The Preparation Of TiO₂ Nano-films

Nano science and technology (Nano-ST) is the new science and technology just been born and emerging at the end of the eighties of the 20th century. Nano-ST is to study the sport law, interaction, technological the science and technologies of questions in the possible practical applications of systems size in the 0.1~100nm. The prospect of nano science and technology is captivating and its development speed is amazing too. Nano materials and its technology is the branch of Nano-ST. It is dynamic and is very abundant to study content.The technology of the films is a frontier branch of science. There is extensive application on industry variedly because of the performance of the films. Because the new-type film material represented by a nano film has a lot of peculiar new performance, and is being received the extensive concern and deep research.At present, nano titanium dioxide film is applied to the photocatalyst mainly. Comparing with nano titanium dioxide powder, nano titanium dioxide films merit with fixing catalyst of titanium, and can also improve the activation of the catalyst and do benefit to regeneration and reclaimation etc. So there are theoretical research and actual using value. There are many kinds of methods to prepare nano titanium dioxide films, but most methods have relatively high requests to equipment and technology etc. It is difficult to realize and control, and the cost is relatively high. In my article we adopted electrophoretic deposition(EPD)that receives much concern in recent years and phase transition auxiliary sintering. Compared by a lot of experiments, we developed: subsection constant voltage and pressing before sintering. And we prepared nano titanium dioxide film. According to certain mix, blend nano TiO2 powder(10g·dm-3), acetone, PE(36 g·dm-3) and PVB(7.5 g·dm-3). Put up suspension in the ultrasonic wave generator. Must make TiO2 particles' surface charge state and suspension state best. When compounding the suspension, its quality is connected with the dosage of component, the order of accession, the dispersion time and the suspension concentration, pH, zeta-potential. They also have influence on the quality of deposited layer.The basis for EPD is stainless steel(35×17×1mm). In order to improve adhesion between the deposited layer and the basis, the basis is treated by a chemical method. The surface of the treated basis has many micro-pores and even nano-pores. The subsection constant voltage has three procedures:Constant voltage(80V)functions 1 minute; Constant voltage(40V)functions 1.5 minutes; Constant voltage(20V)functions 3 minutes.This method solved the questions such as crack, surface roughness, the higher granularity because of high voltage and incomplete layer because of over low voltage. In addition, shortening deposition time and controlling the temperature at room temperature, for guarantee the suspension quality. The deposited layer naturally dried for over to 24 hours.Sintering is a necessary procedure to gain TiO2 nano films. In my article, before the phase transition auxiliary sintering, we pressed the layer under about 7.5MPa. After sintered, the combination force between the particles is high enough, and the film's relative density is above 98%. The phase transition auxiliary sintering uses the power of phase transition. The power makes the film dense at the lower temperature such as 600℃ and do not 800℃～1000℃. When the temperature is above 800℃, the anatase has always transited the rutile and gone with the particle generation. The sintering procedure is confirmed by differential thermal analysis and thermal gravimetric analysis(TG－DTA). Peel off the layer and take 0.2～0.3g for TG－DTA. The temperature rate is 10℃/min, the heating range is 0～800℃ and the heating ambience is air. So the sintering procedure is placing the layer end up in the crucible. Heating in the muffle. 220℃, insulating 60 minutes; 440℃, insulating 60 minutes; 600℃, insulating 60 minutes. Finally take it out w...