The technology of manufacturing a lightweight material suitable for operation in an unprotected lining up to a temperature of 1300 - 1350 ° C is considered. The material has an apparent density of 0.35 to 0.70 g / cm 3 and has good thermal insulation and high strength characteristics. Tab. 1, bibliography: 2 titles.
Heat-resistant capsules containing a granular filler with a particle size of up to 130 ?m from silicon carbide were obtained by slip casting in plaster molds. The silicon carbide content was varied from 30 to 55% by weight. Experimental batches of capsules of various shapes, tested in furnaces on gas fuel and fuel oil, had good operational properties, which made it possible to reduce the rejects of fired products. Table 2, ill. 1, bibliography: 3 titles.
The advantages of the joint preliminary grinding of the feedstock in comparison with the separate one and its influence on the regularities of phase formation in the aluminum oxide - titanium oxide system are considered. Co-activation reduces the time spent on thermal synthesis of TiO 2 x Al 2 O 3 . The effect of stabilizing additives of magnesium, silicon and talc oxides on the kinetics of thermal synthesis of aluminum titanate has been studied. As a stabilizing additive that prevents incongruent melting of TiO 2 x Al 2 O 3 with the formation of the initial components, it is proposed to use talc in an amount of 7%. Tab. 1, ill. 4, bibliography: 12 titles.
Calculation expressions are proposed for determining the density of bidisperse powder materials, taking into account the effect of the ratio of the particle sizes of the material. The obtained expressions are recommended for engineering calculations in the preparation of various mixtures. Il. 1, bibliography: 4 titles.
Methods for the preparation of non-porous fine-crystalline oxide ceramics are considered from the standpoint of the chemistry of defects and nonequilibrium. It is shown that it is necessary to reduce the degree of non-equilibrium of the sintering process by reducing mass transfer due to the introduction of additives that form oxygen vacancies, as well as reducing the likelihood of the appearance of local compaction. Bibliography: 9 titles.
The results of studies of the kinetics of ceramics compaction during sintering under isothermal and non-isothermal heating conditions are presented. Kinetic equations of the compaction process are given using the structural-energy parameter as a dependent variable, on the basis of which the values ??of the apparent activation energy for two stages of the compaction process are determined. It is shown that modification transitions, the formation of unstable phases and solid solutions in the process of ceramics firing have a significant effect on the mechanism of its compaction. Tab. 4, ill. 3, bibliography: 8 titles.
Polymorphic transitions in Al 2 O 3 , tungsten bronzes, 2CaO x SiO 2 , ZrO 2 are considered. Since oxides usually have an excess of oxygen vacancies at high temperatures, a further increase in their concentration due to the introduction of appropriate additives slows down diffusion, prevents the polymorphic transition, and stabilizes the phase. The introduction of additives leading to an increase in the concentration of vacancies in the cation, on the contrary, accelerates diffusion and promotes the polymorphic transition. Bibliography: 10 titles.
The chemical composition of the combustion products of mixtures of freely poured powders of industrial zirconium-aluminum alloy (mass content of zirconium 84%) and ultradispersed aluminum powder obtained by electric explosion of conductors in argon has been studied. It was found that, under certain conditions, the final products can contain up to 60% of a mixture of AlN + ZrN. Tab. 2, ill. 1, bibliography: 5 titles.
A porous high-temperature heat-insulating corundum ceramic based on hollow microspheres obtained using plasma has been developed. The ceramic properties, phase composition and microstructure of the obtained material have been investigated. Tab. 1, bibliography: 8 titles.
It is shown that to assess the physicomechanical characteristics of foam and biporous materials, it is necessary to determine the threshold concentration of the conductive component, which depends on the elongation of the solid phase particles and the ratio of its average size to the size of macropores. Calculations of the thermal conductivity of foamed corundum and the strength of foamed gypsum have been carried out. The proposed method makes it possible to take into account the porosity of the matrix phase and obtain results that are in good agreement with the experimental values. The considered approach is recommended for evaluating the conductivity and strength of foams in engineering calculations. Tab. 1, ill. 3, bibliography: 9 titles.
