Porcelain samples were studied by the method of time-resolved luminescence with excitation by a molecular nitrogen laser. In the photoluminescence spectra of hard, soft and bone china, a combination of bands of optically active centers was revealed: intrinsic O * Si and O * Al and impurity centers Mn 2+ , Cr 3+ , Fe 3+ , Dy 3+ , Sm 3+ , as well as molecular [UO 2 ] 2 + . The OAC Fe 3+ band, differing in intensity, was identified in all porcelain samples
The composition of low-shrinkage ceramics based on pyroxenite has been developed. The natural components used in the ceramic mass, including pyroxenite, low-melting clay, and additionally cullet, make it possible to obtain ceramics with the main crystalline phase - augite and to ensure low shrinkage and high strength. Due to its high mechanical strength, the pyroxenite-based ceramic mass can be used for the production of facing and facade tiles.
Optical microscopy was used to assess the homogeneity of the structure of porcelain items by the orientation of quartz particles (grains) and the distances between them. The distributions of the number of quartz grains by the maximum vertical and horizontal sizes, as well as the distributions of the minimum vertical and horizontal distances between the grains, which are affected by the different orientation of particles in the material and the uniformity of the volume distribution of particles in the material, have been obtained. Deviations of local distributions from the base ones make it possible to evaluate the homogeneity of the structure of the materials and products under study and to analyze the influence of the molding method on their structural features.
The features of the formation of the structure and properties of ceramic bricks are established depending on the content of calcium carbonates and iron oxides based on clay raw materials of various chemical and mineralogical composition during low-temperature firing. The influence of carbonate and ferruginous impurities on the strength properties is revealed.
The aim of this study is to study the patterns of structure and phase formation of composite ceramics based on aluminum oxide and silicon during SHS in the Al-SiO 2 system. Demonstrated the possibility of obtaining Si in the composition of composite ceramics with a crystal size of up to 500 ?m.
An analysis of the conditions and mechanisms of abrasive destruction (wear) and the principles of synthesis of structural ceramic materials is carried out from the material science standpoint. A logistic flowchart has been created for the development and analysis of physicochemical processes and structural engineering mechanisms in technologies for obtaining abrasive and wear-resistant materials, which, from given level of properties
The possibility of increasing the dielectric characteristics of ceramics by introducing nanosized particles of pyrogenic silicon dioxide (aerosil) into the charge is considered. It is shown that the introduction of this additive at a mass content of 5% leads to an increase in strength characteristics, a decrease in open porosity and water absorption, as well as an improvement in dielectric parameters in the centimeter microwave range.
Materials with a nanosized oxide additive of yttrium aluminum garnet were obtained by the method of liquid-phase sintering. Sintering of materials based on SiC and Si 3 N 4 was carried out at temperatures 100 ° C below the sintering of materials with the addition of micron-sized oxide powders. High mechanical properties were obtained: & # 963; bend = 540 MPa, K1C = 5.5 MPa m1 / 2, НV = 20.1 GPa for materials based on SiC and & # 963; out = 650 MPa, K1C = 6.4 MPa m1 / 2, НV = 17.2 GPa for materials based on Si 3 N 4
The results of studies of the rheological characteristics of slurry suspensions based on alumina intended for the manufacture of ceramic filters are presented. It is shown that the replacement of water used as a technological binder in slips with an aqueous solution of carbamide and aluminum oxychloride leads to an improvement in the formability of the workpieces and an increase in the mechanical characteristics of ceramic materials. The ranges of the ratios of the solid (sintered powders) and liquid (technological binder) phases have been determined, at which coagulation and direct contacts are formed in the slips between the particles of the solid phase
The analysis of the existing dependences describing the capillary absorption of liquid in porous materials is carried out on the basis of an ideal model and data of mercury porosimetry. It is shown that when passing from the hydraulic radius of an ideal model to the hydraulic radius of a capillary-porous material, it is necessary to take into account the tortuosity of capillaries and the effect of their narrowing (expansion), the effect of temperature increase associated with the sorption of water vapor, the effect of changing the viscosity of water depending on the hydraulic radius of the capillary. A quantitative assessment of these effects was carried out using experimental data. On this basis, a formula has been proposed for determining the hydraulic radius of the porous structure of ceramic materials for building products
