US3963527A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Chromatizing process and composition
Assignee: Lyndex Recycling Systems Ltd
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Filing: 1975-01-02
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Granted: 1976-06-15
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Expires: 1995-01-02
Abstract
Abstract Zinc articles or, respectively, articles being electroplated with zinc are rapidly coated with a resistant and well adhering colored electroless chromium plating by immersing the articles in an aqueous bath containing besides known wetting agents A. a solution of 12.5 to 37.5 g/l. of sodium dichromate and 12.5 to 37.5 g/l. of sodium nitrate, said solution being adjusted to a pH value of 0.3 with nitric acid, B. 25 to 70 g./l. of formic acid and/or chloroformic acid, C. 0 to 40 ml./l. of glacial acetic acid and concentrated acetic acid respectively and/or glycolic acid, glycocoll, chloroacetic acid, trifluoro-acetic acid and, if desired D. 0 to 15 ml./l. of formaldehyde and maintaining the pH of the solution at a pH value of 1.4 to 2.7.
Inventors
- 👤 Karl H. Lindemann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 20:49
CPC Classifications
C; C23; C23C; C23C22/00; C23C22/05; C23C22/06; C23C22/24; C23C22/30; C23C22/26; C23C22/27
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
135 words
In a process of chromatizing zinc articles and zinc electroplated articles, the step which comprises immersing said articles for a period of less than 60 seconds in an aqueous chromatizing bath containing a. 12.5 g./l. to 37.5 g./l. of sodium dichromate and 12.5 g./l. to 37.5 g./l. of sodium nitrate, said solution being adjusted to a pH of 0.3 by the addition of nitric acid; b. 25 g./l. to 70 g./l. of formic acid or chloroformic acid or both; c. 5 ml./l. to 35 ml./l. of a member of the class consisting of glacial acetic acid, concentrated acetic acid, glycolic acid, glycocoll, chloroacetic acid and trifluoroacetic acid and, optionally d. 5 ml./l. to 12 ml./l. of formaldehyde, calculated on 100% formaldehyde the pH-value of said bath being maintained at a pH between 1.4 and 2.7.
Claim 2
Dependent Claim
135 words
In a process of chromatizing zinc articles and zinc electroplated articles, the step which comprises immersing said articles for a period of less than 60 seconds in an aqueous chromatizing bath containing a. 12.5 g./l. to 37.5 g./l. of sodium dichromate and 12.5 g./l. to 37.5 g./l. of sodium nitrate, said solution being adjusted to a pH of 0.3 by the addition of nitric acid; b. 25 g./l. to 70 g./l. of formic acid or chloroformic acid or both; c. 5 ml./l. to 35 ml./l. of a member of the class consisting of glacial acetic acid, concentrated acetic acid, glycolic acid, glycocoll, chloroacetic acid and trifluoroacetic acid and, optionally d. 5 ml./l. to 12 ml./l. of formaldehyde, calculated on 100% formaldehyde the pH-value of said bath being maintained at a pH between 1.4 and 2.7.
Claim 3
Dependent Claim
116 words
An electroless chromiumplating bath comprising an aqueous solution containing besides a known wetting agent a. an aqueous solution of 12.5 g./l. to 37.5 g./l. of sodium dichromate and 12.5 g./l. to 37.5 g./l. of sodium nitrate, said solution being adjusted to a pH of 0.3 by the addition of nitric acid, b. 25 g./l. to 70 g./l. of formic acid or chloroformic acid or both; c. 5 ml./l. to 35 ml./l. of a member of the class consisting of glacial acetic acid, concentrated acetic acid, glycolic acid, glycocoll, chloroacetic acid and trifluoroacetic acid and, optionally, d. 5 ml./l. to 12 ml./l. of formaldehyde, calculated on 100% formaldehyde said bath having a pH between 1.4 and 2.7.
Claim 4
Dependent Claim
116 words
An electroless chromiumplating bath comprising an aqueous solution containing besides a known wetting agent a. an aqueous solution of 12.5 g./l. to 37.5 g./l. of sodium dichromate and 12.5 g./l. to 37.5 g./l. of sodium nitrate, said solution being adjusted to a pH of 0.3 by the addition of nitric acid, b. 25 g./l. to 70 g./l. of formic acid or chloroformic acid or both; c. 5 ml./l. to 35 ml./l. of a member of the class consisting of glacial acetic acid, concentrated acetic acid, glycolic acid, glycocoll, chloroacetic acid and trifluoroacetic acid and, optionally, d. 5 ml./l. to 12 ml./l. of formaldehyde, calculated on 100% formaldehyde said bath having a pH between 1.4 and 2.7.
References Cited (Backward Citations)
US3653953A
Cited
US3816142A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-06-15 | 1979-12-15 | 1980-06-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-06-15 | 1983-12-15 | 1984-06-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-06-15 | 1987-12-15 | 1988-06-15 | $7700.00 | Window Closed / Lapsed |