Synthesis of millimeter-scale Al2O3 ceramic hollow spheres by an improved emulsion microencapsulation method

Millimeter-scale Al2O3 ceramic hollow spheres have been successfully prepared by an improved emulsion microencapsulation method. That is: Firstly, stable oil-in-water emulsion droplets, using alumina sol as continuous phases (water phase) and dimethicone as dispersion phase (oil phase), are prepared in advance by using self-made T-shape micro-emulsion channel as an emulsion droplet generator. Then, the prepared droplets suffer rotating process for 12 h at 100 °C in a rotary evaporator, and Al2O3 gel hollow spheres are produced. Finally, Al2O3 ceramic hollow spheres with wall thickness of 30~100 μm and diameter of 600~2500 μm are successfully prepared through calcining the produced gel hollow spheres at 1200 °C for 4 h. The main crystalline of the prepared Al2O3 ceramic hollow spheres is α-Al2O3. This method provides a novel synthesizing method for preparing millimeter-scale ceramic hollow spheres which have great potential application in Inertial Confined Fusion (ICF) required hollow pellet.