Synthesis of zirconia sphere particles based on gelation of sodium alginate

Abstract Zirconia sphere particles were synthesized through the gelation process of Na-alginate, and cermet (ZrO 2 –Mo) pellets were fabricated under several conditions. In this process, a zirconia slurry was prepared by mixing oxide powders (ZrO 2 , Y 2 O 3 , Er 2 O 3 , CeO 2 ), distilled water and Na-alginate, and subsequently dropped into CaCl 2 solution. As a result, zirconia sphere particles coated with a gelled film were synthesized. The slurry density (zirconia content in slurry) of 30–64 wt.% and Na-alginate concentration of a few% were good for gelation for up to 10 wt.% CaCl 2 solution. Sphere particles with smaller diameter were obtained by dropping slurry with a mechanical vibration. The prolongation of the ball milling time for mixture of oxide powders was effective to increase the sintered density of zirconia sphere particles, especially for higher CeO 2 concentration. The dense cermet pellets were fabricated for max. 50% volume ratio of zirconia phase for Mo matrix using zirconia particles covered with Mo powder by a rotating granulation method.