Antibacterial Properties and Corrosion Resistance of Nitrogen-doped TiO 2 Coatings on Stainless Steel

Abstract

The Nitrogen-doped TiO 2 (N-TiO 2 ) coatings were fabricated on 304 austenitic stainless steel (SS) substrates by oxidation of titanium nitride coatings, which were prepared by plasma surface alloying technique. Microstructural investigation, corrosion tests and antibacterial tests were conducted to study the properties of N-TiO 2 coatings. Composition analysis shows that the SS substrates were shielded by the N-TiO 2 coatings entirely. The N-TiO 2 coatings are anatase in structure as characterized by X-ray diffraction. The corrosion properties of N-TiO 2 coated SS samples in Hanks' solution were investigated by a series of tests. The electrochemical measurements indicate that the corrosion potential positively shifts from −0.275 V for untrated SS to −0.267 V for N-TiO 2 , while the corrosion current density decreases from 1.3×10 −5 A/cm 2 to 4.1×10 −6 A/cm 2 . The corrosion resistance obtained by fitting the impedance spectra also reveals that the N-TiO 2 coatings provide good protection for SS substrate against corrosion in Hanks' solution. Electrochemistry noise tests indicate that the N-TiO 2 coatings effectively retard the local pitting and crevice corrosion of the SS substrate. The results of the antibacterial test reveal that N-TiO 2 coatings give 304 austenitic SS an excellent antibacterial property.