Effects of di-ammonium citrate: polyvinylpyrrolidone as a complexion dispersants on 3Y-TZP slurries and sintered body properties

Abstract

AbstractA wide application of 3 mol% Yttria-stabilized Tetragonal Zirconia Poly-crystalline (3Y-TZP) makes the concern of ceramic processing required to produce strong and reliable engineering ceramic products. In this study, we successfully improved the 3Y-TZP mechanical properties by paying great concern to the early processing of 3Y-TZP powder. Here, we used the concept of colloidal processing by manipulating the 3Y-TZP inter-particle force as a combination of steric and depletion stabilization. Di-ammonium citrate (DAC) was used to induce steric stabilization utilizing the DAC’s carboxyl group to strongly bond with the OH group of the 3Y-TZP. While Polyvinylpyrrolidone (PVP) which could not bond with 3Y-TZP, leaves it freely as an un-attached polymer in slurries and induces a depletion stabilization mechanism. Using the combination of steric and depletion stabilization, the YSZ slurries stability is improved, and a uniform and smaller particle size can be obtained. As the result, better microstructure and high mechanical properties of the sintered body, such as higher density and Vickers hardness, can be achieved. By comparing to the sintered body of 3Y-TZP containing just DAC and 3Y-TZP containing a combination of DAC and PVP, better-sintered body properties can be found for the 3Y-TZP containing the combination of DAC and PVP, and the results can be listed as follows: grain size reduced from 0.420 to 0.281 um, density is increased from 94.5 to 99.3%, and Vickers hardness increases from 1190 to 1305 HV.