In the course of the study, the possibility of using ash and slag waste from the thermal power plant of the Arctic zone as raw materials for the production of porous ecogeopolymers was studied. The assessment was carried out according to the established three main criteria: radiation activity, chemical composition of ash and slag, namely, the amount of oxides SiO2, Al2O3, CaO and the modulus of their basicity Mo. The possibility of using ash and slag from the Apatitskaya and Severodvinskaya TPPs of the Arctic zone has been established and the main technological parameters for the synthesis of porous ecogeopolymer materials on their basis have been developed
The method of determining the volume-geometric structure of a corundum slip is refined by additional calculation of the average coordination number, the specific surface of the system S0 (the surface of the unit volume of the slip), and the number of contacts between particles per unit volume of the slip. This will eliminate ambiguity in the presented structural parameters of the slip. The calculated structural parameters of the corundum slip are given
The safe treatment of radionuclide-contaminated soil in uranium tailings is of critical importance. In this work, neodymium- and cerium-contaminated soil in uranium tailings were successfully immobilized via mi-crowave sintering to form glasses with the addition of Na2CO3. The phase evolution and chemical durabil-ity of the as-prepared vitrified forms were systematically investigated using various spectroscopic and microscopic techniques. The results indicated that Nd and Ce could be fixed in glass structures, and the ultimate solid solubility of Nd and Ce reached 15 and 5 wt.%, respectively, with 20 wt.% Na2CO3 added. These samples were sintered at 1200 оС for 40 min, and the solidified samples exhibited homogeneous elemental distribution. Moreover, the sintered matrices exhibited excellent chemical durability. The normalized leaching rates of Ce and Nd after 42 days were maintained at low values (~10–6 – 10–7 gm–2 d–1)
BaTiO3 ceramics are common components of capacitors, sensors, and actuators. Recent research has focused on improving the dielectric properties of BaTiO3 by using Zr ions for B-site substitution. Additional additives can further enhance ceramic performance. In this work, BaZr0.15Ti0.85O3 (BZT) ceramics were prepared by a solid-phase reaction at various contents of added Al ions. All of the ceramic samples had a perovskite cubic phase structure. Compared with BZT ceramics without added Al2O3, the size of the grains increased considerably, and the grain size decreased slightly in accordance with increasing concentration of Al ions. Addition of Al ions considerably increased the density of the ceramics, yet excessive addition of Al ions decreased the density. The dielectric constants were relatively large when the Al ion content was 0.25 and 1.0 mol.%: 9117 and 8725 C2/(Nm2), respectively, at the Curie temperature. Compared with BZT ceramics without Al ions, the dielectric properties were greatly improved, by two different mechanisms (depending on the Al content). In accordance with increasing Al content, the hysteresis loop was narrower, the remanent polarization decreased, and the coercive electric field increased
For silicon carbide, when exposed to high temperatures in an oxygen atmosphere, passive and active oxidation processes are characteristic, therefore, materials based on SiC must be protected at temperatures above 1300 ° C. Sodium sulfate, the presence of which is possible as an impurity in the fuel, leads to the destruction of the protective layer of SiO2 formed during the oxidation of SiC. Coatings based on the Y2O3 – Al2O3 – SiO2 system are promising for protecting materials based on silicon carbide from the effects of an oxidizing
atmosphere and water and salt vapors. Studies have been carried out on the interaction of coatings
of the Y2O3–Al2O3–SiO2 system obtained by the sol-gel method with water vapor and Na2SO4 salt. As a result of the studies carried out, it was found that coatings based on the Y2O3 – Al2O3 – SiO2 system have good
oxidative and chemical resistance to water vapor and Na2SO4 salt vapor in the temperature range
of 1300 – 1450 °C. The weight gain for coated samples when tested in Na2SO4 salt vapor did not exceed 1 %. The initial SiC substrates are characterized by active oxidation processes with a weight decrease
from 8 to 11 %. DSC analysis in combination with mass-spectrometry of the crystallized sample of the
Y2O3–Al2O3–SiO2 system coating after heating in Na2SO4 salt vapor to a temperature of 1550 °С showed
that at temperatures above 900 °С Na2SO4 decomposes with the release of SO2 and SO3–
The article presents the results of the work on obtaining titanium nitride whiskers from the gas phase. Previously, a theoretical assessment was made of the possibility of homogeneous formation of micro-substrates
of various types and composition in the gas phase, the conditions for condensation of the titanium nitride phase and the growth of filamentous crystals. Based on the results of thermodynamic analysis of the analyzed system, calculations of the existing critical supersaturation were carried out and the rates of homogeneous condensation in the gas phase of titanium and titanium nitride were estimated. Thermodynamic calculations of the compositions of the Ti–Cl–H, Ti–Cl–N, Ti–Cl–Ar subsystems determined the design elements
of the laboratory installation and the technological features of the titanium nitride crystal growing process. Samples of titanium nitride whiskers were obtained and examined
The paper studies the bioactivity of hybrid composite materials containing calcium phosphates up to 60 %
by weight and polylactide (PLA) with additives of glycerol and sorbitol, in situ and in vitro. Studies
were carried out in PBS and SBF media, cytotoxicity was determined on the cell culture of Neuro-2a mouse neuroblastoma. The use of a mixture of highly dispersed calcium phosphates as the mineral phase of composites with polylactide provides resorption in the PBS solution of the material with water absorption close
to zero. It was found that at a calcium phosphate content of 40 % or more, apatite-type calcium phosphates are produced on the surface of composites during incubation in SBF. Composites in the studied range
of compositions have a weak cytotoxic effect on the cell culture of Neuro-2a mouse neuroblastoma. The data obtained would suggest dynamic resorption and bioactivity of composites in vivo
A number of refractory heat-insulating ceramic materials were obtained using hollow aluminosilicate fly ash microspheres as a lightweight filler. Thermal insulation products obtained by various methods had density values from 0.5 g/cm3, thermal conductivity of 0.23 – 0.48 W/(mK) and compressive strength of at least
1.5 MPa. Low values of shrinkage of the developed materials in the process of high-temperature processing make it possible to obtain large-sized items of complex shape. The obtained materials can successfully
compete with commercially available refractory heat-insulating materials
The article presents a justification for the production of plate heat-insulating foam silicate materials based on by-products of apatite-nepheline ore processing by low-temperature technology. Methods for improving the performance characteristics of foamed materials by introducing mineral additives are proposed. According to the set of properties, the most effective additives are the tailings of the enrichment of vermiculite ores and diopside. Technical characteristics of the developed foam silicates: density 0.38 – 0.51 g/cm3, strength up to 6 MPa, thermal conductivity 0.09 – 0.107 W/(mK) and relatively low water absorption
