US4416742A
Expired / Lapsed
US
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Process and electrolytic bath for making a rhodium-plated article having a black or blue color
Assignee: Nippon Metal Plating Co Ltd
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Filing: 1981-09-23
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Granted: 1983-11-22
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Expires: 2001-09-23
Abstract
Abstract A rhodium-plated article with black or blue color is obtained through electroplating by using a plating bath comprising a conventional acid rhodium bath and an additive consisting of organocarboxylic acid, aromatic sulfonic acid or salts of these, amine, gelatin, butynediol, hypophosphite or a mixture thereof.
Inventors
- 👤 Takashi Kinase
- 👤 Seiji Ichimura
- 👤 Yoshio Kinjo
- 👤 Yosuke Matsumoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 01:20
CPC Classifications
C; C25; C25D; C25D11/00; C25D11/02; C25D11/34; C25D3/00; C25D3/02; C25D3/50; C25D3/52
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
123 words
A process for electroplating rhodium onto a conductive substrate which process comprises: (1) providing an aqueous acidic rhodium plating bath comprised of (a) a free acid, (b) a source of rhodium in a concentration ranging from about 0.10 to 20 g/l based on the rhodium metal, and (c) at least one additive selected from the group consisting of thiomalic acid and salts thereof, phthalic acid and salts thereof, butynediol and hypophosphite, said additive being present in an amount of at least about 0.01 g/l, with the pH of said bath not exceeding 6; and (2) electroplating rhodium onto said substrate as a cathode in said bath under conditions such that the rhodium is plated in the form of a blue or black electroplate.
Claim 2
Dependent Claim
123 words
A process for electroplating rhodium onto a conductive substrate which process comprises: (1) providing an aqueous acidic rhodium plating bath comprised of (a) a free acid, (b) a source of rhodium in a concentration ranging from about 0.10 to 20 g/l based on the rhodium metal, and (c) at least one additive selected from the group consisting of thiomalic acid and salts thereof, phthalic acid and salts thereof, butynediol and hypophosphite, said additive being present in an amount of at least about 0.01 g/l, with the pH of said bath not exceeding 6; and (2) electroplating rhodium onto said substrate as a cathode in said bath under conditions such that the rhodium is plated in the form of a blue or black electroplate.
Claim 3
Dependent Claim
22 words
The process as defined in claim 1, wherein said hypophosphite is present in an amount ranging from about 0.5 to 10 g/l.
Claim 4
Dependent Claim
25 words
The process as defined in claim 1, wherein said free acid is selected from the group consisting of sulfuric acid, phosphoric acid and sulfamic acid.
Claim 5
Dependent Claim
40 words
The process as defined in claim 1, wherein said hypophosphite is selected from the group consisting of an alkali metal salt, an alkaline earth metal salt, a divalent metal salt other than an alkaline earth metal salt, or mixtures thereof.
Claim 6
Dependent Claim
30 words
The process as defined in claim 1 wherein said additive is one selected from the group consisting of thiomalic acid and salts thereof, phthalic acid and salts thereof, and butynediol.
Claim 7
Dependent Claim
23 words
The process as defined in claim 1, wherein said additive is hypophosphite and the pH value of the bath does not exceed 2.5.
Claim 8
Dependent Claim
77 words
An aqueous acidic rhodium electroplating bath comprised of (a) a free acid, (b) a source of rhodium in a concentration ranging from about 0.10to 20 g/l based on rhodium metal, and (c) at least one additive selected from the group consisting of thiomalic acid and salts thereof, phthalic acid and salts thereof, butynediol and hypophosphite, said additive being present in an amount of at least about 0.01 g/l, with the pH of said bath not exceeding 6.
Claim 9
Dependent Claim
77 words
An aqueous acidic rhodium electroplating bath comprised of (a) a free acid, (b) a source of rhodium in a concentration ranging from about 0.10to 20 g/l based on rhodium metal, and (c) at least one additive selected from the group consisting of thiomalic acid and salts thereof, phthalic acid and salts thereof, butynediol and hypophosphite, said additive being present in an amount of at least about 0.01 g/l, with the pH of said bath not exceeding 6.
Claim 10
Dependent Claim
31 words
The rhodium plating bath as defined in claim 7, wherein said additive is selected from the group consisting of thiomalic acid and salts thereof, phthalic acid and salts thereof and butynediol.
Claim 11
Dependent Claim
25 words
The rhodium plating bath as defined in claim 7, wherein said additive is hypophosphite and the pH value of the bath does not exceed 2.5.
Claim 12
Dependent Claim
42 words
The rhodium plating bath as defined in claim 7, wherein said hypophosphite is selected from the group consisting of an alkali metal salt, an alkaline earth metal salt, a divalent metal salt other than an alkaline earth metal salt or mixtures thereof.
Claim 13
Dependent Claim
24 words
The rhodium plating bath as defined in claim 7, wherein said hypophosphite is present in an amount ranging from about 0.5 to 10 g/l.
Claim 14
Dependent Claim
27 words
The rhodium plating bath as defined in claim 7, wherein said free acid is selected from the group consisting of sulfuric acid, phosphoric acid and sulfamic acid.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-11-21 | 1987-05-23 | 1987-11-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-11-21 | 1991-05-23 | 1991-11-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-11-21 | 1995-05-23 | 1995-11-22 | $7700.00 | Window Closed / Lapsed |