Patent US3816142A successfully refreshed from Google Patents.
US3816142A
Expired / Lapsed
US
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Electroless chromium plating process and composition
Assignee: Individual
•
Filing: 1972-05-08
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Granted: 1974-06-11
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Expires: 1992-05-08
Abstract
Abstract Articles being electroplated with zinc are rapidly coated with a resistant and well adhering electroless chromium plating by immersing the articles in an aqueous bath containing A. 8 TO 15 LITERS OF A SOLUTION OF 250 TO 350 G./L. OF SODIUM DICHROMATE AND 200 TO 300 G./L. OF SODIUM NITRATE, SAID SOLUTION BEING ADJUSTED TO PH .3 with nitric acid, B. 3 TO 8 LITERS OF A SOLUTION OF 500 TO 700 G./L. OF 85 PERCENT FORMIC ACID AND C. .5 TO 3 LITERS OF GLACIAL ACETIC ACID AND CONCENTRATED ACETIC ACID RESPECTIVELY EACH PER 100 LITERS AND MAINTAINING THE PH value of the solution at a pH of 2.1 to 2.7.
Inventors
- 👤 K Lindemann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 09:23
CPC Classifications
C; C23; C23C; C23C18/00; C23C18/16; C23C18/31; Y; Y10; Y10T; Y10T428/00; Y10T428/12; Y10T428/12493; Y10T428/12771; Y10T428/12785; Y10T428/12792
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
29 words
The chromatizing process of claim 1, in which the zinc electroplated articles to be chromatized are articles that have been electroplated from a bath comprising sulfuric acid and zinc.
Claim 2
Dependent Claim
98 words
The chromatizing process of claim 1, in which the chromatizing bath is a bath containing per 100 liters a. 11.0 liters to 11.5 liters of an aqueous solution of about 300 g./l. of sodium dichromate and 250 g./l. of sodium nitrate, said solution being adjusted to a pH of 0.3 by the addition of nitric acid, b. 5 liters of an aqueous formic acid solution of a density of 1.133 at 20* C., and c. 6 g./l. to 12 g./l. of glacial acetic acid, the pH-value of said bath being maintained at a pH between 2.1 and 2.7.
Claim 3
Dependent Claim
106 words
An electroless chromium plating bath comprising an aqueous solution containing per 100 liters a. 8 liters to 15 liters of an aqueous solution of 250 g./l. to 350 g./l. of sodium dichromate and 200 g./l. to 300 g./l. of sodium nitrate, and nitric acid in an amount sufficient to adjust the pH of the solution to 0.3; b. 3 liters to 8 liters of an aqueous solution of 500 g./l. to 700 g./l. of 85 percent formic acid or equivalent amounts thereof, and c. 0.5 liters to 3 liters of glacial acetic acid or concentrated acetic acid, said bath having a pH between 2.1 and 2.7.
Claim 4
Dependent Claim
92 words
The electroless chromium plating bath of claim 4, said bath comprising an aqueous solution containing per 100 liters a. 11.0 liters to 11.5 liters of an aqueous solution of about 300 g./l. of sodium dichromate and 250 g./l. of sodium nitrate, and in an amount sufficient to adjust the pH of the solution to 0.3, b. 5 liters of an aqueous formic acid solution of a density of 1.133 at 20* c., and c. 6 g./l. to 12 g./l. of glacial acetic acid, said bath having a pH between 2.1 and 2.7.
Claim 5
Dependent Claim
31 words
An article with a zinc surface, said article being provided with a chromium layer deposited on said zinc surface in an electroless manner by a process as claimed in claim 1.
Claim 6
Dependent Claim
31 words
An article with a zinc surface, said article being provided with a chromium layer deposited on said zinc surface in an electroless manner by a process as claimed in claim 2.
Claim 7
Dependent Claim
31 words
An article with a zinc surface, said article being provided with a chromium layer deposited on said zinc surface in an electroless manner by a process as claimed in claim 3.
Claim 8
Dependent Claim
36 words
A chromatized article with a zinc surface, said article being provided with a chromium layer deposited on said zinc surface in an electroless manner by immersing the article in the electroless chromatizing bath of claim 4.
Claim 9
Dependent Claim
36 words
A chromatized article with a zinc surface, said article being provided with a chromium layer deposited on said zinc surface in an electroless manner by immersing the article in the electroless chromatizing batH of claim 5.
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) | 1977-06-10 | 1977-12-10 | 1978-06-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-10 | 1981-12-10 | 1982-06-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-10 | 1985-12-10 | 1986-06-11 | $7700.00 | Window Closed / Lapsed |