摘要 |
This invention relates to a method of coating a metal surface with zinc and iron phosphate crystals for the purpose of improving corrosion resistance by means of a buffered zinc phosphate solution containing zinc dihydrogen phosphate and a monovalent, alkali metal salt of phosphate in proportions such that a fine, horizontal crystal structure consisting of tertiary zinc phosphate, zinc ferrous phosphate and other crystals of zinc ferrous phosphate is formed on the metal surface. The invention also relates to this composition. |