Vibration method of making ceramic fiber heat-insulating articles

Physico-chemical studies of Arvaten basalt for the production of mineral fiber

“…To determine the chemical and mineralogical composition of the raw materials used and the main characteristics of prototypes based on it, they studied using chemical and X-ray phase analyzes, as well as the generally accepted calculation of the acidity and viscosity modulus [9][10][11][12][13][14].…”

“…At the same time, the value of the acidity modulus for basalt onecomponent mixtures should be in the range from 2.00 to 2.17 [13,15]. It should be noted that the viscosity modulus of one-component batches for normal fiber drawing, according to the authors of [12,16], should be in the range of 2.2-3.2.…”

Some technological laws and properties for highly porous ceramic concretes

“…The authors of [2] present certain data on the production of specimens of zircon ceramic conc=ete with a total porosity of up to 70%. However, in contrast to dense ceramic concretes, the production method and properties of which have been studied in detail [i, 3, 4], special studies into the highly porous ceramic concretes have not been carried out, although data exist on the effective use of such materials [5].High porous ceramic concretes, compared with other highly porous materials (for example, foamed ceramics [2,6,7]), have some technical advantages (much lower water requirements for the molding system, and a reduction in shrinkage at the drying and firing stages), as well as improved exploitation properties, for example, thermal-shock resistance and volume stabi-This article, using ceramic concretes made of zirconia as an example, examines some general problems in obtaining highly porous ceramic concretes, and studies the effect of some technological factors on the material's properties.The original material consisted of highly dispersed (80% particles measuring not more than 5 ~m, maximum size i0 ~m) zirconia, stabilized with yttrium oxide and obtained by chemical precipitation from salt solutions [8]. The suspension (bond for ceramic concrete) was obtained by suspension in HCl-acidified water with a suspension pH of 2.0-2.5.…”

“…Moreover, while for grains measuring 5-10 mm (optimum size of coarse fraction) the porosity was about 80%, then for grains measuring 0.1-0.4 mm (optimum size of fine fraction) it was reduced to 30-35%. In accordance with this the porosity of the ceramic concrete to a large degree is determined by the volume concentration and coarseness of the filler.As an additional pore-forming additive, which can be removed in heat processing, we studied PPS foam polystyrol [7,[12][13][14] which possessses spherical shaped particles with dimensions from 0.4-0.63 to 1.6 mm. The mean values for the packing coefficient KpackWere 0.50 for large filler and 0.45 for fine and 0.55 for medium (PP8).…”

Porous ceramic concrete based on zirconia as a high-temperature heat-insulant

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The Eastern Institute of Refractories has designed a resistance heater from stabilized zirconium dioxide for use in oxidizing atmospheres at temperatures of up to 2500~ [1][2][3], ana has designed furnaces based on it [4][5][6][7].These furnaces are particularly valuable for firing ceramics, growing single crystals, and forming quartz fiber [8][9][10].Experience with these furnaces has shown that to reduce the inertia and increase the working reliability of the heaters it is extremely important to use linings which possess a range of properties which are, in fact, very difficult to combine: application temperature up to 2500~ high resistance to creep, good thermal-shock resistance, and low thermal conductivity and specific heat.Materials based on magnesium and aluminum oxides are unsuitable for these purposes, so zirconia was used to make high-temperature insulation; this has a high refractoriness and low thermal conductivity.Previously [Ii], it was shown that stabilized zirconia obtained by the combined precipitation of components from aqueous solutions, together with a high homogeneity and sintering activity, possesses cementing properties, which means it can be used for making refractory concretes.The technology involved the use of the principles for obtaining porous ceramic concretes [12,13], foamed ceramic from Zr02 [14], and the use of foamed polystyrene to obtain spherical pores in the ceramic products [15].The technology for producing porous ceramic concrete from zirconia is shown in Fig. i. To produce the filler, the foam briquets, made of Zr02 by a method described in [16], were ground in a jaw crusher, and the crushed material was screened into fractions of large and fine fillers.

The suspension was prepared from powdered Zr02 stabilized with 15% (weight parts) Y203, obtained by the combined precipitation of components from solutions of chlorides [ii].

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