KJ Ceramics 31

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Detailed Program

Paper Number : ST-O13

Time Frame : 15:50~16:10

Presentation Date : Friday, 28, November

Session Name : Structual Ceramics & Refractory materials

Session Chair 1# : Do-kyung Kim

Session Chair 2# : Masaki Narisawa

Effect of grain size on properties of porous alumina for support substrates of permselective ceramic membranes

Sawao HONDA

Nagoya Institute of Technology

Keywords: Porous alumina, Grain size, Necking size, Fracture strength, Thermal conductivity

Porous alumina has been investigated as support material for the ceramic permselective membranes. This porous structure design is essential for the separation membrane support to maximize the fluid permeability and minimizes the pressure drop of the permeating fluids by increasing pore volume as much as possible. Generally, fracture strength or thermal shock resistance of porous ceramics can be enhanced by decreasing the porosity or pore size. However, there is a fundamental trade-off between the mechanical properties and the permeation property, and the fluid permeability through the porous support decreases consistently with the decrease in the porosity or pore size. To apply porous alumina as a porous support for microporous ceramic membranes, it is important to establish a novel porous structure design concept to harmonize the simultaneous and sufficient fracture resistance and permeability of the porous alumina. In this research, a series of macroporous alumina with different pore size and porosity were fabricated. The permeability of the macroporous alumina was characterized by measuring nitrogen gas permeance, while the mechanical and thermal properties of the macroporous alumina were evaluated. The relations between the parameters which characterizing the porous structure and the thermo-mechanical properties were discussed from a viewpoint to develop macroporous support for microporous ceramic membranes by the tailored macroporous structure controlling. The nitrogen permeability of porous alumina was increased with pore volume remarkably. The gain necking of porous alumina with higher fracture resistance properties was larger than that of the others. In order to estimate the effect of grain size and grain necking on thermal conductivity, porous alumina were fabricated using various grain size alumina powder and pulse electric current sintering without grain growth, as shown Fig.1, and the numerical analysis was performed using interfacial thermal resistance at grain boundary. The high thermal conductivity was due to the large grain size and grain necking. This research clarified that increasing the grain necking size could improve the fracture resistance without lowering the permeability.

Acknowledgements :

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