Research On Environmental Preparation Technology Of Zinc Protective Layer

Iron and steel material is widely used in various fields in daily life.However,the steel corrosion has brought great economic loss to people.In recent years,steel galvanized and passivation are main means of steel anticorrosion measures,but the cyanide galvanized and the chromium compound passivation are toxic,and they are harmful to environmental protection.A kind of green environmental protection of the steel protecti-ve technology has become an urgent priority.In order to avoid the environment problems of the cyanide zinc,we investigated the alkaline zincate zinc plating in this task and several different organic additives of zincate galvanized had been prepared.The single factor experiments had been done,which involving main brightener concentration,carrier brightener concentration,and the mass proportion of zinc oxide and sodium hydroxide.According to the morphology of the coating,the salt water immersion test and the plating solution dispersion ability,the best solution component concentration had been determined.Based on the above experiments of a relatively optimal galvanized,in order to further improve the corrosion resistance of the zinc coating performance,we chose the molybdate passivation means as the galvanized layer passivation system.Meanwhile,we used a single factor experiment to determine the optimization results of the main composition and concentration of the passivation,which related to the concentration of molybdate,the ratio of molybdate and phosphate,types of organic additive,the concentration of organic additive.In addition,we used the orthogonal test involving the factors solution pH value,passivation time,passivation temperature,aging time,aging temperature to optimize the study,and we obtained optimal molybdate passivation technology.Based on the above optimum experiments,the surface morphology was analyzed by SEM and AFM,the composition and structure was analyzed using EDS,XRD and XPS,the adhesive force of the zinc coating and passivation film were determined by the thermal shock experiments.The results showed the films were uniform and compact.XPS indicated that zinc coating was composed of Zn,and passivation film was consisted of P,O,Mo and Zn.