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Methods of laser micro- and nanomodification structure of transparent dielectrics open promising prospects for the creation of a new type glass-crystalline materials and new applications. In this work, after a brief excursion into the history of glass-ceramics, transparent aluminosilicate glass-ceramics are discussed, mainly using the example of the Li2O–Al2O3–SiO2 system, and the areas of their new applications. The recently discovered possibilities of laser micromodification of structures and direct laser writing of elements photonics and integrated optics in their volume are considered. In this case, special attention is paid to transparent glass-ceramics with coefficient of thermal expansion close to zero.
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The influence of the eutectic additive of the Li2O–B2O3 system on the sintering process and dielectric properties of ceramics based on Li2MgTi3O8 has been investigated. It was determined that the introduction of an additive in the amount of 10.0 – 15.0 % contributes to the sintering of ceramics by a liquid-phase mechanism. Li2MgTi3O8 ceramics, containing a sintering additive in an amount of 15.0 % and obtained at a firing temperature of 900 ?С, demonstrates the following level of properties ?av = 3.04 g/cm3, Po = 5.7 %, ?r = 19.0 and tg? = 0.028. The lowered sintering temperature of ceramic will allow the production of various electronic components based on it using low-temperature cofiring ceramic (LTCC) technology, and the specified level of dielectric properties will allow to miniaturize the devices.
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For the first time, a local Abrio method for estimating birefringence was applied to hardened glasses, and the distribution of microstresses in float glass subjected to ion exchange hardening was studied. The possibility of precision determination of the thickness of the stressed layer is shown, the correlation between the depth of the stressed layer and the penetration depth of potassium cations during ion exchange is established.
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The purpose of this work is to study the effect of scandium in the dodecahedral and octahedral positions of the garnet crystal lattice on the features of vacuum sintering of optical ceramics Y3-хScxAl2-yScyAl3O12:Cr, as well as on its optical and luminescent properties. YSAG:Cr optical luminescent ceramics were manufactured for the first time from ceramic powders of metastable compositions with a high scandium content in a dodecahedral position. The considered compositions were described by the general formula Y3-хScxAl2-yScyAl3O12, where 0,12 ? x ? 1,50 and 0,08 ? y ? 1,00 f. u. with a total scandium content from 0.12 to 1.70 f. u. The following studies of YSAG:Cr: ceramic samples were carried out:
X-ray diffractometry, measurement of the shrinkage kinetics of ceramic compacts by dilatometry, study of the morphology and elemental composition of the ceramic surface by scanning electron microscopy (SEM). The light transmission and luminescence spectra were measured. It is shown that ceramics made from compositions with a predominant scandium content in the dodecahedral position reach maximum density at lower temperatures compared to compositions containing a greater amount of scandium in octahedral positions. It was found that with an increase in the sintering temperature of YSAG:Cr ceramics compositions with a high scandium content in the dodecahedral position become unstable.
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An energy-efficient synthesis of highly porous ceramic materials based on Sc2O3 was carried out using a combination of compaction and technological combustion methods with the participation of active binders. Using XRD, SEM, and EDA methods, it was found that the material has a highly developed multilevel microstructure morphology based on Sc2O3 and tortveitite Sc2Si2O7. The main characteristics of the pore space of the material (porosity, pore size, specific surface area, permeability, etc.) were determined by mercury porosimetry and alternative methods.
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In this study, the changes in the morphology and degree of agglomeration of both precursor powders and ceramic YAG powders under varying grinding conditions was considered. The effect of these parameters on the optical properties and structure of the ceramics was assessed. The YAG precursor powders were obtained through chemical co-precipitation.
The morphology, size of agglomerates, and crystallites was evaluated using scanning electron microscopy, laser diffraction analysis, X-ray phase analysis, and Brunauer–Emmett–Teller gas adsorption.
It was found that milling the YAG precursor powders allows for a reduction in the degree of agglomeration of the ceramic powders. It was discovered that optimal modes can be achieved at a mass ratio of grinding balls to precursor powder of 6.75/1 and a ratio of the mass of the grinding medium to the mass of the precursor powder of 4.5/1. These modes provide the necessary granulometric characteristics and the highest monodispersity. Therefore, it has been demonstrated that the use of an additional milling stage for powders synthesized by chemical precipitation, along with the selection of milling modes, can improve the properties of YAG optical ceramics.
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The article discusses the possibility of using quartz sands from the Oynakum deposit as a promising source of high-quality quartz-containing raw materials for the glass industry in order to obtain higher grades of glass. The chemical, granulometric and mineralogical composition of quartz sands of the Oynakum deposit was studied, high concentrations of quartz sand were obtained using various enrichment schemes.
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According to experimental research and practical experience, the main problems with enamel coated pipes are the roughness inside the pipe, small air bubbles, and cracks that come in different sizes, all of which make the pipes not last as long. Consideration is given to the issue of enamel coating defects, which compromise the enamel's structural integrity. The reasons for these defects are associated with the wrong choice of technological mode when applying enamel coatings to the inner surface of pipes. The choice of the technological mode when applying the coating depends on the geometric dimensions and technological parameters of the pipes.
It is known that incorrect implementation of the technique of applying enamel coatings to pipes leads to the formation of micro cracks. Considering all this, the main task of the research carried out is the automatic adjustment of the parameters of the technical mode of the equipment and the tuning of the control system to prevent the formation of micro cracks during coating and the improvement of the automatic control. of the process.
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This study presents a performance evaluation of MgAl-binary oxide-coated multi-walled carbon nanotubes (MWCNTs) as a reinforcement phase in a magnesium aluminate spinel MgAl2O4 ceramic composite system fabricated using a pressureless sintering technique. The physical properties, including porosity, bulk density, and flexural strength of spinel composites were evaluated in the temperature range of 1500 – 1600 ?C. The results reveal the coated MWCNTs architecture's promising influence on the composite system's property enhancement. The developed thin-film coating on the MWCNTs favors enhanced dispersibility with better matrix-reinforcement interfacial connectivity, thereby improving the mechanical and thermo-mechanical performance of the composites.
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A new heat-resistant multifunctional glass-based coating has been developed in the BaO–B2O3–SiO2 system, which protects parts made of corrosion-resistant steels from high-temperature gas corrosion at temperatures up to 900 ?C. The developed heat-resistant multifunctional coating has increased resistance to high temperatures, high dielectric properties, and therefore is multifunctional. A high level of properties is provided by a composition based on refractory glass and the addition of a bonding activator.
