Glass and Ceramics最新文献

This study investigated the influence of the concentration of sulfate ions at key technological stages of the synthesis of YAG:Cr ceramic powder on the optical properties of ceramics. The particle size and size distribution, the degree of agglomeration, the specific surface area, and the phase composition of the ceramic powder were evaluated. The variations in the microstructure and optical properties of the YAG:Cr ceramic material were assessed in relation to the amount of sulfate ions used at various stages of the synthesis of ceramic powder. It was demonstrated that the use of 0.200 M and 0.045 M solutions of sulfate ions at the stage of precipitation or washing of the precipitate, respectively, resulted in the superior particle size distribution characteristics and the highest monodispersity of precursor powders and YAG:Cr ceramic powders. Furthermore, it improved the optical properties of YAG:Cr ceramics with a transmittance value exceeding 81.5%.

A literature review on oxide compositions developed to modify ceramic aluminosilicate fibers-based filter elements for the selective catalytic reduction of nitrogen oxides during the purification of high-temperature industrial gases is presented. Methods for preparing the catalytic compositions and methods for their introduction into the structure of the ceramic filter elements are also discussed.

The features of glass batch preparation in the production of colorless sheet glass with increased transparency are considered. A non-standard algorithm for dosing and loading selenium, cobalt oxide, erbium oxide, and iron oxide into the mixer was proposed.

The possibility of obtaining high-strength vitrified bricks based on loess by adding 20% of waste glass powder was established. At the same time, the amount of moisture in the material should be close to 10%, which corresponds to the dry-pressing technology.

Currently, the use of ceramic shells for casting metal melts is a common practice in most machine-building enterprises. The primary method of producing ceramic molds involves investment casting, followed by the removal of the pattern material. The formation of ceramics from a ceramic suspension via a repeated application method necessitates the use of processing additives with a number of physico-chemical properties that ensure the quality of the fabricated shells. Processing additives based on water are characterized by a rather complex composition, including several organic compounds. This results in their compatibility issues and a reduction in the long-term performance under continuous mixing of the ceramic suspension susceptible to sedimentation. Furthermore, the composition of the suspension varies due to uneven removal of components during operation. It is evident that in order to develop an efficient processing additive, it is necessary to carry out an in-depth study of the physico-chemical properties of the components and their combined aqueous solutions, which would allow the selection of components and their concentration to be optimized.

The effectiveness of using borate (borax) and fluoride (sodium fluoride) fluxes in the sintering of crystalline (sand) and amorphous (diatomite) silicate raw materials was considered. The change in the density and appearance of samples with varying amounts of fluxes during their heat treatment at different temperatures was described. It was shown that the introduction of 4 wt.% of borax reduces the temperature necessary to reach a density of 1500 kg/m³ by 100°C, and 6 wt.% of borax by 200°C. It was shown that the introduction of fluxes increases the amount of x-ray amorphous glass phase due to depolymerization of the silicon-oxygen network and the formation of a low-temperature melt.

The results of a study into the dielectric properties and harmonic coefficient for barium titanate ceramics obtained from a powder with a particle size of 50 nm at different sintering temperatures are presented. It is shown that ceramics from nanopowders can be produced at lower sintering temperatures than technical ceramics with a particle size of 1 μm. Ceramics obtained at a sintering temperature of 1200°C have the best linear and nonlinear dielectric properties.

The article examines the physical, mechanical, and technological properties of ceramic tiles based on Kulatau clay and dune sands from the Tuprakkala massif in the lower Amudarya region of Uzbekistan. Laboratory and semi-production tests revealed that the optimal composition M-7, fired at temperatures of 1000 – 1050°C, can be used to produce unglazed cladding and floor tiles. Similarly, the optimal composition M-9 fired at temperatures of 1000 – 1050°C, can be used to produce facing and cladding tiles with an opaque glaze.

The glass with a 12.5Li₂O–50GeO₂–37.5P₂O₅ composition was synthesized by melt quenching. Thermal annealing was used to obtain a single-phase LiGe₂(PO₄)₃ composition, which is promising as a solid electrolyte for all-solid-state lithium-ion power sources. By using full x-ray scattering with analysis of the pair distribution function, and diffuse reflectance spectroscopy in the UV-Vis range, the local structure and optical properties of initial (amorphous) glass and crystallized glass were studied. An assessment of the influence of glass crystallization on these properties was carried out. It was shown that structuring in the glass is observed only at the level of the first-second coordination sphere of Ge and P atoms. The presence of F⁺ centers in the glass was revealed in the optical absorption spectra of the initial glass; their concentration decreases as a result of glass crystallization. The estimated value of the band gap for the crystallized glass, i.e., for the LiGe₂(PO₄)₃ phase, is 6.15 eV for the case of direct allowed transitions, which exceeds the calculated value known from the literature by approximately 2 times.

This study presents a review of progress in the sol-gel method for the synthesis of powders of ferroelectric ceramics based on the PbTiO₃–PbZrO₃ system, which involves the controlled hydrolysis of the mixtures of salts or organometallic compounds of lead, zirconium, and titanium. To obtain materials based on the PbTiO₃–PbZrO₃ system, attention is paid to the sol-gel conditions, heat treatment conditions, raw materials, conditions to obtain precursors, gels drying, and PbTiO₃–PbZrO₃ powder crystallization.