Shaping of alumina microbeads by drop-casting of the photopolymerizable suspension into silicone oil and UV curing

Abstract

The alumina microbeads were obtained by forming the drops of alumina suspensions in a silicone oil followed by UV curing. Due to the strong hydrophobic properties, silicon oil is a non-solvent (non-miscible) to the suspensions, thus the formation of perfectly rounded beads occurs spontaneously. The size of beads was controlled by a selection of a needle diameter and the position of needle tip: above or immersed in silicone oil. Thanks to that it was possible to obtain beads with diameters from 1000 to 1300 µm. The obtained alumina microbeads were characterized by quite a narrow size distribution, the differences in the size of the beads, within one series, did not exceed 1.5%. The research showed that the higher alumina volume fraction in suspensions favors the development of microstructure and thus influences mechanical properties. It was proved that the application of the methyl silicone oil as the environment responsible for the formation of the beads does not affect the sintering process.