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Name (Title):
Suarez Gustavo (PhD candidate UNLP – NIMS)
Affiliation:
Fine particle processing group. Nano ceramics center
Address:
1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047
Email: SUAREZ.Gustavo@nims.go.jp
Home Page: http://www.nims.go.jp/fineparticle/index-e.htm
Presentation Title:
Improvements on sintering by optimizing the colloidal processing
Poster Session PM-23
Abstract:
Colloidal processing of nano powders is the most important and the initial step in ceramics
conformation and it is proved to be to the way to control and improve some properties [1].
Ultrasonication treatment is a very useful deagglomeration process however fine particles tend to
form heavy agglomeration that can not be re-dispersed.
The objective of this work is to improve final properties of zirconia designing and controlling
the structure by controlling the colloidal processing. “Bead-milling” treatment makes possible
full deagglomeration and well-mix of multi-component suspensions using 50 µm beads and high
rotation speed.
We already prove Tetragonal zirconia presents better
sinterability if the slip-cast samples are prepared with treated
suspensions [2].
Bead-milling of a mixture 3mol% yttria with 97mol%
monoclinic zirconia can produce by reaction sintering an
homogeneous nanostructure of tetragonal zirconia sintered by
two step sintering presenting a final nanostructure smaller than
3YTZ, 125 nm of average grain size for 3YTZ and 95 nm for
reacted sintering. Cubic zirconia can also be prepared by well
mix and disperse suspension of 8mol% yttria with 92mol%
monoclinic zirconia showing a significant reduction in the grain
growth sintered by normal sintering at low temperature, 1300 °C.
From a final 1.2 microns for 8YSZ to 250 nm prepared by
reacted sintering cubic zirconia.
Textured materials have shown improvements in many
different materials [3]. Tetragonal zirconia is not possible to be
oriented in high magnetic field (HMF) unless is prepared by
reaction sintering with a bead-mill mixture of yttria and
monoclinic zirconia (TZ0) (figure 1).
Fabricating zirconia-based composites with CNT is another
interesting topic for improving their properties. One of the
biggest problems in CNT composites, however, is the dispersion
of the CNT in water. Bead-milling can disperse and well mix
zirconia with CNT homogeneously making possible the sample
preparation with controlled amount of CNT in the matrix.
References:
1. Y. Sakka,”Fabrication of Highly Microstructure Controlled Ceramics by Novel Colloidal
Processing,” J. Ceram. Soc. Japan, 114 371-376 (2006).
2. G. Suárez, Y. Sakka, T. Suzuki, T. Uchikoshi and E. F. Aglietti, “Effect of beads milling
treatment in the dispersion of tetragonal zirconia nanopowder and improvements of the two
step sintering”, in preparation (2009).
3. Y. Sakka and T. S. Suzuki, "Textured development of feeble Magnetic Ceramics by colloidal
processing under High Magnetic Field," J. Ceram. Soc. Jpn., 113 [1] 26 – 36 (2005).
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