Synthesis of zirconia sphere particles based on gelation of sodium alginate

Abstract

a b s t r a c tZirconia 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.

A Forming Technique to Produce Spherical Ceramic Beads Using Sodium Alginate as a Precursor Binder Phase

“…The gelation process of sodium alginate alumina slurry in the presence of calcium chloride solution has the potential of introducing ions after gelation and this can influence the properties of the alumina beads after sintering. Nozaki et al . reported that ion exchange reaction is believed to occur in this fashion To determine the level of purity of the beads after gelation and sintering, elemental analysis was conducted to primarily investigate the presence of Ca 2+ , Na − , and Cl − ions after gelation and sintering.…”

“…Over the years, many methods have been developed to produce pure alginate beads using different types of technologies such as: a rotating atomizer for viscous liquids, perforated plates, a single needle with air flow, a multiple needle system, a nozzle mounted in a rotated cylinder, a double fluid atomizer, rotating disk atomization, electrostatic dripping, vibrating nozzle, dripping, and jet cutting . All these methods were developed to produce spherical beads with uniform diameters ranging between 0.1 and 5 mm using alginates, for immobilization of living cells, enzymes, and encapsulation of liquid food or heavy metals.…”

“…The recent growth of interest in understanding stress‐wave propagation by granular media in one‐dimensional, two‐dimensional, and three‐dimensional systems is what led us to produce spherical ceramic beads using alginates as an in situ gelling template . In the past, many researchers used alginates as an in situ gelling template for making ceramic beads . Nozaki et al .…”

“…In the past, many researchers used alginates as an in situ gelling template for making ceramic beads . Nozaki et al . described using Na alginate as a gelling template when making zirconia spherical particles ranging from 0.24 to 0.48 mm.…”

Design and fabrication of ceramic beads by the vibration method

“…However, these methods only produce beads with diameters below 5 mm [12,[21][22][23][24][25][26][27].…”