US4437944A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process of making long-life thin metal plate for automobile bodies
Assignee: SIDERTEK SPA A CORP ITALY
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Filing: 1980-12-22
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Granted: 1984-03-20
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Expires: 2000-12-22
Abstract
Abstract Thin metal plate is cleaned and electrolytically pickled in an acid solution. A zinc layer is electrodeposited on one face of the plate, after which a chrome-chromic oxide coating is deposited on both faces of the plate from a sulphuric acid solution containing compounds of trivalent and hexavalent chrome. The plate is then subjected to a drying-oxidating treatment in air. The plate may be steel having a thickness between 0.1 and 2 mm. The plate may be surface treated by phosphating, and then painted. The chrome-chromic oxide coating may have a thickness between 0.05 and 5 mu m, and the zinc coating a thickness between 1 and 30 mu m.
Inventors
- 👤 Roberto Bruno
- 👤 Massimo Memmi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 01:34
CPC Classifications
C; C23; C23C; C23C22/00; C23C22/05; C23C22/06; C23C22/24; C23C22/30; C25; C25D; C25D11/00; C25D11/38; C25D13/00; C25D13/20; C25D5/00; C25D5/34; C25D5/36; Y; Y10; Y10T; Y10T428/00; Y10T428/12; Y10T428/12493; Y10T428/12535; Y10T428/12542; Y10T428/12549; Y10T428/12583; Y10T428/1259; Y10T428/12611; Y10T428/12618; Y10T428/12771; Y10T428/12785; Y10T428/12792; Y10T428/12799; Y10T428/12806; Y10T428/12826; Y10T428/12847; Y10T428/12854
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
88 words
A process for producing sheet steel for long life motor vehicle bodies, comprising the steps of: depositing a layer of zinc on only one face of the sheet steel, and thereafter simultaneously applying to both faces of the sheet steel a chrome-chromic oxide coating, said coating being applied by electrodeposition from an aqueous solution comprising, per liter: from 0.05 to 1 ml of H 2 SO 4 at 96%; from 20 to 100 g of CrO 3 ; and from 0.5 to 3 g of CrF 3 .
Claim 2
Dependent Claim
88 words
A process for producing sheet steel for long life motor vehicle bodies, comprising the steps of: depositing a layer of zinc on only one face of the sheet steel, and thereafter simultaneously applying to both faces of the sheet steel a chrome-chromic oxide coating, said coating being applied by electrodeposition from an aqueous solution comprising, per liter: from 0.05 to 1 ml of H 2 SO 4 at 96%; from 20 to 100 g of CrO 3 ; and from 0.5 to 3 g of CrF 3 .
Claim 3
Dependent Claim
20 words
A process according to claim 1, characterized in that the thin plate has a thickness between 0.1 and 2 mm.
Claim 4
Dependent Claim
23 words
A process according to claim 1, characterized by the deposition of the chrome-chromic oxide occurring at a temperature between 30° and 80° C.
Claim 5
Dependent Claim
21 words
A process according to claim 3, characterized by the deposition time for the chrome-chromic oxide being between 1 and 10 seconds.
Claim 6
Dependent Claim
27 words
A process according to claim 4 characterized by the cathodic current density during the deposition of said chrome-chromic oxide being between 5 and 100 A/dm 2 .
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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) | 1987-03-20 | 1987-09-19 | 1988-03-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-03-20 | 1991-09-19 | 1992-03-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-03-20 | 1995-09-19 | 1996-03-20 | $7700.00 | Window Closed / Lapsed |