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This paper describes a new, simple, and convenient method to prepare porous Al2O3 through oxidation of Al3BC3 via a direct pore-forming approach using only Al3BC3 powder as a starting material. Oxidation of Al3BC3 to Al18B4O33 started at 1150 °C, and a porous microstructure was formed because of the volatilization (sublimation) of B2O3 and CO2. When heated at high temperature for a long period, Al18B4O33 decomposed, accompanied by further volatilization of B2O3, resulting in monophasic Al2O3 with high porosity. The highest porosity was 71.6%, and small pores of 1–4 µm and large pores of 20 µm were observed in the present study. The pore size could be controlled by varying the heat-treatment temperature. The bending strength was 34.7–36.3 MPa, which is superior to those of other porous ceramics despite the high porosity of the Al2O3. This high bending strength is likely due to the high homogeneity of the Al2O3 and the formation of a porous Al2O3 network structure in which the particles are firmly bonded together at high temperatures. The proposed method easily provides a homogeneous porous Al2O3 sample without awkward processes such as mixing or dispersing a pore-forming agent into the matrix material.
Research papers (academic journals)
