| 摘要 |
<p>Aqueous alkaline solutions containing ferric chelates of alkalenepolyamine 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 dissolve ferrous ion to the ferric state. This process is improved by adding aqueous hydrogen peroxide to the flowing cleaning solution such as the solution EMF (platinum or iron versus a saturated calomel electrode), as measured at about 80.degree.F (26.6.degree.C) and at a solution pH of about 9.2, becomes more positive than - 250 mV in about one hour. The quantity of hydrogen peroxide used can vary, but about 1.12 pounds (.508 Kg) of commercial 35 percent hydrogen peroxide for every pound of dissolved iron in the cleaning solutions gave excellent results.</p> |
