COATING-FORMING CONDITIONS AND TECHNICAL IMPROVEMENT OF ZINC SYSTEM PHOSPHATING SOLUTION

The optimized film-forming conditions of zinc phosphating solution,including acid ratio and temperature were evaluated on the basis of self developed LS-408 solution.The content of citric acid and improver was also studied.The density and the uniformity of the coating formed were notablely improved by adding 2 g/L improver A and 0.8～1.2 g/L improver B.And corrosion resistance of phosphate coatings increased by 3～4 times without increasing the weight of the coatings.