The effect of complex additives on the critical concentration of structure formation of kaolin suspensions has been studied. The most effective at low concentrations is a complex consisting of oxyphenolfurfural oligomer SB-PF and sodium tripolyphosphate, which can be used as a thinning additive for kaolin suspensions. Il. 2, bibliography: 4 titles.
The features of sintering oxide powders with different dispersion are considered. Powders with nanoscale particles are sintered according to the mechanism of diffusion-viscous flow. This makes it possible to obtain dense and durable materials in different environments. Tab. 4, bibliography: 4 titles.
The effect of fluorine-containing additives (ammonium fluoride and topaz concentrate) on the phase composition of the combustion products of ferrosilicon in nitrogen and the morphology of particles of the resulting silicon nitride is investigated. It is shown that the introduction of topaz concentrate into ferrosilicon in an amount of 0.5% transforms the self-oscillating combustion mode, characteristic of nitriding ferrosilicon without additives, into a layer-by-layer one. It was found that in the presence of ammonium fluoride, a high-temperature & # 946; -modification of silicon nitride & # 946; -Si 3 N 4 is formed, and in the presence of topaz concentrate, a solid solution on based on & # 946; -Si 3 N 4 type SiAlON. Tab. 1, ill. 3, bibliography: 7 titles.
The influence of the degree of aggregation of powders, properties of aggregates (size, strength, porosity) on the degree of sintering and characteristics of the microstructure of the manufactured ceramics is shown. The conditions for obtaining powders with a low degree of aggregation, as well as methods of powder disaggregation, are considered. Requirements for powders that provide the same pore size in compacts and a uniform degree of sintering throughout the volume of products are formulated. Tab. 2, ill. 2, bibliography: 9 titles.
Polycrystalline samples of zirconia stabilized with 10% Y 2 O 3 (molar content) with additions of Li 2 O up to 3% were synthesized by the solid-phase method. It was found that the conductivity of the samples significantly increases with the introduction of Li 2 O and reaches a maximum at an additive content of 1.7%. The activation energy of conduction decreases from 0.85 eV in samples without additions of Li 2 O to 0.56 eV in samples containing 1.7% Li 2 O. It is assumed that lithium ions in the lattice of cubic ZrO 2 form two types of defects: substitutional defects - Li Zr 3- and interstitial defects - Li i + . The latter significantly increase the electrical conductivity of the samples. Il. 3, bibliography: 14 titles.
The main regularities of the color formation of porcelain containing neodymium oxide, which has the ability to change color depending on the light source using absorption and reflection spectra, have been studied. In the metric system CIE 1976, the optimal content of neodymium oxide in porcelain was determined, the dependence of the color of products on the firing environment and the light source was established. Tab. 3, ill. 6, bibliography: 9 titles.
The influence of modifying additives on the sintering process, control of the microstructure and properties of ceramics is shown. The types of additives with different character of interaction with the crystal lattice of the basic oxide during sintering are considered. The most effective additives that significantly affect the sintering process and the formation of the microstructure are oxides that form solid solutions. Tab. 1, bibliography: 11 titles.
The effect of ultrasonic treatment on the rheological behavior of dispersed oxide - thermoplastic bond systems has been studied. The possibility of regulating the characteristics of thermoplastic slips by changing the duration of ultrasonic treatment is shown. Tab. 2, ill. 2, bibliography: 4 titles.
The process of nitriding of commercial FS 65 alloy in the mode of self-propagating high-temperature synthesis has been studied. The influence of the phase composition of the initial alloy on the combustion process has been established. The dependence of the degree of nitriding of combustion products on nitrogen pressure, sample diameter, and dilution of the initial charge with inert and activating additives has been studied. Silicon nitride with a residual iron content of 0.07% was obtained by acid enrichment. Il. 6, bibliography: 3 titles.
The properties of optically transparent ceramic materials based on yttrium oxide and yttrium-aluminum garnet are analyzed. It has been shown that it is promising to manufacture transparent ceramics combining both of these compounds. Methods for the synthesis of yttrium oxide and yttrium-aluminum garnet are considered. The choice of the synthesis method is substantiated. The possibility of creating such materials without introducing modifying additives has been confirmed. Bibliography: 17 titles.
