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The paper studies the effect of adding potassium form of silicon-phosphorus-antimony cationite (K:KFS-cationite) to a potassium nitrate salt bath on the magnitude of compressive stresses on the surface of sodium-calcium-magnesium silicate glass. Compressive stresses are formed as a result of low-temperature ion exchange Na+ (glass) – K+ (salt melt). Two types of potassium nitrate were studied: technical grade B and chemically pure grade Extra pure. To determine the distribution of compressive stresses in the surface layer of glass, the waveguide spectroscopy method was used, with the help of which the profile of birefringence was measured and the stress profile was calculated. To measure microhardness, a PMT-3 microhardness tester was used. It is shown that the introduction of K:KFS cationite into the potassium nitrate melt leads to an improvement in the ion exchange conditions for two grades of nitrate compared to the salt melt without the cationite – namely to an increase in the value of compressive stresses, the depth of the ion exchange layer and microhardness. The increase in compressive stresses in relation to the initial glass after ion exchange with the addition of cationite was 155 MPa for grade B and 450 MPa – for grade Extra pure. The increase in microhardness in relation to the initial glass was 120 % for grade B and 240 % – for grade Extra pure. The cationite significantly improves the ion exchange conditions for technical potassium nitrate grade B. The introduction of cationite into the salt bath melt is a promising direction in ion exchange technology used to increase the mechanical and thermal strength of glass products. This technological approach is especially relevant in glass strengthening production, where cheaper technical potassium nitrate is used.
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Synthesis and properties data of the ceramic material based on 31.0BaO–30.0B2O3–15.0Al2O3–7.0SiO2–6.8MgO–5.9ZnO–4.3MgF2 (mol. %) glass and Al2O3 as a filler are provided. Sintered at 875 °C composite ceramics with an initial glass/Al2O3 mass ratio of 60:40 and has ?r = 8.7 and tan ? = 6.6 ·10–4, at frequency 1 MHz. The flexural strength of such ceramics is 117.5 MPa, CTE = 69.7 10–7 K–1, the composite is chemically compatible with silver and can be promising material for the low-temperature of co-fired ceramics technology.
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In this work, the local atomic structure of neodymium ions embedded in alumoborate glass (5 mol. % Nd2O3) is studied in comparison with the structure of neodymium ions in zinc phosphate glass (0.5 mol.% Nd2O3) using the Fourier analysis of the extended X-ray absorption fine structure (EXAFS) spectra near L3-edge of Nd. The EXAFS spectra of the neodymium oxide recorded at the K- and L3-edges of Nd were considered as an experimental standards. The usage of two absorption edges allowed to determine the spectral characteristics of multielectron excitations contributions to the spectrum and to increase the accuracy of the determined parameters of the local atomic structure. We found that the neodymium atom in alumuborate glass is surrounded, in average, by ~9.6 oxygen atoms at a distance of ~2.4 ?, and in zinc phosphate glass – by ~6.8 oxygen atoms at a distance of ~2.3 ?.
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The article describes the study of the effect of the tempering mode on the mechanical strength of products. It shows the effect of the press settings and the temperature in the tunnel furnace chambers on the nature of glass failure during testing. It is proposed to use a logistic regression model to predict the nature of failure during mechanical strength testing of manufactured glasses and promptly correct the tempering mode.
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A new approach to the enrichment of natural milky-white quartz is proposed. The proposed methods of technological conversion with the smelting of certification glass ingots were tested using quartz from the Naly deposit.
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Ceramic Materials of Compositions (mol. %) 97ZrO2–3Sm2O3 and 94ZrO2–6Sm2O3 based on nanosized powders synthesized by hydrolysis sol-gel method are obtained. It is shown that in ceramic materials a two-phase composition is formed, including tetragonal and cubic form of solid solutions based on ZrO2. It has been found that the amount of Sm2O3 affects the ratio of the phases formed, and accordingly affects the grain composition of the microstructure and the mechanical characteristics of the ceramic materials. It was determined that an increase in the content of the solid solution phase of the tetragonal shape of the ZrO2 from 46 to 85 vol. % determines an increase in the strength of the ceramic material from 600 to 850 MPa and crack resistance according to the parameter K1c from 8.0 to 10.5 MPa · m?.
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The paper studies the effect of vacuum hot pressing (VHP) conditions on the microstructure, density, and optical properties of ZnSe ceramics. Graphite and titanium foils, as well as powdered aluminum oxide, were used to isolate the compact from the graphite mold, allowing for variation in the degree of carbon contamination in the samples. It was found that carbon significantly affects the sintering and recrystallization of ZnSe ceramics, hindering the achievement of high density and transparency in the material. Microstructural analysis revealed that using aluminum oxide as insulation leads to more uniform grain growth and minimizes abnormal grain growth. Spectral studies showed that the maximum transparency of the ceramics in the infrared range is achieved after additional hot isostatic pressing (HIP) treatment of samples with an initial density higher than 97 %. It was demonstrated that further improvement of optical properties requires the complete elimination of carbon contamination, necessitating the replacement of graphite tooling in the VHP process.
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The article presents the results of determining the anti-filtration and sorption capacity of palygorskite and other clays of the Borshchevsky and Voskresensky cement raw material deposits, which are overburden rocks from mining operations. It was experimentally established that the filtration coefficients of the studied samples correspond to the current standard value, which allows their use in the technology of anti-filtration screens for solid municipal waste landfills.
For the palygorskite clay sample, the filtration coefficient is 8?10-10 m/s. The values of the main sorption characteristics for the palygorskite clay sample were determined: specific surface area – 85,1 m2/g, specific volumes of micro- and mesopores, respectively – 0,0138 and 0,127 cm3/g. The values of static sorption capacity for heavy metals from an aqueous solution with a purification efficiency of > 94 % were obtained; the purification efficiency from oil products was > 60 %.
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The peculiarities of obtaining porous materials based on different types of ash and slag materials (fly ash, boiler slag, ash-slag mixture) by the “self-foaming” technology using Na2B4O7 flux were studied. Changes in the internal structure and density of samples depending on the foaming temperature and flux content were considered. It was shown that samples based on boiler slag have the most uniform structure. The patterns of the influence of phase composition on the intensity
of sintering and foaming were described, consisting in increased activity of interaction of glass phase components and simplification of softening of the aluminosilicate mass.
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An overview of the research results on the laser modification of coatings sprayed by HVOF is presented. The review includes information on laser post-treatment of mainly on tungsten carbide-based coatings. Information on the main types of laser machines used for additional thermal treatment of coatings is provided. It was established that laser post-treatment has a significant effect on the microstructure of coatings, provides a higher density, reduces dispersion and porosity by 4 – 6 times, and allows you to adjust the distribution and value of residual stresses. It is shown that with the help of laser post-treatment, it is possible to increase the microhardness of coatings by 20…50 %, to increase the adhesive strength of the coating and the metal base, wear resistance and corrosion resistance, and to reduce the coefficient of friction by 20…65 %. The reasons responsible for the observed changes in the structural and strength characteristics of coatings after laser post-treatment with remelting are indicated.
