Spray drying zirconia

Subramanian, A. Carr, P.W. McNeff, C.V. Use of spray-dried zirconia microspheres in the separation of immuno-globuhns from cell culture supernatant. J. Chromatogr. A,... 

Figures 37.6 and 37.7 show SEM images of sodium chloride powders produced by spray drying of a 2.5 mol/L solution of NaCl at 760,400,250, and 120 Torr, and at reactor temperatures of lOO C and 400 C, respectively. In contrast to zirconia particles that were spherical, these powders are cubic. This is attributed to the crystal growth mechanism of sodium chloride, which is different fi om zirconia powder.

Synthetic raw materials include precursors of glazes (lead oxide, barium carbonate, tin oxide) and special ceramic masses (alumina, zirconia, magnesia), as well as hydrothermally synthesized wollastonite and diopside, and synthetic days such as kaolinite with very narrow grain size distribution and high plastidty for high-performance ceramics. Wet chemical techniques such as coprecipitation, freeze-and spray-drying, and sol-gel synthesis are also applied to produce raw materials for special appHcations. 

In order to produce Y203-stabilized zirconia with homogeneous distribution, sol-gel processes or coprecipitation have been adopted, based on the hydrolysis of stoichiometric mixtures of zirconyl chloride and yttrium trichloride (see, e.g.. Carter et al, 2009). The hydroxides formed are subsequently subjected to aceo-tropic distillation, drying, calcining between 850 and 950 °C, wet milling, and spray-drying. 

Kim, J.-Y., Inoue, M., Kato, Z., Uchida, N., Saito, K., Uematsu, K. (1991). Direct observation of internal structure in spray-dried yttria-doped zirconia granule. Journal of Materials Science, 26(8), 2215-2218. 

The M3YSZ samples sintered at 1550°C were characterized by SEM. Microscopy of polished surfaces revealed very little porosity present but showed the present of large (10 to 50 pm) ball-like agglomerates (see Fig. 2a). EDS revealed that the balls were zirconia-rich. It was discovered that the Tosoh 3YSZ zirconia powders are spray-dried which creates ball-like agglomerates of up to 55... 

Itatani, K., Akiyama, K., Aizawa, M., Scott Howell, F., Okada, I. Sinterability of apatite-zirconia composite powder prepared by ultrasonic spray freeze-drying technique. J. Soc. Inorg. Mater. Jpn. 286,194-202, 2000... 

Spray pyrolysis is a method that can be used to obtain a powder with particle size distribution that is narrow and controllable from micrometer to sub-micrometer order [62]. The size of the particles is reduced to 300 nm by a combinatimi of spray pyrolysis with dry ball milling [63]. To decrease the size of the particles down to 150 nm on average, a wet milling is needed, and performed owing to 45 ml zirconia vial, ethanol being used as a medium [64]. 

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