Commonwealth Scientific and Industrial Research Organisation

Klaus Werner Wittel

Anthony Ewart Hughes

Simon Gerard Hardin

Karen Joy Hammon Nelson

An aqueous acidic solution for forming a rare earth element containing conversion coating on the surface of a metal, said solution being chromate-free and including effective quantities of at least one rare earth element (as herein defined) containing species, an oxidant and at least one accelerator, comprising a metal selected from Groups VA and VIA of the Periodic Table.

Process and solution for providing a conversion coating on a metallic surface I

An aqueous acidic solution for forming a conversion coating on the surface of a metallic material, said solution containing at least one rare earth element (as herein defined) containing species, an accelerator additive selected from the group consisting of metals of Group IB, IIB, IVA, VA, VIA and VIII of the Periodic Table, a peroxidic species and at least one acid selected from the group of mineral acids, carboxylic acids, sulphonic acids and phosphonic acids, wherein said solution contains no more than 20 mg/liter each of fluoride and of phosphate, and the solution is essentially free of chromate.

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Frankfurt-am-Main, Germany

Klaus Werner Wittel