Rheology Colloids and Ceramic Suspensions Group by mikeholy



Rheology, Colloids and Ceramic Suspensions Group
Coordinated by C. Galassi

ISTEC group working on the colloidal processing holds relevant expertise on:
•   Rheological and colloidal properties of ceramic suspensions since early 1990. Attention was
    focused on the colloidal stability of the systems in order to reduce the agglomeration
    phenomena which strongly affect the macroscopic properties and that are more and more
    relevant at decreasing size of the particles. Solid loading, organic additives, temperature and
    pH modification are the parameters usually investigated to control the stability of the systems.
    The parameters tested are zeta potential, rheological parameters (like viscosity, yield stress,
    time-dependency, viscoelastic properties) and interface properties (like surface tension of
    fluids, surface energy of solids and contact angle between solids and fluids).
•   Powder treatments related to shaping techniques involving the R& D of slurries with high solid
    loading and controlled stability. The materials studied are aluminium and zirconium oxides and
    their composites, mullite, hydroxyapatite, silicon nitride and perovskitic powders.
•   Synthesis with chemical methods (spray-drying of the solution of the precursors, sol-gel
    combustion) and characterisation of piezoelectric powders in the system lead zirconate titanate
    (PZT) and bismuth sodium barium titanate (BNBT).
The equipments for the suspensions characterization are:
    Rotational rheometers for the measure of viscosity and the other rheological properties
    Electroacoustic spectrometer for the measure of zeta potential of the particles
    Optical tensiometer for contact angle and interface tensions.


Moreover, other characterization usually performed are:
   particle-size determination by X-ray sedimentation
   specific surface area by BET method
   porosity by mercury intrusion
   scanning electron microscopy with microprobe
   X-ray diffraction for phase analysis
   thermal analyses (TGA, DTA)
and equipments for the preparation of diluted to concentrated suspensions (including high shear
roller mixer for screen printing inks)

Recent Relevant Papers
   Synthesis of La and Nb doped PZT Powder by the Gel-combustion Method
   M. Cernea , G. Montanari, C. Galassi, A. Costa
   Nanotechnology, 17, 1731-1735 (2006)
   Key Role of Milling in the Optimization of TiO2 Nanoinks
   A. Sanson, D. Gardini, G. Montanari, C. Galassi, E. Roncari
   Journal of Materials Science , 21 [6], 1561-1569 (2006)
   Chemico-Physical Properties of Nanosized Ceramic Inks for Ink-Jet Printing
   D. Gardini, F. Matteucci, M. Blosi, A.L. Costa, M. Dondi, C. Galassi, M. Raimondo, G. Baldi, E. Cinotti
   Proceedings of Qualicer 2006 – Castellón (Spain), 397-408 (2006)
   Rheology of Hydroxyapatite Dispersions
   D. Gardini, C. Galassi, R. Lapasin
   Journal of the American Ceramic Society, 88 [2], 271-276 (2005)
   PZT Prepared by Spray Drying: From Powder Synthesis to Electromechanical Properties
   F. Bezzi, A. L. Costa, D. Piazza, A. Ruffini, S. Albonetti, C. Galassi
   Journal of the European Ceramic Society,. 25, 3323–333 (2005)
   Influence of Magnesia Addition on the Rheological Properties of Mullite Suspensions
   C. Galassi, E. Roncari, C. Bassarello, R. Lapasin
   Journal of the American Ceramic Society, 82 [12], 3453-3458 (1999)
   Study of Interactions between Polyelectrolyte Dispersants, Alumina and Latex Binders by Rheological
   A. Kristoffersson, R. Lapasin, C. Galassi
   Journal of the European Ceramic Society, 18 [14], 2133-2140 (1998)

   Reologia, Colloidi e Sospensioni Ceramiche (in Italian)
   D. Gardini, C. Galassi
   Published by CNR (Rome), 2006


   Rheology Applied to Ceramics (Theory and Practice) (in English and Italian)
   Various Authors
   Cap.2 – Rheology of dispersed ceramic systems (D.Gardini, C. Galassi, R. Lapasin)
   Cap.5 – Rheological additives (D. Gardini, C. Galassi)
   Cap.14 – Beyond triangular procedure (D. Gardini, P. Prampolini)
   Published by SALA Editrice (Modena), 2006

1. Collective Research Project ADOPTIC (Additive Optimization for improved ceramics) (EU FP VI)
2. COST Action D 43: Colloid and Interface Chemistry for Nanotechnology
3. Network of 11 Laboratories “Application of fundamental principles of colloid and interface science and
   rheology to ceramic forming processes”. Human Capital and Mobility – (1995-97)


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