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In this paper,one kind of silicate passivation technics was reported and by which method silicate passivation film on galvanized Zn coatings with satisfactory property was got.Zn coatings were prepared by conventional plating technics.The solution composition and operating conditions of passivation are:sodium silicate 10-30 g/L,H2SO4 5 mL/L,HNO3 5 mL/L,H2O2 5-20 mL/L,pH 1.5-2.5,passivation time 5-30 s,temperature 25℃.The corrosion resistance of galvanized Zn coatings with different passivated technics were investigated by NSS corrosion test and compared with Zn coatings treated by Cr(VI)and Cr(III).The silicate passivation film can keep no rust for 72 h and obviously shows the best property.Surface morphologies of galvanized Zn coatings with different passivated method were got by metallurgical microscopy,and the silicate passivation film shows the most uniform surface,and has the least micro-hole.All the results show that silicate passivation technics can provide galvanized Zn coatings superior anti-corrosion performance and simultaneously avoid the pollution of chromium,so this technology has a wide application in future.
In this paper, one kind of silicate passivation technics was reported and by which method silicate passivation film on galvanized Zn coatings with satisfactory property was got. Zn coatings were prepared by conventional plating technics.The solution composition and operating conditions of passivation are: sodium silicate 10-30 g / L, H2SO4 5 mL / L, HNO3 5 mL / L, H2O2 5-20 mL / L, pH 1.5-2.5, passivation time 5-30 s, temperature 25 ° C. The corrosion resistance of galvanized Zn coatings with different passivated technics were investigated by NSS corrosion test and compared with Zn coatings treated by Cr (VI) and Cr (III). The silicate passivation film can keep no rust for 72 h and obviously shows the best property. coatings with different passivated method were got by metallurgical microscopy, and the silicate passivation film shows the most uniform surface, and has the least micro-hole. All the results show that silicate passivation technics can provide galvanized Zn coati ngs superior anti-corrosion performance and simultaneously avoid the pollution of chromium, so this technology has a wide application in future.