The influence of the spheroidization process in the flow of high-temperature plasma of glass based on the Li2O–Al2O3–SiO2 (LAS) system doped with 1.0 mol. % Nd2O3 on its crystallization properties is investigated. The resulting microspheres with a size of 32 – 64 ?m are characterized by a significantly higher glass transition temperature Tg compared to the Tg of the initial glass (751 °C and 677 °C, respectively), which may be due to both a change in chemical composition during spheroidization and a fundamentally different thermal history of microspheres and glass. Despite the delayed crystallization kinetics, the glass-ceramic structure based on ?-eucryptite-like solid solutions of LixAlxSi1 – xO2 is formed in microspheres, as in the initial glass, under the action of heat treatment, indicating the possibility of both obtaining microspheres with the glass-ceramic structure and varying their coefficient of thermal expansion near zero values.
Selective control of the tempered glasses produced was carried out. Deviations of bent products from a given shape are revealed. Linear adaptive models describing the dependence of the shape of products and the results of mechanical strength tests on the quenching mode are compiled. Simulation modeling of the quenching process control algorithm shows the possibility of improving the quality of safe tempered glasses produced.
Some features of the technology for processing container glass cullet were considered. The differentiated optical separation diagrams of colorless, brown and green cullet mixture was presentedduced.
The effect of the addition of magnetite in the form of pyrite stubs on the physico-mechanical and radio-absorbing properties of the synthesized glass composite by the method of “cold” foaming is considered. Replacing glass powder with magnetite in the initial liquid-glass composition reduces the foaming coefficient from 80 to 20 %, which is due to a decrease in the viscosity of the composition due to the particle size of the additive (160 ?m), their high density (5100 kg/m3) and porous structure. It has been established that the optimal content of magnetite for obtaining a material with radio-absorbing properties is no more than 10 %. A porous glass composite with an average pore size of 2, containing 10 % magnetite, has an absorption coefficient of electromagnetic radiation in the high-frequency range (120 – 250 GHz) on average 10 % more than a composite without an additive.
The aim of this paper is exploring an opportunity to improve the thermoelectric properties of the cermet Bi2Te3 + 0.5 at. % Gd composite. It was found that under spark plasma sintering, a composite microstructure consisting of the Ni inclusions, which are randomly distributed inside the grained Bi2Te3 matrix, is really formed. With introducing Ni inclusions in Bi2Te3, the specific electrical resistivity increases, and the total thermal conductivity decreases. The highest thermoelectric figure-of-merit for the composite (~ 0.63) happened to be slightly enhanced as compared to that for the matrix material (~ 0.58).
Three batches of unidirectional basalt fiber-reinforced plastic were fabricated as plates, and continued tests were performed under load at room temperature and in a closed desiccator at a 99 % moisture for 365 days. The moisture absorption of the unconstrained specimens in the desiccator was not above 0.20 – 0.23 %. The residual mechanical properties of the specimens that had been held in the desiccator for 365 days were measured after being dried, and the ultimate strain was found to increase by 10 – 15 %, the elastic modulus by 14 – 21 %, the strength by 19 – 21 %, and the glass transition temperature by 5 – 8 °С.
The possibility of obtaining inorganic block heat-insulating foams based on silica and ash-containing man-made waste is considered. The influence of modifying additives and technological modes on the structure and basic technical properties of foam silicates has been determined. As a result of the studies, the optimal content of ash waste was established in the amount of 5 – 15 %. The obtained foam silicates are characterized by physical and technical properties: density 0,36 – 0,45 g/cm3, strength 2,8 – 5,2 MPa, thermal conductivity 0,089 – 0,106 W/(m?K) and water absorption 14 – 22 %.
The glass-crystalline ceramic materials in SiO2–Al2O3–RO (RO–MgO, SrO, BaO and their combinations) systems have been synthesized by the sol-gel method. The factors influencing on the sol-gel formation process are revealed. The effect of the composition and temperature-time modes of heat treatment on the crystallization properties of gels, phase transformations, phase composition, granulometry and shape of the resulting particles has been studied. The nature of phase transformations in powders is revealed depending on the temperature-time conditions of heat treatment. It is shown that the dominant crystalline phases, depending on the composition, are anorthites or their solid solutions, their formation temperatures have been established: hexagonal celsian is formed at a temperature of 1350 °C, monoclinic strontium anorthite – at 1400 °C, cordierite – at 1450 °C. The influence of pressing and heat treatment conditions on the physic-mechanical, dielectric and thermal properties of the obtained materials is investigated. The synthesized glass-ceramics with low dielectric constant and dielectric loss tangent, high deformation temperatures (above 1500 °C) is a promising replacement for the spodumene-eucryptite and cordierite sitalls currently used as radio-transparent materials, the disadvantage of which is insufficiently high operating temperatures (not higher 900 – 1100 °C).
Effect of quartz tubes crystallization on quality of blanks from quartz ceramics of radio engineering appointment is investigated. The analysis of effect of a way of tubes samples preparation for resistance test to crystallization is carried out. Assessment of effect of impurity mass fraction in quartz concentrates on crystallization of tubes at incoming control, and also on existence of crystal phases in products and on the properties of products controlled in production from quartz ceramics is carried out.
The article describes the mechanisms of formation of the structure of low-temperature porcelain with the use of new non-traditional raw materials. As a result of the research, it was found that the formation of the structure of the experimental porcelain materials is completed at lower firing temperatures (1220 – 1250 °C). The phase composition of the synthesized porcelain consists mainly of crystals of mullite, quartz, cristobalite and the vitreous phase filling the gaps between the crystals.
