Ceramic suspensions silica

Hollow and porous polymer capsules of micrometer size have been fabricated by using emulsion polymerization or through interfacial polymerization strategies [79,83-84, 88-90], Micron-size, hollow cross-linked polymer capsules were prepared by suspension polymerization of emulsion droplets with polystyrene dissolved in an aqueous solution of poly(vinyl alcohol) [88], while latex capsules with a multihollow structure were processed by seeded emulsion polymerization [89], Ceramic hollow capsules have also been prepared by emulsion/phase-separation procedures [14,91-96] For example, hollow silica capsules with diameters of 1-100 micrometers were obtained by interfacial reactions conducted in oil/water emulsions [91],... 

Controlling the stability of suspended particles, and the filtration characteristics of cast suspensions, are very important in the ceramics industry. Here the casting suspensions may comprise clays, silica, oxides, carbides or nitrides [357,793], In slip casting, a suspension is pored into a porous mould and allowed to stand. Water dif-... 

Different methods are used to prepare water-ceramic binding suspensions, depending on initial reagents. Wet grinding (followed by stabilization) is optimal for silica and aluminosilicate materials, while dry grinding and addition them into the suspension are sufficient for magnesia compositions. 

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. 

Yasrebi, M. et al.. Role of particle dissolution in the stability of binary yttria-silica colloidal suspensions, 7. Am. Ceram. Soc., 79, 1223, 1996. 

Zeolite BEA(75) coatings can be deposited on a ceramic cordierite (2AI2O3 5Si02 2MgO) monolithic substrate. The coating is performed with a suspension of zeolite, with silica as the binder, and a surfactant in water. The mixture is well stirred the cordierite monolith is dipped into the mixture and dried at 200°C, and finally is calcined at 400°C for 4 h. ... 

Guo JJ, Lewis JA (1999) Aggregation effects on the compressive flow properties and drying behavior of colloidal silica suspensions. J Am Ceram Soc 82 2345-2358... 

If we want to create a colloidally stable system, some type of interparticle repulsion needs to be introduced to overcome the van der Waals attraction. In a stable system, the maximum attractive interparticle energy should be less than 1 -2 kT to allow thermal motion to readily break all particle-particle bonds. Since the magnitude and range of the attractive van der Waals interaction scales with the effective Hamaker constant, a relatively long-range repulsion is needed to stabilize suspensions of ceramic powders such as alumina and silicon carbide silica, however, is stabilized by a very short-range repulsion. 

These catalytic converters contain a high surface area, a honeycombed ceramic or stainless steel core that is coated with silica and alumina, called a washcoat. Precious metal catalysts, such as platinum, palladium, and rhodium, are added as a suspension to the washcoat. As the hot gases pass through the catalytic converter, they are converted by the catalysts to the reduced or oxidized products. 

Figure 4.6 Adsorption isotherm obtained from suspensions prepared with 20 vol% silica and varying concentrations of poly(vinyl alcohol). (Reprinted from Ref. 19 with kind permission from The American Ceramic Society Inc., Westerville. Ohio, USA.)...

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