The effectiveness of an argon ion cluster beam for polishing the surface of corundum ceramics was investigated. Using atomic force microscopy, changes in the surface relief of VK-100 ceramics were studied after treatment with argon cluster ions in various modes: with small and large average cluster ion sizes. The ranges of lateral sizes of irregularities at which smoothing of the ceramic surface is observed were determined.
The article presents the results of a study on the elemental and chemical–mineralogical composition, as well as the structure and morphology of samples of Shekhzheli basalt, using chemical analysis, X-ray diffraction (XRD), infrared spectroscopy (IR), and scanning electron microscopy (SEM). The main thermo mechanical characteristics of fired basalt rock samples from the Shekhzheli deposit were determined in the temperature range of 1000…1200 °C.
The article presents the development of a technique for producing transparent silica glass products using LCD-stereolithography using a photopolymer composite. It is shown that ultrasonic treatment of the composite makes it possible to destroy agglomerates of SiO2 nanoparticles and achieve a more uniform distribution of them in the organic matrix, significantly reducing the sintering temperature. Optimal printing and removal modes of the polymer matrix have also been determined. As a result of sintering at a temperature of 1175 °C, transparent monolithic silica glass samples with a density of 2,19 g/cm3 and a shrinkage of ~30 % were obtained. The light transmission investigation showed that the samples provide 83,5 % transmission in the visible region of the spectrum.
Ceramics in the CaO–SiO2 and Na2O–CaO–SiO2 systems were obtained from powders synthesized from aqueous solutions of silicic acid and calcium nitrate at a molar ratio of Ca/Si = 0.5 by direct precipitation with the addition of an aqueous solution of ammonia. Solutions of silicic acid prepared via the dynamic ion exchange method passing an aqueous solution of sodium silicate Na2SiO3 through a column with KU-2x8 sulfopolysterol cationite from top to bottom or from bottom to top were used for the synthesis of the starting powders. High-purity silicic acid, which does not contain sodium ions, was obtained by feeding an aqueous solution of sodium silicate Na2SiO3 from the bottom to top. The powders after synthesis contained hydrated calcium silicates and hydrated silicon dioxide. The powder synthesized from acid containing sodium ions included a reaction by-product - sodium nitrate NaNO3. Ceramics with a phase composition including cristobalite SiO2, tridymite SiO2, and sodium calcium silicate Na2Ca3Si6O16 were obtained after firing at 800…1000 °C from a synthesized powder containing sodium nitrate NaNO3. Ceramics with a phase composition including SiO2 (cristobalite, quartz) and CaSiO3 (wollastonite, pseudowollastonite) were obtained after firing at 1000...1200 °C from powder synthesized from high purity silicic acid. The obtained ceramic materials, whose phase composition contains biocompatible phases in CaO–SiO2 and Na2O–CaO–SiO2 oxide systems, can be used to create bone implants after the necessary in vitro and in vivo studies.
This paper describes the process of obtaining VK94-1 ceramics with various TTB (temporary technological bonds) in order to assess the effect of the binder on properties such as apparent density, total porosity and linear shrinkage of the samples. Ceramics obtained using 8 wt. % PEG as a binder showed the best results compared to the material molded using 5 wt. % PVA. This is due to the fact that polyethylene glycol gives a more dense semi-finished product due to the formation of thinner boundary layers.
The article presents X-ray diffraction, dielectric, and pyroelectric results of a PbZrO3 ceramic synthesized from nanodispersed PbO and ZrO2 powders with the addition of BaTiO3 nanoparticles. It was found that the addition of barium titanate results in the formation of a rhombohedral ferroelectric phase in lead zirconate. Pyroelectric measurements showed that the spontaneous polarization of the solid solutions for x = 0,10 is 45…55 ?C/cm2.
The paper presents the results on the formation of boron-based coatings by precipitation of target material from a vapor-plasma phase formed by electron beam exposure to a solid-state target in the forevacuum pressure range. The physicomechanical properties of coatings formed when inert, active, and reactive gases are injected into the region of interaction between an electron beam and a target are investigated. It is shown that a change in the gaseous medium in the region of vapor deposition of the boron target on a titanium substrate does not significantly affect the hardness during nanoindentation (H) and the modulus of elasticity (E) of the formed coatings. At the same time, the obtained hardness values during nanoindentation vary from 19.5 to 20.3 GPa, and the modulus of elasticity varies from 182.5 to 207.7 GPa. Nevertheless, the injection of reactive and active gases into the working volume of the vacuum chamber has a significant effect on the adhesion resistance and roughness of such coatings. It was found that the use of N2 in the deposition of boron-containing vapors increases the adhesive properties of coatings (critical load 22.78 N), while the coating roughness is the highest Ra = 0.306 microns. The injection of O2 into the deposition area contributes to the formation of coatings with the lowest roughness (Ra = 0.045 microns) and adhesive resistance (critical load 0.6 N).
This study presents the development and experimental validation of nanomodified cement obtained by joint grinding of clinker, gypsum, microsilica, polycarboxylate superplasticizer, and dune sand. The optimal composition and technological parameters providing increased strength and performance properties of the binder were studied. A series of cement systems with varying clinker and sand content was prepared, while the amount of gypsum (5 %) and modifier (10 %) remained constant. The results showed that mechanical activation in a ball mill for 110 minutes provided a nanostructured material with a specific surface area of 5500…5700 and an average particle size of 3.5…3.7 ?m. Strength tests have shown that the optimal clinker content is 70...80 %, while replacing up to 20 % of clinker with dune sand does not reduce strength. In this composition, the 28-day compressive strength reached 110…115 МПа, exceeding the control samples by 25…30 %. It was also established that the optimal water-to-cement ratio (W/C = 0.18…0.20) ensures dense microstructure and maximum strength, while higher W/C values lead to increased porosity and strength loss. The findings highlight the potential of nanomodified cement technology for reducing clinker consumption, improving performance, and enhancing the environmental sustainability of cement production.
The microstructure and dielectric properties of manganese-doped zinc titanate (MnxZn1–xTiO3) ceramic samples were investigated as a function of manganese concentration (x = 0.1; 0.3, & 0.5). XRD analysis confirmed that the samples exhibited an ilmenite hexagonal structure, indicating the structural evolution of the material. The dielectric constant was influenced by the Mn content and increased with increasing temperature and decreased with increasing frequency. According to the findings, the dielectric loss and dielectric constant increased with temperature and decreased with frequency. The addition of trace amounts of zinc to the manganese titanate ceramics resulted in a substantial increase in the dielectric constant. The substitution of zinc ions for manganese ions effectively enhanced the dielectric properties of the ceramic samples, which highlights their potential for advanced applications.
The formation of waveguides in the bulk of sintered nanoporous glass pre-impregnated in a bismuth nitrate solution was demonstrated. The influence of laser irradiation regimes on the refractive index change and luminescence intensity in fs laser beam-written tracks was studied. It was shown that the relative luminescence intensity of the formed waveguides depends significantly on the impregnating bismuth nitrate solution concentration. The waveguides exhibit broadband (FWHM ~150 nm) luminescence in the near infrared region (1200…1500 nm) when pumped at a wavelength of 808 nm. This indicates potential for using the formed waveguides as the active medium of waveguide laser amplifiers.
