Stainless Steel Surface Preparation Of Inorganic - Organic Hybrid Coating And Its Corrosion Inhibition Performance Study

In recent years,the stainless steel surface modification to enhance its corrosion resistance and prolong its life,has become the highlight of study.In this paper,the304stainless steels (bare stainless steel,SS)were treated with a Piranha solution to generate a hydroxylated surface(SS-OH).Then,the titanium oxide multilayer coatings were deposited on the hydroxylated surface using the lay-by-lay sol-gel deposition process of toluene/ethanol solution of titanium(Ⅳ) butoxide. Well-control led PVP-grafted titanium oxide surfaces were prepared by surface initiated atom transfer radical polymerization(SI-ATRP) with CuBr/CuBr/tetramethylethylenediamine as a catalyst system and methanol/deionized water mixtures as liquid phase medium and using2-bromopropiomyl bromide to form the intermediate layer and bring into reactive groups of initiator.X-ray photoelectron spectroscopy and static water contact angle were used to characterize the product of each reaction stage in the modification process.The result of measured static water contact angles indicated that the water contact angles decreased from (94.9±1.4)°for the SS to (32.1±2.2)°after modifition.As a comparison.ATRP of N-vinyl-2-pyrrolidone(NVP) was conducted on nano-TiO2powder surface under the same conditions.The FTIR spectrum indicated that poly(N-vinyl-2-pyrrolidone)(PVP) was successfully immobilized on the suface of nano-TiO2powder.The reaction conditions of SI-ATRP were systematically investigated,which result demonstrated that the SI-ATRP of NVP was controlled in methanol/deionized water(10mL/6mL) liquid phase medium.When the SS surface was fully covered by PVP,the static water contact angle was about32°.SEM pictures indicated that the SS surface really wsa fully covered by the so-called PVP brushes.Thus,inorganic-organic hybrid coatings had been successfully immobilized on SS surface.For the inorganic-organic hybrid coatings prepared in this paper,they were bonded by chemical bonds between SS substrate and inorganic coating and the intermediate layer and organic coating.In this paper.the anti-corrosion behavior of SS and modified SS (SS-TiO2and SS-TiO2-PVP) were systematically investigated by electrochemical methods.The result indicated that it was susceptible to corrosion for SS in NaCl solution (3.5wt%.pH=4.5),its corrosion current increased to167.61μA/cm2from18.79μA/cm2 when the exposure time was extended by3days to17days. While the corrosion current of modified SS were lower than9μA/cm2thoughout the exposure period.After17days of exposure,the IE of SS-TiO2was95%and the IE of SS-TiO2-PVP was98%.The anti-bacterial assay of SS and modified SS (SS-TiO2-PVP4and SS-TiO2-PVP8) were quantitatively investigated. After7days of exposure,E.coli number of SS surface was about8000cells·cm-2,while the number of SS-TiO2-PVP4and SS-TiO2-PVP8surfaces were respectively about5000cells·cm-2and3500cells·cm-2.The result indicated that inorganic-organic hybrid coatings SS had excellent anti-bacterial effect,and increasing the thickness and density of inorganic-organic hybrid coatings could enhance the anti-bacterial performance.