Study On The Preparation Process Of Silyl-based Composite Film On Iron And Steel Surface And Its Corrosion Resistance

Steel is indispensable in mechanical manufacturing,but steel is susceptible to corrosion due to external influences.Therefore,phosphating or chromation treatment is often used in the machinery industry to improve the corrosion resistance of steel.However,phosphating and chromation treatment will cause greater environmental pollution,and it is urgent to seek an environmentally friendly steel corrosion resistant treatment.In this paper,it is proposed to carry out the preparation of silyl-based composite film on the surface of steel and its corrosion resistance,that is,the coating treatment of steel is carried out using three environmentally friendly materials,silane,zirconium salt and phytic acid,the surface properties of the film layer are characterized,and the corrosion resistance of the film layer is studied in depth,and the research results will provide a reference for the construction of the corrosion resistant film layer on the surface of steel.Firstly,the preparation process and performance of single silane membrane are studied.It was found that the process parameters of the optimized single silane membrane were silane concentration of 5 vol%,ratio of ethanol to water 80:20,p H 4,impregnation temperature 25°C,impregnation time 50 s,hydrolysis time 24 h,hydrolysis temperature 35°C,curing time 40min,and curing temperature 100°C.Through micromorphological analysis,it was found that the single silane membrane had pore defects.Through Fourier infrared spectroscopy（FTIR）and X-ray photoelectron spectroscopy（XPS）analysis,it was found that the main structure of a single silane membrane was a network structure of Si-O-Si.Through the study of the corrosion resistance of a single silane film,it is found that the corrosion potential of a single silane film is positively shifted compared with the 40Cr matrix,the corrosion current is less than that of the 40Cr matrix,and the impedance modulus value of a single silane membrane in the low frequency region is 8 times that of the 40Cr matrix.Secondly,on the basis of single silane membrane,the preparation process and performance of silane-zirconium salt composite membrane were studied.It was found that the process parameters of the optimized silane-zirconium salt composite film were silane concentration of5 vol%,zirconium nitrate concentration of 0.75 wt%,p H 4,reaction temperature 25°C,reaction time 50 s,curing temperature 100°C,and curing time 40 min.Through micromorphological analysis,it was found that the zirconium salts in the silane-zirconium salt composite film could fill the pore defects of a single silane membrane.Through Fourier infrared spectroscopy（FTIR）and X-ray photoelectron spectroscopy（XPS）analysis,it was found that the main structures of silane-zirconium salt composite membranes were Si-O-Si,Si-O-Zr,and Zr O₂.Through the study of corrosion resistance of silane-zirconium salt composite film,it is found that the corrosion potential of silane-zirconium salt composite film is greater than that of single silane membrane and 40Cr matrix,the corrosion current is less than that of single silane membrane and 40Cr matrix,and the impedance modulus value of silane-zirconium salt composite film in the low frequency region is 26 times that of 40Cr matrix.Finally,on the basis of silane-zirconium salt composite membrane,the preparation process and performance of silane-zirconium salt phytic acid composite membrane were studied.It was found that the process parameters of the optimized silane-zirconium salt phytic acid composite membrane were 0.75 wt%phytic acid concentration,40 min curing time and 100°C curing temperature,and other process parameters were the same as those of silane-zirconium salt composite membrane.Through micromorphological analysis,it was found that there were flocculent substances in the silane-zirconium salt phytic acid composite film,which could fill the pores of the film layer well.The main structures of silane-zirconium salt phytic acid composite membranes were PO₄^3-chelate complexes of Si-O-Si,Si-O-Zr,Zr O₂ and phytic acid by Fourier infrared spectroscopy（FTIR）and X-ray photoelectron spectroscopy（XPS）.Through the study of corrosion resistance of silane zirconium salt phytic acid composite film,it is found that compared with silane zirconium salt composite film,single silane film and 40Cr matrix,the corrosion potential and corrosion current of silane zirconium salt phytic acid composite film are the largest,and the impedance modulus value of silane zirconium salt phytic acid composite film in the low frequency region is 41 times that of 40Cr matrix.The above research results will provide a reference for the research and development of environmentally friendly corrosion-resistant film layers on steel surfaces.