Preparation of Nano Alumina Bulk Ceramics by Aqueous Gelcasting

In the present study an aqueous gelcasting process for the production of dense nano alumina ceramics has been described. To investigate the stability behavior of nano alumina (20 nm in size) slurries, dispersed using different types of dispersants and to increase the solid loading while keeping the viscosity low, sedimentation and viscosity experiments were carried out. By applying the optimum dispersing conditions, alumina slurries with solid loading as high as 40 vol. % were prepared by performing three step attrition milling. Deairing was used to remove air bubblesfrom the slurry and near net-shaped parts of alumina was successfully formed by gelcasting. Furthermore, to produce crack free pieces drying, binder burn out and sintering have been studied extensively. Finally, alumina bodies with density as high as 95 % were produced by performing pressureless sintering at 1600 C for 3 hours. SEM micrographs showed dense, submicron sized microstructure.

کلیدواژه ها:

Nano-Powder ، Alumina ، Rheology ، Dispersant ، Gelcasting