Method of coating metal surfaces with an alkali phosphate solution, aqueous concentrate and use of metal surfaces coated with this type of coating

摘要

Process for coating metallic surfaces with aqueous acidic alkali phosphating solution (APS), especially for subsequent deposition of electrodip paint layers, where this layer is deposited from aqueous APS, optionally containing sulfate ions, and based on phosphates/oxides/hydroxides, formed in the surface of the metal, e.g. aluminum, iron and/or zinc, where alkali APS contains precipitating agent for precipitation of sulfate ions at pH exceeding 3.5-7. An Independent claim is included for an aqueous concentrate for applying the APS for deposition of the alkali phosphate layer.