Glass and Ceramics最新文献

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.

This study investigates the influence of tempering parameters on the mechanical strength of safety glass products. We examined the effects of press configuration and temperature settings within the chambers of tunnel furnace on the fracture patterns of glass during strength testing. A logistic regression model was developed to predict fracture behavior during mechanical strength testing of produced glass, facilitating real-time adjustments to the tempering process. This approach aims to enhance quality control and optimize production efficiency.

This study investigates the physical and mechanical properties of ceramic materials with compositions 97ZrO₂–3Sm₂O₃ and 94ZrO₂–6Sm₂O₃ (mol.%), fabricated from initial nanopowders. The ceramics exhibit a two-phase structure comprising tetragonal and cubic solid solutions based on ZrO₂. The Sm₂O₃ content is shown to significantly influence the phase ratio, thereby affecting the grain structure and properties of the material. An increase in the volume fraction of the tetragonal ZrO₂-based solid solution from 46 to 85 vol.% leads to an enhancement in mechanical strength from 600 to 850 MPa and in fracture toughness K_1c from 8.0 to 10.5 MPa · m^1/2.

This study examines the synthesis of YAG:Ce precursor powder and luminescent ceramics by reverse chemical co-precipitation. We investigated the effects of sintering additives (CaO, MgO, and TEOS), Ce³⁺ activator concentration, vacuum sintering temperature, and the temperature of air annealing on the luminescent properties of YAG:Ce ceramics. The optimal parameters for achieving high luminescence efficiency were defined: sintering additive concentration of 0.01 wt.%, TEOS as the sintering additive, vacuum sintering temperature of 1800°C, and air annealing temperature of 600°C for TEOS-containing samples. A ceramic sample exhibiting a luminescence efficiency of 319 lm/W was achieved under laser radiation with a power of 190 mW and a spot diameter of approximately 5 mm.

The paper proposes a beneficiation approach for natural milky-white quartz. By using quartz samples from the Naily gold deposit (South Urals), we validated the developed processing methods through the melting of certified reference glass ingots.

This study examines the synthesis of porous materials derived from various types of coal combustion by-products (fly ash, boiler slag, and bottom ash) using a self-foaming approach with the fluxing agent Na₂B₄O₇. The internal structure and density of the samples were analyzed in relation to foaming temperature and flux content. The results indicate that samples based on boiler slag exhibit the most uniform structure. The study also elucidates the influence of phase composition on sintering and foaming intensity, including the enhanced reactivity of glass-phase components and the facilitated softening of aluminosilicate matrices.