WO2005047570A2 - Procede de finition de surface pour l'argent et ses alliages - Google Patents

Procede de finition de surface pour l'argent et ses alliages Download PDF

Info

Publication number
WO2005047570A2
WO2005047570A2 PCT/EP2004/012761 EP2004012761W WO2005047570A2 WO 2005047570 A2 WO2005047570 A2 WO 2005047570A2 EP 2004012761 W EP2004012761 W EP 2004012761W WO 2005047570 A2 WO2005047570 A2 WO 2005047570A2
Authority
WO
WIPO (PCT)
Prior art keywords
ranging
seconds
solution
silver
bath
Prior art date
Application number
PCT/EP2004/012761
Other languages
English (en)
Other versions
WO2005047570A3 (fr
Inventor
Antonio Fochesato
Marco Calegaro
Original Assignee
F.Lli Calegaro Di Luigi Di Francesco Calegaro S.P.A.
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 F.Lli Calegaro Di Luigi Di Francesco Calegaro S.P.A. filed Critical F.Lli Calegaro Di Luigi Di Francesco Calegaro S.P.A.
Priority to EP04797802A priority Critical patent/EP1685279A2/fr
Publication of WO2005047570A2 publication Critical patent/WO2005047570A2/fr
Publication of WO2005047570A3 publication Critical patent/WO2005047570A3/fr

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
    • 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
    • C25D3/00—Electroplating: Baths therefor
    • C25D3/02—Electroplating: Baths therefor from solutions
    • C25D3/50—Electroplating: Baths therefor from solutions of platinum group metals

Definitions

  • the present invention relates to a surface finishing or plating method for silver and its alloys. More specifically, it relates to a physico-chemical finishing method in an electro-galvanic bath, which provides a new surface finishing or plating of silver and its alloys.
  • One of the main problems to be faced with the use of silver and its alloys, is the formation of silver sulphide (Ag 2 S) on the surface of silver and its alloys, when in contact with air, with the consequent browning of the silver.
  • Finishing treatments based on electro-plating or plat- ing in galvanic baths of silver objects are already known, but these forms of treatment produce an end- product in which the finishing has the following drawbacks: poor duration with time and consequent attack on the part of the hydrogen sulphide present in the air, with the formation of a dark surface patina.
  • the objective of the present invention is consequently to solve the above-mentioned problem by means of a new finishing method which allows the drawbacks of the known art to be overcome.
  • a particular finishing method has been surprisingly found, which allows the production of silver and its alloys which do not react with H 2 S and are therefore permanently rustproof.
  • An object of the present invention consequently re- lates to a method for the surface finishing or plating of silver and/or its alloys, characterized in that it comprises the following steps: a washing pre-treatment of a silver object to be subjected to finishing, which comprises: a. washing in an ultrasound bath having frequen- cies higher than 40,000 Hertz; b. subsequent washing of the object in a bath containing a solution consisting of perchloro ethylene and dichloro propane in a weight ratio ranging from 70/30 to 50/50: c. washing in a bath with distilled water; immersion in a galvanic bath containing a solution of a metal belonging to groups 8, 9, 10 and 13 of the periodic table.
  • the perchloro ethylene/dichloro propane ratio is preferably equal to 60/40.
  • the metal belonging to groups 8, 9, 10 and 13 is selected from rhodium, palladium, osmium, ruthenium and indium.
  • Step a. of the washing pre-treatment is carried out over a period of 60 to 120 seconds, at a temperature ranging from 20 to 60°C.
  • Step b. of the washing pre-treatment is carried out over a period of 30 to 150 seconds, at a temperature ranging from 20 to 60°C.
  • Step c. of the washing pre-treatment is carried out over a period of 30 to 120 seconds, at a temperature ranging from 20 to 60°C.
  • the main advantage of the method according to the present invention consists in the fact that it allows the production of manufactured products made of silver or its alloys, i.e. silver having a titre of 1000, 925 and 800 and its alloys, permanently rust- and scratch-proof.
  • a further advantage is that the method according to the present invention allows manufactured products to be obtained, which, depending on the type of solution used in the galvanic bath, have surface finishings which are permanently rustproof and with a different optical appearance.
  • the finishing treatment according to the present invention by means of plating with a rhodium solution, allows an end-product to be obtained, having a shiny white surface with a pale blue shading, whereas the use of a solution of palladium produces an end-product having a white surface with a light grey shading.
  • a solution of osmium an end-product is obtained, with a very shiny white surface
  • the use of a solution of ruthenium produces an object with a surface appearance whose colour varies from dark grey to black ac- cording to the concentration of metal used.
  • White surface does not refer to a white-coloured surface (of the Ti0 2 type) but a silver coloured surface with a white shading.
  • the washing pre-treatment phase of the end-product is essential for obtaining a perfect silver plating.
  • the washing is carried out in three steps with: a) an ultrasound bath with frequencies higher than 40,000 Hertz which effects a first removal of the particles forming the "dirt" deposited on the surface of the metal; b) a bath in a solution of perchloro ethylene/dichloro propane for the definite removal of the dirt particles; c) a bath with distilled water for washing the degreas- ing solution so that not even the slightest trace remains, of products containing chlorine on the surface of the metal.
  • the selection of electrodes in the electro-galvanic bath is also important for obtaining a plated end-product with optimum characteristics.
  • Niobium electrodes allow a better equalization of the cathode/anode current compared to titanium electrodes.
  • the same electrodes are also used in plating with palladium.
  • the best electrodes are those made up of a mixed oxides, in particular a mixture of iridium dioxide and tantalum pen- toxide, coated with titanium which are preferred for the lower oxidation potential with respect to electrodes coated with platinum.
  • the finishing method according to the present invention when effected with a solution of rhodium, provides an end-product with the characteristics described below.
  • the finishing method according to the present invention effected by means of silver plating with a rhodium- based solution, gives the silver object a shiny white surface with permanent rustproof properties and a much higher surface hardness than that of silver.
  • Rhodium-plated silver does in fact have a Mohs hardness of 4.3 against 3.75 of 925 titre silver.
  • Rhodium- plated silver consequently has much higher scratch resistance and punch resistance properties.
  • An electro-galvanic bath, modified with platinum electrodes coated with niobium, is used for silver finishing with rhodium.
  • the solution used is made up of rhodium sulphate or rhodium phosphate in a solution of phosphoric or sulphuric acid.
  • the metal concentration ranges from 0.8 to 5.0 g/1, whereas the concentration of acids ranges from 25 to 50 ml/1.
  • the current intensity ranges from 20 to 100 A/m 2 , over a time of 20 to 60 seconds.
  • the plating thickness ranges from 0.05 to 1.5 microns.
  • the finishing method according to the present invention effected with a palladium solution, allows a manufactured product to be obtained, having the characteristics specified below..
  • the finishing method according to the present inven- tion effected by means of silver plating with the palladium solution, gives the silver end-product a white-grey surface appearance and a very high resistance to oxidation and scratching.
  • palladium represents a valid alternative to rhodium, as its cost is much lower than the cost of rhodium.
  • Palladium chloride is normally used as plating salt, with a palladium concentration ranging from 1 to 9 g/1 in acid baths, or a concentration of 10/15 g/1 in alkaline baths . Palladium has a Mohs hardness of .8 against 3.75 of 925 titre silver.
  • the electro-galvanic baths used for palladium finishing are chelated basic (ammonia solution) baths or acid baths.
  • the ammonia baths contain from 10 to 15 g/1 of pal- ladium ammonium nitrate or palladium ammonium chloride with a current intensity ranging from 1 to 25 A/m 2 , over a period of 15 to 60 seconds.
  • the acid baths contain palladium chloride at a concentration varying from 1 to 9 g/1 of palladium in hydro- chloric acid, with a current intensity ranging from 1 to 10 A/m 2 , for a time of 15 to 60 seconds.
  • the plating thickness ranges from 0.2 to 1.25 microns .
  • the finishing method according to the present invention effected by means of silver plating with a ruthe- niu solution, gives the silver manufactured product a surface appearance whose colour varies from grey to black depending on the amount of ruthenium; plating with ruthenium is in fact similar to black nickel plating, but the ruthenium characteristics are much higher.
  • Plating with ruthenium gives the silver manufactured product extremely high scratch resistance properties as Mohs hardness of ruthenium is 6.5 and therefore higher both than that of rhodium and palladium.
  • Ruthenium sulfamate or nitrosyl sulfamate is used as plating salt at concentrations ranging from 5.0 to 5.5 g/1 in sulfamic acid with an acid concentration ranging from 6 to 8.0 g/1, or ruthenium chloride in water at concentrations ranging from 1 to 10% by weight.
  • the current density ranges from 108 to 320 A/m 2 for a time of 25 to 60 seconds, whereas the plating thickness ranges from 0.25 to 1.5 microns.
  • Ruthenium chloride in water can also be used as plating salt, with a ruthenium concentration ranging from 1 g/1 to 10 g/1.
  • the current intensity ranges from 100 to 320 A/m 2 for a time of 15 to 60 seconds.
  • the finishing method according to the present invention when carried out with an indium solution, allows a manufactured product to be obtained, having the following characteristics.
  • the finishing method according to the present invention effected by means of silver plating using an indium solution, gives the silver manufactured product a surface appearance having a characteristic extremely shiny silver white colour (gleaming white) .
  • Indium is a soft and low-melting (156.2 °C) metal with a Mohs hardness of 1.2. Indium is much softer than silver and therefore does not confer scratch resistance to the silver manufactured product, but gives a characteristic gleaming-white colour to silver and makes it rustproof.
  • electro-galvanic baths Three types are used for the plating, based on cyanide, sulfamate or fluoro bo- rate.
  • Indium is the only trivalent metal which can be rap- idly deposited by means of an electro-galvanic bath in a hydrocyanic solution.
  • An indium cyanide bath is used a high plating layer must be obtained.
  • the electro-galvanic baths contain from 30 to 40 g/1 of metal indium and from 90 to 120 g/1 of total cyanide.
  • the current density ranges from 162 to 216 A/m 2 , for a time ranging from 20 to 60 seconds.
  • Indium sulfamate is extremely stable and relatively easy to control, and is characterized by a high yield at the cathode.
  • the baths normally contain indium sulfamate having an indium concentration ranging from 80 to 110 g/1 in sulfamic acid from 20 to 40 g/1.
  • the current density ranges from 108 to 1080 A/m 2 , for a time ranging from 20 to 60 seconds.
  • the electro- galvanic baths contain from 200 to 310 g/1 of indium in boric acid and the acid concentration ranges from 20 to 40 g/1.
  • the current density ranges from 160 to 280 A/m 2 , for a time of 20 to 40 seconds.
  • SILVER plating with RHODIUM The manufactured product to be subjected to finishing first undergoes a washing pre-treatment which includes: washing in an ultrasound bath having a frequency higher than 40,000 Hertz, which provides a first removal of the particles of the "dirt" deposited on the metal surface, for a period of about 60 seconds, at a temperature of about 25°C; a subsequent bath in a perchloro eth- ylene/dichloro propane 60/40 solution for the final re- moval of the dirt particles, for about 30 seconds, at a temperature of about 30°C; finally, a bath with distilled water for washing away the degreasing solution, so that no traces of products containing chlorine remain on the metal surface, for about 30 seconds, at a temperature of approximately 40 °C; the plating procedure is then started.
  • a washing pre-treatment which includes: washing in an ultrasound bath having a frequency higher than 40,000 Hertz, which provides a first removal of the particles of the "dirt" deposited on the metal
  • a solution was prepared, containing rhodium III sulphate Rh 2 (S0 4 )3 in an H 2 S0 4 solution, as plating agent, having a concentration of 0.8 to 5 g/1 of rhodium sul- phate - H 2 S0.
  • a solution was prepared consisting of 1 g/1 of rhodium III sulphate in a ratio 1:50 (1 part by weight of rhodium for every 50 parts by weight of H 2 S0 4 ) to which a further 15% of sul- phuric acid at 23°C was added.
  • the electrodes are platinum coated with niobium (niobium-plated platinum) .
  • the process has a duration of 30 seconds with a current intensity equal to 30 A/m 2 .
  • the thickness of rhodium deposited on the silver is 1.2 microns. Cathode efficiency > 90%.
  • the rhodium deposition on silver is perfect, with no stains, smudges and false reflections.
  • EXAMPLE 2. SILVER plating with PALLADIUM The manufactured product to be subjected to finishing first undergoes a washing pre-treatment following a procedure analogous to that described in example 1 and the plating treatment is then started. Palladium tetrachloride H 2 PdCl 4 is used as plating agent, in an alkaline solution (ammonia solution) .
  • the solution used is typically H 2 PdCl 4 at 37% in an ammonia salt.
  • Process temperature 25°C.
  • Process duration 40 seconds with a current intensity equal to 20 A/m 2 .
  • the thickness of the deposited palladium layer is 1.1 microns.
  • the deposition of palladium on silver is perfect, with no stains, smudges and false reflections.
  • EXAMPLE 3. SILVER plating with RUTHENIUM. The manufactured product to be subjected to finish- ing first undergoes a washing pre-treatment following a procedure analogous to that described in example 1, and the plating treatment is then started.
  • Ruthenium chloride RUCI 3 ⁇ 2 O soluble in water is used as plating agent, in the form of a solution contain- ing 25% of ruthenium chloride.
  • Process temperature 40°C.
  • Process duration 50 seconds with a current intensity equal to 35 A/m 2 .
  • the thickness of the deposited ruthenium layer is 1.25 microns.
  • the deposition of ruthenium on silver is perfect, with no stains, smudges and false reflections.
  • Plating with RuCl 3 confers a solid grey-black col- ouring to the silver, with a shiny appearance, with no stains and smudges.
  • EXAMPLE 4. SILVER plating with INDIUM.
  • the manufactured product to be subjected to finish- ing first undergoes a washing pre-treatment following a procedure analogous to that described in example 1 and the plating treatment is then started.
  • Indium sulfamate is used as plating agent, with dextrose and triethanol a ine present in the bath, as growth inhibitors of the metal granules and for the control of the particle size of the spherulites, respectively.
  • indium is in fact a soft metal (Mohs 1.2) and during the plating operation is deposited on the silver in the form of mi- cro-granules (visible under a microscope) .
  • Deposit in the form of micro-granules is a common characteristic of all low-hardness metals .
  • very small granules must be obtained, and it is therefore necessary to operate with a low intensity current of about 10 A/m 2 and to use a bath with vigorous stirring.
  • a solution containing 105 g/1 of indium metal was used.
  • Plating with rhodium gives the silver an opaque surface with a frozen effect, with no stains and smudges.
  • EXAMPLE 5 Comparative. The procedure described in example 1 was repeated, without effecting the washing pre-treatment .

Landscapes

  • 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)
  • Electroplating And Plating Baths Therefor (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)

Abstract

La présente invention a trait à un procédé pour la finition ou le placage de l'argent et/ou de ses alliages caractérisé en ce qu'il comprend les étapes suivantes: un prétraitement de lavage d'un objet en argent destiné à être soumis à une finition, comprenant: (a) un lavage dans un bain ultrasonique présentant des fréquences supérieures à 40000 Hertz : (b) un lavage ultérieur de l'objet dans une solution composée de perchloroéthylène et de dichloropropane dans un rapport pondéral entre 70/30 et 50/50 ; (c) un lavage dans une solution avec de l'eau distillée ; l'immersion dans un bain galvanique contenant une solution d'un métal appartenant aux groupes 8, 9, 10 et 13 du tableau périodique.
PCT/EP2004/012761 2003-11-14 2004-11-10 Procede de finition de surface pour l'argent et ses alliages WO2005047570A2 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP04797802A EP1685279A2 (fr) 2003-11-14 2004-11-10 Procede de finition de surface pour l'argent et ses alliages

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITMI20032218 ITMI20032218A1 (it) 2003-11-14 2003-11-14 Metodo di finitura superficiale dell'argento e di sue leghe
ITMI2003A002218 2003-11-14

Publications (2)

Publication Number Publication Date
WO2005047570A2 true WO2005047570A2 (fr) 2005-05-26
WO2005047570A3 WO2005047570A3 (fr) 2005-08-11

Family

ID=34586995

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2004/012761 WO2005047570A2 (fr) 2003-11-14 2004-11-10 Procede de finition de surface pour l'argent et ses alliages

Country Status (3)

Country Link
EP (1) EP1685279A2 (fr)
IT (1) ITMI20032218A1 (fr)
WO (1) WO2005047570A2 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1801266A1 (fr) * 2005-12-21 2007-06-27 F.Lli Calegaro di Luigi di Francesco Calegaro S.P.A. Méthode pour le finissage de surface d'argent et de ses alliages
CN109267128A (zh) * 2018-10-22 2019-01-25 嘉兴学院 一种镀银件黑化处理剂及镀银化学黑化处理方法

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0679729A1 (fr) 1994-04-29 1995-11-02 Wmf Württembergische Metallwarenfabrik Ag Procédé pour empêcher le ternissement de produits

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2338063A1 (de) * 1973-07-26 1975-04-03 Siemens Ag Verfahren zum beschichten von hochfrequenz-heizspulen aus kupfer, messing, silber oder aluminium
JPS63213655A (ja) * 1987-02-27 1988-09-06 Nippon Dento Kogyo Kk 装身具
US6878411B2 (en) * 1999-12-23 2005-04-12 Umicore Galvanotechnik Gmbh Bath for the electrochemical deposition of high-gloss white rhodium coatings and whitening agent for the same

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0679729A1 (fr) 1994-04-29 1995-11-02 Wmf Württembergische Metallwarenfabrik Ag Procédé pour empêcher le ternissement de produits

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1801266A1 (fr) * 2005-12-21 2007-06-27 F.Lli Calegaro di Luigi di Francesco Calegaro S.P.A. Méthode pour le finissage de surface d'argent et de ses alliages
CN109267128A (zh) * 2018-10-22 2019-01-25 嘉兴学院 一种镀银件黑化处理剂及镀银化学黑化处理方法
CN109267128B (zh) * 2018-10-22 2019-07-26 嘉兴学院 一种镀银件黑化处理剂及镀银化学黑化处理方法

Also Published As

Publication number Publication date
ITMI20032218A1 (it) 2005-05-15
WO2005047570A3 (fr) 2005-08-11
EP1685279A2 (fr) 2006-08-02

Similar Documents

Publication Publication Date Title
US6331239B1 (en) Method of electroplating non-conductive plastic molded products
US1968483A (en) Plating aluminium and its alloys
US4242180A (en) Ammonia free palladium electroplating bath using aminoacetic acid
US6989087B2 (en) Metal finishes
US5085744A (en) Electroplated gold-copper-zinc alloys
KR101861626B1 (ko) Pc-abs 수지 부품의 비전해성 금속도금방법
US1949131A (en) Rhodium plating
US3759802A (en) Corrosion resistant ornamental chromium plating
DE647334C (de) Elektrolyt zur Erzeugung elektrolytischer Niederschlaege von Ruthenium
EP3807452B1 (fr) Procédé de traitement électrolytique pour le revêtement d'objets en acier inoxydable
EP1685279A2 (fr) Procede de finition de surface pour l'argent et ses alliages
US8211286B2 (en) Electrolyte and method for depositing decorative and technical layers of black ruthenium
CN104583457B (zh) 金属表面处理液、金属基材的表面处理方法及由此而得的金属基材
JP4467794B2 (ja) ニッケル／ホウ素含有塗料
US3515651A (en) Plating solutions for rhodium and rhodium alloy platings having low internal stress
US2836510A (en) Nickel plating by chemical reduction
CA1153978A (fr) Revetement d'alliages d'aluminium a l'aide de cyanure-borate avant la galvanoplastie au bronze
US5182172A (en) Post-plating passivation treatment
US3915814A (en) Method of electroplating bright white gold alloy coatings
US3528895A (en) Plating low stress bright rhodium
US4470886A (en) Gold alloy electroplating bath and process
JPS634635B2 (fr)
US2650902A (en) Electrodeposition on magnesium and magnesium-base alloys
EP3604626A1 (fr) Bain électrolytique pour déposer un alliage noire, procédé pour le dépôt électrochimique d'un alliage noir sur un substrat, alliage noir et article recouvert d'un tel alliage noir
EP4043202A1 (fr) Alliage pt-ni non allergénique électroplaqué et bain et cycle galvanique associés

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A2

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BW BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE EG ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NA NI NO NZ OM PG PH PL PT RO RU SC SD SE SG SK SL SY TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A2

Designated state(s): BW GH GM KE LS MW MZ NA SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LU MC NL PL PT RO SE SI SK TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
WWE Wipo information: entry into national phase

Ref document number: 2004797802

Country of ref document: EP

WWP Wipo information: published in national office

Ref document number: 2004797802

Country of ref document: EP