A Research On The Preparation And Properties Of Inorganic Oxide Composite Ceramic Membrane

This thesis aims to adopt sol-gel method to get composite membranes by heat treatment through preparing Al₂O₃-TiO₂,Al₂O₃-ZrO₂,SiO₂-TiO₂,SiO₂-ZrO₂composite sols based on using aluminum isopropoxide,TEOS as the precursor.The results of the characterized analysis which use testing instruments such as thermogravimetric?TG-DTG?,fourier transform infrared?FT-IR?,atomic force microscopy?AFM?to analyze thermal stability,surface morphology,internal structure of composite membranes demonstrate that:?1?Al₂O₃-TiO₂ composite sol was prepared by mixing Al₂O₃ sol and TiO₂ sol,and the best performance sol was got when Al₂O₃/TiO₂=1 by investigating the effect of chemical composition on the properties of Al₂O₃-TiO₂ composite sol.The heat treatment system of Al₂O₃-TiO₂ sol are dried gels at a temperature of 60?,relative humidity of 70%RH,and heated to 275?at a rate of 0.25?in muffle furnace and keeped for a certain time in the vicinity of the 260?and 130?,then heated to 600?at a rate of 1?/min and keeped for 3 hrs,finally cooled to room temperature TG-DTG,FT-IR and AFM analysis showed that the composite film had good thermal stability,and the film surface was compact and smooth.The analysis of TG-DTG,FT-IR and AFM shows that the composite film has good thermal stability,and the surface of the thin film is dense and smooth.?2?The study found that the addition of DMF and ZrO₂ in Al₂O₃-ZrO₂ composite had an effect on the properties of the composite sol.When the water temperature is 30?,stirring time is 45min,ZrO₂ and DMF addition amount is 50%and 30%respectively,sol performance is best.The test analysis shows that the Al₂O₃-ZrO₂ composite film has AlZrO phase,which shows that the prepare of composite film formed a solid solution,and with the increase of sintering temperature,there is no instable phase formation at 1000?,which shows that the addition of ZrO₂ inhibited the phase transformation of Al₂O₃,and improves the phase transition temperature of ZrO₂ and Al₂O₃ by comparing with pure Al₂O₃ and ZrO₂ crystal.And the surface of the composite film is smooth,the particle shape is more regular,the pore diameter reaches to12nm.?3?When SiO₂:TiO₂=1:1,hydrolysis temperature is room temperature,stirring time is3h,the addition amount of DMF is 30%,the properties of the composite are better.New chemical bond Si-O-Ti is generated in the SiO₂-TiO₂ composite membrane by heating treatment,which means that the two sols is combined by chemical bond not only physical mixing,that improves the thermal stability of the membrane,However,the composite membrane also has Si-O and Ti-O bond,which shows that the composite membrane has not completely reacted.The composite membrane have high porosity and uniform internal structure.?4?The properties of SiO₂-ZrO₂ composite sol was changed with the changing of ZrO₂adding amount,water temperature,stirring time and DMF adding amount,and no cracks of composite membranes was obtained after drying,only when ZrO₂ adding amount is 20%,t is 40?,T?stirring time?is 30min,DMF added amount is 30%.The analysis of modern testing means sintering temperature have effect on the internal structure of the membrane,and the main bond of membrane is Si-O-Zr below 600?,but when the temperature rises to 800?,the Si-O-Zr bond can fracture and generate Si-O-Si bond,this can reduce the thermal stability of the composite membrane,so the optimum heat treatment temperature is 600?,and the composite membrane is smooth and have porous structure and good thermal stability.