Ceramic suspensions alumina

Commercial native tapioca and com starches from Thailand (Tesco) were purchased and used as received. Alumina powder (99.5% purity, Amarin, Thailand), wherein the particle size distribution is shown in Figure 1, was used as the ceramic raw material. Ceramic suspensions were prepared to different % solid loadings with sodium silicate (Amarin, Thailand) as a dispersant, having a fixed concentration of 3 wt.% on a dry alumina basis. The wt.% starch powders were added in different quantities 5 wt.%, 10 wt. %, 15 wt.% and 20 wt.% on a dry alumina basis, which corresponded to 69%, 66%, 63% and 60% solid loadings, respectively. Homogenization was carried out by ball... 

Khan AU, Mahmood N, Luckham PF (2012) Rheological characterization of alumina ceramic suspensions in presence of a dispersant and a binder. J Dispersion Sci Technol 33 1210-1217... 

A ceramic block such as alumina is generally used because of its chemical inertness and the orifice is bored or drilled to precise dimensions. The block is placed so that two (2) chambers result. Then if a DC voltage is applied across the electrodes, a current will flow onty through the orifice, and an effective resistance arises which depends upon the voltage applied and the size (volume of the conducting solution) of the orifice. Particles are added to one side of the two chambers created by the ceramic block, and the suspension is pumped through to the other side. There will be an electrical pulse as each particle passes through the orifice. 

Hidber et al. [9] described the colloidal processing of wet-milled a-alumina suspensions by centrifugal casting from a 80 wt-% suspension at pH 4.3. The mean particle diameter of the a-alumina powder was 0.3 pm and the BET surface area 8.59 m /g. Nitric acid or ammonia was used for electrostatic stabilisation. Very dense ceramics could be obtained with relative densities up to 99.9%. 

Steinlage et al. [25] indeed used electrosteric stabilisation with APMA for a-alumina suspensions to prepare dense tube- and gear-shaped ceramic components by centrifugal slipcasting. The aqueous suspensions contained 20-33 vol-% solids and 8 vol-% APMA and were brought at pH 9.5 with NH4OH after which the slurries were treated with ultrasound. 

J. Cesarano III, I.A. Aksay and A. Bleier, Stability of Aqueous a-Alumina Suspensions with Poly(methaciylic acid) Polyelectrolyte , J. Am. Ceram. Soc., 71 [4] 250-55 (1988). 

Yang, Y.-P. and Sigmund, W., Effect of particle volume fraction on the gelation behavior of the temperature induced forming (TIE) aqueous alumina suspensions, J. Am. Ceram. Soc., 84, 2138, 2001. 

Van Houten [33] has shown that the maximum packing fraction obtained from the rheology of concentrated alumina suspensions is predictive for the maximum wet packing fraction that can be obtained in colloidal ceramic processing. 

Fig. 6.22. Volume fraction versus compressive yield stress of a flocculated polydisperse alumina suspension in decalin with various magnitudes of the attractive particle interaction energy. (From Bergstrom et al., /. Am. Ceram. Soc., 75 (1992) 3305.)...

A. P. Philipse, B.C. Bonekamp and H.J. Veringa, Colloidal filtration and (simultaneous) sedimentation of alumina and silica suspensions Influence of aggregates. /. Am. Ceram. Soc., 73 (1990) 2720-2727. 

Hidber, P, Graule, T., and Gauckler, L., Interactions of dispersants and binders with a-alumina in aqueous suspensions, Ceram. Trans., 54, 23, 1995. 

Hruschka, M.K.M. et al.. Processing of P-silicon nitride from water-hased a-silicon nitride, alumina and yttria powder suspensions, J. Am. Ceram. Soc., 82, 2039, 1999. 

Greenwood, R. and Kendall, K., Acoustophoretic studies of aqueous suspensions of alumina and 8 mol% yttria stabilized zhconia powders, J. Eur. Ceram. Soc., 20, 77, 2000. 

Baader, F.H., Graule, T.J., and Gauckler, L.J., Rheology of concentrated aqueous alumina suspensions, in Ceramics Charting the Future, Vincenzini, P., ed., Techna, Faenza, 1995. 

Briscoe, B.J., Khan, A.U., and Luckham, P.E, Optimising the dispersion on an alumina suspension using commercial polyvalent electrolyte dispersants, J. Eur. Ceram. Soc., 18, 2141, 1998. 

Goski. D.G. et al., Effect of kyanite on rheological properties of dense aqueous alumina suspensions, Br. Ceram. Trans., 98, 192, 1999. 

Wang, G. and Nicholson, P.S., Influence of acidity on the stability and rheological properties of ionically stabilized alumina suspensions in ethanol, 7. Am. Ceram. Soc.,i, 1977, 2001. 

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