US4511633A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Galvanized steel sheet protected by chromium and chromium oxide layers
Assignee: Zincroksid SpA
•
Filing: 1984-02-10
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Granted: 1985-04-16
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Expires: 2004-02-10
Abstract
Abstract Steel sheet, especially suitable for car-body fabrication, galvanized and further protected by a layer of metallic chromium and hydrated oxides of chromium, electrolytically deposited. The improvement is that the metallic chromium is present in extremely fine particles that exert a very marked covering and protective effect on the underlying zinc. In this way, and with the help of the chromium oxides that further cover and protect the underlying layers, a product is obtained whose corrosion resistance is far superior to that of similar products.
Inventors
- 👤 Roberto Bruno
- 👤 Massimo Memmi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 21:39
CPC Classifications
C; C25; C25D; C25D11/00; C25D11/38; Y; Y10; Y10T; Y10T428/00; Y10T428/12; Y10T428/12493; Y10T428/12535; Y10T428/12583; Y10T428/1259; Y10T428/12771; Y10T428/12785; Y10T428/12792; Y10T428/12799; Y10T428/12806; Y10T428/12826; Y10T428/12847
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
56 words
Steel sheet, protected by a zinc coating overlaid with a protective layer of chromium and hydrated oxides of chromium, the chromium metal being in the form of particles having average dimensions of about 0.03 micron, while at least 40% by volume of the metallic chromium is in the form of particles measuring less than 0.02 micron.
Claim 2
Dependent Claim
56 words
Steel sheet, protected by a zinc coating overlaid with a protective layer of chromium and hydrated oxides of chromium, the chromium metal being in the form of particles having average dimensions of about 0.03 micron, while at least 40% by volume of the metallic chromium is in the form of particles measuring less than 0.02 micron.
Claim 3
Dependent Claim
53 words
Steel sheet as claimed in claim 1, in which the protective layer of metallic chromium and hydrated oxides of chromium has a total chromium content of between 0.2 and 1.0 g/m 2 , the chromium metal accounting for between 80 and 90% of that figure, the remainder being chromium contained in the oxides.
Claim 4
Dependent Claim
25 words
Steel sheet as claimed in claim 2, in which the total chromium content of the protective layer is between 0.4 and 0.6 g/m 2 .
Claim 5
Dependent Claim
37 words
Steel sheet as claimed in claim 1, in which the metallic chromium layer leaves uncovered areas averaging less than 0.02 micron in size, the total proportion of uncovered zinc being less than 0.1% of the total area.
Claim 6
Dependent Claim
30 words
Steel sheet as claimed in claim 1, in which the chromium-oxide layer is colloidal and non-crystalline and is insoluble in water and alkalis and only very slightly soluble in acids.
Claim 7
Dependent Claim
21 words
Steel sheet as claimed in claim 1, in which the maximum particle size of the chromium metal is about 0.07-0.08 micron.
References Cited (Backward Citations)
US3323881A
Cited
US3428441A
Cited
US3816082A
Cited
US4159230A
Cited
US4421828A
Cited
US4437944A
Cited
US4411964A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-04-15 | 1988-10-15 | 1989-04-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-04-15 | 1992-10-15 | 1993-04-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-04-15 | 1996-10-15 | 1997-04-16 | $7700.00 | Window Closed / Lapsed |