-
Details
-
Hits: 146
The article presents the results of a study on the development of a composition of technical ceramics for ceramic grinding bodies and the influence of dispersed oxide on its basic properties. It is shown that waste from a gas processing industry catalyst was used as an alumina-containing component. Dispersed aluminum oxide was obtained from chemical reagents by the citrate sol-gel method. It has been established that the introduction of nanodispersed aluminum oxide in an amount of 3 wt. % over 100 wt. % of the total mass improves the abrasion coefficient, acid resistance, density, and strength of the developed samples of technical ceramics.
-
Details
-
Hits: 129
The article presents the results of a study devoted to the development of a laser-induced breakdown spectroscopy (LIBS) method for monitoring the homogeneity of the chemical composition of optical glasses. A quantitative method for studying lead distribution over the surface area of samples in lead-silicate glasses based on LIBS has been developed. The parameters of laser radiation action on the surface of lead-silicate glasses (pulse energy, laser pulse repetition rate, laser wavelength, delay between the pulse and registration of the analytical signal) have been optimized. The minimum step of scanning the chemical composition over the surface area of the sample has been set at 300 ?m.
-
Details
-
Hits: 120
Composite ceramic materials based on SiO2–Al2O3–ZrO2 nanopowders were obtained by sintering and their properties were studied. Before sintering, the powders were subjected to mechanical activation in a planetary ball mill using zirconium dioxide balls as grinding bodies. The activated powders were pressed under pressing pressures of 50, 100, 200 and 300 MPa. Consolidation was carried out in an atmospheric high-temperature furnace at 1700 ?. The surface of the sintered bulk samples was examined using a scanning electron microscope. Elemental analysis made it possible to establish patterns in the distribution of chemical elements. It was found that in all the studied samples two phases were formed – Al6Si2O13 and ZrSiO4. The porosity of the samples was determined and the dependence of this parameter on the applied pressing pressure was established. The mechanical properties of the samples were studied using nanoindentation: indentation hardness and elastic modulus, and the bending strength limits of the studied samples were determined during Scratch testing. The crack resistance of the samples was determined by the indentation method using the Marshall-Evans relationship. The effect of the ratio of the initial components and the applied pressing pressure on the physical and mechanical properties of the resulting composite ceramics was determined.
-
Details
-
Hits: 148
The paper presents the results of the studies of borophosphate glasses containing an additive of the FLiNaK salt, an eutectic mixture of alkali metal fluorides of the composition 46.5 mol. % LiF – 11.5 mol. % NaF–42 mol. % KF, as one of the types of radioactive waste from the developed molten salt nuclear reactors. The obtained glasses demonstrate a high percentage of FLiNaK inclusion, reaching 20…25 wt. %, and retain a homogeneous amorphous structure with a uniform distribution of elements throughout the volume. Starting with a FLiNaK content of 25 wt. %, the glasses crystallize with the formation of the elpasolite phase K2NaAlF6. According to X-ray diffraction studies, depending on the fluoride content in the glass, certain regularities were found indicating the presence of a correlation between the transformation of the local structure of the glass and the formation of the crystalline phase, which will be further studied in more detail. Studies of the chemical and mechanical stability of the obtained glasses with a FLiNaK content of no more than 20 wt. % indicate that these glasses meet the regulatory requirements for glass matrices used to immobilize radioactive waste. At the same time, the dependence of these properties on the FLiNaK content revealed the presence of an extremum at a value of 7 wt. % FLiNaK, but no correlations with structural changes were detected.
-
Details
-
Hits: 114
Silica adsorbents with organosilsesquioxane fragments containing organic radicals have been obtained for use in the adsorption separation of oxygen-argon mixtures by the PSA method. The sol-gel scheme of the process of directed copolycondensation of the reagent mixture was chosen as the basic method for the synthesis of adsorbents. The obtained materials were characterized by thermogravimetry and low-temperature nitrogen adsorption. The results of studying their adsorption properties for oxygen and argon are presented. The highest selectivity for argon was demonstrated by a silica sample containing (diethylaminomethyl)silsesquioxy groups with the maximum value of the total volume of micro- and mesopores and a wide distribution of mesopore volumes by radii.
-
Details
-
Hits: 109
Restoration of natural ecosystems has now become one of the main tasks requiring urgent search for effective solutions. Due to the serious negative impact of mass pollution on the environment, it is important to actively participate in the restoration of this environment. The most promising option for recycling drilling mud is the synthesis of effective materials such as wedging agents, slamolites and keramstenes. In addition, the use of drilling mud as raw materials will reduce the industry's need for natural raw materials. The article describes the physico-chemical studies of drilling waste and their possibility of use for the synthesis of effective aluminosilicate materials.
-
Details
-
Hits: 160
The process of phase formation of new antimony pyrochlore (sp. gr. Fd-3m) Bi2.7Zn0.46Ni0.70Sb2O10 + ? during solid-phase synthesis from oxide precursors was studied. The process of solid-phase synthesis of antimony pyrochlore Bi2.7Zn0.46Ni0.70Sb2O10 + ? is a complex multi-stage process. It was shown that the interaction of oxide precursors occurs at a temperature of 600 ?С and higher, bismuth stibatate – Bi3SbO7 is formed as an impurity phase. Oxide precursors, including bismuth (III) and antimony (III, V) oxides, are fixed in the sample up to 750 ?С, at which the intermediate cubic phase Bi3M2/3Sb7/3O11 (sp. gr. Pn-3) is formed, stable up to 900 ?С. The pyrochlore phase in the sample appears at 650 ?С, a significant increase in the proportion of pyrochlore occurs at a temperature of 850 ?С and above. Phase-pure pyrochlore is formed at 950…1050 ?С. At a temperature of 1050 ?С, sintering of fine-grained ceramics occurs, a low-porosity microstructure is formed due to the fusion of small grains with the formation of coarse crystallites with a longitudinal size of 2…4 ?m. The unit cell parameter of pyrochlore in the range of 650…1050 ?С changes non-monotonically, at 800 ?С the minimum value of 10.464 ? is fixed, the unit cell constant of phase-pure pyrochlore Bi2.7Zn0.46Ni0.70Sb2O10 + ? is equal to 10.474 ?.
-
Details
-
Hits: 152
The technological properties of clay raw materials from the Stolinskiye Khutora deposit (Vidibor area, Brest region) were studied, which allowed it to classify according to GOST 9169–2021. It was found that the clay is refractory, highly plastic, semi-acidic or acidic (depending on the depth), with a high or medium content of coloring oxides, coarsely dispersed, unsinterable in the firing temperature range of 900…1200 ?. The phase composition of the clay material, as well as the processes occurring upon heating were investigated. It was deter-mined that this clay can be used for producing ceramic bricks, clinker material, as well as ceramic floor tiles. Samles of building ceramics synthesized in the laboratory using clay from the Stolinskie Khutora deposit had the necessary set of physicochemical and performance characteristics.
-
Details
-
Hits: 168
The results of a study of the chemical and mineralogical composition of the mineral hematite from the Kyzyltash deposit before and after firing are presented, and methods for its enrichment are selected. Red and brown pigments were synthesized and the results of X-ray diffraction and electron microscopy analyzes were analyzed. The coloring properties of the resulting red and brown pigments were studied. It has been established that hematite from the Kyzyltash deposit can be used as a raw material component at production enterprises in the building materials industry of Uzbekistan for the preparation of ceramic glazes and coloring pigments.
-
Details
-
Hits: 164
Spectral-luminescence properties of zinc-phosphate ZnO–P2O5 (PZ) glasses doped with 0.25…1.00 mol. % Er2O3 were studied. It has been shown that an increase in the Er2O3 concentration in the synthesized glasses leads to intensity growth of the luminescence band with a maximum at a ~1537 nm. The values of the intensity phenomenological parameters ?t (t = 2, 4, 6) of Judd–Ofelt were estimated and the probabilities of radiation transitions, branching ratio, cross sections of the induced radiation and radiation lifetimes of the excited state were calculated. The obtained results demonstrate the potential of using the material under study as an infrared amplifier.
