Glass and Ceramics最新文献

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.

The process of manufacturing CeO₂ powders by the method of reverse deposition is investigated. The CeO₂ content in the resulting products reached 99.2 wt.%. The main phase was cerium dioxide with a cubic lattice. The average particle size of the powder was about 42 μm, and the specific surface area was about 38.6 m²/g. Heating of the material from 50 to 1200°C leads to a mass loss of 18%. This mass loss is accompanied by endothermic effects with peaks on the DTA curve at temperatures of 144, 280, and 374°C. Further research directions include optimization of the properties of the obtained material, in particular its morphology, and determination of prospective application areas.

This paper investigates the possibility of heat treatment of phosphogypsum, a waste product of the chemical industry. Partial dehydration of dihydrous calcium sulfate occurs when phosphogypsum is dried, and complete dehydration occurs when it is calcined at temperatures of 600 – 1200°C. The samples were found to actively absorb water after heat treatment below 800°C. During the heat treatment of phosphogypsum in the presence of a reducing agent, two endothermic effects related to the sequential dehydration of CaSO₄· 2H₂O were observed, as well as a broad peak of exothermic effect due to the heat degradation of the reducing agent and the formation of calcium sulfide from phosphogypsum. Heat-treated phosphogypsum samples in the presence of the reducing agent acquire the ability to emit yellow-orange luminescence under the action of ultraviolet radiation. Synthesized pigments can be used to produce water-based paints and varnishes.

The processes of thermal compaction of nanoporous glass surfaces using carbon dioxide laser radiation have been investigated. Successful formation of a thermally compacted layer with a thickness of (20 ± 1) μm was demonstrated under the following thermal compaction regime: average radiation power 10.5 W, defocusing ∆f = 16 mm of an F-theta lens with a focal length of 157 mm, scan speed 40 mm/sec, and track spacing 100 μm. It was shown that birefringent structures can be recorded through the thermally compacted layer using femtosecond pulses, with the magnitude of their phase shift serving as an indirect indicator of glass porosity.

The study presents the results of the investigation of the properties (solubility, anti-scaling, anti-corrosion, algicidal, and bactericidal) of a glassy copper-containing phosphate compounds (Cu–Zn phosphate, Cu–Zn–PC). These compounds are obtained using a zero-waste ecological technology for the purpose of corrective treatment of feed water in central heating systems. The study identifies a synergistic effect resulting from the combined presence of long-chain phosphates and alternating copper and zinc cations in the composition. This effect strengthens and evenly distributes the protective film on the surface of the system components, providing maximum effectiveness in combating scale, corrosion, and biofouling.

The chemical-mineralogical composition and technological properties of the ceramic production wastes of Kulol JSC, used as a component of the raw mix for the production of Portland cement clinker, have been extensively studied. It was found that full or partial replacement of natural clayey raw material (loess) by ceramic production wastes during firing increases the reactivity of the raw mixes, accelerates the process of CaO absorption and promotes the completion of the mineral formation process with good clinker granulation at a relatively low temperature stage — below 1450°C. Portland cement produced from synthesized clinker is classified as additive-free Portland cement CEM I according to GOST 31108–2020.