According to experimental research and practical experience, the main problems with enamel coated pipes are the roughness inside the pipe, small air bubbles, and cracks that come in different sizes, all of which make the pipes not last as long. Consideration is given to the issue of enamel coating defects, which compromise the enamel's structural integrity. The reasons for these defects are associated with the wrong choice of technological mode when applying enamel coatings to the inner surface of pipes. The choice of the technological mode when applying the coating depends on the geometric dimensions and technological parameters of the pipes. It is known that incorrect implementation of the technique of applying enamel coatings to pipes leads to the formation of micro cracks. Considering all this, the main task of the research carried out is the automatic adjustment of the parameters of the technical mode of the equipment and the tuning of the control system to prevent the formation of micro cracks during coating and the improvement of the automatic control. of the process.
This study presents a performance evaluation of MgAl-binary oxide-coated multi-walled carbon nanotubes (MWCNTs) as a reinforcement phase in a magnesium aluminate spinel MgAl2O4 ceramic composite system fabricated using a pressureless sintering technique. The physical properties, including porosity, bulk density, and flexural strength of spinel composites were evaluated in the temperature range of 1500 – 1600 ?C. The results reveal the coated MWCNTs architecture's promising influence on the composite system's property enhancement. The developed thin-film coating on the MWCNTs favors enhanced dispersibility with better matrix-reinforcement interfacial connectivity, thereby improving the mechanical and thermo-mechanical performance of the composites.
A new heat-resistant multifunctional glass-based coating has been developed in the BaO–B2O3–SiO2 system, which protects parts made of corrosion-resistant steels from high-temperature gas corrosion at temperatures up to 900 ?C. The developed heat-resistant multifunctional coating has increased resistance to high temperatures, high dielectric properties, and therefore is multifunctional. A high level of properties is provided by a composition based on refractory glass and the addition of a bonding activator.
A comparative study was carried out on the possibility of controlling the average sizes of nano-sized powders of silicon dioxide and aluminum oxide obtained by electron beam evaporation, pyrogenic, liquid chemical and plasma chemical methods, by keeping them in the temperature range of 800 – 1300 ?C in an air atmosphere. The average size of the resulting particles was estimated from specific surface area measurements using the Brunauer–Emmett–Taylor (BET) adsorption method at liquid nitrogen temperature. Crystallographic parameters in the treated powders were assessed using X-ray diffraction analysis. It has been shown that by appropriate choice of temperatures and initial powder, it is possible to achieve an average particle size in the resulting powder close to a given one and a phase composition.
Using the method of self-propagating high-temperature synthesis (SHS) SHS compositions based on the Si3N4–Yb2O3 system were obtained. Synthesis by combustion was carried out in a nitrogen atmosphere at a pressure of 4 MPa in a reactor with a volume of 30 liters. The mass of the loaded mixture was 3 kg. It has been established that the amount of ytterbium oxide in the charge affects the combustion temperature and the phase composition of the synthesis products. With an increase in the proportion of ytterbium oxide in the mixture, the content of the alpha phase decreases, and the secondary phases are represented by quaternary ytterbium-silicon oxynitride and ytterbium disilicate.
In this work, the effect of sintering additives based on magnesium oxide (MgO) and silicon oxide (TEOS) in concentrations from 0.02 to 0.10 wt. % and 0.2 to 0.5 wt. %, respectively, was investigated on the microstructure and optical properties of ceramics of the composition Y2,82Yb0,15Er0,03Al5O12, made from powders synthesized by chemical co-deposition. The results presented in the paper showed that the introduction of a sintering additive based on MgO into a ceramic powder does not affect its phase composition, structural and morphological characteristics. It is shown that for ceramics of the composition Y2,82Yb0,15Er0,03Al5O12, the best value of the optical transmission coefficient was achieved at a vacuum sintering temperature of 1800 °C and a concentration of sintering additives of 0.06 wt. % MgO and 0.3 wt. % TEOS. It is shown that the sintering mechanism of ceramics Y2,82Yb0,15Er0,03Al5O12 depends on the ratio of sintering additives MgO and TEOS.
From a cheap perlite as the basic raw material an opaque glass-crystalline material was synthesized containing nanosized crystals of wollastonite and gehlenite with an average size of 100 nm. The phase composition, microstructure and strength properties of the material were investigated. Changes in the composition and size of crystal grains caused by varying the amount of catalyst and the content of quartz in the initial mixtures make it possible to control the physico-mechanical properties of the obtained material. High strength and hardness allow using this material for protection against high-speed impact, including small arms bullets.
The purpose of this article is to apply an integrated research approach for the reconstruction of ceramic production technology in the territory of the Kyrgyz Republic based on the results obtained by modern methods. The paper summarizes for the first time the results of the study of physical-mechanical and physical-chemical properties and an attempt is made to reveal the methods of technical analysis of ceramic artifacts. An unified scientific approach to ceramics of various periods from the II millennium BC to the X-XII centuries, excavated in Kyrgyzstan, to determine the relationship between their microstructure and physical and mechanical properties. Ceramics technology, like no other industry, requires this kind of research due to the specifics of technical information associated with both natural and social factors. Lack of solid knowledge in the field of ceramics technology has prevented them from obtaining important information about Kyrgyz history, culture, and economy, which is the subject of their nation-building efforts. However, a comprehensive study of the production technique, types, composition and quality of ceramics would open up completely new prospects for confirming the antiquity of Kyrgyzstan.
Compositions of muffled glasses for the upper layer and the lower structural layer of composite glass-crystal cladding material based on phosphorus industry waste have been developed: phosphoric slag, phosphorite fines, coal dust and cullet.
The effect of immersion in a coffee drink solution on the color stability of two CAD/CAM ceramic restorations was investigated in this in vitro study. To this end, zirconia-reinforced lithium silicate (ZLS) and lithium disilicate (LDS) glass-ceramic blocks were surface-treated using mechanical polishing and glazing techniques. In addition, their color was examined before and after immersion in a coffee solution using a spectrophotometer, and the color changes were evaluated. A two-way analysis of variance (ANOVA) was used to examine the color changes. The material type significantly influenced color changes (P < 0.001). After glazing and mechanical polishing, LDS exhibited considerably less color change in both groups than ZLS. In both types of ceramics, the glazed group experienced less color variation than the mechanically polished group. Color changes were clinically acceptable across all groups. The glazing surface treatment produced superior color stability than the mechanical polishing technique. LDS exhibited more color stability than ZLS in both surface treatments.
