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The article presents the results of a study of the influence of humidity, oxygen on the formation of the structure and strength properties of products based on magnesium oxide and organic binder SFPR-054. It has been established that carrying out the polymerization process at a temperature of 25 ?C without access to air increases the strength of the samples by about 5 times compared to samples polymerized in dry form at a temperature of 300 ?C. The obtained results suggest that the increase in the structural and mechanical properties of products based on magnesium oxide will be facilitated by the moistening of the mixture, the settling of the pressed product and the polymerization process in an oxygen-free environment or in an atmosphere of water vapor.
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The paper considers the issue of the possible use of stainless steel grade 20Cr23Ni18 and its foreign analogue AISI 310S, instead of steel 12Cr18Ni10T, as a material for the manufacture of a shaping die in the production of glass insulators from electrovacuum glass grade G93-3M, widely used in the radio-electronic industry as cases for magnetic contacts.
It is shown that at working temperatures there is a chemical interaction between both steels and glass of grade G93-3M, which leads to a deterioration in the quality of products due to the appearance of a large number of gas bubbles in it.
It has also been shown that due to additional heat treatment it is possible to reduce the consequences of this chemical interaction, thereby increasing the quality of the resulting product.
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The characteristics of glass-ceramic materials obtained using thermal plasma have been studied. The effect of TPP ash on the properties of glass-ceramic materials should be taken into account. Samples with a mass content of ash of 70 % were obtained. They have the following characteristics: compressive strength 530 MPa, flexural strength 110 MPa, density 3000 kg/m3.
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The possibility of obtaining complex-shaped mechanical engineering products based on reaction-sintered silicon carbide using two methods - mechanical processing of polymerized blanks before sintering and hot slip molding under pressure, has been studied. The obtained silicon carbide ceramic materials are characterized by a low density of about 3.04…3.07 g/cm3, a porosity of ? 1 % and a bending strength of 320…360 MPa. Materials based on silicon carbide modified with boron carbide have a density of 2.72 g/cm3, a porosity of about 1 % and a bending strength of 280 MPa.
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Ceramovermiculite thermal insulation on a wollastonite bundle was obtained from chalk, diatomite and expanded vermiculite by the method of solid-phase synthesis of components. The influence of the granulometric composition of expanded vermiculite, as well as the composition of the charge on the phase composition, physical, mechanical and thermophysical properties of ceramic materials has been studied. The main crystalline phase of ceramic samples is biotite and wollastonite. The developed ceramovermiculite thermal insulation has an apparent density from 310 to 510 kg/m3 and can be operated at temperatures up to 1050 °C inclusive. The developed materials can be used as refractory thermal insulation of industrial furnaces, equipment, etc.
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The paper presents the results of a study of the processes of glass formation during the production of a frit by the method of induction heating. According to X-ray phase analysis, the resulting frit is completely amorphous. The frit meets the standard requirements for a 45 mm flow and a thermal expansion coefficient of 120?10–7 K–1. The enamel coating has a high chemical resistance to acids and alkalis. A comparative analysis of frit synthesis in a laboratory electric furnace using an induction heating device showed that the duration of frit induction heating is halved, energy consumption is reduced by 23 %, and the process efficiency is increased four times on average.
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A method is proposed for processing the reverse side of silicon transistor structures before the metal deposition process and obtaining contact to the collector of the transistor being formed. The parameters of the surface roughness of the silicon surface treated with carbide–silicon sand are studied in order to improve the adhesive properties before spraying the contact to the collector region of the transistor.
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Purpose of this work is to establish the features in the microstructure and thermoelectric properties of composites consisting of Bi2Te2.7Se0.3-based matrix and a Fe filler. The composition with a filler content of 0.3 wt. % Fe has a higher thermolectric figure of merit as compared to the Bi2Te2.7Se0.3 matrix. For this composition, the maximum value of ZT reaches ~0.75, while for Bi2Te2.7Se0.3 ZT does not exceed ~0.63. Thus, in the composite of the Bi2Te2.7Se0.3 + Fe system, the thermoelectric figure of merit can be increased by about 20 %.
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Using absorption spectroscopy, differential scanning calorimetry, and X-ray powder diffraction, we studied the effect of a small addition of CeO2 on the process of thermally stimulated formation of plasmonic Au nanoparticles in the glass of the ZnO–MgO–Al2O3–SiO2 system containing TiO2 and ZrO2 as nucleating agents. It is shown that when the glass is heated from temperatures slightly above Tg to temperatures in the region of the exothermic peak, the plasmon resonance band of Au nanoparticles undergoes a nonlinear shift; however, the addition of CeO2 significantly expands the the shift to the long wavelength region of the spectrum. We performed the computer simulation of the experimental optical absorption spectra, estimated the sizes of the formed nanoparticles and proposed the mechanism of the effect of the CeO2 addition on the formation of plasmonic Au nanoparticles.
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The formation of microtracks in the volume of porous glass samples by femtosecond laser pulses which is of importance for laser writing of active optical waveguides was studied. It was found that impregnation of nanoporous glass in bismuth nitrate solution leads to the appearance of an orange luminescence band under 488 nm light excitation and this luminescence band is enhanced in the laser-wriiten tracks. It is shown that increasing the laser pulse energy to 200 nJ allows increasing the phase contrast of the tracks laser-written in nanoporous glass doped with bismuth compared to the ones formed in nanoporous glass without additives.
