Coarsening of Mesoporous α-Al2O3 Ceramics

Until recently, the processing of high surface area alumina ceramics has been restricted to transitional phases such as gamma, delta, and theta. In this study, a nanocrystalline alpha-Al(2)O(3) powder(100 m(2)/g) was processed into mesoporous alpha-Al(2)O(3) ceramics with surface areas in the range 20 to 80 m(2)/g. Hence, the opportunity exists to study the effect of thermal treatment on the pore structure of a high surface area alpha-Al(2)O(3) ceramic in the temperature range 600 degrees C to 1000 degrees C. The reduction in surface area was characterized as pure coarsening by surface diffusion. Examination of the pore structure showed both intraparticle pores and interparticle pores in the temperature range 600 degrees C to 800 degrees C and only interparticle pores above 800 degrees C. The powder particles were dense and polycrystalline. However, much of theirinternal structure is lost in heat treatments above 1000 degrees C.