Method for blackening the surfaces of a body of ferrous metal
US4149908A · kind A · utility
3Cited by
7References
9Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Sep 26, 1977 |
| Grant date | Apr 17, 1979 |
| Priority date | — |
| Expiry date | Sep 26, 1997 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC23C22/72
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
The surfaces of a ferrous metal body are coated with a heat-fusible, chemically-oxidizing composition, such as sodium nitrate or potassium nitrate. Then, the coated body is heated above the melting temperature of the coating, preferably above 350.degree. C., until the coating melts, spreads over the surfaces, reacts with the material of the surfaces and produces a black oxide coating thereon.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.