d'une couche de protection, et bain associé - Google Patents

Procédé galvanique pour l'électrodéposition d'une couche de protection, et bain associé

Info

Publication number
EP4127273A1
EP4127273A1 EP20735459.8A EP20735459A EP4127273A1 EP 4127273 A1 EP4127273 A1 EP 4127273A1 EP 20735459 A EP20735459 A EP 20735459A EP 4127273 A1 EP4127273 A1 EP 4127273A1
Authority
EP
European Patent Office
Prior art keywords
ruthenium
tin
aqueous solution
protective layer
acid
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP20735459.8A
Other languages
German (de)
English (en)
Inventor
Luca CAPACCIOLI
Andrea CAPACCIOLI
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Italfimet SRL
Original Assignee
Italfimet SRL
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Italfimet SRL filed Critical Italfimet SRL
Publication of EP4127273A1 publication Critical patent/EP4127273A1/fr
Pending legal-status Critical Current

Links

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
    • C25D3/60—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of tin
    • 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

Definitions

  • the present invention relates to a galvanic process for the electrodeposition of a protective layer, and to the associated bath.
  • this process entails causing an electrolytic reaction in a tank (galvanic bath), in which the object to be coated (which acts as a cathode) is immersed in an aqueous solution of the metal to be deposited.
  • the anode may be made of the very metal to be deposited, or may also be made of an inert metal or graphite.
  • a potential difference at the two electrodes by applying a potential difference at the two electrodes, a flow of ions of the metal to be deposited is generated and the metal progressively accumulates on the cathode, indeed forming the desired layer.
  • Stainless bronze has progressively replaced more traditional solutions (sharing indeed their high resistance to corrosion and wear), which entailed the use of galvanic baths containing nickel, which are now known to be capable of causing allergies and which are potentially toxic. The use of nickel is therefore now highly discouraged, if not forbidden by the relevant statutory provisions.
  • the aim of the present invention is to solve the problems described above, providing a galvanic electrodeposition process that allows to deposit on an object a protective layer that ensures high resistance to corrosion and/or wear.
  • an object of the invention is to provide a galvanic bath that allows to deposit on an object a protective layer that ensures high resistance to corrosion and/or wear.
  • Another object of the invention is to provide a process and a galvanic bath that allow to deposit a protective layer on an object in a non-toxic and environmentally sustainable manner, without using substances that are noxious for human beings and/or for the environment.
  • Another object of the invention is to provide a method and a galvanic bath that have low costs, without requiring the use of palladium or other precious metals.
  • Another object of the invention is to provide a method (and a bath) that ensures high reliability in operation and high stability, allowing furthermore to provide protective coating layers of high quality, in terms of aesthetic appearance, mechanical performance, and not only.
  • Another object of the invention is to provide a process that adopts a technical and structural architecture that is alternative to those of processes of the known type.
  • Another object of the invention is to provide a process and a bath that can be obtained easily starting from commonly commercially available elements and materials.
  • Another object of the invention is to provide a process that can be performed in a simple manner.
  • the galvanic process for the electrodeposition of a protective layer comprises a step of coating with a protective layer at least one object immersed in a galvanic bath, which in turn comprises an aqueous (water- based) solution.
  • the process is performed by applying a potential difference to two electrodes, one of which, the cathode, is constituted by the object to be coated, while the anode can be constituted by the metal to be deposited, by an inert metal, by graphite or others.
  • the generated flow of metal ions produces their accumulation on the object, so as to obtain progressively the forming of the desired protective layer. It is possible to immerse in the bath any number of objects (of any shape and size), insofar as allowed by the dimensions of the tank filled with the aqueous solution and by the limitations and the technical requirements of each specific situation.
  • the process according to the invention can be used for the deposition of a protective layer aimed at constituting a sub-layer (substrate) of the finished product that one wishes to obtain; at the same time, also in view of the high quality of the layer that, as will become apparent, the invention allows to obtain on the object to be coated (also in aesthetic terms), the invention can constitute the outer layer of the finished product. Furthermore, the possibility is not excluded to perform the process according to the invention to provide a sort of self-supporting shell, i.e., in which the object coated during the process is removed at the end of the process itself (and in which, typically but not exclusively, the finished product is indeed constituted by the deposited layer).
  • the aqueous solution comprises at least tin in the form of a soluble complex (capable therefore of constituting an adequate source of tin ions during the electrodeposition step, such as for example tin salts and/or tin compounds), in a quantity comprised between 0.5 grams and 100 grams per liter of solution.
  • a soluble complex capable therefore of constituting an adequate source of tin ions during the electrodeposition step, such as for example tin salts and/or tin compounds
  • the tin in the form of a soluble complex is selected from the group consisting of sodium stannate, potassium stannate, tin oxide, tin monoxide, tin sulfate, tin fluoborate, tin methane sulfonate, tin chloride and tin octanoate (although the adoption of different practical choices, without abandoning the protective scope claimed herein, is not excluded ).
  • the aqueous solution comprises at least ruthenium in the form of a soluble complex (capable therefore of constituting a suitable source of ruthenium ions during the electrodeposition step, such as for example ruthenium salts and/or ruthenium compounds), in a quantity comprised between 0.1 grams and 50 grams per liter of solution.
  • the ruthenium in the form of a soluble complex is selected from the group consisting of ruthenium trichloride, ruthenium sulfamate, ruthenium nitrosyl nitrate, ruthenium sulfate, ruthenium phosphate, ruthenium gluconate and ruthenium oxalate (although the adoption of different practical choices, without abandoning the protective scope claimed herein, is not excluded).
  • the aqueous solution comprises at least one conducting salt; in this regard, it is stressed that the aqueous solution can comprise a single specific type of conducting salt or a larger number of different conducting salts, as a function of the specific requirements.
  • the conducting salt is selected from the group consisting of a sulfate, a phosphate, a carboxylate, a chloride, a sulfamate, a citrate, a tartrate, an oxalate and a gluconate (although the adoption of different practical choices, without abandoning the protective scope claimed herein, is not excluded).
  • the method according to the invention also provides that during said step in which the object (each object) is coated with the protective layer, the aqueous solution is kept at a pH that is greater than or equal to 0.1 and lower than 7 (in other words, the aqueous solution is kept at an acid pH).
  • the protective scope claimed herein is extended to any substance (an acid or an aqueous solution containing an acid, for example) or practical choice that the person skilled in the art would know how to adopt, by drawing from the ordinary skills of the field, in order to keep the pH of the solution within this range.
  • the bath is kept at a constant temperature comprised between 25°C and 70°C.
  • the applied current density is comprised between 0.2 A/dm 2 and 5 A/dm 2 .
  • the aqueous solution can comprise various and different substances, as an integration of the ones already described, in order to give the bath additional functionalities and/or optimize its particularities (and those of the resulting protective layer therewith). Some of these substances are therefore mentioned in the paragraphs that follow, but it is appropriate to stress that it is possible to add additional substances, even not directly mentioned in the present description, without thereby abandoning the protective scope claimed herein.
  • the aqueous solution comprises at least one surfactant, preferably from the group of the amphoteric surfactants (be they anionic and/or non-ionic, or others).
  • said surfactant is selected from the group consisting of alkyl polyoxyethylene ether, alkyl phenyl polyoxyethylene ether, polyoxyethylene alkylamine, polyoxyethylene alkylamide, polyoxyethylene fatty acid ester, polyoxyethylene polyhydric alcohol ether, surfactant block copolymer with ethylene oxide and propylene oxide, betaine, alkyl sulfate, alkyl ether sulfate, alkyl ether phosphate, alkyl sulfonate, alkyl sulfosuccinate, alkyl benzene sulfonate, polyethylene glycol, and mixtures thereof.
  • said surfactant is contained in the group of the amphoteric surfactants (be they anionic and/or non-ionic, or others).
  • said surfactant is
  • the aqueous solution comprises at least one complexing agent; although other embodiments are not excluded, preferably said complexing agent is selected from the group consisting of a carboxylic acid, an amino acid, a polyamine, an amine, a phosphonic acid, a sugar and/or a derivative thereof. Furthermore, preferably said complexing agent (whether it belongs or not to the group indicated above) is contained in the aqueous solution in a quantity comprised between 5 grams and 500 grams per liter of solution.
  • complexing agents that can be used in the context of performing the process according to the invention are: nitrilotriacetic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, 1 -hydroxy ethane 1,1-diphosphonic acid, nitrilotris(methylene) triphosphonate, sulfamic acid and/or methanesulfonic acid, mercapto succinic acid, formic acid, benzoic acid and succinic acid.
  • the aqueous solution comprises a complexing agent (an acid among the ones indicated above, another acid, or something else) indeed for the (already discussed) purpose of keeping the pH of the solution between 0.1 and 7.
  • a complexing agent an acid among the ones indicated above, another acid, or something else
  • methanesulfonic acid is of particular practical interest.
  • the aqueous solution comprises at least one organic brightener and/or at least one inorganic brightener.
  • the organic brightener (which can be selected from an aromatic or non-aromatic compound) is preferably present in a quantity between 0.01 grams and 5 grams per liter of solution. Furthermore, although other embodiments are not excluded, said organic brightener is preferably selected from the group consisting of a benzene sulfanate, 3- mercaptopropionic acid, 3 -mercapto- 1-propanesulfonic acid, benzoic acid, a benzoic acid derivative, gallic acid, resorcinol, phenol and a phenol derivative.
  • the inorganic brightener is preferably present in a quantity comprised between 0.01 grams and 5 grams per liter of solution.
  • said inorganic brightener is preferably a salt of an element (metal or semimetal) selected from the group consisting of copper, zinc, rhodium, platinum, palladium, gold, gallium, germanium, bismuth, silver, thallium, tellurium, indium, iron and antimony.
  • an element metal or semimetal
  • a galvanic bath comprising an aqueous solution according to what has been described so far and indeed aimed at performing said process is also subject matter of the present description.
  • a protective layer which can be obtained by means of a process and/or a bath of the type outlined so far is also subject matter of the present description.
  • said layer thus obtained comprises tin in a quantity comprised between 30% and 95% by weight and ruthenium in a quantity comprised between 5% and 70% by weight, these percentages being referred to the total weight of the layer.
  • the protective layer according to the invention consists of (or at least comprises) an alloy of tin and ruthenium in the quantities indicated above.
  • the layer comprises tin in a quantity comprised between 50% and 90% by weight and preferably in a quantity equal to 80% by weight, the percentages being once again referred to the total weight of the layer.
  • the protective layer comprises ruthenium in a quantity comprised between 5% and 30% by weight and preferably in a quantity equal to 20% by weight, the percentages being once again referred to the total weight of the layer.
  • the aqueous solution comprises, for each liter of solution:
  • the bath is kept at a constant temperature of 40°C and the applied current density (in a Hull cell) is equal to one A/dm 2 .
  • the object After depositing on an object the protective layer with the formulation described above for 10 minutes (thus obtaining an alloy of tin and ruthenium), the object (immersed in a nitric acid solution) does not exhibit alterations of the surface, thus showing the high degree of resistance to corrosion and oxidation.
  • the process entails, according to per se traditional methods, the application of a potential difference to the electrodes immersed in the galvanic bath, wherein the object (each object) to be coated with a protective layer acts as a cathode.
  • the innovation of the invention which allows to overcome the limitations of known processes, lies in the composition of the aqueous solution of the bath (in which the object to be coated is indeed immersed) and in the choice to maintain an acid pH.
  • the protective layer obtained by means of the process according to the invention comprises or consists of a tin-ruthenium alloy that in fact allows to provide glossy objects with a high resistance to oxidation, corrosion and wear, to be used in the field of fashion, jewelry, eyewear, faucets, electronics and in any other sector in which a substrate that is indeed resistant to oxidation and corrosion is required.
  • this layer in a bath kept at an acid pH allows to extend for a considerable amount of time the electrodeposition step, allowing to give the protective layer a thickness of 50 microns or more (therefore very high in addition to being resistant).
  • a layer with such a high thickness can be used effectively in all applications in which known practice would require a bath with the presence of nickel (a metal which is now discouraged since it is allergenic) or bronzes (stainless or not) containing cyanide (which are toxic).
  • the high thickness of this deposition ensures a high resistance to corrosion and oxidation and a surprisingly high resistance to wear, which is comparable with that observed in substrates made of nickel and nickel phosphorus.
  • This layer can be used first of all as a substrate/intermediate layer between objects of various kinds, particularly containing copper, and the final finishing layer.
  • the high resistance to corrosion and oxidation also ensures the preservation of the aesthetic quality of the obtained protective layer, and this allows to use the latter as a final finish.
  • the protective layer and the alloy of which it is composed provide a smooth coating to the object to be coated and prevent the diffusion of the metals from the lower layers to the finishing layer and vice versa. Therefore, a change in color over time is prevented.
  • the invention therefore allows to extend the life of an object without color changes, at the same time increasing its resistance in terms of durability under performance tests.
  • the benefits described above are obtained without having to resort to nickel, cyanide and/or other metals and materials that are noxious, toxic (for humans and/or for the environment) or allergenic.
  • the protective layer that is deposited by virtue of the invention is therefore environmentally sustainable, non-toxic and hypoallergenic, and the risk of skin irritations in subjects that come into contact with it is therefore avoided.
  • This allows to resort to the invention for example in fields (such as eyewear) in which baths of nickel and/or chromium that are highly toxic and allergenic are currently used in order to ensure high resistance to wear.
  • the protective layer according to the invention provides for a far lower production cost while ensuring a similar protection against corrosion.
  • the invention allows to reduce or even eliminate bronzes containing cyanide and lower production costs further, thus reducing or in some cases eliminating some steps of the subsequent treatments, which, according to known methods, use precious metal such as gold, palladium, platinum.
  • the bath according to the invention exhibits high stability, without requiring continuous additions of OH- ions in order to compensate for the absorption of the CO 2 that is present in the surrounding environment, which is indeed observed in some known alkaline solutions (with consequent instability of the bath).
  • the acid environment renders the tin insensitive to impurities as instead might occur in a basic environment: this avoids the danger of obtaining protective layers that are dark, wrinkly and/or dusty and is a further confirmation of the quality (also aesthetic) of results that can be obtained by means of the invention.
  • the protective layer obtained by means of the invention has a high adherence and is not subject to passivation phenomena (as sometimes occurs by resorting to known methods), which might create problems for subsequent treatments.
  • the galvanic products obtained by means of the invention have been subjected to a copper diffusion test: copper migration and barrier properties are evaluated by heating the product for 48 hours at 180°C. In these conditions, the appearance of the overlying layer of precious metal has not undergone alterations and no copper diffusion phenomena have been revealed, as shown by the summary table provided hereinafter.
  • the invention allows to avoid phenomena of diffusion of the copper that originates both from the raw material and from the galvanic copper plating and/or from the copper alloys (bronzes).
  • the oxidation resistance capacity of the protective layers obtained from galvanic baths according to the invention makes them applicable in various fields (whenever glossy objects and/or substrates with a high resistance to corrosion, oxidation and/or wear are required) and in particular in the fields of high fashion, clothing, costume jewelry, shoes, leatherwear, faucets, eyewear and electronics.
  • the protective layer according to the invention meets all the requirements set by this field (and in particular as regards jewels and articles made of leather), as highlighted by the table in the following page, which lists the outcome of the many tests performed by the applicant on the following alloys:
  • Alloy 1 5-micron Sn-Ru alloy
  • Alloy 2 10-micron Sn-Ru alloy
  • the materials used, as well as the dimensions, may be any according to the requirements and the state of the art.

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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 And Plating Baths Therefor (AREA)

Abstract

Un procédé galvanique destiné à l'électrodéposition d'une couche de protection, qui comprend une étape de revêtement d'une couche de protection sur au moins un objet immergé dans un bain galvanique comprenant une solution aqueuse. La solution aqueuse comprend au moins : - de l'étain sous forme d'un complexe soluble, en une quantité comprise entre 0,5 gramme et 100 grammes par litre de solution, - du ruthénium sous forme d'un complexe soluble, en une quantité comprise entre 0,1 gramme et 50 grammes par litre de solution, - un sel conducteur ; en outre, au cours de l'étape de revêtement dudit objet, la solution aqueuse est maintenue à un pH qui est supérieur ou égal à 0,1 et inférieur à 7.
EP20735459.8A 2020-03-30 2020-03-30 Procédé galvanique pour l'électrodéposition d'une couche de protection, et bain associé Pending EP4127273A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/IT2020/000032 WO2021199087A1 (fr) 2020-03-30 2020-03-30 Procédé galvanique pour l'électrodéposition d'une couche de protection, et bain associé

Publications (1)

Publication Number Publication Date
EP4127273A1 true EP4127273A1 (fr) 2023-02-08

Family

ID=71401814

Family Applications (1)

Application Number Title Priority Date Filing Date
EP20735459.8A Pending EP4127273A1 (fr) 2020-03-30 2020-03-30 Procédé galvanique pour l'électrodéposition d'une couche de protection, et bain associé

Country Status (2)

Country Link
EP (1) EP4127273A1 (fr)
WO (1) WO2021199087A1 (fr)

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4375392A (en) * 1981-06-02 1983-03-01 Occidental Chemical Corporation Bath and process for the electrodeposition of ruthenium
EP2757180B1 (fr) * 2013-01-18 2015-08-12 Valmet Plating S.R.L. Procédé de dépôt électrolytique d'un alliage à base de ruthénium et d'étain, bain électrolytique qui permet le dépôt de l'alliage et alliage obtenu au moyen dudit procédé

Also Published As

Publication number Publication date
WO2021199087A1 (fr) 2021-10-07

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