Study On Preparation And Properties Of Alumina Ceramic Membrane Support

Porous alumina ceramic has the advantages of great strength,oxidation resistance,high temperature resistance,and good chemical stability,while it is relatively low in manufacturing costs,which is widely used in the fields of mechanical,electronic,aerospace,especially in food,chemical,water treatment in liquid separation effect is significant.Tubular alumina ceramic membrane support withα-Al₂O₃ as aggregate,Carboxymethyl Cellulose（CMC）as pore-forming agent and binder,Glycerol as lubricant and plasticizer,CuO-TiO₂ as multiphase sintering agent was prepared by extrusion-forming method and solid sintering method.The sample was characterized by thermal gravimetric analysis（TG-DTG）,X-ray diffraction（XRD）,scanning electron microscopy（SEM）,mercury intrusion method and self-assembly equipments.The effects of amount of pore-forming agent（mass fraction,the same below）、sintering agent and lubricant on the porosity and flexural strength of porous alumina ceramics support were analyzed by orthogonal experiment.The primary and secondary sequence which influence the porosity of alumina ceramic support is amount of pore-forming agent、sintering agent and lubricant,and that which influence the flexural strength of alumina ceramics support is amount of pore-forming agent、lubricant and sintering agent.According to comprehensive consideration,the best experimental raw material ratio of the alumina ceramic support preparation is determined as that the amount of pore-forming agent CMC is 4%,sintering agent CuO-TiO₂ is 1.5%+3%,lubricant glycerin is 3%,and the optimization is verified.At the same time,the effect of pore-forming agent CMC、multiphase sintering agent CuO-TiO₂ and lubricant glycerin on the pore structure,such as porosity,pore size distribution,pure water flux and microstructure,flexural strength,acid and alkali corrosion and crystal phase composition of alumina ceramics support was investigated.The sintering mechanism of alumina ceramics and multiphase sintering agent CuO-TiO₂ at low temperature were analyzed.TiO₂ dissolved into Al₂O₃ and formed Al₂TiO₅ solid solution,and the diffusion coefficient improved largely with the augment of Al³⁺vacancy concentration to promote the densification of alumina ceramics,meanwhile the temperature of TiO₂ dissolved into Al₂O₃ could be lowed with the effect of liquid wetting of CuO,and then generated liquid eutectic mixture CuAl₂O₄ is helpful to realize low temperature sintering.The optimal heating rate in the process of sintering is determined by TG-DTG curve,such as at room temperature to 200℃,200℃to350℃,350℃to 800℃,and 800℃to 1200℃,the temperature rise rate is constant respectively at 4,4,2,2℃/min,insulating 0.5 h at 350℃,1h at 800℃,and 2h at1200℃,cooling to room temperature finally.According to the sintering system,sintered at1200℃,the diffraction peaks of CuAl₂O₄ and Al₂TiO₅ is appeared in the XRD analysis,and microstructure is fine,the porosity,the average pore size,the most probable aperture,pure water flux,the flexural strength,acid/alkali corrosion mass loss of the support was33%,844.5nm,1626.87nm,5107.68 L/m²hMPa,104.4MPa,0.02%/0.09%respectively.