Glass and Ceramics最新文献

This study examines the production of thermal insulation materials using mineral raw materials sourced locally in Uzbekistan. Refractory, comprising a porous filler in the form of expanded rocks such as hydrobiotite and perlite, was developed by employing ceramic or ceramic-chemical binders based on clay raw materials characterized by varying refractoriness and plasticity. The structural transformations of the materials at elevated temperatures were analyzed using x-ray diffraction and electron microprobe analysis. The density of samples based on hydrobiotite and a clay-phosphate binder increased by 30 – 35% compared to samples based on a ceramic binder. In samples containing perlite filler, the introduction of a phosphate binder had no significant effect on apparent density. The incorporation of a pre-synthesized clay-phosphate binder based on red-firing clay into the initial perlite mixture resulted in a two-fold increase in strength without increasing density or thermal conductivity of the material. The testing of strength characteristics in perlite–ceramic samples with different phosphate binders over the temperature range of 300 – 950°C revealed strength stability up to 800°C, which indirectly reflects the structural transformation and operational temperature range of the material. Thermal insulation materials with enhanced thermal and mechanical properties were fabricated by semi-dry pressing using the following compositions: expanded hydrobiotite – secondary Samarkand kaolin and expanded perlite – secondary Samarkand kaolin – clay-phosphate binder based on red-firing clay. These materials are suitable for use at operating temperatures of 850 – 1100°C.

The paper presents the results of studying the properties of polycrystalline powders and films of CsCu₂Br₃ and CsCu₂I₃ compounds obtained by vacuum thermal evaporation. X-ray phase analysis confirmed the formation of single-phase films which showed good agreement with the initial compositions. The microstructure of the films was studied by scanning electron microscopy. The CsCu₂I₃ and CsCu₂Br₃ films were found to comprise rounded crystals ranging in size from tens nanometers to 200 nm. The obtained results confirm the potential of applying vacuum thermal evaporation for depositing CsCu₂Br₃ and CsCu₂I₃ films for application in the field of optoelectronics. However, in order to obtain thicker and more continuous films, a sufficiently long duration of the sputtering process must be ensured.

This study demonstrates the potential for using pyrolysis products of oil-containing waste, including oil sludges, in the synthesis of porous ceramics. The high carbon content in oil sludge pyrolysis products determines their suitability for use as a burnout additive with the potential to partially replace the green body in the production of aluminosilicate ceramics. The presence of both naturally occurring and industrial metal oxides in the pyrolysis products contributes to a reduction in firing temperature from 1150°C to 1080°C, compared with clay-based ceramics without additives. It is recommended that the pyrolysis products of oil-containing waste be introduced into the raw material composition in amounts of up to 20 wt.%.

In this work, we present a technology for plasma synthesis of a ceramic pigment based on vanadium waste. The chemical and phase composition of the pigment is studied. The effect of the waste-based pigment on the aesthetic and consumer properties of wall ceramics is studied. The CIE L^*a^*b^* system is used to determine the color characteristics of wall ceramics.

This paper explores the possibility of producing high-quality fireclay crucibles for assaying ores from the most high-grade local raw materials of Uzbekistan, kaolin of AKF-78 grade and fireclay obtained from this grade of kaolin. In order to increase physical and technical properties of fireclay crucibles, the masses were supplemented with pre-fired waste catalyst of Shurtan Gas Chemical Complex with 90.22% of Al₂O₃. The optimum mass with the 8% of alumina-containing waste withstands more than 11 – 13 melts without corroding, and the heat resistance of the samples increases up to eight heat cycles. Meanwhile, the amount of mullite formed after firing at 1420°C increases significantly. The development is aimed at utilizing local materials and recycling industrial waste, which is in line with the goals of sustainable development through waste reduction and efficient utilization of mineral resources.

This paper presents the results of developing a direct-on enamel frit that exhibits increased chemical resistance against acid and alkali environments, intended for protection of steel pipelines. Zinc oxide was introduced into the frit composition, which improved the resistance of the material due to the higher energy of the metal ion–oxygen chemical bond compared to alkali metal ions. At the same time, the addition of ZnO in the amount of 10 wt.% reduces the flow temperature of the frit. The developed frit composition meets the standard requirements in terms of spreading capacity (45 mm) and thermal coefficient of linear expansion (112 × 10 ^–7K^–1 ). The introduction of zinc oxide in industrial borosilicate enamel in the amount of 5 wt.% leads to an increase in its chemical resistance against acids and alkalis by 4 and 8 times, respectively, compared to conventional industrial frit.

The processes for deposition of selective vanadium-containing layers on the external surface of α-Al₂O₃ based tubular ceramic membranes, for use in the petrochemical industry, were investigated. The V₂O₅ · 1.6H₂O layer deposited on the outer surface of the ceramic membrane was obtained by the sol-gel method. The temperature of thermal treatment was varied from 400 to 700°C. The chemical stability of membranes in an aqueous environment with the applied layer subjected to thermal treatment at 650°C was investigated. The chemical stability of the membranes with the V₂O₅ layer applied was found to be within the pH range of 5 to 8. The optimum temperature for thermal treatment to obtain a layer with high adhesion to the substrate was determined to be 650°C.

This study explores the basic principles of cement stone structure formation and examines the correlation between the properties of concrete mixtures with different fillers and those of materials produced by hyperpressing. An effective technology for the production of construction materials using local resources, including non-standard raw materials and industrial byproducts, has been developed. This development is significant in both environmental and economic terms. The experimental phase focused on the application of semi-dry pressing and hyperpressing techniques to improve the operational properties of concrete mixtures. During the pressing process, especially under hyperpressing conditions (pressure greater than 40 MPa), intense interparticle interactions are expected to form macrostructures that contribute to a more robust cement stone structure. The involvement of van der Waals forces and valence bonds between filler particles and hydrated clinker minerals, as well as molecular interactions, is considered to be the central mechanism promoting the increase in strength and stability of the material. An important aspect is the use of low plasticity clays and overburden rocks, as well as industrial waste, which allows a significant reduction in production costs and improves environmental sustainability. Hyperpressing technology has been shown to shorten production cycles, reduce energy consumption per unit of output, and improve economic efficiency. These attributes make the technology highly promising for the production of environmentally friendly building materials. This research facilitates the development of novel approaches for incorporating secondary and indigenous materials into construction. New ways to improve the efficiency and sustainability of building material manufacturing processes are presented.

Glass-ceramic composites based on low-alkali aluminoborosilicate glass and barium titanate mixed in various proportions were successfully synthesized using the sintering method in the vicinity of the softening point of the glass used. The electrical properties of the samples were investigated in the microwave range. According to XRD analysis, the synthesized materials are a mixture of barium titanate and an amorphous phase, as well as, under certain heat treatment conditions, products of glass crystallization (SiO₂ – quartz and tridymite) and its interaction with the ferroelectric filler (Ba₂TiSi₂O₈ – fresnoite). The level of dielectric permittivity of the studied glass composite samples, measured at a frequency of 1 GHz, ranged from 9.2 to 25.0 with a dielectric loss tangent of 0.007 – 0.012.

Micro-impurities and defects in glass produced by a two-step method from natural quartz from the Urals have been identified. The study revealed that glass quality is determined by the presence and distribution of mineral and gas-liquid inclusions in natural quartz, as well as the fractional composition of the crushed material. In addition, the conditions of the melting process significantly affect the final product. In particular, almost all trace elements present in the quartz are transferred to the molten glass. Therefore, the trace element composition of the starting quartz is a critical factor in determining its suitability for producing high quality transparent quartz glass.