Study On Titanium Dioxied Thin Film Prepared By Thermal Oxidation With Or Without Nitrogen

Process parameters have important influence on the chemical composition, microstructure and properties of titanium dioxide thin films. In this work, titanium dioxide and nitrogen-doped titanium dioxide thin films were prepared by thermal oxidation method and their microstructure, composition and properties were studied subsequently. A preliminary study on the titanium dioxide thin film prepared by double glow discharge reactive sputtering technique was done also. Conclusions are listed as following:1. The titanium dioxide thin films without and with nitrogen-doped formed on the surface of pure titanium prepared by thermal oxidation method between 500℃and 800℃has been studied. The result indicates that the temperature has a great effect on the forming of the film. No oxide of titanium was detected at 500℃. In the range 600- 800℃, titanium dioxide rutile thin films were formed and the thickness increases with the temperature increasing. The oxygen atoms diffuse from the surface to the matrix in gradient. The nitrogen elements exist in the film in the form of solid solution but not nitrides. In the thermal oxidation process with nitrogen doped, the nitrogen flow has great effect on the forming of the titanium dioxide thin films and appropriate quantity of nitrogen will be favorable for the forming of the films.2.The titanium dioxide thin films formed on the surface of pure titanium at different temperature have different absorption peaks in ultra-violet absorption spectrum. The absorption peak of the titanium dioxide thin films shows a shift towards longer wave length with the temperature increasing from 500℃to 700℃, while the film formed at 800℃is different from the rule because of stripping. Compared with the titanium dioxide, the absorption peak of the nitrogen-doped titanium dioxide films gets a moderate red shift when the quantity of doped nitrogen increases.3.The hardness test result indicates that the surface hardness of pure titanium treated by thermal oxidation with nitrogen is harder than that without nitrogen. For the two kinds of thermal oxidation processes with and without nitrogen, the surface hardness of the treated specimen increases with the temperature increasing.4.Double glow discharge reactive sputtering technique is used to form titanium dioxide thin film on the surface of stainless steel and the oxygen flow is one of the key factors. Large flow will induce poisoning of the target to decrease the sputtering rate and even make the forming of titanium dioxide films unavailable. While too low flow will lead to the forming of mixed crystal of TiO and Ti₂O but not titanium dioxide.