Process for removing copper and copper oxide encrustations from ferrous surfaces
US4443268A · kind A · utility
11Cited by
2References
12Claims
0Family size
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Inventor
Key dates
| Filing date | Nov 12, 1981 |
| Grant date | Apr 17, 1984 |
| Priority date | — |
| Expiry date | Nov 12, 2001 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC23G1/19
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
Aqueous alkaline solutions containing ferric chelates of alkylenepolyamine polycarboxylic acids (e.g. EDTA) have been used to remove plated copper from freshly cleaned ferrous metal surfaces. Normally, an oxidant is added during the copper removal stage to oxidize ferrous ion to the ferric state. This process is improved by adding aqueous hydrogen peroxide to the flowing cleaning solution at a rate such that the solution EMF (platinum or iron versus a saturated calomel electrode), as measured at about 80.degree. F. and at a solution pH of about 9.2, becomes more positive than -250 mV in about one hour.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.