ISSN 0862-5468 (Print), ISSN 1804-5847 (online) 

Ceramics-Silikáty 44, (1) 1 - 8 (2000)


STABILIZATION OF BIOCERAMIC SUSPENSIONS PREPARED FROM ALUMINA-CONTAINING ZIRCONIA POWDERS
 
Kuneš Karel, Havrda Jiří, Hroníková Kateřina, Gregorová Eva, Pabst Willi
 
Department of Glass and Ceramics, Institute of Chemical Technology, Prague, Technická 5, 166 28 Prague 6, Czech Republic

A stable, agglomerate-free suspension with almost Newtonian flow behavior is one of the basic requirements when slip casting is to be used as a shaping process for bioceramic materials. In this work suspensions of three commercial zirconia powders with different alumina admixtures (Tosoh TZ-3Y, TZ-3YE, TZ-3Y20A) are investigated. The rheological behavior is determined by rotational viscometry, the particle size distribution by low-angle laser light scattering. For the powder types studied the alkali-free polyelectrolyte Dolapix CE64 turned out to be the most effective deflocculant. The optimum deflocculant concentration is approx. 0.6 wt.% in all cases. It has been found that peptization alone is not sufficient for destroying the agglomerates, mechanical dispersion (ball-milling) is also necessary. The concentrational changes during the evacuation step are in the order of several percent and lead to non-negligible viscosity changes.


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