The effect of the concentration (from 18 to 6 %) of an alkaline activator (AA) solution on the viscosity and basic properties of geopolymer composites based on chamotte with additives of foam glass production waste, multi-walled carbon nanotubes (MWCNT) and air-entraining additive (AEA) after heat treatment at different temperatures. In specimens with АЕА, the density decreases from 1600 to 1240 kg/m3, strength from 20.0 to 2.6 MPa and shrinkage from 5.9 to 1.5 % after firing at a temperature of 1000 °C. Combined use of АЕА and MWCNT allows to increase strength up to 7.9 – 10.3 % and reduce specimen shrinkage up to 16.0 – 8.2 %.
The effect of boron oxide additives in the amount from 0 to 11 mol. % was studied on the melting characteristic of glasses in the SrO–Al2O3–TiO2–ZrO2–B2O3–SiO2 system for use as fillers in dental filling composites in order to reduce the melting temperature to technologically acceptable values (no more than 1500 ?C) and increase the transparency of the produced granulate. It was found that with an increase in the B2O3 content, the melting temperature can be reduced from 1600 ?C (in glasses without B2O3 additives) to 1480 ?C with a B2O3 content of 11.8 mol. %, while the glass transition temperature decreases from 820 to 743 ?C. Already with a B2O3 content of 6 mol. % at a melting temperature of 1500 ?C, transparent glasses with light transmission of 80 % are produced, promising for the creation of sealing composites.
Glasses were obtained in the SiO2–Al2O3–SrO–P2O5–F system with a phosphorus oxide content in the range of 7 – 12 mol. %. The set of properties of the obtained glasses (refractive index 1.514 – 1.535, TCE 44?10–7 – 61?10–7 K–1, transmittance above 85 %, radiopacity not less than 300 %) in the aggregate with the processability of synthesis (melting temperature below 1500 ?C) indicates that they are promising candidates for use as fillers of glass ionomer cements for dentistry.
Modern trends in the development of technologies for matting glass and glass products are considered. An effective technology of glass matting using alternative energy sources, in particular low-temperature plasma, has been developed. It is shown that when matting with iron powders with a dispersion of 160 and 450 microns, a high-quality matte surface of the “frosty” matting type is formed. The microstructure of the matted surface is investigated. Theoretical aspects of glass matting are considered. The technological parameters of matting are determined and the economic efficiency of the developed technology is shown.
A study was made of the heat maximum transfer coefficients and thermal conductivity of glass coatings of heat exchange tubes. A formula is obtained for determining the optimal value of the thermal conductivity coefficient of a glass coating. It has been established that during long-term operation of the apparatus, the heat transfer coefficient of the glass coating of the pipe practically does not depend on the operating time due to the cleanliness of the glass surface. It has been established that during long-term operation of the apparatus, the heat transfer coefficient of the glass coating of the pipe practically does not depend on the operating time due to the cleanliness of the glass surface. At the same time, in brass or copper pipes, over time, a sharp drop in the heat transfer coefficient occurs due to the formation of a durable layer of scale and corrosion products. For this purpose, a formula has been derived for calculating the value maximum of the heat transfer coefficient of coatings.
Dielectric properties of ceramic materials based on BN–ZrB2 and BN–ZrO2 systems synthesized in the mode of self-propagating high-temperature synthesis (SHS) from a mixture of boron B powders, boron nitride BN and zirconium dioxide ZrO2 in an atmosphere of nitrogen N2 have been studied. The experimental results showed that ceramics synthesized from the initial mixture of (30B + 10ZrO2 + 60BN, wt. %) composition have permittivity (?) and tangent of the dielectric loss angle (tg) values of 2.63 and 0.006, respectively, at room temperature.
We studied the chemical and mineralogical compositions and determined the values of the limiting adsorption of methylene blue on samples of opal-cristobalite rocks. We found that the use of rocks with a high content of clay minerals is promising for water purification from high soluble organic compounds.
Technological features for container glass cullet cleaning from paper labels were considered. The analysis of some types of equipment operation, which help to realize such cleaning, was made. Constructive solutions of vibrating feeders to remove light impurities were suggested.
The influence of the structure and properties of acrylate monomers on the rheology and polymerization of suspensions containing partially stabilized zirconium dioxide, a dispersant and a photoinitiator as a ceramic filler is investigated. It has been shown that the use of the DISPERBYK 2013 additive makes it possible to obtain suspensions containing 1,6-hexanediol diacrylate, dipropylene glycol diacrylate and tripropylene glycol diacrylate with a viscosity value below 5 Pa?s at high (up to 41 vol. %) filling with TZ-3YS-E powder. The possibility of using the obtained suspensions for three-dimensional printing of high-density ceramic products with complex geometry has been established.
Today ceramic materials occupy more and more new niches of application. These include deep-water apparatuses for various purposes. For example, at present time oil production industry confronts the problem of discovering new oil and gas reserves, 40 % of which are connected with the development of ever-increasing sea depths that, in its turn, requires certain buoyancy of the submersibles to support the payload. The buoyancy can be provided either by a durable hull, or by using buoyant crafts (modules), or by both methods simultaneously. Due to high values of compressive strength, ceramics are considered as a promising material for operation at great depths, where hydrostatic pressure is significantly increased. The paper presents the results of analysis of domestic and foreign literature in the field of creation of hollow macrospheres based on ceramics for their use in modules of buoyancy of deep-water vehicles instead of syntactic foams with glass microspheres. It is shown that the most promising material is ceramics based on aluminum oxide. The results of ceramic spheres tests under the influence of pressures corresponding to the work of deep-water apparatus at different depths are presented. The analysis of the strength evaluation of ceramic macrospheres is given, which is necessary to assess their performance efficiency.
