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The article examines a topic of study of statistical data on the strength of flat glass. The issues of theoretical models of the strength of flat glass, parameters affecting its strength, the probabilistic nature of the destruction of flat glass under operating conditions of glass in building, the selection of the distribution of values of the strength of flat glass, data censorship, determination of the strength characteristics of the strength of flat glass, including the normative bending strength.
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Within the framework of a quasi-static unrelated thermoelasticity problem, a criterion for the thermal strength of a freely pinched plate during pulsed laser annealing is obtained, taking into account the reflection of laser radiation from the back surface of the plate. The possibility of reducing the maximum tensile stresses in the plate by 15…65 %, and energy costs for annealing by 8…30 % is shown. It is established that taking into account the reflection of laser radiation from the back surface of the plate leads to a decrease in the region of variation of the dimensionless parameter ?h (the product of the absorption index by the thickness of the plate), in which plate destruction by thermoelastic stresses during annealing is possible.
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The work is aimed at developing a method for forming an octacalcium phosphate (OCP, Ca8H2(PO4)6·5H2O) coating on the surface of ?-tricalcium phosphate (TCP, Ca3(PO4)2) ceramics. The coatings were formed by keeping the ceramics in buffer solutions with the main ionic composition of CH3COO– and Na+ with varying conditions (time, pH value and temperature). Crystallization of the OCP coating occurred sequentially by partial dissolution of the surface layers of TCP ceramics and crystallization of the intermediate phase of dicalcium phosphate dihydrate (DCPD, CaHPO4·2H2O). The effect of the buffer solution composition and the process conditions (time, pH value and temperature) on the phase composition, morphology and thickness of the coatings was studied.
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The article describes the features of the synthesis of a new oxide pyrochlore Bi2.7Ni0.7Mg0.46Sb2O10+? (sp. gr. Fd-3m, a = 10.4703 ?) containing antimony (V) and bismuth (III) cations from a stoichiometric mixture of oxide precursors using a modified sol-gel method (method Pecini). It is shown that the formation of antimony (III, V) and bismuth (III) compounds that are volatile upon calcination can be prevented by dissolving the precursors in sulfuric or nitric acid solutions, and excluding the use of hydrochloric acid or chloride solutions. A step-by-step synthesis of two samples obtained from sulfuric and nitric acid media was carried out, and the phase composition of the preparations calcined in the temperature range of 350…950 ?C was analyzed. When calcining the sample obtained from the sulfuric acid solution, the Bi12.67O14(SO4)5 phase was revealed, which prevents the formation of pyrochlore in the low-temperature region. In the sample synthesized from the nitric acid solution, bismuth stibates Bi3SbO7, BiNbO4 are recorded as intermediate phases Sb2O4, Bi12MgO19, Bi7.47Ni0.53O11.73, Bi3Ni2/3Sb5/3O11, NiSb2O6 were identified as other intermediate phases in the samples. The synthesis temperature of single-phase Bi2.7Ni0.7Mg0.46Sb2O10+? with the pyrochlore structure is 950 ?С. The phase purity and chemical composition of the sample were established by X-ray phase analysis and energy-dispersive X-ray analysis.
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An overview of the dielectric properties of ceramic materials based on solid solutions of alkali-earth metal titanates with a perovskite structure is presented. The ranges of solubility of the components of two- and three-phase solid solutions are determined and the influence of the component concentration ratios, production methods and technological parameters on the dielectric properties of ceramics is shown. Based on the literature data, a three-component phase diagram for BaTiO3, CaTiO3, and SrTiO3 was compiled for the first time, which shows the relative permittivity values characteristic of various regions in the phase diagram. It was found that ceramics with a content of Ba2+ > 40 mol. %, Sr2+ < 60 mol. % and Ca2+ < 40 mol. % have the highest values of relative permittivity (>700), and an increase in the proportion of Sr2+ and Ca2+ leads to its significant decrease.
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The article briefly provides basic information about the 26th International Exhibition “World of Glass” held in Moscow, which was directly attended by more 200 companies from 10 countries. New technologies of production and quality control of glass products, the main structural elements of glass furnaces, methods of their high-quality production were demonstrated. Examples of the most successful enterprises of the glass industry are given.
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In this paper, we show fast femtosecond laser writing of birefringent waveplates in nanoporous glass (NPG) volume. The possibility of laser writing acceleration on the order of magnitude is shown in NPG relative to fused silica. In situ measurements of birefringent plate retardance are performed for heating and cooling stages in the 20…650 ?С temperature range. Femtosecond laser-written birefringent elements are found to have greater thermal stability relative to conventional crystal quartz plates in highly varying temperature environments. The obtained results are of particular interest to the industrial fabrication of laser-written phase optics elements in NPG.
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The influence of diamond grinding modes on the structure and mechanical properties of ceramics based on zirconium dioxide stabilized with magnesium oxide has been studied. Powders of the composition ZrO2 – 6 mol. % MgO was obtained by chemical co-precipitation from solutions of zirconium and magnesium chloride salts. The blanks of the samples were made by cold isostatic pressing at maximum pressures of 55 and 200 MPa, followed by sintering at a temperature of 1700 ?C for 4 hours. The resulting blanks (both porous and high-density) were machined with different cutting depths in the range of 0.003…0.010 mm. It was found that the surface roughness of the samples increased with increasing cutting depth. After mechanical processing of high-density samples obtained at a maximum pressure of 200 MPa, conditions are created on their surface for the implementation of a phase transition. Grinding promotes the transition of the tetragonal phase of zirconium dioxide (t-ZrO2) to the monoclinic phase (m-ZrO2) on the surface of the samples, which leads to an increase in the critical stress intensity coefficient (K1c) from 4.3 to 6.4 MPa·m1/2. Mechanical processing of samples with an open porosity of 3.0…3.5 % obtained by pressing at a maximum pressure of 55 MPa does not lead to phase transformations on their surface and K1c remains within the margin of error.
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This article describes the process of obtaining VK94-1 ceramics modified with zirconium dioxide ZrO2, in order to determine and compare such properties of the resulting composite material as: apparent density, mechanical bending strength and Vickers hardness (microhardness) with the properties of ceramics VK94-1, as well as the effect on these properties of changes in the percentage of zirconium dioxide in the samples. The influence of the firing temperature on the sintering of samples has been studied. Samples with different component ratios VK94-1/ZrO2 (90/10, 80/20, 70/30) were pressed on an isostatic press at a pressure of 150 MPa. The firing was carried out at different temperatures: 1500, 1550 and 1600 ?C in different firing mediums.
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The technology of plasma synthesis of ceramic pigment based on vanadium waste has been developed. The chemical and phase composition of the pigment has been studied. The effect of a pigment based on waste on the aesthetic and consumer properties of wall ceramics has been studied. The CIE L*a*b* system defines the color characteristics of wall ceramics.
