Feasibility Study on the Forming of Alumina Beads by Agar Gel casting

摘要

The alumina grinding beads are usually formed by a pan granulator method, however it is difficult to form small size beads (1-2 mm diameter). This work is focused on a new forming method which uses agar as gelling agent in gel casting. The mixture of alumina suspension and agar solution (concentration 1.5-4wt percent) is dropped into cooled oil using a pipette. The shape of drop becomes sphere by its surface tension. After the drop transforms to gel, it is separated from cooled oil. Later the gel beads are dried in air and finally sintered at 1300-1400 deg C. Tellus 46 oil at 0 deg C has the optimum viscosity for forming. When concentration of agar solution is 1.5 wt percent, the shape of drop at tip of dropper is almost sphere. The shape after drying and the sintered density are affected by the final agar content in the mixture.