High-temperature Mode Research Articles

Higher-order-operator corrections to phase-transition parameters in dimensional reduction

The dynamics of phase transitions (PT) in quantum field theories at finite temperature is most accurately described within the framework of dimensional reduction. In this framework, thermodynamic quantities are computed within the 3-dimensional effective field theory (EFT) that results from integrating out the high-temperature Matsubara modes. However, strong-enough PTs, observable in gravitational wave (GW) detectors, occur often nearby the limit of validity of the EFT, where effective operators can no longer be neglected. Here, we perform a quantitative analysis of the impact of these interactions on the determination of PT parameters. We find that they allow for strong PTs in a wider region of parameter space, and that both the peak frequency and the amplitude of the resulting GW power spectrum can change by more than one order of magnitude when they are included. As a byproduct of this work, we derive equations for computing the bounce solution in the presence of higher-derivative terms, consistently with the EFT power counting.

High-temperature tribological properties and wear mechanisms of multilayered cubic-BN/nanocrystalline diamond tool coatings

Wear failure of cutting inserts is the main form of failure that occurs when cutting difficult-to-machine materials at high speeds. To obtain cutting inserts with outstanding tribological properties, multilayered cubic boron nitride (cBN) and nanocrystalline diamond (NCD) coatings (cBN/NCD) were prepared on WC-6 wt% Co tool substrates. The tribological properties of the multilayered cBN/NCD coatings were studied at different temperatures, and the results showed that the coefficient of friction (COF) and wear rate of the coatings were closely interrelated to the temperatures, and the COF gradually decrease and the wear rate gradually increase as the temperature increased from room temperature (25 °C) to 600 °C. The COF and wear rate of the multilayer coatings at 600 °C were ∼0.05 and 8.43 × 10−6 mm3/(N⋅m), respectively. The wear resistance of the cBN/NCD coatings was higher than that of TiAlN coatings and PcBN tool materials by more than 3 and 4.5 times, respectively. The high-temperature wear failure modes of the multilayered cBN/NCD coatings were abrasive wear, diamond graphitization, and BN hydrolysis. Coating wear accelerated when pores were formed on the cBN surface of a multilayered cBN/NCD coating due to the low nucleation density of diamond. These results would guide the application of cBN/NCD-coated cutting tools in high-speed cutting processes.

Effect of lithium carbonate solution sealing treatment on corrosion resistance of anodized AA2099-T83 alloy

In order to develop a new surface treatment technology for aluminum−lithium alloys, an AA2099-T83 alloy was anodized in a tartaric−sulfuric acid bath and then post-treated in lithium carbonate (Li2CO3) solutions of different temperature−concentration combinations. The results show that the post-treatment in Li2CO3 solutions can greatly improve corrosion resistance of the anodized alloy (withstanding up to 1300 h of neutral salt spray test). It is found that the sealing process is distinctly different for high-temperature/low-concentration and low-temperature/high- concentration combinations. Specifically, the anodic film is only partially sealed in high-temperature mode but more fully sealed in low-temperature mode. The mechanism for the high corrosion resistance of the treated alloy is ascribed to the barrier effect of the sealing products (i.e., Li−Al−LDH and/or boehmite) on the surface and in the interiors of the anodic film.

Alternating load failure analysis under the high-temperatures vibration of thermal barrier coatings

During thermal barrier coatings (TBCs) service, high-temperature and vibration are environmental factors that cannot be ignored. The vibration fatigue damage mode of TBCs under operating conditions that couple vibrations with high temperatures is unclear. In this paper, a high-temperature vibration coupled environment simulator was developed to investigate the evolution of high-temperature vibration fatigue damage modes of LaZrCeO/7-YSZ(LZC/YSZ) TBCs under alternating loads by employing acoustic emission detection. The results show that in the initial fatigue stage, the damage appears as discrete micro-cracks formed by the initial defects in the TBCs. With the increase in the number of cycles, the initiation of transverse microcracks began to occur inside the LZC layer and at the LZC/YSZ interface. When the transverse microcracks accumulate to the critical value, the applied alternating loads accelerate the propagation of opening interfacial cracks. Finally, the columnar crystal structures of the ceramic layers fracture at different heights under cyclic loading by high-temperature vibrations.

Formulation of high-temperature strength equation of 9Cr-ODS tempered martensitic steels using the Larson–Miller parameter and life-fraction rule for rupture life assessment in steady-state, transient, and accident conditions of fast reactor fuel

This paper discusses the applicability of Straalsund et al.’s technique for combining the Larson–Miller parameter (LMP) and life-fraction rule to form a single high-temperature strength equation for 9Cr-oxide-dispersion-strengthened (ODS) tempered martensitic steels (TMS). It uses the extensive dataset on creep rupture, tensile, and temperature-transient-to-burst tests of 9Cr-ODS TMS cladding tubes in the α-phase, α/γ-duplex, γ-phase matrices, which are accumulated by the Japan Atomic Energy Agency so far. The technique is adequately applicable to 9Cr-ODS TMS cladding tubes. A single high-temperature strength equation expressing the mechanical strength in different deformation and rupture modes (creep, tensile, temperature-transient-to-burst) is derived for 9Cr-ODS TMS cladding tubes. This equation can predict the rupture life of the cladding tubes under various stresses and temperatures over time. The applicable range of the high-temperature strength equation is specified in this study and the upper limit temperature for the equation is found to be 1200 °C. At temperatures higher than 1200 °C, the coarsening and aggregation of nanosized oxide particles and the γ to δ phase transformation are reported in previous studies. The high-temperature strength equation can be well applied to the creep and tensile strength in the α-phase matrix, the creep strength in the γ-phase matrix and the temperature-transient-to-burst strength in both phases except for the low equivalent stress (43 MPa) at temperatures exceeding 1050 °C. The mechanism of the notable consistency between creep and tensile strength in the α-phase matrix is discussed by analyzing the high-temperature deformation data in the light of existing deformation models. The study suggested the thermal activation process is dominant even for the high-temperature deformation modes exceeding yield stress in the 9Cr-ODS TMS with the fine-grained matrix.

Insight into the Mechanism Underlying the Reduction of Digestibility and IgG/IgE Binding Ability in Ovalbumin during Different High-Temperature Conduction Modes-Induced Glycation.

Effects of different high-temperature conduction modes [high-temperature air conduction (HAC), high-temperature contact conduction (HCC), high-temperature steam conduction (HSC)]-induced glycation on the digestibility and IgG/IgE-binding ability of ovalbumin (OVA) were studied and the mechanisms were investigated. The conformation in OVA-HSC showed minimal structural changes based on circular dichroism, fluorescence, and ultraviolet spectroscopy. The degree of hydrolysis analysis indicated that glycated OVA was more resistant to digestive enzymes. Liquid chromatography-Orbitrap mass spectrometry identified 11, 14, and 15 glycation sites in OVA-HAC, OVA-HCC, and OVA-HSC, respectively. The IgG/IgE-binding ability of OVA was reduced during glycation and digestion, and the interactions among glycation, allergenicity, and digestibility were further investigated. Glycation sites masked the IgG/IgE epitopes resulting in a reduction in allergenicity. Digestion enzymes destroyed the IgG/IgE epitopes thus reducing allergenicity. Meanwhile, the glycation site in proximity to the digestion site of pepsin was observed to cause a reduction in digestibility.

An innovative method for measuring the hysteresis effects of soil moisture on meteorological variables at various time scales and climate conditions

ABSTRACTUnderstanding the feedback and reactions of soil moisture to meteorological factors in meteorological-hydrological processes is essential due to the growing importance of soil moisture in energy and water cycles in critical zones. Using soil moisture and meteorological data from 1984 to 2018, based on Mann-Kendall and Sen slope trend, two possible patterns of land–atmosphere interaction were discovered in the Yangtze River Basin (YRB), low soil moisture model with less precipitation and higher evapotranspiration, and high-temperature mode with less soil moisture and less evapotranspiration. To measure the hysteresis between soil moisture and precipitation, temperature, and evapotranspiration, a novel method named Three-Step Method was put out. The lag times were measured at ground stations spread across various climatic zones and timescales. The findings demonstrated that the lag times are generally controlled by the regional climate, with shorter lag times in drier regions. Both long-term and short-term responses were seen in soil moisture to meteorological variables. On a monthly scale, soil moisture correlated positively with precipitation but negatively with temperature and evapotranspiration. On an annual scale, precipitation (temperature, evapotranspiration) lagged by roughly 0 to 2 months in the upper and middle regions and by －2 to －6 months in the lower region of the YRB. The contribution rates of meteorological elements on soil moisture were enhanced by taking lag time into account. This study provides a unique perspective for better understanding climate process forecasts and related drought management by considering the hysteresis of soil moisture on the feedback and responses of climate variables.

SIMULATION OF THE PROCESS OF VIBRATING SUNFLOWER DRYING

This work is devoted to the research and substantiation of the technology of drying sunflower seeds and the development of technological and technical proposals for the creation of drying equipment that would ensure work on this crop, both in seed and food modes. The technological value of sunflower seeds is determined by their oil content. Therefore, it is important to preserve the quantity and quality of oil. Under optimal drying conditions, the oil content in sunflower seeds increases. Therefore, the question of selecting technological equipment for the drying process arises. Analysis of the mechanical and technological parameters of series-produced dryers showed that these machines are mainly intended for the processing of grain crops. The disadvantages of well-known mine grain dryers are low moisture removal during one pass of the material through the dryer, overheating of the seed and a decrease in its quality in the area of contact with the surface of the intake boxes, increased fire hazard. Drum grain dryers when drying sunflower seeds are very fire-hazardous and do not allow obtaining seeds with uniform moisture content, and the use of high-temperature modes leads to a decrease in the sowing qualities of seeds due to overheating. When drying sunflower seeds in recirculation type dryers, it is very important to evenly distribute the seeds over the entire cross-section of the chamber, as well as to prevent the accumulation of oil dust in the heating chamber and to eliminate the ingress of sparks from the furnace into the heating chamber. One of the promising methods of drying bulk materials is the method of drying in a vibrating fluidized bed, which can be achieved on vibrating dryers of various types. A number of experiments were conducted to substantiate the technological and technical proposals for the process of drying sunflower seeds and to determine the operating parameters of the dryer. Based on the results, graphs were constructed. The results of the research proved the expediency and necessity of using vibrating dryers during drying of sunflower seeds. The best parameters of the infrared radiation drying process with a selected wavelength of 1,5-3,0 μm , a sunflower seed layer height of 15 mm, and a heat flow density of IR radiation were found. 5 kW/m 2 , the height of the placement of the IR generator blocks relative to the layer of the irradiated product is 25 mm, while the drying time will be 11 minutes.

Thermal Processing of Solid Vegetable Waste by Slow Conductive Pyrolysis

Pilot plants were developed to analyze heat and mass exchanges during the thermal decomposition of ligninocellulose. Methods of experimental research to determine the properties of thermal decomposition products were presented. Studies of thermal decomposition of plant raw materials for classical and high-temperature modes of slow pyrolysis were carried out. The pore structure of the obtained carbonate samples was studied. Optimal modes of slow conductive pyrolysis of vegetable raw materials were proposed. The paper presents the variant of industrial pyrolysis of plant waste into activated carbon.

Effects of different high-temperature conduction modes on the ovalbumin-glucose model: AGEs production and regulation of glycated ovalbumin on gut microbiota

Food high-temperature processing frequently induces the production of advanced glycation end products (AGEs) in the food industry. In this study, the effects of three high-temperature conduction modes on the AGEs production derived from ovalbumin (OVA)-glucose model and the regulation of glycated OVA on gut microbiota were investigated. The peak time of OVA shifted maximally from 13.72 to 13.57 due to the rise in molecular weight, confirming successful coupling between OVA and glucose. The inhibition of superheated steam (SS) on AGEs was observed, with the sample treated by SS showing the lowest content among glycated OVA groups. The analysis revealed an increase in AGEs during digestion and a decrease in fermentation, suggesting the release during digestion and the availability by intestinal flora. Furthermore, an expansion of Bifidobacterium and Lactobacillus, and the inhibition of Desulfovibrio and Escherichia-Shigella were observed, indicating the prebiotic activity of glycated OVA and its potential to improve intestinal health. These results provide valuable information for controlling high-temperature processing to inhibit AGEs formation and highlight the positive effects of glycated proteins on intestinal health.

Highly biomimetic triboelectric-generating soft actuator with a hollow bilayer structure for sensing, temperature-sensitive switching and high-temperature alarm

Biomimetic soft actuators have garnered significant attention due to their exceptional motion performance, which mimics the body structure of animals to deform upon stimulation. However, creating actuators that can generate electricity, emit light, and produce sound like animals remains a daunting challenge. Therefore, a triboelectric-generating soft actuator (TEG-SA) with a hollow bilayer structure that combines a triboelectric nanogenerator (TENG) with a liquid crystal elastomer (LCE) was prepared. The LCE is equipped with poly(vinylidene fluoride) (PVDF) electrospun film and nylon 6/6 film as electric friction layers. Upon deformation by heat, the LCE drives the PVDF and nylon 6/6 to rub together, generating electrical signals, enabling it to achieve self-sensing and obtain the relevant information of the stimulus. Furthermore, the electrical signal can be processed by electronic component and converted into light and sound to alarm for high temperature. The TEG-SA can switch between high-temperature disconnection and conduction modes by a facile position change. The integration of TENG with soft actuators enriches the design of highly bionic actuators, making it a framework for the development of intelligent soft actuators with more stimulus responses.

Humidity effect on temperature behavior of proton diffusion coefficient in sulfonated co-polynaphthoyleneimide membranes measured by 1H NMR diffusometry

Proton diffusion in the co-PNIS85/15 membrane was investigated in the temperature range from 200 to 363 K at different water contents (4 ≤ λ ≤ 21) using 1H SFG NMR diffusometry. At high hydration values, above the threshold value λ0 = 10.5, the ln(DNMR(1/T)) dependences show two different activation modes, separated by a crossover point Tcr ≈ 250–260 K. At temperatures above Tcr, the activation energy is Ea ~ 0.20 eV, which is close to the value for bulk water (Ea ~ 0.17 eV). At temperatures below the crossover point, the ln(DNMR(1/T)) dependences for different water contents merge together into one straight line characterized by a much higher Ea = 0.46 eV. At low hydration values λ < λ0, the activation energies for the high-temperature and low-temperature modes converge, so that at λ = 4, the dependence ln(DNMR(1/T)) is described by one straight line throughout the studied temperature range with Ea = 0.38 eV. A model is proposed that phenomenologically describes the diffusion in the co-PNIS membrane at different moisture contents λ.

Hydrophobic, Mechanical, and Physical Properties of Polyurethane Nanocomposite: Synergistic Impact of Mg(OH)2 and SiO2.

Polyurethane (PU) is one of the most well-known polymer coatings because of its favorable characteristics, which include its low density, nontoxicity, nonflammability, longevity, adhesion, simple manufacture, flexibility, and hardness. However, PU does come with several major drawbacks, among which are poor mechanical properties as well as low thermal and chemical stability, particularly in the high-temperature mode, where becomes gets flammable and loses adhesion ability. The limitations have inspired researchers to develop a PU composite to improve the weaknesses by adding different reinforcements. Magnesium hydroxide, having the ability to be produced with exceptional properties such as flammability, has consistently attracted the interest of researchers. Additionally, silica nanoparticles with high strength and hardness are one of the excellent reinforcements of polymers these days. The hydrophobic, physical, and mechanical properties of pure polyurethane and the composite type (nano, micro, and hybrid) fabricated with the drop casting method were examined in this study. 3-Aminopropyl triethoxysilane was applied as a functionalized agent. To confirm that hydrophilic particles turned into hydrophobic, FTIR analysis was carried out. The impact of size, percentage, and kind of fillers on different properties of PU/Mg(OH)2-SiO2 was then investigated using different analyses including spectroscopy and mechanical and hydrophobicity tests. The resultant observations demonstrated that different surface topographies can be obtained from the presence of particles of different sizes and percentages on the hybrid composite's surface. Surface roughness allowed for exceptionally high water contact angles, which confirmed the hybrid polymer coatings' superhydrophobic properties. According to the particle size and content, the distribution of fillers in the matrix also improved the mechanical properties.

Mathematical Model and Numerical Method of Calculating the Dynamics of High-Temperature Drying of Milled Peat for the Production of Fuel Briquettes

Milled peat must be dried for the production of peat fuel briquettes. The current trend in the creation of drying technologies is the intensification of the dehydration process while obtaining a high-quality final product. An increase in the temperature of the drying agent, above 300 °C, significantly accelerates the reaching of the final moisture content of the peat. In the final stage, it is also accompanied by partial thermal decomposition of the solid phase. Its first stage, which is the decomposition of hemicellulose, contributes to a decrease in weight and an increase in the caloric content of the dry residue. The development of high-temperature drying modes consists of determining the temperature and velocity of the drying agent, wherein the duration of the material reaching the equilibrium moisture content will be minimal and the temperature of the material will not rise above the second-stage decomposition temperature of cellulose. This problem can be solved by the mathematical modeling of the dynamics of peat particles drying in the flow. The article presents a mathematical model of heat and mass transfer, phase transitions, and shrinkage during the dehydration of milled peat particles. The equations of the mathematical model were built based on the differential equation of mass transfer in open deformable systems, which, in the absence of deformations, turns into the known equation of state. A numerical method for implementing a mathematical model has been developed. The adequacy of the mathematical model is confirmed by comparing the results of numerical modeling with known experimental data.

PZT-based high-temperature ultrasonic dual mode transducer applicable to cubic-anvil apparatus for sound velocity measurement

The ultrasonic transducer is an indispensably critical component for sound velocity measurement. With the increasing demand of high-temperature ultrasonic dual mode transducer applicable to cubic-anvil apparatus, where experiments of high-pressure and high-temperature sound velocity are routinely conducted, a PZT-based ultrasonic dual mode transducer was presented in this study. It was made of a sandwich of two PZT piezoceramic wafers, the upper one generating P-waves and the lower one generating S-waves. The transducer was directly bonded onto a WC anvil of cubic-anvil apparatus using high-temperature adhesive, and then heated in an oven while measuring the bottom echoes from the WC anvil. The results showed that the high-temperature transducer could work up to 140 °C. The transducer features low cost, easy fabricating, and highquality signals, and so we believe it is useful for sound velocity measurement at high temperatures in cubic-anvil apparatus.

ADAPTIVE INFLUENCE OF PRESSURE CHANGE OF THE HYDRAULIC SYSTEM OF THE HYDRAULIC DRIVE

The efficiency of hydrogenated machines of various technological purposes depends to a large extent on the temperature of the environment. Temperature is the main factor in the efficiency of the hydraulic drive, which changes the physical properties of the working fluid: viscosity, moisture content, gases and mechanical impurities, which determine its modulus of elasticity. Efficiency is significantly reduced both at low temperatures and at high temperatures. The high-temperature mode of the hydraulic drive reduces the technical and operational performance of hydraulic machines (construction and road, mountain, agricultural and other self-propelled machines). High temperature is one of the most important factors that intensively affect the aging of the working fluid. An increase in the temperature of the lubricant above 70° C leads to a decrease in the lubricating capacity and premature wear of the equipment, an increase in the leakage of the lubricant, a decrease in its viscosity, thermal destruction with the formation of tarry deposits on the internal surfaces of the hydraulic equipment. Intensive wear is observed due to a decrease in the lubricating capacity of the friction surfaces, a decrease volumetric efficiency of hydraulic machines, changes in the linear dimensions of heated elements, as a result, the accuracy of technological operations deteriorates and the resource of hydraulic equipment is significantly reduced. All this leads to a decrease in the parameters of productivity and reliability of machines. Hydrogenated machines operated at elevated temperatures require a number of measures to increase heat transfer and stabilize the temperature regime. This article examines the issue of determining the given modulus of elasticity of the hydraulic system of a volumetric hydraulic drive using the example of the experimental model of the TT4M-23L tracked crawler tractor and the relationship of the given modulus with pressure and temperature. An equation is calculated that allows establishing the relationship between pressure and the given modulus of elasticity of the hydraulic system.

Optimization of Aluminum Boride Synthesis in the Self-Propagating High-Temperature Synthesis Mode to Create Waste-Free Technology

This paper is the continuation of our previous paper. In this work, we optimized the synthesis of aluminum borides by the SHS method. The purpose of the research was to develop the foundations of waste-free technology. The initial components were powders of boric anhydride (B2O3), aluminum (Al), the oxide-heating additive (KNO3), various fluxing additives, including mixed ones. The optimal ratios of the initial components for increasing the yield of aluminum boride with a high boron content and obtaining slag suitable for the production of high-alumina clinkers were determined. Studies have shown that the development of a waste-free technology for producing aluminum borides by the method of self-propagating high-temperature synthesis (SHS) is possible and yields target (alloy) and by-product (slag) products that meet the requirements for chemical and phase composition.

Synthesis in hydride cycle of Ti–Al–C based MAX phases from mixtures of titanium carbohydrides and aluminum powders

MAX phases are new type of easily machinable cermets, demanded in modern materials science as construction materials. One of the most widely studied and promising representatives of the titanium-based MAX phases are hexagonal Ti2AlC and Ti3AlC2. Current methods of their synthesis are unsuitable for their mass production. The creation and development of new methods and technologies for their producing are urgent tasks of materials science. The modern technologies are required providing high quality and productivity, cost-effective, environmentally friendly and easily scaled methods. In 2007, in our Laboratory of High-Temperature Synthesis of the IChPh of Armenian NAS, the Hydride Cycle method (HC) for synthesis of refractory alloys and intermetallic compounds was elaborated. The gist of this method is the use of the synthesized by Self-propagating High-temperature Synthesis mode (SHS) transition metal hydrides as starting materials. In the present work, for the first time, the HC method was applied in the synthesis of Ti2AlC and Ti3AlC2 MAX phases. Preliminarily, HCP TiC0.45H1.07÷1.17, FCC TiC0.5H0.22÷0.73 and TiC0.67H0.31-0.39 titanium carbohydrides were synthesized in the SHS mode and used as starting reagents. The present work was set to study the effect on the phase composition and structure of the synthesized MAX phases of conditions of HC. The analysis methods, used to certify the synthesized MAX phases, were: chemical, differential-thermal, X-ray phase. The microstructures of the samples were snapshot on SEM Prisma E scanning electron microscope. The work resulted in the synthesis in HC of single-phase Ti2AlC and Ti3AlC2 MAX phases with unit cell parameters [а = 3.0553; c = 13.6459; c/a = 4.466; P63/mmc] and [a = 3.0552; c = 18.7396; c/a = 6.132], respectively. This work demonstrated advantages of HC over the traditional methods of MAX phases synthesis.

In Ukrainian

The ratchet effect is a directed nanoparticle flux phenomenon induced by nonequilibrium fluctuations in a system with spatial and (or) temporal asymmetry. One is used as the way to create a controlled nanotransport and is the basis of the theory of Brownian motors. Fluctuation motion simulation is a promising way to calculate the main characteristics of Brownian motors, it avoids complex calculations and quickly obtains predictions about the appearance or absence of generated directional motion in a specific model. Nonequilibrium fluctuations are usually introduced into the system by a dichotomous process that switches two periodic asymmetric potential profiles at certain fixed intervals (deterministic process), or randomly with average potential lifetimes (stochastic process). We investigate the modeling of the process of the ratchet effect in the framework of the Brownian motor jump-like model by the method of Parrondo’s paradoxical game for the stochastic dichotomous process and compare results with a similar deterministic process. A calculus method for the main characteristics obtaining of the motor with stochastic dichotomous process is proposed, it is shown correspondence to the analytical description of this model in extreme cases. It is shown that the stochasticity of the process directly affects the characteristics of the ratchet effect: the trajectories of the average displacements of nanoparticles fundamentally differs in the deterministic description, and a gradual difference in these processes is observed at low values. The study of asymmetric dichotomous processes for different temperature modes of motor operation is carried out. The model allows one to analyze the peculiarities of the directional motion starting at the level of single jumps, as well as to formulate recommendations for possible improvement of motor efficiency for different temperatures. For high-temperature mode, it is advisable to reduce the lifetime of the state with the active potential, and for low-temperature mode, arbitrary, it should be increased.

3D 변형 공정 지도 기반 AISI 4340 소재의 열간 단조 온도 및 변형률 속도 제어

This paper investigated the hot deformation behavior of an AISI 4340 material through high-temperature compression experiments. The compression tests were performed to obtain stress-strain curves at processing temperatures of 900, 1,000, 1,100, and 1,200℃, and the strain rates of 0.01, 0.1, 1, and 10 sSUP-1/SUP up to a true strain of 1.0 in the high-temperature compression mode of GleebleSUP®/SUP 3,500. A novel 3D processing map, constructed through power dissipation efficiency and Ziegler