Agglomeration Control of Ultrafine Y_2O_3-ZrO_2 and (MgO, Y_2O_3)-ZrO_2 Powders Synthesized by Coprecipitation Process

TheadventofstrongandtoughZrO2 basedce ramicshasgeneratedconsiderablescientificandtech nologicalinterestinthisclassofstructuralceram ics1—3]. Nowfine grainedsinteredceramicscanbeproducedusingcommerciallyavailableultrafinepow ders,whichcanbesinteredtofulldensityatrelativelylowtemperatures. High qualityZrO2 powderisvitalforthesuccessfuldevelopmentofadvancedZrO2 ce ramics. Severalwetchemicalmethodshavebeende velopedforpreparationofsuchhigh purity, homoge neousandsinterableceramicspowders,…

Agglomeration Control of Ultrafine Y2 O3-ZrO2 and (MgO, Y2 O3)-ZrO2 Powders Synthesized by Coprecipitation Process

Chemical coprecipitation was used to produce ultrafine and easily sinterable Y_2O_3-stabilized and (Y_2O_3,MgO)-stabilized ZrO_2 powders. Six precipitation processes for preparation of ZrO_2-based ultrafine powders were designed separately, meanwhile different techniques used to control the agglomeration formation were proposed. By means of TEM, SEM, Raman spectroscopy and IR spectroscopy, the mechanisms of agglomeration control in the precipitation processes and post-precipitation and drying process were investigated. The experimental results show that adding appropriate anion surface active agents (such as PAA1460) or polymer (PEG1540 matching with PEG200) in aqueous solution systems during precipitation processes could reinforce charge effect and location effect for gel particles interface. Adding wetting agents to wet gels washing with distilled water during drying process could change interface structure of gel particles and decrease surface tension between gel particles. The agglomeration control in the precipitation, post-precipitation and drying processes had remarkable influence on the characteristics of powders. By adding various macromolecules in the processes, the agglomeration state could be controlled efficiently, and the characteristics of powders were improved.