Research On Stabilization Of Rust Layer On Weathering Steel Surface And Treatment Liquid

Weathering steel has been widely employed in several aspects of construction such as vehicles,bridges,towers and so on due to its excellent atmospheric corrosion resistance and low cost.The high corrosion resistance of weathering steel is attributed to the formation of dense,adherent and cation selective rust layer under the alloy elements such as Cu,Cr and Ni.The effectiveness of the protective layer depends on it's phase compositions and density.The gradual development of the protective layer on weathering steel requires 3¹0 years before steady-state conditions are obtained in nature atmosphere,and when the weathering steel nakedly used in the natural environment,prior to form stable rust layer,the rust liquid will flowing,suspension and flying in the surface,and the environment will be polluted.The rust layer stabilization treatment is to accelerate the formation of protective rust layer on the surface of weathering steel and reduce pollution.The alloy elements in the weathering steel play a significant role and can promote formation of a protective layer.In view of this,a new rust stabilizer which aims to speed up the formation of protective rust on weathering steel was designed and by spraying it on the surface of weathering steel to pretreat the samples.And then the application properties of the new rust stabilizer and the rusting evolution of pretreated weathering steel in simulated coastal and industrial atmospheres were studied by corrosion kinetics,the composition and the surface morphology of the rust layer and so on.Simulated wet/dry cyclic corrosion tests were employed for the study,and the main results for this study are as follow:Based on the alloying elements on atmospheric corrosion performance of weathering steel,a new rust stabilizer mainly including Cr?OH?SO₄ and Cu?NO₃?₂was designed.The new rust stabilizer can synergistically improve the stability and compactness of the rust layer to improve the weatherability of the weathering steel.During the dry/wet cyclic corrosion test of 60 CCT,the corrosion weight gain of the bare and pretreated weathering steel samples is in line with the power function growth law.The corrosion weight gain of the two samples is small in the early stage,but with the progress of the experimental period,the phenomenon that the corrosion weight gain of the pretreated sample is smaller than that of the bare steel sample becomes more obvious,and the phenomenon is in the simulation industry.Especially prominent in the atmospheric environment.The new rust stabilizer does not change the type of corrosion product formed on weathering steel.The rust layer formed on the bare steel sample and the pretreated sample in the simulated industrial atmosphere mainly contains?-FeOOH,?-FeOOH and Fe₃O₄/?-Fe₂O₃;the rust layer formed on the two type of samples in the simulated coastal atmosphere contains?-FeOOH,?-FeOOH,?-FeOOH and Fe₃O₄/?-Fe₂O₃.The corrosion rate of the pretreated sample decreases as the corrosion process proceeds,and which is closely related to the properties of the rust layer on sample,mainly due to the rust layer become more and more stable and compact.However,due to the large amount of highly aggressive Cl^-in the marine atmosphere,the degree of compaction of the rust layer is difficult to increase significantly.The stabilization process of the rust layer is not only the transformation process of the phase,but also the process of gradual densification.The pre-treated weathering steel has a relatively low content of?-FeOOH in the rust layer formed in the early stage of the experiment,and there are many cracks,porousness and so on.However,with the development of the experimental period,the relative content of?-FeOOH in the rust layer It is on the rise and the density of the rust layer is also improved.