Corrosion Characteristic And Evolution Mechanism Of Rust Layer Research Of B480GNQR Weathering Steel In Typical Atmospheric Environment

Metal material prone to corrosion in the atmosphere could lead to the destroy of the entire structure.So it is of great significance to study the atmospheric corrosion characteristics of weathering steel which has been widely applied because its low-cost and highly protection.The wire beam electrode method?WBE?was used to explore the influence of Cl^-?SO₄^2-and NO₃^-on atmospheric corrosion under thin film.The results showed that the localized corrosion behavior of weathering steel was most obviously in NO₃^-environment,while the corrosion rate of weathering steel in SO₄^2-environment was more fast than other environment.Localized corrosion rate of weathering steel is not obvious in Cl^-environment because of its strongly erosion,conductivity,permeabilityThe influence of ?-Fe OOH which is the main component of protective rust layer on localized corrosion of B480 GNQR weathering steel in simulated marine film were investigated using WBE?Wire Beam Electrode?and EIS?Electrochemical Impedance spectroscopy?method.The results showed that anode corrosion areas were less than scene of no ?-Fe OOH after 10 min of immersion,while after immersed for 1440 min,it ws showed that anode corrosion areas reduced in both two scenes?coved with?-Fe OOH and the original steel?.The surface color of the probes of WBE coved with?-Fe OOH turned from orange to black-brown simultaneously related to reaction between Fe²⁺ with ?-Fe OOH and phase transition from ?-Fe OOH to ?-Fe OOH.loose monophase?-Fe OOH can not protect metal perfectly,"weathering" characteristics of weathering steel is mainly determined by the dense inner rust layer.According to the research of Dillmann[27],protective rust layer is mainly constituted of stable ?-Fe OOH and electrochemically active ?-Fe OOH,in addition he proposed ?/? as the index of the rust protection.???????-Fe OOH were prepared,X-ray diffraction?XRD??Scanning electron microscope?SEM?and Infrared Spectrometer?IR?were used to characterized the products.Image processing method and BP neural network were used to study the composition of corrosion rust.The results showed that what we prepared were pure ?,?,?,d-Fe OOH.The parameter value obtained by decomposing the improved images using wavelet packed-based image analysis correlated with ?/?.