Patent ID: 8097093
Filing Date: 2012-01-17
Classification: C23C

Abstract:
1. A method for coating a ferrous metal substrate, comprising: (a) contacting the ferrous metal substrate with an aqueous pretreatment composition having a pH of 4 to 5.5 and comprising: wherein the Group IIIB and/or IVB metal compound is present in the pretreatment composition in an amount of 10 to 150 ppm metal and the weight ratio of Group IIIB and/or IVB metal to phosphate ions in the pretreatment composition is at least 2:1; and wherein the phosphate ions are maintained in a bath of the pretreatment composition in an amount: (b) contacting the substrate with a coating composition comprising a film-forming resin to form a coated metal substrate that exhibits corrosion resistance properties.