PREPARATION AND THERMAL BEHAVIOR OF CaCO
3
/SiO
2
NANOCOMPOSITE
Ladislav Pach
1
, Zdenek Hrabe
1
, Stefan Svetik
1
, and Sridhar Komarneni
2
*
1
Slovak University of Technology, Faculty of Chemical Technology, Department of
Ceramics, Glass and Cement, 812 37 Bratislava, Slovak Republic
2
Materials Research Laboratory, The Pennsylvania State University, University Park,
PA 16802, USA
(Refereed)
(Received October 10, 1997; Accepted April 9, 1998)
ABSTRACT
The preparation of CaCO
3
from a supersaturated solution of Ca(HCO
3
)
2
in a
microwave oven was studied at 25°C and pH of 7.1 and 7.3, with and
without colloidal SiO
2
as an additive. SiO
2
particles controlled the nucleation,
size, and shape of crystals and were incorporated into the CaCO
3
/SiO
2
nanocomposite. Incorporation of SiO
2
increased with increased SiO
2
addition
into the solution and with increased rate of precipitation. Heating the above
nanocomposite precipitate led to crystallization of calcium silicate at a low
temperature of 450°C, due to intimate contacts of CaCO
3
and SiO
2
in the
composite. © 1998 Elsevier Science Ltd
KEYWORDS: A. ceramics, A. composites, B. chemical synthesis.
INTRODUCTION
The biomimetic approach to the synthesis of inorganic material involves the control of the
nucleation process by means of functional groups of surfaces in aqueous medium [1]. This
approach, derived from the observation of the synthesis of bioceramics by living organisms,
takes place through nucleation of inorganic crystals (most frequently CaCO
3
and
Ca
5
(PO
4
)
3
OH) on the surface of polymers (collagen and polysaccharides) [2]. An alternative
*To whom correspondence should be addressed.
Materials Research Bulletin, Vol. 33, No. 11, pp. 1653–1660, 1998
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