US4422906A
Expired / Lapsed
US
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Process for direct gold plating of stainless steel
Assignee: Individual
•
Filing: 1981-09-17
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Granted: 1983-12-27
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Expires: 2001-09-17
Abstract
Abstract Stainless steel can be directly plated with gold by a process wherein stainless steel is dipped in an activating solution; the activated stainless steel is subjected to cathodic electrolysis in a cathode electrolytic activation solution and then the treated stainless steel is directly plated with gold. A preferable activating solution contains (i) 3-20 wt. % of HCl, (ii) 2-30 wt. % of H 2 SO 4 , (iii) 0.1-5 wt. % of a nonionic or cationic surfactant and (iv) 0.1-20 wt. % of 2-pyrrolidone or N-alkyl-2-pyrrolidone. A preferable cathode electrolytic activation solution contains (i) 5-20 wt. % of H 3 PO 4 , (ii) 2-10% HNO 3 , (iii) 0.1-5 wt. % of a nonionic or cationic surfactant and (iv) 0.1-20 wt. % of 2-pyrrolidone or N-alkyl-2-pyrrolidone.
Inventors
- 👤 Masami Kobayashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 18:47
CPC Classifications
C; C23; C23G; C23G1/00; C23G1/02; C23G1/08; C25; C25D; C25D5/00; C25D5/34; C25D5/36
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
120 words
A process for direct gold plating of stainless steel which comprises the steps of: dipping stainless steel in an activating solution which is an aqueous mixed acid solution containing, based on the weight of the solution, (i) 3% to 20% by weight of hydrochloric acid, (ii) 2 to 30% by weight of sulfuric acid, (iii) 0.1 to 5% by weight of a nonionic or cationic surface active agent, and (iv) 0.1 to 20% by weight of a compound selected from the group consisting of 2-pyrrolidone and N-alkyl-2-pyrrolidone, the alkyl moiety having 1 to 5 carbon atoms; subjecting the activated stainless steel to cathodic electrolysis in a cathode electrolytic activation solution: and then electroplating the cathodically electrolyzed stainless steel with gold.
Claim 2
Dependent Claim
120 words
A process for direct gold plating of stainless steel which comprises the steps of: dipping stainless steel in an activating solution which is an aqueous mixed acid solution containing, based on the weight of the solution, (i) 3% to 20% by weight of hydrochloric acid, (ii) 2 to 30% by weight of sulfuric acid, (iii) 0.1 to 5% by weight of a nonionic or cationic surface active agent, and (iv) 0.1 to 20% by weight of a compound selected from the group consisting of 2-pyrrolidone and N-alkyl-2-pyrrolidone, the alkyl moiety having 1 to 5 carbon atoms; subjecting the activated stainless steel to cathodic electrolysis in a cathode electrolytic activation solution: and then electroplating the cathodically electrolyzed stainless steel with gold.
Claim 3
Dependent Claim
133 words
A process for direct gold plating of stainless steel according to claim 1, wherein the activating solution used in the first step is an aqueous mixed acid solution containing, based on the weight of the solution; (i) 3 to 10% by weight of hydrochloric acid, (ii) 0.5 to 4% by weight of nitric acid, (iii) 2 to 15% by weight of sulfuric acid, (iv) 1 to 5% by weight of acetic acid, (v) 3 to 10% by weight of citric acid, (vi) 0.1 to 3% by weight of a nonionic or cationic surface active agent, (vii) 0.1 to 10% by weight of a compound selected from the group consisting of 2-pyrrolidone and N-alkyl-2-pyrrolidone, the alkyl moiety having 1 to 5 carbon atoms, and (viii) 1 to 5% by weight of an acetylenic glycol.
Claim 4
Dependent Claim
35 words
A process for direct gold plating of stainless steel according to claim 1 or 2, wherein the nonionic surface active agent contained in the activating solution used in the first step is polyoxyethylene alkyl ether.
Claim 5
Dependent Claim
32 words
A process for direct gold plating of stainless steel according to claim 1 or 2, wherein the N-alkyl-2-pyrrolidone contained in the activating solution used in the first step is N-methyl-2-pyrrolidone or N-ethyl-2-pyrrolidone.
Claim 6
Dependent Claim
31 words
A process for direct gold plating of stainless steel according to claim 2, wherein the acetylenic glycol contained in the activating solution used in the first step is 2-pentyne-1,4-diol or 2-butyne-1,4-diol.
Claim 7
Dependent Claim
97 words
A process for direct gold plating of stainless steel according to claim 1, wherein the cathode electrolytic activation solution used in the cathodically electrolyzing step is an aqueous mixed acid solution containing, based on the weight of the solution: (i) 5 to 20% by weight of phosphoric acid, (ii) 2 to 10% by weight of nitric acid, (iii) 0.1 to 5% by weight of a nonionic surface active agent and (iv) 0.1 to 20% by weight of a compound selected from the group consisting of 2-pyrrolidone and N-alkyl-2-pyrrolidone, the alkyl moiety having 1 to 5 carbon atoms.
Claim 8
Dependent Claim
144 words
A process for direct gold plating of stainless steel according to claim 1, wherein the cathode electrolytic activation solution used in the cathodically electrolyzing step is an aqueous mixed acid solution containing, based on the weight of the solution: (i) 5 to 10% by weight of phosphoric acid, (ii) 2 to 10% by weight of citric acid, (iii) 1 to 5% by weight of oxalic acid, (iv) 2 to 5% by weight of nitric acid, (v) 3 to 20% by weight of sulfuric acid, (vi) 0.1 to 3% by weight of a nonionic or cationic surface active agent, (vii) 0.5 to 10% by weight of gluconic acid, (viii) 0.1 to 10% by weight of a compound selected from the group consisting of 2-pyrrolidone and N-alkyl-2-pyrrolidone, the alkyl moiety having 1 to 5 carbon atoms. (ix) 1 to 5% by weight of an acetylenic glycol.
Claim 9
Dependent Claim
32 words
A process for direct gold plating of stainless steel according to claim 6 or 7, wherein the nonionic surface active agent contained in the cathode electrolytic activation solution is polyoxyethylene alkyl ether.
Claim 10
Dependent Claim
29 words
A process for direct gold plating of stainless steel according to claim 6 or 7, wherein the N-alkyl-2-pyrrolidone contained in the cathode electrolytic activation solution is N-methyl-2-pyrrolidone or N-ethyl-2-pyrrolidone.
Claim 11
Dependent Claim
30 words
A process for direct gold plating of stainless steel according to claim 6 or 7, wherein the acetylenic glycol contained in the cathode electrolytic activation solution is 2-pentyne-1,4-diol or 2-butyne-1,4-diol.
Claim 12
Dependent Claim
42 words
A process for direct gold plating of stainless steel according to any one of claims 1 or 2, wherein at the first activating step, the stainless steel is dipped in the activating solution at room temperature for 30 seconds to 7 minutes.
Claim 13
Dependent Claim
29 words
A process for direct gold plating of stainless steel according to claim 11, wherein the dipping treatment of the activating step is carried out under irradiation with ultrasonic waves.
Claim 14
Dependent Claim
60 words
A process for direct gold plating of stainless steel according to any one of claims 1, 6 and 7, wherein at the cathodically electrolyzing step, electrolysis is carried out at a cathode current density of 1 to 7 A/dm 2 for 30 seconds to 5 minutes by using a platinum coated titanium anode and the stainless steel as the cathode.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-12-26 | 1987-06-27 | 1987-12-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-12-26 | 1991-06-27 | 1991-12-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-12-26 | 1995-06-27 | 1995-12-27 | $7700.00 | Window Closed / Lapsed |