Evaluation of Powder Properties in Aqueous Processing of Microwave Dielectric Ceramics

Abstract

As-received calcium titanate and neodymium aluminate of median sizes 4.0 and 1.2μm, respectively, showed fast sedimentation within 10min because of the formation of hard agglomerates about 1-10μm. When ball-milling time became longer, the larger particles were selectively ground and the particle size distributions became narrow. The dispersibility of 96h-milled powders was greatly improved by addition of polyacrylic ammonium (PAA) of 2mass%. The viscosity of suspension depended on the amount of PAA adsorbed and was lower for CaTiO₃ suspension than NdAlO₃ suspension. Consolidation of the suspensions and sintering behavior of the CaTiO₃-NdAlO₃ system were also studied.