| The coating system is a commonly used and effective measure for corrosion prevention of metals.Especially the pretreatment lay provides not only a temporary protective performance but good adhesion to both metal surface and top coat.In the past,chromate and phosphate conversion layers were widely employed as the pretreatments on many metallic substrates before painting.However,the high toxicity and carcinogenic of chromate treatment and substantial quantity of waste residues of phosphate treatment would increase more burden for environment.So,the new and environmentally friendly processes have been developed in the last decades.The pretreatments based on the deposition of organosilane film on metal surfaces are believed as one of the most promising alternatives,which are supposed to be applied in the production.Actually,silanization has been studied a lot for the use in galvanized steel and aluminium alloys,which seen as a rapid upsurge of chromate and phosphate replacement.Nevertheless,it is hard to be applied in steel which is largest used metallic material,such as structural components,industrial pipes,and kitchen appliances,because the silane film on steel is very thin and non-uniform,which leading to poor temporary protection performance and binding ability with top paints.Aim of this paper is to solve the above problems of silanization on steel,we studied how the anodization and chemical oxidation methods affect the surface states(elemental composition and chemical components)of pure iron,and investigated the film-forming quality and anti-corrosion performance of the silane film on the iron surface pretreated by different oxidative processes by characterization technique,electrochemical measurements and corrosion tests.Results show that silanzation is easier on the iron substrate anodized in the sodium hydroxide solution solution or borate buffer,so which improving the shot-term protection on iron.chemical oxidation in sodium molybdate solution will have a parallel result. |
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