Research On Preparation And Corrosion Resistance Mechanism Of Silane Composite Film On Steel Surface

Silanization is a new surface treatment technology,the process has the advantages of green,poisonless and harmless,simple process,low-cost and so on.However,the traditional single silane film still has surface defects such as pores and microcracks,which affect the corrosion resistance of silane film.Graphene oxide（GO）has a dense two-dimensional planar structure and nanometer thickness,with excellent thermal and chemical stability,and it can be used as a diffusion barrier on metal surfaces.In this paper,the single silane film was modified by adding graphene oxide,and the article explored the preparation technology,structure,corrosion resistance and mechanism of the hybrid silane.The main results are as follows:1.In the article,bis-[3-（triethoxysily）propyl]tetrasulfide（BTESPT）was selected as the main agent of silane fluid and the reagent was used to prepare hybrid silane film on the surface of 40 Cr alloy steel.Go was characterized by scanning electron microscope（SEM）and infrared spectroscopy（FTIR）,it was found that GO presented a folded and stacked state,the characteristic peak was obvious and the degree of oxidation was high.The optimum addition range of GO was determined by single factor experiment.The best preparation technology of hybrid silane film was obtained by two-step orthogonal test.The conductivity of silane solution was measured by the conductivity meter,and it was found that the conductivity first increased,then decreased and finally tended to balance due to the change of solution viscosity.The infrared spectra of the hydrolyzed silane solution were analyzed,the result showed that the peaks of Si-O-Si and Si-OH were enhanced,which proved that the condensation and hydrolysis reactions occurred in the silane solution.2.The morphology of single silane film and hybrid silane film was observed by scanning electron microscope,and it was found that the single silane film was smooth and flat,but still had some defects,while many fine graphene oxide sheets were distributed on the surface of hybrid silane film.It is found that the contact angle of hybrid silane film was larger than that of single silane film,indicating that the hybrid silane film had better hydrophobicity.The two kinds of silane films were characterized by infrared spectroscopy.It was found that the addition of GO promoted the formation of silane films and the new Si-O-C bonds were formed in the films.The composition and morphology of elements on the surface of hybrid silane film were analyzed by XPS,and it was proved that BTESPT silane film was formed on the surface of matrix,as well as unhydrolyzed-O-C₂H₅ and uncondensed Si-OH were found in the films.The presence of the C=O bond proved that the hybrid silane film was filled with graphene oxide.3.The corrosion resistance of mixed silane was better than that of single silane film by copper sulfate titration and brine immersion.It was found that both single silane film and mixed silane film prepared by the best process had good adhesion by the test of dry and wet adhesion.In the acid and base immersion experiment,it was found that the two kinds of silane films had strong alkaline corrosion resistance and weak acid corrosion resistance,while the mixed silane films had slightly stronger acid corrosion resistance than the single silane films.In this paper,the electrochemical properties of single silane film and hybrid silane film were tested by polarization curve and electrochemical impedance spectrum,and it was found that hybrid silane film had lower current density and higher impedance value than single silane film.The hybrid silane film had better densification and hydrophobicity,which could bring better protection effect.By analyzing the corrosion durability of the hybrid silane film,it was found that the sample soaked in brine for two days still had a good protective effect.4.A structure model of hybrid silane film was proposed through experimental analysis and silane film forming mechanism.In the hybrid silane film,some GO particles were dispersed in the silane film in a physically filled manner,while the-OH on other GO particles reacted with Si-OH,which was bonded together by chemical bonds.Therefore,the corrosion resistance barrier of hybrid silane film was established,and the corrosion protection ability of silane film was improved.