Preparations And Properties Of Light Weight And High Strength Micron Porous Alumina Ceramics

Air pollution is worsening constantly in recent years and the haze has become a big concern to the people.The great amount of vehicle exhaust with micron sized solid particles is one of the most important sources of haze.These micrometer sized particles is formed due to incomplete combustion of large molecular hydrocarbon in the fuel. Online pyrolysis technology for large molecular hydrocarbon fuel for clean combustion is an important development to solve the pollution problem. The key to realize the innovation is the high strength lightweight porous ceramic material with micron through holes.Slurry rheological properties and the formation mechanism of aggregate were researched in slurry in this paper. Adjusting the amount of dispersant and solid loading can lead to ideal slurry of low viscosity without aggregate which lays a good foundation for the following processes to preparation of porous ceramic.Porous alumina ceramics can be effectively prepared through gel casting with tert butyl alcohol solvent. Apply the mechanism to adjust the solid loading regulates porosity, pore size, compressive strength and thermal conductivity of the porous ceramics. MgO, as sintering aids, has been used to improve the compressive strength of alumina porous ceramics made by gelcasting.Porous alumina ceramics with hole pore structure have been prepared by unidirectional freezing the water-based slurry and drying. Utilizing environmentally friendly sodium alginate as binder, not only strengthens the green body but also promotes a non-toxic and harmless simple process with strong operability and low cost. Porous alumina ceramics is characterized by their uniformly distributed fishbone like unidirectional parallel pores with open porosity between48.8%-80%, compressive strength between3.4MPa-32.3MPa, permeability more than4×10-11m2.Porous alumina ceramics with highly aligned through hole structure have been successfully fabricated by sodium alginate ionotropic gelation. By controlling of the hole forming and drying process, the aperture maintained between80～250miron. The permeability is improved by an order of magnitude compared with alumina bubble porous ceramic with the same porosity. The compressive strength of44.2±5.4MPa, for a solid loading of only15%is also far higher than porous ceramics with random porosity.