Bulk alumina support with high tolerant strain and its reinforcing mechanisms

Bulk porous Al2O3 support was fabricated using a mixture of fine alpha -Al2O3 powder and Al(OH)(3) particles, followed by pressureless sintering at temperatures between 1100 degreesC and 1300 degreesC. Al2O3 support with high surface area was obtained, due to the presence of transitional Al2O3 phases that were produced by the decomposition of Al(OH)(3) even after sintering. The Al2O3 support exhibited superior mechanical properties and high strain to failure, compared with those fabricated by traditional methods. The strain to failure increased with the amount of Al(OH)(3) in the mixture, but decreased with increasing sintering temperature. A conceptual model for the microstructural evolution and reinforcing mechanisms, based on transmission electron microscopy (TEM) observations, is proposed. It reveals that the interface bonding of the Al2O3 boundaries formed at the initial nucleation stage during theta- to alpha -Al2O3 transformation is stronger than that formed by subsequent grain growth. The interface bonding between the Al2O3 grains, which came from the decomposition of AI(OH)(3), is stronger than that between the original Al2O3 grains in the starting mixture. (C) 2001 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.