Research Of Photocatalytic Property And Corrosion Resistance Of Carbon-doped Ti-O Films Prepared By Magnetron Sputtering

With the development of the society, people pay more attention to the issue of environmental pollution. People began to have a strong interest in the research of heterogeneous catalysis since Fujishima and Honda had caught sight of the photocatalytic splitting of water by TiO2 electrodes. TiO2 is one of the most suitable photocatalysts due to its high photocatalytic activity, good chemical and biological stability, relatively low cost and non-toxicity.It is useful in various fields such as degradation,antibacterial agents and corrosion prevention.But photocatalytic activity of TiO2 was only excited by ultraviolet light due to its wide band gap.Thus,its use is limited in many fields.People try to synthesize new carriers and photocatalysts or make their modification by exploring the reaction mechanism, and to improve the photocatalytic activity of TiO2 by optimizing the preparation and modification methods. In this paper, carbon-doped Ti-O films were prepared by magnetron sputtering (MS) and different process parameters were designed. Various analysis and characterizations, photocatalytic property test and electrochemical corrosion test were used in order to explore better process of films preparation. Furthermore, we also study the effect of interface layer process to surface morphology and mechanical properties of the films in order to optimize the interface layer process.Stainless steel (type 304) was used as substrate materials. Firstly, substrate was treated by nitrogen ion implantation technology. The carbon-doped Ti-O (C-Ti-O) films were prepared on stainless steel after nitridizing by MS using high purity titanium as titanium plasma source and CO2 gas as C and O source. There are a serious of C-Ti-O films were made by changing the volume flow ratio of the CO2 and O2. The composition, structure, morphology and optical property of C-Ti-O films are studied by XPS, XRD, SEM, EDX, Raman and UV-vis. The results showed that C-Ti-O films were prepared successfully by MS using CO2 as C and O source and more carbon will be doped into Ti-O lattice with increase of CO2/O2. The films are made of TiO whose particle sizes are between 13.67nm to 46.23nm, the atomic ratio and weight ratio of the synthetic samples of made by CO2 are lower than that of made by O2. The films are smooth, density and good uniformity.The columnar crystal of the sample made by CO2 is more obvious whose lattice structure is better and the degree of crystallinity is high.The band gaps decreased after carbon doping.Secondly, the photocatalytic activity of synthesized C-Ti-O films were also evaluated by the degradation test of methyl orange under UV light irradiation. The tests of electrochemical impedance and polarization curves were done using electrochemical workstation in order to value corrosion resistant of C-Ti-O films.The results indicate that all the films have photocatalytic activity. The doping amount of carbon, UV light intensity and initial pH value have a great effects to photocatalytic activity of C-Ti-O films. Meanwhile, the carbon incorporated into the TiO2 lattice is beneficial for extending the life of photon-generate carrier, decreasing the electronic exchange of resistance and making the oxidation-reduction reaction emerge on the surface, but not beneficial for the increase of capacitance performance. Though the probability of corrosion decreased than that of non-doped sample, the size of corrosion rate still can not be made sure. There are no significant changes in the outdoor atmospheric corrosion and microbial corrosion experiment by using weighing and light microscopy, Further research need to be done in the future.The interface layer is important to propertied of coatings, especially mechanical properties. Thus, four interface layer process were designed combined nitrogen ion implantation with Ti metal transition layer. On the interface layer, C-Ti-O films were prepared using same process. AFM and optical microscope were used to observe the surface morphology, nanoindentor, nano-scratch tester and friction and wear testing machine measured the mechanical properties of the films. The results showed that Ti metal transition layer was beneficial for improving wear resistance, surface quality of the films and adhesion between film and substrate. Instead, though hardness of C-Ti-O films can be raised by nitrogen ion enhanced treatment, C-Ti-O films were also obtained with high surface roughness,low wear resistant and adhesion.The conclusions could be inferred by initial research in this thesis that C-Ti-O films with different composition and structure are prepared successfully by MS using CO2 gas as C and O source.The carbon doped is effective and beneficial for improving photocatalytic activity Ti-O fims, but the effect of carbon-doped on corrosion resistance was still not certain and corrosion resistant mechanism of as-prepared C-Ti-O films needs to be further testing analysis to determine.