Surface-treated steel sheet coated with chromate film for fuel tanks and method of fabricating the same
US6565671B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 20, 2001 |
| Grant date | May 20, 2003 |
| Priority date | — |
| Expiry date | Jul 20, 2021 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC23C2222/20
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
The present invention relates to a surface-treated steel sheet coated with a chromate layer having excellent corrosion resistance, fuel resistance and seam weldability, and a chromate solution used for preparing the surface-treated steel sheet. Specifically, the chromate solution of the present invention comprises (a) a main solution prepared by adding to a chrome solution having 0.4 to 0.8 of trivalent chrome composition and 7 to 50 g/l of dissolved chrome, on the basis of the chrome in the chrome solution, 50 to 80 w % of phosphate, 20 to 40 w % of fluoric acid, 300 to 2000 w % of colloidal silica, 5 to 15 w % of sulfuric acid, and 25 to 40 w % of sodium phosphate, and (b) a hardener solution containing added epoxy silane or glycidyl silane of 2 to 10 w % on the basis of total hardener solution, the pH of which is controlled between 2 and 3, wherein 10 to 60 w % of the hardener solution being added to the main solution.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.