| In many semiconductor catalyst, TiO2 as a commonly semiconductor catalytic material has characteristics of high catalytic activity, oxidative capacity and high stability. Since the environment in the whole world deteriorates, using TiO2 photocatalytic activity and super-hydrophilicity to purify environment becomes a hot topic.Preparation of this thesis is to super-hydrophilic property of the SiO2/TiO2 composite film and to explore its composition and changes in surface roughness on the performance of hydrophilicity. Nano TiO2 sol was prepared with precursor titanium tetrachloride (TiCl4) at low temperature in mediums of nitric acid. The effect of the pH value of TiO2 solution on the diameter and crystal phase was studied. The 2θvalue of TiO2 sols were the 25.3°with the pH value 0.5,1.0,1.5The XRD diffraction peaks of the pH values 0.5,1.0 of TiO2 sols were high and narrow;The XRD diffraction peaks of the pH values 1.5 of TiO2 sols were low.SiO2 sols were prepared with precursor tetraethyl orthosilicate (TEOS) and NH3.H2O as catalyst through the sol-gel technology. The effect parameters such as TEOS concentration, ammonia concentration and temperature towards the size of silica nanoparticles have been investigated. The results show the size of silica nanoparticles increase with the increasing of TEOS and NH3 concentration,however,decreased with the increasing of reaction temperature. Nano SiO2 sols with a diameter of 34nm-145nm were prepared. The SiO2 films were prepared with the SiO2 sols of a diameter of 46nm,70nm,85nm,105nm,145nm by spraying method. The surface roughness of SiO2 films increase with the diameter of SiO2. SiO2/TiO2 composite films were prepared with glass slide of SiO2 films by spraying method. The SiO2/TiO2 composite films were characterized by SEM and hydrophilicity test.The results show that: The SiO2/TiO2 composite films were made by large diameter of SiO2 and small diameter of TiO2.The TiO2 film keeps hydrophilic for 8 hours,The SiO2/TiO2 composite films which were prepared by the SiO2 sols of a diameter of 85nm,105nm,145nm keep hydrophilic for 120 hour.The surfaces roughness of SiO2/TiO2 composite films increase with SiO2 diameter, The larger surface roughness of SiO2/TiO2 keeps hydrophilic more long time.
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