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Deflocculation of nanozirconia powders
|Anna W. Danelska , Mikołaj Szafran , Ewa Bobryk
Warsaw University of Technology, Faculty of Chemistry, Noakowskiego 3, Warszawa 00-664, Poland
Agglomeration phenomenon seems to be the most serious obstacle which makes difficult the nanopowders technology. Porous and non-nanometric size agglomerates attend every stage of nanopowders processing. To reduce agglomeration process in nanoceramic slurries some additions called deflocculants agents are widely used. Recently, studies on deflocculation of alumina nanopowders have met with great interest and has been studied in detail. There were found some noteworthy deflocculants agent of mentioned nanopowder, particulary monosaccharides. Because zirconia such like alumina is the most fundamental ceramic structural material there is a need to examine its properties in nano-size also.
The purpose of presented studies was to investigate, how selected deflocculants, especially monosacharides, can influence the rheological properties of ceramic slurries made of nanometric zirconia powders. Two powders chosen for this research were stabilized by 3 mol.% of yttria and were obtained by means of wet chemical synthesis using co-precipitation route. Nanozirconia powders with an average particle size of 17 and 44 nm were purchased from CEREL and Inframat Advanced Materials (IAM), respectively.
It was found that addition of monosaccharides decreases the viscosity of ceramic slurries made of nano-ZrO2 with an average particle size of 17 nm and increases the viscosity of those made of nano-ZrO2 with an average particle size of 44 nm particles, but explanation of mentioned problems requires further studies.
Using both of the nanopowders some samples were prepared by means of slip casting method. Subsequently they were sintered at 1300°C with one- and two-step route. Sintered bodies made of nano-ZrO2 CEREL were of high open porosity (30-40%) and had rather low relative density (60-75% of TD). Sintered samples made of nano-ZrO2 IAM were of zero open porosity and had high relative density (>97% of TD).
Presentation: Poster at E-MRS Fall Meeting 2009, Symposium I, by Anna W. Danelska
See On-line Journal of E-MRS Fall Meeting 2009
Submitted: 2009-05-08 13:43 Revised: 2009-06-07 00:48