Investigation of chemical passivation effect on galvanized sheet in powder paint coating process

It is stated in the literature that the passivation process before painting increases the paint adhesion ability and corrosion resistance. In this study, the effect of paint adhesion ability and the effect of passivation conditions was examined by using in different concentration organic and inorganic acids, those are found easiliy, by applying powder coating to pasivated samples. Coatings are made on DX51 + Z galvanized sheet. In the chemical passivation process, the application of citric acid, formic acid and nitric acid at different concentrations (1%, 3 and 5% w/v), at different times (20, 40 and 60 seconds) was applied. Passive plates were rinsed with deionized water for 30 seconds. Samples were dried for 1 hour at 105oC after rinsing. The dried plates were powder coated and cured for 10 minutes at 200oC. Cross-cut test, brine test, hot water test, impact test, cylindrical bending test, cupping test and spray salt test were used to examine the adhesion effectiveness between the metal surface of the electrostatic powder coated plates coated with the chemical method and the powder paint. Cross-cut test, salt water resistance test, hot water resistance test, impact test, cylindrical bending test, cupping test and salt spray test were applied to investigate the adhesion effectiveness between the metal surface of electrostatic powder coated plates and powder paint. As a result according to the tests, the powder paint adhesion efficiency with formic acid was found to be quite good. Adhesion efficiency of passivated with citric acid and nitric acid has observed as weak.