Improved microstructure of alumina ceramics prepared from DBD plasma activated powders

Submicron Al2O3 powders were activated by Diffuse Coplanar Surface Barrier Discharge (DCSBD) plasma. The influence of the plasma treatment on the powder properties and their impact on the microstructure of dry and wet shaped ceramics were investigated. Raman and FTIR analyses of treated powders showed a substantial increase of the powder's surface hydroxylation, surface cleaning, and the presence of adsorbed NOx originating from the DCSBD. Sintering of the dry shaped plasma treated powders did not influence sintering behavior. On the other hand, the plasma treated powder was able to form stable water suspension without any chemical stabilization aid. Slip cast samples exhibited finer pore size distribution, a higher sinterability, and a finer final microstructure. The grain size of slip casted plasma treated powder was reduced by a factor of 1.7, which facilitated a grain size of 0.68 mu m at the relative density of 99.54% t.d. obtained by pressure-less sintering.