ZHAO Kai, ZHANG Shao - bo, WANG Zhi - bin, WANG Sheng - min, ZHAO Xiao - jun, QIU Wen - li, CHEN Pan
For improving the anti - corrosion performance of the mechanical galvanized layer, the centrifugal dipping was used to prepare the Ruspert coating and the Luxiubao coating on its surface independently. The surface morphology of the coatings was observed and analyzed with a metallurgical microscope. The cross - sectional morphology and element distribution of coatings were characterized by scanning electron microscope (SEM, equipped with EDS energy spectrum). The salt spray corrosion products of the coatings were analyzed by XRD, and the adhesive strength of the coatings was tested and analyzed through the cross - cut method. Moreover, the porosity of the coatings was tested by the filter paper method, and the corrosion resistance of the coatings was evaluated by the salt spray test. Results showed that the mechanical galvanized composite coating was composed of a mechanical galvanized layer and a coating prepared on it subsequently. The bonding interface between the mechnical galvanized layer and the coating had no pores, spallings or cracks. In addition, the two types of coatings were both formed by alternately stacked scaly Al. The salt spray corrosion products mainly included Zn5(CO3)2(OH)6, Mg4Al2(OH)14·3H2O, Al2SiO5, Zn4CO3(OH)6·H2O and ZnCO3. The adhesive strengthes between the two post - treatment coatings and the galvanized layer were good, and the surface porosity of the two coatings was zero. The time for the appearance of red rust for the Ruspert coating was 1 000 h, which was 650 h longer than that for the mechanical galvanized layer, while the time for the appearance of red rust for the Luxiubao coating was 1 500 h, which was 1 150 h longer than that for the mechanical galvanized layer. To sum up, the application of Ruspert and Luxiubao coatings on the surface of the mechanical galvanized layer could significantly extend the service life of the galvanized layer, and the effect of Luxiubao coating was better. The Ruspert and Luxiubao coatings had broad application prospects as post - treatment processes for mechanical galvanizing.
