VOL 98, No. 6 (2025)

Samples of zinc-tellurite glasses, activated by magnetite and barium titanate nanoparticles, were synthesized by melt-quenching method. Functional properties of the glasses were experimentally investigated with X-Ray diffraction method, optical and polarization spectroscopies, and SQUID magnetometry. Results of X-ray diffraction analysis confirm the amorphous structure of the glasses. Based on the optical spectroscopy data, the band gaps of the samples were obtained. The results of investigation of electric and magnetic field dependences of electric polarization and special magnetization indicate the evolutionary development of the loop shape and magnetic hysteresis depending on the composition of glasses due to the interaction of charged ?-Fe2O3 clusters and barium titanate nanoparticles.

The article examines a topic of study of statistical data on the strength of flat glass. The issues of theoretical models of the strength of flat glass, parameters affecting its strength, the probabilistic nature of the destruction of flat glass under operating conditions of glass in building, the selection of the distribution of values of the strength of flat glass, data censorship, determination of the strength characteristics of the strength of flat glass, including the normative bending strength.

Within the framework of a quasi-static unrelated thermoelasticity problem, a criterion for the thermal strength of a freely pinched plate during pulsed laser annealing is obtained, taking into account the reflection of laser radiation from the back surface of the plate. The possibility of reducing the maximum tensile stresses in the plate by 15…65 %, and energy costs for annealing by 8…30 % is shown. It is established that taking into account the reflection of laser radiation from the back surface of the plate leads to a decrease in the region of variation of the dimensionless parameter ?h (the product of the absorption index by the thickness of the plate), in which plate destruction by thermoelastic stresses during annealing is possible.

The work is aimed at developing a method for forming an octacalcium phosphate (OCP, Ca8H2(PO4)6·5H2O) coating on the surface of ?-tricalcium phosphate (TCP, Ca3(PO4)2) ceramics. The coatings were formed by keeping the ceramics in buffer solutions with the main ionic composition of CH3COO– and Na+ with varying conditions (time, pH value and temperature). Crystallization of the OCP coating occurred sequentially by partial dissolution of the surface layers of TCP ceramics and crystallization of the intermediate phase of dicalcium phosphate dihydrate (DCPD, CaHPO4·2H2O). The effect of the buffer solution composition and the process conditions (time, pH value and temperature) on the phase composition, morphology and thickness of the coatings was studied.

The article describes the features of the synthesis of a new oxide pyrochlore Bi2.7Ni0.7Mg0.46Sb2O10+? (sp. gr. Fd-3m, a = 10.4703 ?) containing antimony (V) and bismuth (III) cations from a stoichiometric mixture of oxide precursors using a modified sol-gel method (method Pecini). It is shown that the formation of antimony (III, V) and bismuth (III) compounds that are volatile upon calcination can be prevented by dissolving the precursors in sulfuric or nitric acid solutions, and excluding the use of hydrochloric acid or chloride solutions. A step-by-step synthesis of two samples obtained from sulfuric and nitric acid media was carried out, and the phase composition of the preparations calcined in the temperature range of 350…950 ?C was analyzed. When calcining the sample obtained from the sulfuric acid solution, the Bi12.67O14(SO4)5 phase was revealed, which prevents the formation of pyrochlore in the low-temperature region. In the sample synthesized from the nitric acid solution, bismuth stibates Bi3SbO7, BiNbO4 are recorded as intermediate phases Sb2O4, Bi12MgO19, Bi7.47Ni0.53O11.73, Bi3Ni2/3Sb5/3O11, NiSb2O6 were identified as other intermediate phases in the samples. The synthesis temperature of single-phase Bi2.7Ni0.7Mg0.46Sb2O10+? with the pyrochlore structure is 950 ?С. The phase purity and chemical composition of the sample were established by X-ray phase analysis and energy-dispersive X-ray analysis.

Materials based on silicon carbide (SiC) and the SiC–20B4C–1C–0.5B system were produced using spark plasma sintering. The properties of powder mixtures and finished products were studied using thermal analysis, electron microscopy, X-ray diffraction analysis, and flexural testing. Thermal analysis showed that SiC powders with B and C additives had an accelerated mass loss, indicating their ability to sinter more effectively and form a grain boundary phase consisting of boron-carbon compounds. The addition of boron carbide led to the formation of an additional hardening phase in SiC. The main phase in the material was 6H-SiC polytype with a hexagonal alpha-SiC structure. Mechanical testing of the SiC-20B4C-1C-0.5B composite material revealed that its bending strength at RT reached 332 MPa. The study was not completed.

The possibility of using pyrolysis products of oil-containing waste, including oil sludge, in the synthesis of porous ceramics is shown. High carbon content in pyrolysis products of oil sludge determines the expediency of their application as a burnout component for partial replacement of raw material in the production of aluminosilicate ceramics. The presence of metal oxides of natural and anthropogenic origin in pyrolysis products of oil sludge contributes to the reduction of firing temperature in comparison with clay samples without additives from 1150 to 1080 ?С. It is advisable to introduce pyrolysis products of oil-containing waste in the raw material mixture in the amount of up to 20 %.

The work is devoted to the issues of obtaining thermal insulation materials using local mineral resources. The focus of this study is to create refractory thermal insulation consisting of a porous filler in the form of expanded rocks (hydrophlogopite, perlite) using the technology of ceramic or ceramic-chemical binders based on clay raw materials of varying fire resistance and plasticity. The study of structural changes in the obtained materials understep by step raised temperature conditions was carried out using X-ray phase and microprobe analysis. Analysis of the results showed that the density of hydrophlogopite-based samples on a clay-phosphate binder increases by 30…35 % compared to samples on a ceramic binder. In samples with perlite filler, the introduction of a phosphate binder does not have a significant effect on the apparent density. Pre-synthesized clay phosphate binder on red-burning clay, introduced into the initial perlite mixtures, allows increasing the strength of samples by 2 times without increasing density and thermal conductivity. A study of changes in the strength characteristics of perlite ceramic samples on various phosphate binders in the temperature range of 300…950 ?С showed the stability of the material in strength up to 800 ?С, which indirectly characterizes the transformation of the structure and its operating temperature. Based on the compositions “expanded hydrophlogopite-secondary Samarkand kaolin” and “expanded perlite-secondary Samarkand kaolin-clay phosphate binder on red-burning clay”, thermal insulation materials with improved thermomechanical properties for operating temperatures of 850…1100 ?С were obtained by the method of semi-dry pressing.