Characterization of Corrosion Behavior of Painted Galvanized Steel under Accelerated Conditions

摘要

In the present study three systems of carbon steel (1008) are evaluated, which were provide of twocorrosion control methods, barrier and cathodic protection (painted and galvanized respectively)commonly used in the construction industry. They were evaluated under accelerated conditionsexposed in fog chamber, according to ASTM B-117, which specifies continues exposition of sodiumchloride at 5% and 35 C. The main aim of the research was to characterize the corrosion resistanceand to determine the degradation mechanism under test conditions. The results after 1080 and 3500hours of exposure are presented, with adhesion measure (ASTM D-3359) and scratch resistancemeasure (D-1654) for each exposure time, as well as the characterization of corrosion attack throughthe mapping analysis of Scanning Electron Microscope / Energy Dispersive X-ray. According to theresults it is proposed that the corrosion of the systems under study begins at galvanized metal baseinterface. Later advances due to formation of porous layer of zinc hydroxi-chloride, which itcharacteristic of environments with chloride ions, forming zinc corrosion products like zinc oxideand zinc hydroxide on the porous layer until iron starts to dissolve, producing iron oxide and iron oxy- hydroxide on the zinc corrosion products and porous layer.