Final Temperature Research Articles

Smart Nanocomposite in the SiC-Si-Al-Al2O3-Geopolymer System

Goal-obtaining of composite in the SiC-Si-Al-Al2O3 (nanopowder)-geopolymer system with the metal-thermal method in the nitrogen medium. Method- In the present paper nanocomposite with SiALON was obtained through alum-thermal process in the nitrogen medium on the base of Geopolymer (kaolin and pology cley – Ukraine), SiC, alumina oxide nanopowder, aluminum nanopowder and Si powder with small additives of glas perlite (Aragatz, Armenia) by the reactive baking method. The advantage of this method is that compounds, which are newly formed thanks to interaction going on at thermal treatment: Si3N4, Si, AlN are active, which contributes to SiALON formation at relatively low temperature, at 1250-13000C. Results-ß-SiAlON was formed at the sintering of SiC-aluminium and silicium powder, geopolymer at 14500C. Porosity of carbide SiAlON composite obtained by reactive sintering, according to water absorption, equals to 13-15%. The samples were fragmented in a jaw-crusher and were powdered in attrition mill till micro-powder dispersion was obtained. Then samples were hot-pressed at 16200C under 30 MPa pressure. Hold-time at the final temperature was 8 min. Sample water absorption, according to porosity, was less than 0.4%. Further studies were continued on these samples. Conclusion-the paper offers processes of formation of SiC-SiAlON composites and their physical and technical properties. Phase composition of the composites was studied by X-ray diffraction method, while the structure was studied by the use of optic and electron microscope. Electric properties showed that the specimen A obtained by hot-compression is characterized by 2 signs lower resistance than the porous material B, which was used to receive this specimen. Probably this should be connected with transition of the reactively baked structure of the hot-compressed material into compact structure. Obtained materials are used in protecting jackets of thermo couples used for melted metal temperature measuring (18-20 measuring) and for constructions used for placing objects in factory furnaces.

Multi-Output Prediction Model for Basic Oxygen Furnace Steelmaking Based on the Fusion of Deep Convolution and Attention Mechanisms

The objective of basic oxygen furnace (BOF) steelmaking is to achieve molten steel with final carbon content, temperature, and phosphorus content meeting the requirements. Accurate prediction of the above properties is crucial for end-point control in BOF steelmaking. Traditional prediction models typically use multi-variable input and single-variable output approaches, neglecting the coupling relationships between different property indicators, making it difficult to predict multiple outputs simultaneously. Consequently, a multi-output prediction model based on the fusion of deep convolution and attention mechanism networks (FDCAN) is proposed. The model inputs include scalar data, such as the properties of raw materials and target molten steel, and time series data, such as lance height, oxygen supply intensity, and bottom air supply intensity during the blowing process. The FDCAN model utilizes a fully connected module to extract nonlinear features from scalar data and a deep convolution module to process time series data, capturing high-dimensional feature representations. The attention mechanism then assigns greater weight to significant features. Finally, multiple multi-layer perceptron modules predict the outputs—final carbon content, temperature, and phosphorus content. This structure allows FDCAN to learn complex relationships within the input data and between input and output variables. The effectiveness of the FDCAN model is validated using actual BOF steelmaking data, achieving hit rates of 95.14% for final carbon content within ±0.015 wt%, 84.72% for final temperature within ±15 °C, and 88.89% for final phosphorus content within ±0.005 wt%.

Vanillin based phthalonitrile and acetylene bifunctional resins

AbstractThe renewable and biosynthetic molecule, vanillin, were used in the preparation of new phthalonitrile (PN) and ethynylbenzene (EB) bifunctional resins without pre‐modification of the vanillin structure. This PN resin was characterized by differential scanning calorimetry, thermogravimetric analysis, nuclear magnetic resonance spectroscopy, rheometry, and single crystal x‐ray diffraction. The monomers exhibited excellent rheometric viscosities below 250 Cp at processing temperatures and a good pot life. After complete curing, the PN polymers exhibited thermal stability above 500°C, a glass transition temperature (Tg) above the final postcure temperature of 380°C, and exceptional retention of structural integrity over a large temperature range. These results suggest that vanillin derived EBPN based resins are excellent candidates for use in a variety of applications where high temperature and mechanical stability is critical.

Effect of initial grain size on microstructure, texture and magnetic properties of non-oriented electrical steel

The effect of initial grain size prior to cold rolling on the microstructure, texture evolution, and magnetic properties of Fe-3.5 wt% Si non-oriented electrical steel (NOES) was investigated through the introduction of normalization. There were massive intragranular shear bands in {111}<110> and {111}<112> deformed grains in the cold-rolled sheet with large initial grain size, providing nucleation sites for new recrystallized grains with Goss ({110}<001>), λ-fiber, γ-fiber, and {113}<631> components. Subsequent annealing resulted in weaker γ-fiber ({111}<110>−{111}<112>), stronger α*-fiber concentrated at {113}<631>, along with Goss and λ-fiber ({100}<001>−{100}<012>) textures. In addition, appropriate final annealing temperature effectively reduced iron loss. The simultaneous optimization of texture and grain size by normalization and annealing treatments led to improved magnetic properties, with the superior magnetic induction (B50 = 1.719) T, and the lowest core loss (P15/50 = 2.69 W/kg, P10/400 = 16.337 W/kg).

Physical field regulation of magnesium alloy wheel formed by backward extrusion process with multi-stage variable speed

To reduce the tonnage required during the forming process of magnesium (Mg) alloy wheels by backward extrusion (BE) and refine the grains at the wheel bottom, the multi-stage variable (MSV) speed process is proposed based on the characteristics of Mg alloy wheels formed by BE. A numerical model for the BE process of Mg alloy wheels using the Defrom-3D was constructed, and the effects of constant speed and MSV speed processes on the physical fields and DRXed grain size evolution during the forming of Mg alloy wheels were investigated. Lastly, the simulation results were indirectly verified by industrial trial production. The results show that constant speed extrusion has a small effect on the effective stress, but a large effect on the wheel temperature distribution, where the forming speed of the upper rim plays a decisive role in the final temperature distribution of the wheel. MSV speed process is used to regulate the physical field evolution during wheel forming based on the effect of constant speed on the physical field of the wheel. With the high-speed forming of the rim and low-speed forming of the upper wheel rim (9-9-1 mm/s), the temperature and effective stress distribution of the wheel blank are reasonable while reducing the forming tonnage and refining the grains at the wheel bottom.

Garnet solid-state electrolyte: A new single-step elaboration by electric arc-melting

The garnet Li7-xLa3Zr2-xTaxO12 (LLZTO) has attracted a real scientific interest in the last decade as it is one of the safest solid-state electrolytes for next generation high energy lithium batteries. However, its elaboration requires several steps from phase stabilization to densification of the part. This final step, with long and high temperature treatment induces lithium loss due to sublimation. Electric arc-melting allows short time elaboration of dense parts in one-step, eventually minimizing Li sublimation. Thus, the synthesis by arc-melting of LLZTO is exposed here. Stabilized phases and microstructures are studied depending on chemical composition and casting parameters. The direct obtaining of dense parts instead of powder allows better moisture stability thanks to fast growth of protective layer preventing in-depth penetration of the H+/Li+ exchange. Finally, ionic conductivity of fused parts is in a similar range to sintered pellets produced using Spark Plasma Sintering with powdered fused parts. Those results confirm the interest of electric arc-melting synthesis as an alternative LLZTO elaboration.

IMPROVING THE TEMPERATURE IN THE METAL CONVERTER AGGREGATE, WITH USING OF THE MULTI-TIERED TUYERE

The oxygen-converter method is the most common of the industrial production of steel in both Ukraine and the world. According to scientific and statistical sources, from 2017 the fate of oxygen-converting steel in the Ukraine was more than 70 % of the total steel production. To date, in the face of invasion of our sovereign state and a full-scale liberation war in Ukraine, the metallurgical enterprises operating with the oxygen converting way of obtaining steel has conditions for significant resource limitations and increasing the cost of energy, fuel resources. Therefore, there is a need for technological solutions that will increase the energy efficiency of blowing in the bath of converter without the use of external fuel resources and energy. Accordingly was developed and tested in the laboratory with physical high temperature modeling, of the tuyere with multi-tiered construction. The developed technological solution allows to organizeted blowing in the melt for help of supersonic oxygen jets through Laval’s nozzles and forming torches flame of the {CO} to {CO2}, which directly act on the surface of the melt, due to their formation with curtain sonic oxygen jets, who organizated with help of two separate groups of the cylindrical nozzles. Thanks to the video and photography and chemical selection of the melt samples, out gases from the converter and the measurement of the melt temperature, during the entire purification blowing of the melt, established the peculiarities of the conversion of the melt with using of the multi-tiered tuyere in the space of the converter bath. It is confirmed that with the use of the multi-tiered tuyere the course of converting of the melt, as with the classical multi-nozzle tuyere, consists of three main technological periods: the first — slag formation and “ignition of the melt”; the second — intense carbon oxidation; the third — getting of final chemical composition and temperature of the melt. It is established that the main difference in the use of multi-tiered tuyere lies in the more intensive begining and progress of thermodynamic, hydrogasodynamic and cerculation heating processes, along with the appearance of forming torches flame of the {CO} to {CO2} from the moment of “ignition of the melt”. Directly burning {CO} to {CO2} in a mixture of waste gases leads to a release of the large amount of heat 565 kJ/mol O2. At the same time, it should be noted that the temperature during burning {CO} to {CO2} in a mix of the waste converter gases with oxygen streams reaches up to 3000 °C in a created combustion flame torch. The predominant formation of the flame torches {CO} to {CO2} was observed after the “ignition of the melt” at the first period at the expense a lower group of cylindrical nozzles. The highest intensity of the formation of the flame torches {CO} to {CO2} was obtained in the second period at the blowing in the melt in the conditions of intense oxidation of carbon of melt, until the carbon in the melt was from 1.2 % to 0.9 % it is value of the transition concentration. Formation of the flames torches {CO} to {CO2} was be for all sonic jets from cylindrical nozzles of the lower and upper block of the blowing. At the same time, the location of the blowing blocks and the angle of inclination of the cylindrical nozzles to the vertical axis of the multi-tiered tuyere in these blocks are calculated so as to ensure the interaction of the flames torches {CO} to {CO2} with the layers of melt and transfer up to 65 % of the heat formed from flames torches {CO} to {CO2} to the melt. It is established that the use of the multi-tiered tuyere with group of Laval’s nozzles and two groups of cylindrical nozzles was use to create sonic oxygen jets, that allows increases the burning {CO} to {CO2} in the range from 29 % to 43 %, it is exceeding corresponding indicators with the use of a two-tiered tuyere in the range of 14 % to 28 %, and compared to the multi-nozzles tuyere of the classic conctruction from 24 % to 38 %. At the same initial temperature of liquid cast iron and other conditions in laboratory experiments of the high-temperature physical modeling with using a multi-tiered tuyere with group Laval’s nozzels and with two groups of cylindrical nozzles for blowing, the finaly temperature of the liquid semiproduct of the steel was higher comparatively with use classic multi-nozzles tuyere, only thanks to increasing burning {CO} to {CO2} without the use of external fuel resources and energy during blowing of the melt. Accordingly, this indicates an improvement in the energy efficiency of the converter process with helps of the multi-tiered tuyere. Bibl. 23, Fig. 4.

Transformation Behaviors and Microstructure Modifications in Hydrogen-Charged Ti–Ni Shape Memory Alloy

AbstractThe effect of hydrogen charging duration on the transformation behavior, microstructural evolution, and dynamic microstructural changes associated with thermoelastic martensitic transformation in Ti–Ni shape memory alloy was investigated. Compared with the uncharged specimen, the martensitic transformation start (Ms) and reverse transformation finish (Af) temperatures increased with charging time, whereas the martensitic transformation finish and reverse transformation start temperatures remained almost unchanged. In situ SEM results were consistent with these behaviors. Upon cooling, the transformation progressed from the center to the surface in charged specimens, indicating a higher transformation temperature in the center than the surface. The latent heat of transformation decreased with increasing charging time, quantitatively attributed to an untransformed region consisting of hydrogen-induced martensite and a hydrogen-affected layer. The hydrostatic effect from those layers on the interior B2 phase was proposed as the origin of the increased Ms and Af temperatures.

Practitioner dashboard feedback improves glycemic but not temperature compliance during cardiac surgery: A single center retrospective analysis

Study ObjectiveTo determine the association of practitioner dashboard feedback of intraoperative glycemic and temperature control on maintenance of normoglycemia and normothermia. DesignRetrospective review. SettingSingle tertiary care institution. PatientsPatients over the age of 18 undergoing cardiac surgery from February 17, 2021 through February 16, 2023. During the study interval, 15 anesthesiologists providing care during 2255 procedures were analyzed: 1114 prior to the individual faculty dashboard distribution and 1141 after commencement of dashboard distribution. InterventionsOn February 17, 2022, anesthesia faculty members began receiving monthly individualized dashboards indicating their personal intraoperative glycemic and temperature compliance rates. MeasurementsBaseline patient demographic characteristics, surgical and cardiopulmonary bypass times, perioperative temperature and glucose concentrations, and the incidence of sternal wound infections. Glycemic compliance was defined as final serum glucose between 80 and 180 mg/dL. Temperature compliance was defined as an average temperature during the final 30 min of the surgical procedure between 35 and 37.3 °C inclusive. Main resultsDashboard distribution was associated with a significant decrease in the average glucose concentration (median location shift by −6 mg% (95% confidence interval (CI) -8, −4), p < 0.001) from 157 mg/dL to 152 mg/dL and final glucose concentration (median location shift by −17 mg/dL (95% CI -19, −14, p < 0.001) from 161 mg/dL to 145 mg/dL. The intervention was associated with an improvement in glycemic compliance from 71.4% to 87.1% (odds ratio (OR): 2.71(95% CI 2.19, 3.37, p < 0.001)). There were no significant differences in final temperature (36.3 °C [Q1, Q3: 36.0, 36.6] vs. 36.3 °C [Q1, Q3: 36.0, 36.7] (p = 0.232)) with the intervention nor were there any statistically significant differences in temperature compliance (93.9% vs. 92.9%, OR: 0.79 (95% CI 0.55–1.14, p = 0.25). There were no statistically significant changes in the incidence of superficial, deep, or any wound infections with the intervention. ConclusionsIndividualized practitioner dashboard distribution may be an effective tool to increase intraoperative glycemic control.

Physical mechanisms for dependence of temperature-induced phase transition and shape memory effect on grain size in nanocrystalline NiTi shape memory alloys

Physical mechanisms for dependence of temperature-induced phase transition and shape memory effect (SME) on grain size (GS) of nanocrystalline NiTi shape memory alloys (SMAs) were revealed by combining experiment and molecular dynamics simulation. Influences of GS on phase transition temperature and stress level during tension loading below martensite transition finish temperature Mf are interpreted by core-shell theory that energy of shell (grain boundary (GB)) is higher than that of core (grain interior), so shell becomes an obstacle to deformation of the core and the obstacle increases with reducing GS because the fraction of GB increases with decreasing GS. Due to the constraint of shell, martensite transition during cooling is so incomplete that stress-induced martensite occurs in nanocrystalline NiTi SMAs deformed below Mf. After unloading, some stress-induced martensite phases are retained due to the lack of driving force for reverse martensite transition at low temperature. This is why SME occurs in the alloy with GS below 10 nm when no temperature-induced phase transition happens. Under the same tension strain, inelastic strain after unloading increases with increasing GS. The increase of GS causes the increase of SME strain, and the residual strain after heating the deformed nanocrystalline NiTi SMAs stems from the plastic deformation of martensite and austenite in grain interior during tension.

Effect of UV LED and Pulsed Light Treatments on Polyphenol Oxidase Activity and Escherichia coli Inactivation in Apple Juice.

Enzymatic browning in fruits and vegetables, driven by polyphenol oxidase (PPO) activity, results in color changes and loss of bioactive compounds. Emerging technologies are being explored to prevent this browning and ensure microbial safety in foods. This study assessed the effectiveness of pulsed light (PL) and ultraviolet light-emitting diodes (UV-LED) in inhibiting PPO and inactivating Escherichia coli ATTC 25922 in fresh apple juice (Malus domestica var. Red Delicious). Both treatments' effects on juice quality, including bioactive compounds, color changes, and microbial inactivation, were examined. At similar doses, PL-treated samples (126 J/cm2) showed higher 2,2- diphenyl-1-picrylhydrazyl inhibition (9.5%) compared to UV-LED-treated samples (132 J/cm2), which showed 1.06%. For microbial inactivation, UV-LED achieved greater E. coli reduction (>3 log cycles) and less ascorbic acid degradation (9.4% ± 0.05) than PL. However, increasing PL doses to 176 J/cm2 resulted in more than 5 log cycles reduction of E. coli, showing a synergistic effect with the final temperature reached (55 °C). The Weibull model analyzed survival curves to evaluate inactivation kinetics. UV-LED was superior in preserving thermosensitive compounds, while PL excelled in deactivating more PPO and achieving maximal microbial inactivation more quickly.

Biomass fast pyrolysis kinetics using curie-point pyrolysis: Comparison with pyroprobe and thermogravimetric analysis

In this study, the kinetics of fast pyrolysis of pine wood biomass at short timescales is evaluated using analytical Curie-point and Pyroprobe® pyrolyzers. Curie-point pyrolysis was highly effective in ensuring that the biomass was heated to the set temperatures at very high heating rates and precise time scales. This is the first time the mass loss data of lignocellulosic biomass using a Curie-point pyrolyzer is being reported at short timescales of the order of 10−1 s. COMSOL Multiphysics® simulations, employed to determine the time required for the sample to heat-up to the final reaction temperature, proved that it was 0.2 s in the Curie-point pyrolyzer and 6–8 s in the Pyroprobe® reactor. Within a time period of 0.5 s for temperatures greater than 400 °C, complete conversion of the biomass was achieved using a Curie-point pyrolyzer. The conventional reaction kinetic models were not able to explain the pyrolysis behavior of the sample in a Curie-point pyrolyzer, especially at short timescales of 0–0.5 s. However, the kinetics until 0.4 s, corresponding to the release of light volatiles, is shown to follow the sigmoidal Avrami model, while the major devolatilization stage in the range of 0.4–0.5 s could not be described by a standard kinetic model. This showed that the reactions at short time scales are highly complex processes governed by the competing decomposition rates of the biomolecules. The isothermal mass loss experiments using the Pyroprobe® showed that pyrolysis followed first-order kinetics, and the rate of decomposition was slower as it took 10–20 s for the conversion to attain a steady value. The kinetic compensation for the pyrolysis of pinewood was constructed using the fast pyrolysis data and the kinetics of slow pyrolysis using isoconversional models, and it was found to be ln(A) = 0.18*Ea – 3.12.

CFD Characterization and Field Test Study on Plugging Air Leakage with Time-Varying Viscosity Solidified Foam to Prevent Coal Spontaneous Combustion

ABSTRACT From the perspective of plugging air leakage paths and preventing coal spontaneous combustion in the goaf of coal mines, filling and plugging the ends of the working face is crucial. Generally speaking, rapidly solidified foam slurry is beneficial to plugging air leakage paths. However, researchers have not yet clarified the accumulation and diffusion rules of rapidly solidified foam, resulting in low efficiency in plugging air leakage paths. To solve the above problems, this study takes the goaf of 1301 working faces of the Shandong Lilou Coal Industry as the research object, uses the computational fluid dynamics modeling method to construct a physical model of pressure injection foam slurry, and optimizes the on-site application process parameters of plugging the end of the working face. The numerical simulation results show that coagulant can improve the accumulation characteristics and plugging efficiency of foam slurry, and the optimal addition amount is 3 wt%. In addition, as the perfusion flow increases from 5 to 15 m3/h, the airflow rates on the working face gradually increases and the oxidation zone gradually shrinks. Therefore, the grouting flow is preferably 15 m3/h. Field test results show that rapid-setting inorganic solidified foam blocks the airflow at the air inlet corner from leaking into the goaf and weakens the composite reaction of coal and oxygen. The temperature at each monitoring point first decreased, then stabilized, and the final temperature was maintained at 27-28°C. The CO concentration gradually decreased and finally remained below 20 ppm. The CO concentration of the mine’s total return airflow is stable below 10 ppm. This study can provide theoretical guidance for the technological design of using solidified foam to rapidly plug the air leakage paths at the end of the fully mechanized caving working face.

Quantifying tissue temperature changes induced by infrared neural stimulation: numerical simulation and MR thermometry.

Infrared neural stimulation (INS) delivered via short pulse trains is an innovative tool that has potential for us use for studying brain function and circuitry, brain machine interface, and clinical use. The prevailing mechanism for INS involves the conversion of light energy into thermal transients, leading to neuronal membrane depolarization. Due to the potential risks of thermal damage, it is crucial to ensure that the resulting local temperature increases are within non-damaging limits for brain tissues. Previous studies have estimated damage thresholds using histological methods and have modeled thermal effects based on peripheral nerves. However, additional quantitative measurements and modeling studies are needed for the central nervous system. Here, we performed 7 T MRI thermometry on ex vivo rat brains following the delivery of infrared pulse trains at five different intensities from 0.1-1.0 J/cm2 (each pulse train 1,875 nm, 25 us/pulse, 200 Hz, 0.5 s duration, delivered through 200 µm fiber). Additionally, we utilized the General BioHeat Transfer Model (GBHTM) to simulate local temperature changes in perfused brain tissues while delivering these laser energies to tissue (with optical parameters of human skin) via three different sizes of optical fibers at five energy intensities. The simulation results clearly demonstrate that a 0.5 second INS pulse train induces an increase followed by an immediate drop in temperature at stimulation offset. The delivery of multiple pulse trains with 2.5 s interstimulus interval (ISI) leads to rising temperatures that plateau. Both thermometry and modeling results show that, using parameters that are commonly used in biological applications (200 µm diameter fiber, 0.1-1.0 J/cm2), the final temperature increase at the end of the 60 sec stimuli duration does not exceed 1°C with stimulation values of 0.1-0.5 J/cm2 and does not exceed 2°C with stimulation values of up to 1.0 J/cm2. Thus, the maximum temperature rise is consistent with the thermal damage threshold reported in previous studies. This study provides a quantitative evaluation of the temperature changes induced by INS, suggesting that existing practices pose minimal major safety concerns for biological tissues.

Ablation Resistance of ZrB2-SiC-Si Composite Coatings Applied on Graphite Substrate by Spark Plasma Sintering

In this research, a protective composite coating made of ultra-high-temperature ceramics (UHTCs) was applied on the graphite substrate to boost the ablation resistance of the graphite substrate. Spark plasma sintering (SPS) was used to create such coatings on the graphite substrates. Efforts were made to identify the appropriate chemical composition for the composite coating and the conditions for the SPS (temperature, pressure and holding time). The coatings with a base composition of ZrB2-15 vol.% Si-15 vol.% SiC as well as MoSi2 and WC additives in the same amounts of 0 vol.%, 2.5 vol.% and 5 vol.% of each were applied on the graphite substrates under sintering conditions of final temperature of 1875 ± 25°C, initial pressure of 10 MPa, final load of 25 MPa and holding time of 5 min. The results obtained from the ablation test by oxyacetylene flame verified that the presence of the protective composite coating significantly increases the ablation performance of the graphite substrate. The sample without WC and MoSi2 additives had the lowest mass reduction in longer ablation times, which indicates the high ablation resistance of the base sample compared to the samples with those additives.

Experimental Study on Microwave Drying Aluminum Hydroxide

The aluminum hydroxide produced by the Bayer process contains a large amount of water which leads to the consumption of a large amount of heat for moisture removal in the calcination process, resulting in an increased energy consumption. The effects of temperature and microwave power on the dehydration ratio and the dry matter ratio of aluminum hydroxide were investigated. The characteristics of temperature variation during drying were discussed. X-ray diffraction (XRD), scanning electron microscopy (SEM), laser particle size, Fourier transform infrared (FTIR) spectroscopy, and dielectric property analyses were made to characterize the dried materials. The analysis results showed that within the range of bench-scale experimental parameters, the dehydration ratio was higher and the proportion of dry matter was lower at a higher final temperature. Within the range of pilot-scale experimental parameters, the dehydration ratio increased with the increasing microwave power from 500 W to 1500 W. XRD spectra revealed that when the final temperature exceeded 220 °C, a part of the aluminum hydroxide underwent a low-temperature phase transition to boehmite. The SEM images and a particle size analysis showed that there was no significant difference between the morphologies of the powder obtained by microwave drying and conventional drying methods. The powder obtained by both processes had an average particle size of around 80 μm. The dielectric constant and the dielectric loss of the dried material decreased greatly.

HYSICO-CHEMICAL STUDIES OF DIABASES OF KARAKALPAKSTAN IN THE PRODUCTION OF SILICATE CONSTRUCTION MATERIALS

The article presents the results of experimental studies of diabases from the Keklitau and Sheikhzheli deposits of Karakalpakstan using chemical-mineralogical, X-ray diffraction, analyses. The results of physico-chemical analysis confirmed that diabase from the Keklitau deposit in Karakalpakstan can be used instead of the feldspar component to develop the composition of ceramic products as a grog agent, depending on the final temperature of the fired material.

Effects of Different Initial Conditions on Combustion Process of Ammonium Dinitramide-Based Energetic Propellant in Straight Nozzle

As a new type of green propellant, ammonium dinitramide (ADN)-based energetic propellants have wide application value and development potential in the field of space propulsion. This paper delves into the intricate impact of varying initial temperatures, pressures, and propellant component ratios on critical parameters, including temperature, combustion rate, and heat release, in the straight nozzle of an ADN-based propellant. The findings indicate that an elevation in both initial temperature and ADN ratio expedites the thermal decomposition rate of ADN, thereby elevating the average temperature in the nozzle. However, the elevation in initial temperature has a negative effect on the overall rise amplitude of average temperature. Furthermore, the initial pressure setting is crucial in determining whether the oxidation reaction of the fuel CH3OH occurs in ADN propellants. When the initial pressure is greater than 10 atm, CH3OH is completely consumed, and the final average temperature is about 2650 K, which increases by 558.89% compared with that at 1 atm. Our work aims to provide theoretical guidance and practical optimization strategies for enhancing propellant performance and optimizing thruster structure design.

Multifunctional Nanocomposites in B4C-Tic-Tib2-Sic-BN-Al2O3-Sialon-C Carbon Fiber System for Armor Fillets, Turbine Discs and Wings, High-Temperature Wear Resistant Nodes

Goal - to receive on first stage β - SIALON containing nanocomposites by reactive sintering method at 14000C, with nitrogen pro-cess from origin composition in TiC-BN-SiC-B4C-Si-Al-Al2O3 (nanopowder) system. By using this method of synthesis, it became possible to receive nanocomposites with different percentages of β - SIALON. Our task was to study the phase composition of re-ceived consolidated materials in the TiC-TiB2-BN-SiC-B4C-β-SiAlON-Al2O3 (nanopowder-400nm.) system. Method. The obtained mass was grounded in an attritor and the consolidated composite was obtained by hot pressing at 16200C during 40 minutes, with glass perlite (Armenia) dope 2 mass%, delaying at final temperature for 8 min, under 30 MPa pressure and vacuum – 10-3 Pa. Perlite from Aragatc contained 96 mas. % glass. To study the phase composition of the composites, we conducted an X-ray structural analysis on the DRON-3 device. And to study the microstructure, we conducted research on an optical microscope -AC100 and a raster electron microscope “Nanolab 7” of the company "OPTON”. The values of the electrical parameters of the studied composites were calculated on the basis of the ob-tained "lgp- t" dependence. We have studied mechanical properties. Result. In TiC-TiB2-BN-SiC-B4C- β-SiAlON-Al2O3 – C Carbon Fiber system we obtained nanocomposites with high mechanical proper-ties. The advantage of this method is that compounds, which are newly formed thanks to interaction going on at thermal treat-ment: Si3N4, Si, AlN are active, which contributes to β-SiALON formation at relatively low temperature, at 1300-13500C. It is evi-dent that inculcation of ALN in crystal skeleton of ß-Si3N4 is easier since at this temperature interval crystal skeleton of Si3N4 is still in the process of formation. ß-SiAlON was formed at 14500C. Part of boron carbide was transformed into boron nitride in ni-trogen environment and in titanium diboride, which in the case of both composites is in small quantities. Conclusion. The phase composition of the obtained composite provides high physical-technical and performance properties of these nanocomposites. Compression strength-2198 MPa, Bending strength-271 MPa, Thermal expansion coefficient a20-700-3.8 10-6 0C.

Theoretical and experimental study on total heat recovery of condensing gas boiler flue gas by gas engine-driven compression heat pump

How to improve the utilization efficiency of natural gas and achieve the goal of carbon reduction has gradually become the focus of people’s attention. The exhaust temperature of the condensing gas boiler is between 50℃ and 80℃, which still contains some heat that is not used, so it is necessary to recover this part of the heat. This paper mainly studies the total heat recovery and utilization of waste heat from low-temperature flue gas of condensing gas boiler. In the research field of gas boiler flue gas waste heat recovery, the use of gas compression heat pump to recover gas boiler flue gas waste heat is still very few. Based on the principle of reducing the cold source temperature, a low-temperature flue gas recovery scheme of a gas engine-driven compression heat pump coupled condensing gas boiler is proposed. The low-temperature chilled water produced by gas engine-driven compression heat pump is used to recover flue gas waste heat from condensing gas boiler and gas engine, which can improve the utilization efficiency of natural gas and eliminate the “white smoke phenomenon” simultaneously. In addition, the waste heat of flue gas is used as the low-temperature heat source of gas engine-driven compression heat pump to ensure the stable operation of the heat pump in the low-temperature environment. The flue gas waste heat recovery technology has been improved compared with other flue gas waste heat recovery technologies in terms of primary energy utilization efficiency, system stability, corrosion resistance of flue gas heat exchangers, and investment recovery cycle. The experimental results show that when the water inlet temperature of the flue gas heat exchanger is 15℃, the overall power of the unit can reach 645 kW, and the final exhaust temperature is below 25℃. The overall primary energy utilization rate of the GEHP&CB can reach 110 %, which is 10 %∼20 % higher than that of the condensing gas boiler. The payback period of the increased initial investment is 1.4 heating seasons. Due to the improvement of natural gas utilization efficiency significantly reduces natural gas consumption and pollutant discharge.