| abstract |
Steel sheet coated with a nontoxic, relatively insoluble, inorganic, corrosion resistant coating. A silicate coating is formed on a steel sheet by rinsing the sheet for at least 30 seconds in an alkaline aqueous solution containing 0.005 M silicate, 0.005 M metal salt and having a temperature of at least 25°C. The sheet is dried to form an adherent silicate coating having a thickness of at least 2 nm prior to being treated with an aqueous solution containing 0.5-5 vol.-% silane. If the sheet is painted, the silane film forms an adherent bond between the paint and the silicate coating. A silane treated silicate coating minimizes red rusting on terne coated steel by sealing pin holes. A silane treated silicate coating also provides good corrosion protection and paint adherence on cold-rolled or galvanized steel. |