High-surface-area alumina ceramics fabricated by the decomposition of Al(OH)(3)

Al2O3-based porous ceramics with high surface areas were fabricated by addi ng AI(OH), to the starting powder, followed by pressureless sintering at te mperatures >1100 degreesC, Three types of starting powders were used in the present study: pure alpha -Al2O3, alpha -Al2O3 + Al(OH)(3) and alpha- Al2O 3 + ZrO2 + Al(OH)(3). The addition of Al(OH)(3) considerably increased the surface area of the porous Al2O3 and the addition of ZrO2 further increased the surface area; a surface area as high as 36.39 m(2)/g was obtained, and the high surface area was retained at higher temperature. The pore size di stribution of the specimens with high surface area was bimodal, with one pe ak at similar to 100 nm and the other, which contributed most of the surfac e area, at similar to 10 nm, X-ray analysis showed that in the sample with the fine pores and high surface area, there was theta -Al2O3 phase produced by the decomposition of Al(OH)(3), presumably because the phase transforma tion of theta -Al2O3 to alpha -Al2O3 was incomplete after low-temperature s intering, Moreover, the porous Al2O3 with high surface area retained superi or mechanical propel ties, attributed to the good sinterability of the fine alpha -Al2O3, powder used in the present study. The sintered specimens cou ld be large and designed to any shape, because pressureless sintering was u sed for fabrication, The present approach provides a new way of fabricating porous Al2O3 ceramics that could be widely used as catalyst supports in in dustry, especially for high-temperature catalysis.