Performance of zinc-based coatings in a tropical marine atmosphere of high agressiveness

the objective of this research is to study the effect of different applications on the behavior of zinc based coatings (discontinuous galvanized, thermal sprayed by electrical arc and flame processes) exposed to a tropical marine atmosphere during 24 months. for this, coupons of carbon steel (sae 1010) of 10 cm × 5cm × 3mm were evaluated, covered with zinc by the three processes. the sheets were characterized by means of coat thickness, microstructure, and porosity, being evaluated monthly by visual inspection and photographic record. after 24 months of exposure, they were withdrawn and analyzed in the laboratory by measuring the thickness of the coating remaining, morphology of the corrosion products and microscopic analysis of the cross-sectional area. the results show that the zinc corrosion rates for all systems, exceed the maximum established in iso 9223 (> c5), besides being very sensitive to corrosion-erosion resulting inappropriate in this type of atmospheres.