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
  • C25D3/62—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of gold

Definitions

• composition and process for obtaining bright deposits of about 14 to about 23.5 carat gold with improved color is to provide a composition and process for obtaining bright deposits of about 14 to about 23.5 carat gold with improved color.
• This invention is based on the discovery that the addi tion of a small amount of an alkali soluble titanium compound to an alkali cyanide gold plating bath containing silver not only leads to an extended bright range and more brilliant deposits, but the addition of this addition agent also leads to deposits less green in color than those obtained from baths containing larger quantities of silver than as described under said US.
• Reissue Patent No. 24,582. Exceptionally brilliant gold-silver alloy deposits are obtained when the titanium compound is added in conjunction with a small amount of an alkali-soluble selenium compound.
• This invention is carried out most advantageously by employing a typical cyanide gold plating solution containing 4-32 g./l. of gold, 10 to 200 grams per liter of alkali cyanide, and 0.1 to 12 g./l. of potassium silver cyanide.
• the prefer-red composition and limiting concentrations are shown in Table 1 (below) from which it is obvious that a wide range for each constituent is possible.
• the ratio of silver to gold in the deposit will vary considerably dependent upon the AuzAg ratio in the bath, but wide variations can be accomplished by manipulation of the brightener content due to varying effects upon the polarization curves for gold and silver. Most striking is the development of low carat deposits going from gold to white with little evidence of the green color common to low-carat, gold-silver alloys.
• any titanium compound soluble in the bath may be employed, but particularly satisfactory results have been obtained by adding titanium coordination compounds having at least one ligand selected from the class consisting of polyols and alkanolamines, since these compounds are unusually stable for titanium salts in aqueous solution.
• the aminoalcohol titanates which may be employed in the practice of the present invention include the titanate esters of aminoalcohols which have the formula,
• R is selected from the group consisting of ethylone and alkyl substituted ethylene radicals and R and R" are selected from the group consisting of hydrogen, alkyl hydrocarbon groups, B-amino-alkyl and B-hydroxy alkyl "ice radicals.
• These aminoa-lcohol esters are stabilized in solution by the addition to said ester of a compound selected from the group consisting of inositol, sucrose and the more or less related saturated and/ or unsaturated straight chain aliphatic alcohols and monocarboxylic acid derivatives thereof containing 3 to 7 carbon atoms and 3 to 6 hydroxy groups such as gluconic, sorbic, aconitic, glucoheptonie acids and the alkali salts thereof.
• the mechanism of the stabilization may involve the formation of a coordination compound between the aminoalcohol titanates and the polyhydroxy compounds.
• the exact structure is not known, but in general the greater the number of hydroxy groups, the more efilective is the compound as a stabilizer.
• Aminoalcohol titanates per se, are disclosed in US. Patent No. 2,894,966 but the following Examples A-C illustrate specific methods of producing such titanium compounds.
• a suitable stabilized ethanolamine titanate may be prepared by adding 1 mole of ethanolamine to mole of isopropyl titanate. The solution will become warm, then mole of sorbitol hemihydrate in 100 ml. of water is added and the mixture is heated to drive oil. the isopropyl alcohol after which the stabilized ethanolamine titanate is taken up in 250 ml. of water. The aqueous solution serves as the addition agent for the gold bath.
• EXAMPLE B The triethanolamine titanate was prepared by the same process as set forth in Example A by substituting 1 mol of triethanolamine for the ethanolamine.
• EXAMPLE C The solution of titanates of Examples A or B may also be stabilized by substituting or" a mol of inositol, sodium gluconate, sodium glucoheptonate, or similar polyliydroxy compound for the sorbit-ol.
• the gold bath normally is made up with potassium salts according to Table I, but sodium salts may be substituted in which case somewhat less brilliancy may be expected.
• EXAMPLE 1 A bath containing 4 g./l. of gold as KAu(CN) 0.04 g./l. of silver as KAg(CN) 0.05 g./l. of titanium as stabilized triethanolamine titanate and 10 g./l. of free potassium cyanide gave bright, yellowish gold deposits on a 2.5 x 10 cm. brass panel plated at .2 ampere/dmP'.
• EXAMPLE 2 A gold plating solution containing 8 g./l. of gold (as potassium gold cyanide), 3 g./l. of silver (as potassium silver cyanide), g./l. of potassium cyanide, 0.1 g./l. of titanium (as the ethanolamine titanate of Example A) and 0.1 g./l. of selenium diethyldithio-carbamate.
• posits were obtained on 2.5 x 10 cm. panels which were bright at 0.4, 0.6, 1.2, and 1.8 amperes/dmF.
• EXAMPLE 3 A bath was made up containing 8 g./l. of gold added as potassium gold cyanide, 4 gl/l. of silver, added as potassium silver cyanide, 90 g./l. of potassium cyanide and carbon-treated with 1 g./lite-r of carbon. At 0.6, 0.8 and 1.2 amperes/dm. the deposit was hazy. The 0.1 g./'l. of titanium as triethanolamine titanate of Example B and 0.1 g./l. of selenium as sodium selenite was added. The deposit became brilliant at 0.6, 0.8 and 1.2 amperes/dmf EXAMPLE 4 A bath was made up containing 8 g./l.
• Example 3 the deposits were hazy at 0.6, 0.8 and 1.2 amperes/dmf".
• EXAMPLE 5 A gold plating solution was prepared as for Examples 2 and 3. A characteristic haxy golden deposit was brightened considerably by as little as 0.05 g./l. of stabilized triethanolamine titanate and became brilliant when 0.1 g./l. of selenium diethyldithi-o-carbamate was also added.
• An aqueous alkali cyanide gold plating bath containing about 4 to 32 g./l. of gold, about 0.04 to 12 g./l. of silver, about 10 to 200 g./l. of alkali cyanide and about 0.05 to 5 g./l. of a water-soluble titanium compound.
• An aqueous alkali cyanide gold plating bath containing about 4 to 32 g./-l. of gold, about 0.04 to 12 g./l. of silver, about 10 to 200 g./l. of alkali cyanide, about 0.05 to 5 g./l. of stabilized amin'oaloohol titanium compound and about 0:03 to 3 g./l. of a bath-soluble selenium compound.
• a process of producing a bright gold alloy which comprises electrodepositing a gold-silver alloy of about 23.5 to about 14-ca1'at from an aqueous solution containing from about 4 to 32 g./l. of gold added as alkali gold cyanide, about 0.4 to 12. g./l. of silver added as alkali silver cyanide, about 10 10,200 g./l. of free alkali cyanide and about 0.05 to 5 g./l. of a soluble titanium compound.
• a process according to claim 6 comprising adding to said bath, in addition, 0.03 to 3 g./l. of selenium.
• a process according to claim 8 wherein the titanium compound is t-riethanolamine titanate and the selenium compound is diethyldithio-carbamate.

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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)
• Chemically Coating (AREA)

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  • NL NL277803D patent/NL277803A/xx unknown
• 1961
  • 1961-05-01 US US106541A patent/US3092559A/en not_active Expired - Lifetime
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  • 1962-01-09 CH CH19962A patent/CH410576A/fr unknown
  • 1962-02-01 GB GB3952/62A patent/GB929220A/en not_active Expired
  • 1962-03-01 DE DES78269A patent/DE1213196B/de active Pending
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