Influence of Grinding and Centrifugation Parameters on the Particle Size and Separation of Agglomerates of Alumina

Ceramic processing can lead to the formation of hard agglomerates of particles, which impede uniform sintering and preparation of high-density ceramics. In this paper, we report a study of α-Al2O3 powder. Major attention is paid to the effect of grinding and centrifugation parameters on the final particle size on the addition of NH4OH for electrostatic stabilization, which prevents particle agglomeration. Analysis of the centrifugate yield as a function of centrifugation conditions (rotation rate and α-Al2O3 content) allows processing parameters to be optimized so as to maximize the yield of particles of required size. The particle size was evaluated by the dynamic light scattering method, which offers the possibility of determining the particle size distribution as well, which is necessary for investigation of the properties of the material. Besides, we have calculated the milling time needed for reaching a particle size of 0.4 μm and determined the grinding rate constant. In addition, for particles about 0.4 μm in size we have ascertained whether the sedimentation–diffusion equilibrium condition can be met without centrifugation. The results of this study can be helpful in improving methods for the preparation of high-quality α-Al2O3 powder, which finds wide application in various industrial sectors (in the manufacture of ceramics, electronics, catalysts, etc.).