Preparation And Characterization Of Nano-sized TiO₂ Powder And Ceramics

Nano-sized TiO2 has high photocatalysis performance, by means of which organic substances and nitric oxides in the air can be decomposed. Nano-sized TiO2 can be used as self-cleaning material because of its dual characteristic of lipophilicity and hydrophilicity under the condition of optical irradiation, and the ultraviolet light in the sunlight can maintain the decontamination function of the TiO2. Because of the environment protection action and the sustainability, nano-sized TiO2 becomes a hotspot of scientific research.In this work, nano-sized TiO2 is prepared by chemical precipitation. The reaction of tetrabutyl titanate, oxalic acid solution and absolute ethyl alcohol is executed to prepare the precursor (TiO(OH)2·2H2O) under the condition that the pH value is 6, and the precursor is dispersed by glycol. The thermal decomposition process of the precursor is studied by the TG-DTA curves in order to prepare nano-sized TiO2, the X-ray diffractometer (XRD) is used to analyze the crystal form and the grain size of nano-sized TiO2, and the scanning electron microscope (SEM) is used to analyze the appearance and the dispersivity of nano-sized TiO2. The influence of the concentration of the oxalic acid solution, the proportion of the materials, the maturing time, the calcining temperature and the calcining manner on the powder property of nano-sized TiO2 are discussed to determine the optimum preparation process ultimately. The result shows that tetrabutyl titanate, oxalic acid solution (0.2 mol·L-1) and absolute ethyl alcohol with the volume ratio of 1:1:1 react for 4 hours at 50℃to prepare the precursor. Nano-sized TiO2 powder with the mean grain size of 11nm, average grain fineness distribution and good dispersivity can be prepared when the precursor is calcined at 350℃. Phase transition temperature of nano-sized TiO2 can be reduced by high temperature-energy ball milling.Nano-sized Ti powder and nano-sized TiO2 powder are used as the materials to prepare nano-sized TiO2 conductive ceramics. The experiment researches the influence of the body molding pressure on the density of the ceramics and the influence of the doping content of Ti powder on the conductivity of the ceramics. The structure and the appearance of the ceramics are characterized by means of XRD and SEM. The result shows that the density of the ceramics can be improved following the increase of the body molding pressure, but microcrack appears on the surface of the ceramics if the molding pressure is too high. The conductivity of the ceramics can be different following the variation of the doping content of the Ti powder. The ceramics have lower densification degree when sintered at 1100℃, so that the sintering temperature should be raised.