SOLUTION OF PREPROCESSING BEFORE CHROMATE TREATMENT FOR ELECTRIC ZINCKED STEEL PLATE

摘要

PURPOSE: A preprocessing solution is provided to enhance corrosion resistance and covered film bonding property by preprocessing an electric zincked steel plate before processing the plate with chromate. CONSTITUTION: A preprocessing solution contains nickel salt having 20 to 70g/l of nickel elements, nitric acid having 10 to 50g/l of nitric acid ion and organic phosphoric acid having 30 to 80g/l of phosphoric acid elements. The nickel salt is selected among nickel sulfate, nickel nitride and nickel chloride. The nitric acid is selected among sodium, potassium and ammonium. The organic phosphoric acid is selected among dimethyl phosphate, diethyl phosphate and diphenyl phosphate. Due to the preprocessing solution, a metal film is formed on the material surface of a steel plate and the surface is activated. The material and a chromate film are bonded well and the surface is flattened.