Preparation And Properties Of Porous Al₂O₃ Ceramic Membrane

This paper study on liquid radioactive wastes disposal, we selected a-Al2O3 as ceramic powder, PVB as binder, DBP as plasticizer, ethanol as dissolution medium, charcoal powder,boehmite, PL-3 as pore forming agents respectively. Prepared Al2O3 ceramic green sheet through tape casting, and got the porous ceramic membrane after debinding and sintering. The effect of plasticizer and powders content on the properties of slurries and substrates were discussed. Study on the influence of pore-forming agent on the porosity and pore size distribution.Characterize and analysis the microscopic morphology of Al2O3 porous ceramic membrane with SEM.We also study the properties of Al2O3 ceramic filtering membranes via porous size distribution, scanning electron microscopy and X-ray diffraction.The results showed that when the ratio of plasticizer and binder was 0.8, and the optimal ratio of m (PVB): m (DBP): m (composite powder): m (ethanol) is 3: 2.4: 21: 22, a stable and preferable Al2O3 slurry of tape casting can be gained, the viscosity of which was 9220mPa·s.Then after removing bubble, tape casing, drying, we can get the green Al2O3 ceramic substrates which has high quality. The density, the thickness, the porosity, and the elongation at break of the green substrates were 2.27g/cm3、0.245μm、13.91%、45.77% respectively.With the adding of pore-forming agent, the viscosity of slurry was increasing and the properties of green substrates was declining, and the density and the elongation at break of the green substrates were decreasing, while the thickness of green sheets was increasing.A reasonable debinding process was established according to the thermo-gravimetric(TG)analysis of Al2O3 green sheet. 1500℃ and 120min were chosen as final sintering parameters by comparing the performance of the Al2O3 ceramic films. The results showed that different forming agent lead different pore structures of the porous Al2O3 ceramic membranes. The membranes prepared with PL-3 show the best performance. The porosity of the porous Al2O3 ceramic membranes with PL-3 as pore-forming agent 31.06%, and the pore size was 0.65μm when the forming agent added 5wt%; increased the PL-3 add to 20wt%, the porosity and pore size turns to 51.52% and 1.11μm.Through experimental investigation, confirm the ratio of m (PVB): m (DBP): m(composite powder): m (ethanol) is 1: 0.8: 6.3: 7.3. PL-3 was chosen as the suitable pore-forming agent. When the content of PL-3 was 15wt%, and the temperature and the time of sintering process parameters were 1500℃, 120min respectively, we can get Al2O3 ceramic filtering membranes with a circular pore structure, the pore size and the porosity of which were 0.99μm and 44.85%, respectively.