The chemical resistance of glasses in the PbCl2–PbO–B2O3–NdF3 system has been studied. Oxochloride lead-borate glasses have demonstrated good water resistance and alkali resistance, while low acid resistance. Volumetric glass samples were exhibited in the tropical climate of Southeast Asia during the year. The spectral-luminescent characteristics of neodymium ions in these matrices maintain good stability in a tropical climate.
The possibility of using waste from the enrichment of ferruginous quartzites of KMA is considered. The chemical composition of waste from Lebedinsky GOK has been investigated. It has been established that the main components of the waste are quartz, magnetite, as well as dolomite, calcium and magnesium carbonates. It is shown that the chemical and granulometric composition of waste is characterized by stability, which allows them to be used as a corrective additive to ceramic masses in the production of wall ceramics.
The purpose of this work is to obtain ceramic filter materials as substrates and to develop a methodology for their application for the study of biological objects by electron microscopy. The composition, structure, pore sizes and morphology of ceramic substrates made of foamed silicate before and after the application of inverse opals made of silicon oxide were evaluated by X-ray phase analysis and SEM methods. A description of the use of the obtained filtering substrates in an experiment with biological objects is given. The substrates seem promising for electron microscopy, because they can be used for sample preparation of biological samples with the use of metal spraying or the introduction of ionic liquid. This technique, together with the filtering porous material and the technical capabilities of the microscope, preserves the physical characteristics of biological objects unchanged.
The article investigates the high-temperature interaction and sintering processes of samples of high-alumina masses of low-temperature firing for technical ceramics based on the ternary system kaolin–alumina-containing component–dolomite and establishes the areas of formation of high-alumina mass for technical ceramics on the triple diagram. It is shown that as a result of high-temperature interaction, new formation of crystalline phases of minerals occurs in the form of mullite, corundum, ?-cristobalite, as well as in a small amount of anorthite and an amorphous glassy phase, which impart the necessary physical and mechanical properties to the fired sample. The area of optimal compositions for obtaining high-alumina ceramic masses of low-temperature sintering based on the ternary system kaolin–alumina-containing waste–dolomite has been determined.
The chemical composition and technological properties of clay polymineral raw materials of the northwest of the Orenburg region have been studied. According to the chemical composition, the raw material can be attributed to semi-acidic sanded clays with a high content of coloring iron oxide Fe2O3 (4.83 %). The dependences of the viscosity of clay suspensions at sufficiently high concentrations (up to 0.16 vol. %); the linear character is confirmed by a high correlation coefficient and proves the absence of hydrate shells around particles containing a large amount of quartz in their composition. The values of the coefficient ? included in the Einstein equation are calculated, it turned out to be in the range 2.44 ? ? ? 3.0. The low plasticity of the raw materials, the studies of which were carried out in two ways – by squeezing the balls and bending the flagella, indicates a high content of sand. Sintering in the temperature range from 600 to 1000 °C did not happen, the samples cracked. Macroparameters of sintering and color parameters of samples under the influence of high temperature, as well as the results of the analysis of the phase composition do not allow us to assume satisfactory mechanical characteristics of ceramics from the studied raw materials. Low sorption properties of mineral raw materials with respect to copper and lead ions have been established. It is shown that the use of this raw material in the ceramic industry is not advisable, its use in road construction, landscaping, as thinning additives to reduce the plasticity and shrinkage of clays during drying and firing is more practical.
In this work, a study was made of the possibility of obtaining ceramics for microwave technology in the system of ZrO2–SnO2–TiO2 oxides by solid-phase synthesis using a sintering additive, lanthanum (III) oxide. Ceramics based on zirconium-tin titanate composition Zr0.8Sn0.2TiO4 with additions of 2, 4, 6 wt. % La2O3, its properties were studied using various methods of analysis. The densest ceramic specimens were obtained at a firing temperature of 1400 ?C and a La2O3 content of 4 wt. %.
Based on calculations, spatial distribution of the local electric field (LEF) for various structural configurations of silver nanoparticles (NPs) in silicate and zinc-phosphate glasses was studied. The features of this distribution determine the efficiency of energy transfer from plasmonic NPs to rare earth (RE) ions located in particles vicinity. The mechanism of energy transfer through field enhancement, caused by the surface plasmon resonance of particles, is a dominant for NPs of sizes of ?5 nm and is determined by several factors. To clarify their roles and significance, the dependences of LEF upon the size, spatial distribution and degree of agglomeration of silver NPs in glass were studied. With this aim, a visual representation of the spatial distribution of the LEF in the vicinity of agglomerates of plasmonic NPs was proposed, which allows to perfom an effective, comparative analysis of the nature of the field enhancement in places of hypothetical location of RE ions. Based on simulations, the dependencies of LEF intensity enhancement, spatial distribution of such places in relation to the nearest plasmonic particle, upon concentration of NPs, their size, degree of agglomeration and the presence of small (?5 nm) particles in the sample along with the relatively large ones, were determined. It was revealed that the optimal configuration of silver particles in glass for obtaining of the maximum average enhancement of LEF intensity per the site of possible location of RE ion is an agglomerate of NPs with sizes slightly larger than 25 nm and average distances between particle centers ~30 nm.
Zinc magnesium aluminosilicate (ZMAS) glasses have been obtained with the addition of Na2O (from 1.1 to 7.0 mol. %). Influence of the Na2O content on glass forming ability and effectiveness of the ion-exchange treatment in molten KNO3 was studied. Dependences of depth and strain of subsurface layer on treatment duration have been also studied, concentration shifts of alkaline cations in result of ion-exchange process have been evaluated. It was showed that glass Vickers hardness increases both with the Na2O content in glass and with the duration of ion-exchange. Vickers hardness of the ion-exchanged glasses with 7 mol. % of Na2O treated duration for 72 h reaches 900 HV. Possibility of ion-exchange process usage with glass-ceramics, obtained from glasses of ZMAS system modified with sodium oxide, has been discussed.
Refractory and heat-resistant materials with a coarse-grained and large-porous structure were obtained using silica glass suspensions with mullite, spinel, corundum and quartz fillers. The influence of sintering temperature on the phase composition, structure, porosity and density of the materials were studied. It was found that the strength of the ceramics increases in the temperature range 1300…1400 ?C and decreases at 1500…1600 ?C due to the crystallization of the silica glass. The composites in the silica glass–corundum system have the most stable strength characteristics.
The processes of obtaining hafnium diboride by the carbothermic reduction of hafnium oxide by heat treatment in a vacuum furnace and a spark plasma sintering installation have been studied. When the charge was heat treated in a vacuum furnace, hafnium diboride powder was obtained in the temperature range 1500...1700 °C, but it is characterized by the presence of secondary crystalline phases. Monophase hafnium diboride powder with a fine-grained uniform structure was obtained using the spark plasma sintering method at a temperature of 1500 °C.