PASSIVATION PROCESS OF A STEEL TINPLATE

The present invention concerns a Cr-free passivation process of a tinplate comprising the following steps in sequence:a. subjecting said tinplate to at least one cathodic electrolytic treatment in an aqueous solution containing at least one sulphate of an alkali metal to obtain a tin oxide surface l...

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Bibliographische Detailangaben
Hauptverfasser:	GIANNETTI, Armando, ASTENGO, Giovanni, MARTINES, Stefano
Format:	Patent
Sprache:	eng ; fre ; ger
Schlagworte:	APPARATUS THEREFOR CHEMISTRY ELECTROFORMING ELECTROLYTIC OR ELECTROPHORETIC PROCESSES METALLURGY PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTIONOF COATINGS
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Beschreibung
Zusammenfassung:	The present invention concerns a Cr-free passivation process of a tinplate comprising the following steps in sequence:a. subjecting said tinplate to at least one cathodic electrolytic treatment in an aqueous solution containing at least one sulphate of an alkali metal to obtain a tin oxide surface layer having thickness lower than 6 mC/cm2;b. subjecting said tinplate to at least one cathodic electrolytic treatment in an aqueous solution containing at least sulphate ions and zirconium ions to form a passivation layer containing zirconium on said tin oxide surface layer.The process allows obtaining passivated tinplates on which the coatings, such as enamels, paints and polymeric films, adhere well, without using chromium-containing compounds.