Glass and Ceramics最新文献

Nanoscale amorphous thin films of the (InSe)₂₀(GaSe)₈₀ and (InSe)₅₀(GaSe)₅₀ compositions were subjected to phase and elemental analysis, as well as to surface morphology studies. The optical transmission analysis of the films established their absorption to correspond to indirect allowed transitions in accordance with the Tauc model under the optical band gap values (E_g) of 1.26 and 1.07 eV for the (InSe)₂₀(GaSe)₈₀ and (InSe)₅₀(GaSe)₅₀ thin films, respectively.

Ceramics based on yttrium aluminum garnet doped with ruthenium ions were synthesized. Ceramic samples were obtained by non-reactive sintering of nanocrystalline powders formed by chemical coprecipitation. The results of XRD and EDX analysis indicated that the yttrium-aluminum garnet matrix can accommodate up to 0.5 àt.% of ruthenium cations without the formation of secondary phases or impurities. Minor deviations from the stoichiometry of the composition did not hinder the incorporation of ruthenium into the structure of yttrium aluminum garnet. In addition, changes in the valence of the sintering additive had no effect on the solubility of ruthenium ions in the ceramic material.

This paper presents the BDTR-500 robot, which is designed for crack diagnostics in silica-enamel coated pipes. The main achievements of the system include the use of GPS navigation and positioning methods, which ensure accurate location and rapid identification of emergency zones. New algorithms based on artificial intelligence and machine learning enable autonomous robot movement and high-quality data processing. High-megapixel cameras with smart lighting effectively visualize defects, while an intelligent energy management system extends autonomous operation time. Real-time data processing enables rapid damage localization and repair, and built-in sensors improve image stability on uneven surfaces. The robot can detect cracks as small as 0.1 mm. The project results confirm the high efficiency of the BDTR-500 in diagnostics and open up new possibilities for the application of this technology in pipeline monitoring and other challenging operating conditions.

This article examines the synthesis and properties of a composite ceramic material based on a glass with the composition 31.0BaO – 30.0B₂O₃ – 15.0Al₂O₃ – 7.0SiO₂ – 6.8MgO – 5.9ZnO – 4.3MgF₂ (mol.%) and an Al₂O₃ filler. The composite ceramic, prepared with an initial glass-to-Al₂O₃ mass ratio of 60 : 40 and sintered at 875°C, exhibits a relative permittivity ε_r of 8.62 and a loss tangent tan δ of 12.1 × 10 ^–4 at 1 MHz. The material demonstrates a flexural strength of 117.5 MPa, a coefficient of linear thermal expansion (CLTE) of 69.7 × 10 ^–7 K ^{– 1}, and chemical compatibility with silver electrodes. These properties suggest its applicability in low-temperature co-fired ceramic (LTCC) technology.

This study examines the influence of vacuum hot pressing (VHP) conditions on the microstructure, density, and optical properties of ZnSe ceramics. Graphite and titanium foils, as well as alumina powder, were used to isolate the compact from the graphite mold, thereby enabling the variation in carbon contamination levels. Carbon was found to significantly affect the sintering and recrystallization of ZnSe ceramics, hindering the achievement of high density and transparency. Microstructural analysis revealed that the use of alumina as an insulating layer promotes more uniform grain growth, while minimizing abnormal grain enlargement. Spectral analysis demonstrated that maximum infrared (IR) transparency was achieved in samples with initial densities exceeding 97% after additional hot isostatic pressing (HIP). However, further enhancement of the optical properties necessitates the complete elimination of carbon contamination, which demands the replacement of graphite tooling in the VHP process.

The article examines a glass-forming region in the ternary TeO₂–ZnO–MoO₃ system at two melt cooling rates. Glasses containing up to 80 mol.% molybdenum trioxide were obtained with varying TeO₂/ZnO ratios. X-ray diffraction (XRD) was used to study the phase formation in the batch and glass samples under thermal treatment. No significant interaction between the initial binary oxides was observed in the temperature range of 20 – 300°C. However, further heating led to the formation of complex oxides of tellurium (IV), zinc, and molybdenum (VI), including Te₂MoO₇, Zn₂Te₃O₈, ZnMoO₄, and ZnTeMoO₆. These phases were also formed during controlled glass crystallization. The transmission spectra of the glasses exhibited a redshift of the absorption edge with an increase in molybdenum trioxide content.

For the first time, we obtained a series of ceramic powders with garnet structure, (Y_1–xLu_x)₃Yb_0.15Er_0.03Al₅O₁₂ (YLuAG), using the coprecipitation method with ammonium sulfate. The atomic ratio of Y³⁺/Lu³⁺ cations was varied from 80/20 to 20/80. It was determined that the formation of the garnet phase under the synthesis conditions proceeds through the formation of intermediate phases, whose composition depends on the Y/Lu ratio in the initial salt solution. The differential thermal analysis (DTA) of precursor powders and x-ray diffraction (XRD) of (Y_1–xLu_x)₃Yb_0.15Er_0.03Al₅O₁₂ ceramic powders obtained at 800, 900, 1000, and 1150°C facilitated the identification of the temperature ranges for the formation and decomposition of intermediate crystalline phases obtained during the thermal synthesis of the garnet phase, including Y₂O₂SO₄, Y₂(SO₄)₃, Lu₂(SO₄)₃, and Lu_1–xY_xAlO₃.

This article examines the local atomic structure of neodymium ions introduced into boroaluminate (5 mol.% Nd₂O₃) and zinc phosphate (0.5 mol.% Nd₂O₃) glasses by extended x-ray absorption fine structure (EXAFS) spectroscopy near the Nd L₃-edge. The reference spectra of neodymium oxide recorded at both the K- and L₃-edges facilitated the identification of multielectron excitation features and enhanced the determination accuracy of local structural parameters. The findings revealed that, on average, neodymium ions in the boroaluminate glass are coordinated by approximately 9.6 oxygen atoms at a Nd–O distance of approximately 2.4 Å, whereas in the zinc phosphate glass, they are surrounded by approximately 6.8 oxygen atoms at approximately 2.3 Å.

This article examines the influence of the potassium form of silicon-phosphorus-antimony cation exchangers (K:SPA-cation exchangers) added to a potassium nitrate melt on the compressive stresses on the surface of sodium-calcium-magnesium silicate glass. Compressive stresses are induced by low-temperature ion exchange between Na⁺ ions in the glass and K⁺ ions in the molten salt. We compared two types of potassium nitrate: technical grade B and chemically pure grade CP. The distribution of compressive stresses in the surface layer of the glass was analyzed using waveguide spectroscopy; we determined the birefringence profile to calculate the stress profile. Microhardness was measured using a PMT-3 microhardness tester. The addition of a K:SPA-cation exchanger into the potassium nitrate melt was shown to improve ion exchange conditions for both types of nitrate compared to the salt melt without a cation exchanger, leading to an increase in compressive stress, depth of the ion-exchanged layer, and microhardness. Following ion exchange with the addition of a cation exchanger, an increase in compressive stress relative to the initial glass was 155 MPa and 450 MPa for grade B and grade CP, respectively. Microhardness increased by 120% and 240% for grade B and grade CP, respectively. The cation exchanger significantly improves ion exchange conditions for technical-grade potassium nitrate (grade B). The introduction of cation exchangers into the salt bath melt holds promise for advancing ion exchange technology, which is used to enhance the mechanical and thermal strength of glass products. The potential of this method is particularly relevant in glass strengthening production, where cheaper technical-grade potassium nitrate is used.

This review summarizes research findings on the laser modification of coatings produced by high-velocity oxygen fuel (HVOF) spraying, with a primary focus on the laser post-treatment of tungsten carbide-based coatings. We discuss the main types of laser systems used for additional thermal processing of coatings. The results demonstrate that laser post-treatment significantly influences the microstructure of coatings, leading to higher density, a 4 – 6-fold reduction in porosity and dispersion, and the ability to control the distribution and magnitude of residual stresses. The review further demonstrates that laser post-treatment increases the micro- hardness of coatings by 20 – 50%, improves adhesion strength between the coating and the metallic substrate, enhances wear and corrosion resistance, and reduces the friction coefficient by 20 – 65%. The underlying mechanisms of the observed variations in structural and mechanical properties of remelted coatings are discussed.