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Polymeric flocculation of ceramic slurry obtained by the Direct Coagulation Casting

Katarzyna Jach ,  MikoĊ‚aj Szafran 

Warsaw University of Technology, Faculty of Chemistry, Noakowskiego 3, Warszawa 00-664, Poland


The role of enzymes in Direct Coagulation Casting forming method consists in the decomposition of an appropriately selected substance, which results in slow release over the whole volume of a substance changing the pH of the system modifying the double electric layer. In the case of applying a powder of a suitable composition, profiles of high density and relatively high mechanical strength in the green state enabling the removal of a green product from the form without destruction can be obtained by this method.
The assurance of a respective mechanical strength of a green samples is a technological problem when forming products of a complicated shape. This requires the introduction of a certain amount of a polymeric binder, often of high molecular weight. Such binders cause a considerable increase in the viscosity of ceramic casting slips, which in turn precludes the exact filling of the form.
This problem can be partly minimized by introducing a binder simultaneously playing the role of a flocculant of the ceramic casting slip. If the flocculation is carried out with the participation of enzymes, then at a relatively small rate of such a reaction appropriate fitting of the ceramic powder particles is possible, which should lead to an improvement in the uniformity of thickening in the ceramic product formed.
The slow decomposition of a respective starting material by an enzyme should cause a change in the character of interactions between particular bundles of the polymer chains and change their conformation to a dense net of entanglements. This should result also in the transfer of the ceramic casting slip from the state of small viscosity to that of a stiff material, additionally strengthened by a bond between the individual particles of the ceramic powder and the binder.


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Presentation: poster at E-MRS Fall Meeting 2003, Symposium B, by Katarzyna Jach
See On-line Journal of E-MRS Fall Meeting 2003

Submitted: 2003-05-27 18:00
Revised:   2009-06-08 12:55