High dispersibility of α-Al2O3 powders from coprecipitation method by step-by-step horizontal ball-milling

α-Al2O3 powder is widely used in numerous applications, especially in optical ceramics and crystals growth. However, achieving perfect dispersibility is essential in these applications and requires a complete understanding of the dispersion mechanism as well as high technology processing. In this paper, a step-by-step horizontal ball-milling method was adopted to improve the dispersibility of α-Al2O3 powders through coprecipitation. Effects of ball milling processes and Al3+ concentration on the particle size and the dispersity of alumina precursor were systematically investigated. The presence of absorbed sulfate ion on the surface of the particles could inhibit aggregation processes. Precursors were evolved into α-Al2O3 phase after subsequent calcination of 1180 °C in air. The work shows that step-by-step horizontal ball-milling achieves a well-dispersible powder with quasi-spherical morphology and narrow size distribution in the range of 150 ~ 200 nm.