Conversion coatings prepared or treated with calcium hydroxide solutions
US6395106B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 7, 2000 |
| Grant date | May 28, 2002 |
| Priority date | — |
| Expiry date | Feb 7, 2020 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC23C22/83
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
A conversion coating process that forms a stable and corrosion-resistant oxide layer on metal or metal oxide substrates or layers. Particularly, the conversion coating process involves contacting the metal or metal oxide substrate or layer with the aqueous calcium hydroxide solutions in order to convert the surface of the substrate to a stable metal oxide layer or coating. According to the present invention, the calcium hydroxide solution is prepared by removing carbon dioxide from water or an aqueous solution before introducing the calcium hydroxide. In this manner, formation of calcium carbonate particles is avoided and the porosity of the conversion coating produced by the calcium hydroxide solution is reduced to below about 1%.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.