The process of nitride formation during the combustion of an iron-silicon alloy in gaseous nitrogen has been investigated. It was found that the synthesis of silicon nitride occurs at temperatures (2100 ° C), significantly higher than the temperature of the appearance of the liquid phase (1206 ° C). In the process of synthesis, silicon is in a liquid state in the form of an iron-silicon melt and in a gaseous state. Electron microscopic studies have shown that the growth of silicon nitride crystals is carried out by two mechanisms: vapor - liquid - crystal and crystallization from iron-silicon melt. The ratio of the contributions of these mechanisms to the structure formation process of silicon nitride is determined by the synthesis conditions. Il. 4, bibliography: 8 titles.
It has been shown that when molding ceramics by hot casting, volumetric changes in the slip in the hard-plastic state, amounting to 85% of total shrinkage, can be compensated for by plastic deformation of the casting. In this case, the completeness of the compensation for volumetric changes in the slip will be determined by the pressure gradient created in the casting during its solidification. Tab. 1, ill. 1, bibliography: 3 titles.
An unconventional method for determining the color of clay and ceramic materials in an air-dry and fired state in the coordinates of an equal-contrast color space using color characteristics (saturation, hue, yellowness, lightness, color coordinate) was used to classify clays of the Gzhel deposit and is recommended for adjusting the color gamut of ceramic products ... Tab. 1, ill. 1, bibliography: 2 titles.
A model of polarization of a water molecule fixed on the surface of a solid by oxygen and hydrogen ions is considered. With an increase in the dielectric constant, the overlap voltage of solid dielectrics decreases. When designing insulators, one should take into account the nature of surface contamination (alkaline or acidic) in the places of use. Il. 2, bibliography: 6 titles.
Possible mechanisms of plasticity and fracture of nanoceramic materials based on ZrO 2 and Y 2 O 3 and their mixtures are considered. It was found that the most probable source of plastic strain transfer in nanocrystalline ceramics are macrodislocations - linear defects of the translational symmetry of the macrolattice, the nodes of which are nanograins. For a continuous description of the mechanical properties of macrolattices, it is correct to use the models of the theory of dislocations and fracture. In particular, on this basis it is possible to describe the mechanisms of plastic deformation and fracture of nanoceramic materials. The most probable reasons for the low plasticity margin of nanoceramics are the high inhomogeneity of the nanostructure and significant pore sizes after sintering. The most probable mechanism of destruction is the growth of large pores, induced by the emergence of a significant number of macrodislocations on their surface. Il. 3, bibliography: 36 titles.
The results of a study of colored glaze coatings containing coloring oxides (Cr 2 O 3 , CuO, CoO, Mn 2 O 3 ), introduced into the charge both when cooking colored frits and when grinding a frit of a transparent glaze. The effect of these oxides on the LTEC, microhardness of glazed glasses and migration of boron, aluminum, chromium, copper, cobalt, and manganese ions from coatings into a 4% solution of acetic acid has been established. The relationship between changes in the structure of colored glassy coatings and the migration of harmful substances from them has been determined. Tab. 1, ill. 1, bibliography: 8 titles.
A computational and experimental study of the technological process of mouthpiece pressing of large-sized porcelain covers has been carried out. Mathematical modeling of the process of pressing cylindrical tubular billets from an alumina mass, which is presented as a non-Newtonian fluid, performing a laminar flow through the forming channel of a vacuum press, has been carried out. Recommendations are given on the choice of a rational configuration of the forming system of a vacuum press for the production of a cylindrical tubular semi-finished product. Il. 3, bibliography: 6 titles.
By introducing a eutectic additive of the CaO - ZnO - Al 2 O 3
- SiO 2 system and tetragonal zirconia into the alumina synthesized by calcining the hydroxide, dispersion-hardened material with an average bending strength of 580 - 40 MPa, promising as a structural one. The sintering temperature of such ceramics is 1550 ° C. The properties of the eutectics of this system have been analyzed, the optimal composition of the liquid phase has been established, which promotes intensive sintering of aluminum oxide. Tab. 3, bibliography: 5 titles.
We investigated samples of lanthanum lithium titanate with the general formula La 2/3-x Li 3x TiO 3 , which have different vacancy content, which varies with the ratio of lanthanum to lithium. The synthesis procedure, neutron diffraction data of the obtained samples, the results of measurements of the lithium-ion conductivity of equilibrium and quenched samples, nuclear magnetic resonance on 7 Li nuclei, dynamic characteristics of heat release (heat absorption) and magnetic susceptibility of some samples are presented. Tab. 1, ill. 6, bibliography: 4 titles.
The use of the method for determining the compaction coefficient and the distance between particles for industrial ceramic slips is shown. High values ??of the compaction coefficient result in increased viscosity and rate of structure formation. The application of the method for determining the physical parameters of the slip mass according to the granulometric composition data makes it possible to evaluate the filtration properties of the slip mass during the casting of sanitary ware. Tab. 1, ill. 1, bibliography: 3 titles.
