Gulnara A. Ulyeva

Microsilica recovered from silicon-production off-gases offers a secondary feedstock for silica-based ceramics. This study evaluates its consolidation by spark plasma sintering (SPS), with purchased commercial nanosilica serving as a reference. Both feedstocks were processed at a monitored die temperature of 1300 °C, 50 MPa, and a 10 min hold. Characterization combined powder microscopy, qualitative X-ray diffraction, hydrostatic weighing, ultrasonic contact impedance (UCI), and axial compression. Mean hydrostatic densities were 2.246 ± 0.007 and 2.254 ± 0.007 g·cm⁻³ for microsilica and nanosilica, respectively. Mean maximum nominal stresses were 208 ± 13 and 188 ± 6 MPa for Ø14 × 2 mm disks; values are mean ± sample standard deviation (n = 3 per feedstock). The microsilica specimens exhibited a 10.3% higher mean maximum nominal stress under this loading configuration and higher comparative UCI indications. Both cooled ceramics showed reflections consistent with α-cristobalite. The study extends earlier waste-processing work through a comparison with commercial nanosilica that relates powder characteristics and phase identity to replicate property measurements under a common SPS schedule. The results demonstrate the material feasibility of consolidating microsilica waste into coherent ceramic bodies and support further development of this utilization route.

This article investigates the synthesis of silicon carbide through the efficient processing of microsilica, a technogenic waste by-product of silicon production at «Tau-Ken Temir» LLP. High-purity microsilica and P804T-grade carbon were utilized as the starting components. The powder mixture was blended in a WiseMix BML-2 planetary mill at 200 rpm for 24 hours, followed by processing in a «Labox 650, Sinter Land» spark plasma sintering system. Sintering was conducted at a temperature of 1800 °C, a pressure of 50 MPa, and a holding time of 10 minutes. Thermodynamic analysis, performed using the Thermo-Calc software package, demonstrated that 1800 °C is the optimal temperature for silicon carbide formation in the Si-C-O system. Furthermore, the results confirm that the selected technological parameters intensify reaction kinetics and ensure complete phase transformations. The study revealed that the resulting material possesses high density (3.22 g/cm³), hardness (286 HB), and a homogeneous nanostructure. According to X-ray diffraction (XRD) analysis, the predominant phase is β-SiC (98.2 %). Microstructural studies showed that the average particle size is 108.4 nm, and the material is characterized by a dense, virtually defect-free structure without pores. The absence of electrical conductivity (<0.5 MS/m) indicates high material purity. These results demonstrate the effectiveness of the spark plasma sintering method for converting metallurgical waste into high-value-added materials, while also confirming the potential of this technology for energy conservation and environmental optimization of production. Keywords: silicon carbide, microsilica, spark plasma sintering, carbothermic reduction, metallurgical waste, nanostructured material.

The article is devoted to the study of the properties of the obtained heat-insulating refractory materials, based on fireclay scrap of various fractions (2.5 mm, 1.0 mm, 0.5 mm, and 0.1 mm) using a complex of mineral and oxide additives. The fillers used were titanium dioxide powder and silicon production wastes, which included microsilica powder, aluminum oxide, zinc oxide, zirconium oxide, chromium oxide, iron oxide, cement, lime, and baking soda. The choice of these fillers was due to the fact that they initially have corrosion resistance. Liquid glass acted as a binder. The resulting thermal barrier material was tested to determine its physical and mechanical properties, namely, thermal conductivity, porosity, compressive strength, and microstructure. According to the obtained results for the physical and mechanical properties, the secondary refractory material had properties close to GOST. So, according to GOST 12170-2021, the thermal conductivity values of the obtained materials were included in the 0.03–15.0 W/(m·K) range. The porosity values of the obtained samples complied with GOST 2409-2014 and were not more than 30%. The maximum compressive strength was 171.31 kgf/mm². The microstructure of the material of the obtained samples was very porous, and the pores were evenly distributed throughout the volume, which is extremely important for heat-insulating materials. A distinctive feature of the technology was the absence of a high-temperature firing stage: the required physical and mechanical properties of the material were achieved when heated to 180–300 °C with subsequent slow cooling in the furnace, which significantly reduces energy consumption compared to traditional refractory technologies. The use of waste from the production of chamotte scrap and microsilica will help to reduce negative impacts on the environment, save natural resources, and expand the raw material base.

This study investigates the effect of complex nanomodification combined with the simultaneous application of magnetic fields and mechanical vibration on the structure formation and performance properties of medium-alloy steel 40CrNi3MoV. Improving the structural homogeneity and operational characteristics of such steels remains an important task due to their widespread use in components operating under severe loading and wear conditions. The introduction of the nanostructured modifier InSteel-7 at a concentration of 0.03%, together with simultaneous magnetic and vibrational treatment of the melt, resulted in pronounced structural homogenization and grain refinement. Quantitative metallographic analysis using Thixomet Pro image analyzer revealed a significant refinement of the dendritic structure, with the secondary dendrite arm spacing decreasing from 73.9 μm to 27.9 μm. X-ray phase analysis confirmed the preservation of phase composition while indicating increased structural uniformity of the BCC matrix. Energy-dispersive spectroscopy and elemental micro-mapping demonstrated high chemical purity of the alloy and a uniform distribution of the modifier components. The combined treatment significantly improved the mechanical and tribological characteristics of the material. The average hardness increased from 390 HV to 510 HV, while tribological tests showed a reduction in wear track depth from 5.16 μm to 0.87 μm and a decrease in surface roughness from Ra 2.13 μm to 0.20 μm, indicating enhanced wear resistance.

For many countries the problem of industrial and household waste disposal is particularly acute, since the annual accumulation of all types of waste is quite large (about 7 billion tons), and their reuse does not exceed 30 %. At the same time, industrial waste has a negative impact on living organisms and the environment. Therefore, ways of recycling household and production wastes are necessary. This article considers the problems of utilization, processing (recycling) of industrial and household waste and the prospects of their application in various industries. The influence of different formulations of initial components (microsilica, blast furnace slag, slaked lime), their fractions on physical and mechanical properties of the obtained new composite materials is considered. The obtained materials were investigated in order to determine the values of compressive strength and percentage of water absorption. Thus, all samples have low water absorption percentage (0 – 13.12 %), except for Sample 7 (41.34 %), consisting of 2 parts of microsilica, 1 part of slag and 1 part of lime. It was found that high values of compressive strength are observed in the samples which include microsilica. Samples 3 and 4, composed of microsilica and slag jointly, have the lowest compressive strength of 14.74 and 17.18 kgf/cm², respectively. However, Sample 8, which is composed of 2 parts of microsilica, slag and lime simultaneously, is characterized by the highest compressive strength value of 51.16 kgf/cm². Microsilica has a greater influence on the increase of strength properties. At the same time, the use of industrial waste in the creation of new secondary materials leads to a reduction in the cost of production, expansion of the raw material base of the country, as well as reducing the environmental load of the region.

The article is devoted to the study of coating for road markings. Because road marking coatings are highly weatherproof, resistant to temperature extremes, moisture resistance, and good anti-corrosion properties, they can be used to protect exposed steel structures, but their main purpose is to apply road markings. When choosing the type of materials for marking, it is important to take into account their technical characteristics. It is very important that the markings are clearly visible at any time of the day. During the day, visibility is affected by the size and brightness of the markup. This work describes a series of laboratory experiments with samples coated with paints and reveals their protective properties in contact with water and acid. The highest quality coverage was also identified. Work in this direction continues. Thus, the authors are currently conducting experiments to develop a polymer coating for the protection of concrete and concrete products.

В данной работе были получены сополимеры, отработана методика их синтеза. Были выбраны различные наполнители для получения полимерного покрытия – микросилика и диоксид титана. Разработана новая рецептура защитного полимерного покрытия на основе сополимеров, обладающих коррозионными свойствами. Приводится возможность использования этих полимерных покрытий в целях защиты от воздействия агрессивных сред неметаллических поверхностей различных изделий. Были определены физико-химические свойства неметаллических образцов (бетонов) с защитным полимерным покрытием, свежеприготовленные и выдержанные в течение трех месяцев, а именно водопоглощение и предел прочности на сжатие. Так, у образцов с полимерным покрытием после трехмесячной выдержки выше предел прочности на сжатие составляет 93,3 кгс/см2, у свежеприготовленных – 53,0 кгс/см2. Такая же картина наблюдается у выдержанных и свежеприготовленных образцов после водопоглощения (75,2 кгс/см2 против 24,0 кгс/см2, соответственно). Процент водопоглощения у выдержанных образцов составляет 0,0–11,63, кроме образца с комбинированным полимерным покрытием серии 1 (водопоглощение составляет 23,28 %). Процент водопоглощения свежеприготовленных образцов составляет 4,8–15,1, что находится в хороших пределах. При этом образцы с полимерным покрытием и наполнителем микросилика (серия 3) и комбинированным полимерным покрытием серии 3 обладают минимальным водопоглощением (4,8 %). Ключевые слова: синтез сополимеров, сополимер, полимер, полимерное покрытие, защитное покрытие, бетоны, наполнитель, диоксид титана.

Сopolymers and the methodology for their synthesis are presented. In order to protect metal products and structures from the effects of corrosion processes, various fillers for polymer coating were selected: silicon production waste (microsilica) and titanium dioxide, as well as their combined mixtures. The obtained copolymers exhibit good adhesion required for composite protective coatings. An experiment was conducted to evaluate the corrosion resistance of metals subjected to aggressive environment, as well as to determine the hardness and thickness of the obtained polymer coatings. Thus, the corrosion score of the polymer coating with titanium dioxide filler is 2 in 5% NaCl and 5% KOH aggressive media and is 3-4 in acidic media with 10% KOH. Polymer coating with microsilica filler has a corrosion score of 2 in salt and acid aggressive media, but in alkaline media such coating performed worse and has a corrosion score of 4. The best corrosion resistance values are for the series 2 combination polymer coating consisting of methyl methacrylate, styrene and vinyl butyl ether, with a corrosion score of 2 in salt and acid media and a corrosion score of 4 in alkaline media. Series 1, methyl methacrylate, maleic anhydride, and vinyl butyl ether combined coating has the worst corrosion resistance: corrosion score of 4, 5, 6 in 10% H2SO4 and in an alkaline media (5 and 10% KOH), respectively. At the same time, the developed polymer coatings exhibit satisfactory adhesion properties even after the exposure to aggressive media.