pH stable trivalent chromium coating solutions
US10400338B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 14, 2018 |
| Grant date | Sep 3, 2019 |
| Priority date | — |
| Expiry date | May 14, 2038 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC23C2222/10
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
A stable trivalent chromium coating solution can be prepared by heating the chromium coating solution and adjusting the pH of the chromium coating solution. The coating solution can be heated to at least 35° C. for no more than 24 hours. While the solution is hot, a basic or acidic material can be added to increase or reduce the pH to a target value, respectively. In some embodiments, the chromium coating solution can have a pH of 3.5 to 4.0 and the pH can vary no more than ±0.15 while in storage for at least 20 days. The trivalent chromium coating solution can include a fluoride compound, a zirconate compound, a corrosion inhibitor compound, a chelating agent, a phosphorous compound, and/or other compounds.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.