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Digital image correlation (DIC) method was employed to analyze the dynamic bending of a metallized Si3N4 substrate in thermal cycles ranging from −40°C to 250°C. The substrate was monitored by DIC over several consecutive cycles, spanning from 0 to 2501. Three DIC measurement intervals, specifically during 999–1001, 1999–2001, and 2499–2501 cycles, were selected to analyze the bending behavior in response to temperature fluctuations. By the scanning acoustic microscope (SAM), the substrate revealed negligible delamination after 1001 cycles, light delamination after 2001 cycles, and serious delamination post‐2501 cycles. The dynamic bending remained unchanged during 999–1001 cycles. A curve with a negative bending was observed during 1999–2001 cycles, with a peak curvature of.024 mm−1 at −40°C; the negative bending intensified with a curvature reaching.050 mm−1 at −40°C during 2499–2501 cycles. The bending curve then decreased during the heating phase and returned to a non‐bent state at elevated temperatures. The bending curve reversed to positive at 250°C during thermal cycles from 2499 to 2501. The bending behavior throughout thermal cycles was discussed in relation to the asymmetric delamination observed on both sides of the substrate, as well as the distribution of delamination. [ABSTRACT FROM AUTHOR]

The results of research on the improvement of low-temperature plasma generators for surface treatment of wearing parts of technological equipment, as well as for modification of the surfaces of parts before the start of their operation, are presented. An analysis of the applied schemes of low-temperature plasma generators is carried out. Based on this analysis, the optimal scheme for the low-temperature plasma generators under consideration is selected and their main technical characteristics are presented. It has been established that, with a rational design and layout scheme and the correct choice of processing modes, the thermal efficiency of plasma processes increases with a simultaneous increase in the service life of the cathode of the low-temperature plasma generator. The results of this research made it possible to develop low-temperature plasma generators with an increased resource and improved energy characteristics for surface treatment of parts of technological equipment for beet sugar production. [ABSTRACT FROM AUTHOR]

Phase change materials (PCMs) have attracted increasing attention due to their efficient heat storage capability and small temperature fluctuation. And encapsulation has been recognized as an effective method to solve issues such as corrosion and leakage. For a long time, restricted by thermal expansion, encapsulation of PCMs has remained in the low‐temperature field and liquid‐state coating. In recent years, with the expansion of PCMs encapsulation into the medium and high temperature field and the development of solid‐state coating technology, encapsulation methods that consider thermal expansion have greatly improved the cycle life of encapsulated PCMs and make solid‐state coating of medium and high temperature PCMs possible. Herein, first, this paper summarizes the thermal expansion rates of common core and shell materials, as well as the thermal expansion behavior and stress analysis within confined spaces, proposing the necessity to solve thermal expansion issues. Subsequently, the solution strategies for solving thermal expansion issues in both macrocapsules and microcapsules are introduced. On this basis, the advantages and disadvantages of each strategy have been compared, and the applications of encapsulated PCMs after resolving thermal expansion issues have been introduced. Finally, the current issues, corresponding solutions, and future research directions have been put forward. [ABSTRACT FROM AUTHOR]

This paper presents the results of the adhesion resistance before and after cyclic thermal treatments in NiCoCrAlY bond-coat (BC) coatings reinforced with dispersed SiC-ZrB 2 particles and conventional NiCoCrAlY. The ASTM-C-633 standard test method for the adhesion or cohesion strength of thermal spray coatings was used. The microstructure and morphology of the coatings were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. Microhardness and coefficient of thermal expansion were also measured. The addition of SiC-ZrB 2 particles improved the long-term adhesion resistance by 1825 % compared to the system without reinforcement after 275 cycles. This improvement is attributed firstly to a self-healing mechanism and secondly to the lower thermal expansion coefficient (32.60 % lower) of the BC layer reinforced with SiC-ZrB 2 , which delayed the formation of cracks at earlier stages associated with CTE mismatch. [ABSTRACT FROM AUTHOR]

This paper provides a comprehensive evaluation of using 3D-printed composite molds to produce components for the automotive sector in carbon fiber-reinforced polymers (CFRPs). Two molds in Carbon PA, i.e. PA6 reinforced with 20% by weight short carbon fibers, were realized via fused filament fabrication and subjected to multiple thermal cycles to simulate successive curing operations. Mold distortions were measured using a coordinate measuring machine before and after each heat treatment. Additionally, finite element method (FEM) and life cycle assessment (LCA) analyses were performed to obtain a complete overview of the 3D printed mold use and provide an industrial decision-making tool. Results showed that the mold distortion increases with temperature, and the clamping effect is more pronounced at the mold's edges, and it is reduced in the center. Irrespective of the thermal cycle temperature, the highest distortion was observed on the upper surface, with reduced deformation on the composite layup plane. FEM simulations confirmed that, following bolt tightening, the molds can resist without critical stress or plastic deformation. LCA analysis demonstrated that 3D-printed molds reduce environmental impact by 18% compared to aluminum ones, leading to more sustainability benefits for low-volume production, making them ideal for prototyping, small batches, or customized components. The potential of 3D-printed molds as a valid alternative to traditional methods to produce low-volume CFRPs was demonstrated. The implications of this study highlight the efficiency and sustainability benefits of 3D printing technology in composite manufacturing, offering a flexible solution for industries where small production runs and customization are critical. [ABSTRACT FROM AUTHOR]

The burning chamber wall of the ramjet engine is facing an extremely thermal environment during normal conditions. Thermal protection measures must be taken on the wall surface of the combustion chamber. At the same time, the aircraft faces high-power electrical demand problems under high-speed cruising states. To address these issues, a second fluid-closed Brayton cycle system was introduced in this paper. Helium was utilized as the secondary fluid medium, while kerosene was used as the final heat sink. The ramjet engine chamber wall was cooled by the helium cycle system. At the same time, part of the heat absorbed by the helium cycle was transformed into electric power by a generator. This work proposes a new method of thermal management in a closed cycle. Unlike traditional methods, this proposal can regulate the mass flow rate of helium based on the requirement of heat load. A zero-dimensional numerical calculation method was established for thermodynamic analysis. The results show that as the equivalence ratio of 0.8~1.5 for the kerosene flow rate, the system can suffer the thermal load of 200~350 kJ/kg on the combustion chamber wall at the maximum kerosene allowable temperature. To ensure the normal operation of the circulating system, the mass flow ratio between the helium and the air changes from 0.02 to 0.045. Compared with the direct kerosene cooling method, the second fluid circulation method leads to the kerosene equivalent saving ratio by 2% to 14%; at the same time, such a system could generate 160~500 kJ/kg of electrical energy. This new thermal management method can achieve kerosene saving, electric power generating and suffering more thermal loads under the premise of satisfying normal work. [ABSTRACT FROM AUTHOR]

In this paper, the effect of heat input on the temperature of bobbin tool friction stir welding (BT-FSW) joint in 16-mm-thickness 6061-T6 aluminum alloy plate is investigated by means of COMSOL Multiphysics 5.6 multi-physics field simulation software and K-sheathed thermocouple. Furthermore, the effect of heat input on the microstructure and mechanical properties of the joint is explored through the use of confocal laser scanning microscope (CLSM), electron back scatter diffraction (EBSD), and hardness and tensile measurements. The thermal impact factor (f) is regarded as a representation of heat input, and the experimental results show that when the f-value increases from 1.5 to 2.5, the simulated peak temperature increases from 426.85 to 467.85 °C, and the simulated temperature is higher about 10℃ than the measured temperature. Hole-type defects are observed at the junction of advancing side (AS) thermal-mechanically affected zone (TMAZ) and stirred zone (SZ) of the joint when f-value is 2, and the size of the defect increases when f-value is 2.5. The average grain size and the degree of recrystallization of SZ increase, but the dislocation density decreases as the f-value increases. Comparing the microhardness curves of the three groups of joints, it is found that the microhardness of each region decreases with the increase of f-value, with the microhardness of SZ decreasing from 88 to 72 HV. The tensile strength of the joints decreases from 225 to 199 MPa, the elongation increases from 8.33 to 10.32%, and the fracture morphology changes from equiaxial dimple to parabolic dimple. [ABSTRACT FROM AUTHOR]

The relationship between thermal cycle, microstructures and properties of the joint in bobbin tool friction stir welding (BT-FSW) of aluminum alloys thick plates has not been reported in the literature, and the variations of microstructures and properties along the thickness direction needs to be explored. The objective of this paper is to interpret the evolution of thermal cycle, microstructures and mechanical properties of 16 mm thick 6061-T6 aluminum alloy BT-FSW joint in the thickness direction. With a traverse speed of 200 mm/min and 300 r/min of rotation speed, the thermal cycle temperature of the joint central layer is about 6 ℃ lower than that of the Shoulder Affected Zone (SAZ), and the Retreating Side (RS) are about 20 ℃ higher than the Advancing Side (AS). In order to illustrate the differences in the thickness direction of the joint, the joint was divided equally into three slices along the thickness direction. It is found that the equiaxed grains sizes of the Stir Zone (SZ) are 19.6 µm, 15.2 µm and 21.3 µm respectively in each region of the SZ1, SZ2 and SZ3 in the thickness direction, and the recrystallization extent of the SZ1 and SZ3 is higher than that of the SZ2. Transition from the SZ to the Heat-Affected Zone (HAZ), where the precipitates changes from the cluster-GP zone and β phase to the β” and β’ phases. The Vickers hardness curves for the cross-section of the joint are W-shaped, and the minimum Vickers hardness is found in the transition zone of the Thermal-Mechanically Affected Zone (TMAZ) and HAZ, which is 60 HV, and the SAZ has roughly 10 HV greater hardness than that of the central layer of the SZ. Along the thickness direction, the average tensile strength of the slices #1, #2 and #3 of the joints are 188 MPa, and 160 MPa, and 180 MPa respectively. The fracture of the three slices is ductile fractures. [ABSTRACT FROM AUTHOR]

Copyright of Necmettin Erbakan University Dental Journal (NEU Dent J) is the property of Necmettin Erbakan University Dental Journal (NEU Dent J) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Improper thermal cycles on duplex stainless steels can lead to the formation of detrimental phases or alter the proportion of ferrite and austenite phases, thus influencing the material's mechanical properties and corrosion resistance. Therefore, this study aimed to evaluate the effect of aging (at 850 and 950 °C) and solubilization (at 1000 and 1150 °C) thermal treatments on microstructure, indentation hardness, elasticity modulus, and susceptibility to intergranular corrosion of UNS S32205 duplex stainless steel. The sigma phase (σ) formation in the aged samples, with hardness values between 8 and 10 GPa, was confirmed. Furthermore, the pieces treated from 1000 °C upwards showed that increased temperature favored the formation of more equiaxial grains and the ferrite fraction growth. The thermal treatments barely affected the elasticity modulus of austenite and ferrite grains, increasing the hardness of ferrite. The effect of sulfuric acid concentration in the intergranular corrosion was evaluated. Also, the deconvolution of the corrosion curves permits the determination of the influence of the different phases in the corrosion performance. These tests revealed sensitization only at the σ phase grain boundaries in the samples treated at 850 °C in electrolytes containing H2SO4 2.5 mol/L and HCl 1 mol/L. Although the treatment at 950 °C led to the σ phase formation, its higher corrosion resistance was ascribed to the lower volumetric fraction of this phase, its morphology, and its increased Cr mobility compared to the 850 °C treatment. Therefore, it was shown that the σ characteristics and the sulfuric acid concentrations are determining factors in the UNS S32205 intergranular corrosion resistance. [ABSTRACT FROM AUTHOR]

The influence of thermal damage on macroscopic and microscopic characteristics of different rocks has received much attention in the field of rock engineering. When the rocks are subjected to thermal treatment, the change of macroscopic characteristics and evolution of micro-structure would be induced, ultimately resulting in different degrees of thermal damage in rocks. To better understand the thermal damage mechanism of different rocks and its effect on the rock performance, this study reviews a large number of test results of rock specimens experiencing heating and cooling treatment in the laboratory. Firstly, the variations of macroscopic behaviors, including physical parameters, mechanical parameters, thermal conductivity and permeability, are examined. The variations of mechanical parameters with thermal treatment variables (i.e. temperature or the number of thermal cycles) are divided into four types. Secondly, several measuring methods for microstructure, such as polarizing microscopy, fluorescent method, scanning electron microscopy (SEM), X-ray computerized tomography (CT), acoustic emission (AE) and ultrasonic technique, are introduced. Furthermore, the effect of thermal damage on the mechanical parameters of rocks in response to different thermal treatments, involving temperature magnitude, cooling method and thermal cycle, are discussed. Finally, the limitations and prospects for the research of rock thermal damage are proposed.

The objectives of this study were to evaluate the bonding durability of four different self-etch adhesives to dentin after 24 h and thermal cycling (TC) and to measure the degree of polymerization conversion (DC) in situ. Two-step self-etch adhesives, Clearfil SE Bond 2 (SE2, Kuraray Noritake Dental) and G2-Bond Universal (G2B, GC), and one-step self-etch adhesives, Scotchbond™ Universal Plus Adhesive (SBU, 3M ESPE) and Clearfil Universal Bond Quick (UBQ, Kuraray Noritake Dental), were used. The labial surfaces of bovine teeth were ground to create flat dentin surfaces. The adhesives were applied according to the manufacturers' instructions. After resin composite buildup and 24 h water storage, the specimens were sectioned into beams and all groups were subjected to thermal stress for 0, 10,000 (10k), or 20,000 (20k) cycles followed by micro-tensile bond strength (µTBS) testing. In situ DC was investigated with a laser Raman microscope. The µTBS data were statistically analyzed and subjected to a Weibull analysis. The different groups were compared at the characteristic strength (63.2% probability of failure) (α = 0.05). Two-Way ANOVA was used to show the effect of different adhesives and thermal cycling on the mean DC% followed by Tukey's multiple comparison post hoc test. G2B/TC10k resulted in a significant increase in the µTBS compared to TC0. SBU/TC20k showed significantly higher µTBS compared to TC0. For comparison between different tested adhesives, SBU showed a significantly lower µTBS compared to G2B after TC10k. G2B and SBU showed a greater number of adhesive failures after TC. Mean DC% was different for each adhesive. The newly developed MDP- and HEMA-free 2-SEA showed similar bonding performance with the gold-standard 2-SEA. However, there is still room for further improvement in terms of SEAs. [ABSTRACT FROM AUTHOR]

Components used for the structure of the GLObal SolarWind Structure experiment in the NASA Interstellar Mapping and Acceleration Probe space mission, made of AA6061-T6 alloy, are subjected to the coating process, where the temperature affects its mechanical properties. This paper aims to examine the impact of the coating thermal cycle on the mechanical properties of AA6061-T6 alloy, which is the load-carrying material in a spaceborne instrument. As a part of the manufacturing process, the parts made of AA6061-T6 are subjected to a coating process at a temperature of about 220°C for a time longer than 1 hour. This treatment modifies the mechanical properties of the alloy. To evaluate the consequences of this change for spaceborne components, mechanical testing, and numerical simulation were conducted. It was found that as a result of the coating process, the reduction in AA6061-T6 yield strength is about 16%, which entails a decrease in the margins of safety by 25% at its maximum. [ABSTRACT FROM AUTHOR]

At present, additive technologies, especially the electric arc growth method as the most universal and productive, have been used for the production of individual machine parts. The problem of studying the process of alloy structure formation during electric arc additive growth to ensure the necessary parameters of the material microstructure and its mechanical properties has been especially relevant. Samples for research from steel 09G2S have been produced using a developed stand implementing the technology of 3D printing by electric arc surfacing, the method of microstructural studies on an optical microscope has been applied, and microhardness measurements have been carried out. The features of the structure formation of the 09G2S alloy during additive electric arc growth have been determined, and controlled parameters have been identified to ensure the necessary indicators of the structure and, consequently, the mechanical properties of the alloy. During the study of the samples, it has been found that the linear energy of the surfacing process and the temperature of the thermal cycle play a significant role in the formation of the material structure. The performed study and the established dependencies make it possible to control the structural state of steel 09G2S during surfacing to ensure the required parameters of the microstructure and mechanical properties of the material. [ABSTRACT FROM AUTHOR]

This study presents experimental findings from rotary friction welding of AA5083-H112 and AA7075-T6, conducted at consistent 1700 rpm rotational speed with four time intervals. The focus was on exploring the welding parameters influence on joint properties, assessed through mechanical testing, metallography and hardness tests. Prolonged welding led to elevated temperatures, expanding the heat-affected zone, grain growth and microhardness at the interface. The temperatures effect on joint toughness was evaluated through Charpy impact testing at different temperatures, showing lower impact strength at −192 °C. Fracture surfaces exhibited increased micro voids and dimples as the temperatures decreased. The study highlighted a positive link between extended welding times and improved cryogenic impact strength and mechanical properties. [ABSTRACT FROM AUTHOR]

Copyright of Journal of the Chinese Society of Rare Earths is the property of Editorial Department of Journal of the Chinese Society of Rare Earths and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the present scenario, research on Thermal Barrier Coatings (TBCs) is attracting significant attention in high-temperature applications due to the rising demand in industrial applications, such as gas turbine blades and internal combustion engine components. To meet these demands, it is essential to enhance the mechanical and oxidation properties of thermal barrier coatings. The atmospheric plasma spray methodology for producing these coatings has become a central focus in recent times. In this work, TBCs were prepared by blending pure alumina and Yttria-Stabilized Zirconia (YSZ) in equal proportions. Extensive study of TBCs carried out under high-temperature conditions through thermal cycle tests at elevated temperatures, around 850 °C. A total of 350 thermal cycles were conducted, and microstructures of the coating surface were examined at 150, 250, and 350 cycles. High-temperature stress, generated due to the sintering of the coating, also influences the life of the coatings. Specimen with a topcoat thickness of 300 μm, exhibited good thermal shock resistance compared to the specimens with topcoats of thickness of 100 μm and 200 μm. The effects of process parameters, porosity, and thermal shock resistance are presented in detail. The topcoat with a thickness of 300 μm demonstrated excellent thermal shock resistance and reduced formation of thermally grown oxide (TGO). The porosity of the coating, found to be between 2% and 3%, contributed to its dense nature, effectively reducing oxidation rates and enhancing the coating's lifespan under cyclic high-temperature conditions.

Repassivation characteristics of carbon steel experienced thermal cycles in tropical marine environments were investigated in a simulated concrete pore solution (SCPS). The results suggested that the damage of passive films on the carbon steel mainly occurred during the cooling process in thermal cycles. The damaged passive films gradually recovered in the SCPS, and the duration of repassivation extended with the amplitude of thermal cycles and cyclic number in the high-amplitude thermal cycles (20–60 °C and 20–70 °C), while it was not significantly affected by the cyclic number in the low-amplitude thermal cycles (20–40 °C and 20–50 °C). [ABSTRACT FROM AUTHOR]

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The tungsten-copper alloy is commonly used for the electrical contact in high current vacuum switch, where precise temperature monitoring of the contact is crucial for ensuring stable operation of the switch by radiation thermometry. However, accurate emissivity data of this alloy is necessary when using radiation thermometry for temperature measurement. Thus, the directional spectral emissivity of tungsten-copper alloy is investigated within the temperature range of 400–700 ℃ under vacuum in this work. The hemispherical total emissivity is calculated by numerically integrating the directional spectral emissivity. Experimental results found this tungsten-copper alloy agrees with the theoretical prediction of the electromagnetic theory, that is, the emissivity increases with increasing temperature, and decreases with increasing wavelength. A convergence phenomenon of spectral emissivity occurs when the polar angle exceeds approximately 50°. This means that the normal wavelength dependence undergoes a shift at high polar angles, which is typical behavior of metallic emissivity. Additionally, the effects of thermal cycle, surface roughness, and chemical composition on emissivity are analyzed in detail. Surface stress relaxation process results in a significant decrease in emissivity. Emissivity increases as the surface roughness and tungsten composition of alloy increases. However, the effects of surface roughness and chemical composition on emissivity gradually disappear at long wavelengths and high polar angles. [ABSTRACT FROM AUTHOR]

Copyright of Necmettin Erbakan University Dental Journal (NEU Dent J) is the property of Necmettin Erbakan University Dental Journal (NEU Dent J) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In fusion welding processes, the components to be joined are subjected to a thermal cycle which influences their microstructure and thus the resulting mechanical properties and the behavior of the resulting welded construction in exploitation. The paper presents the possibilities of monitoring the temperature of the welding thermal cycle for fusion welding of S890QL type steel using the Gas Metal Arc Welding robotic process. For the measurement of the temperature values related to the thermal cycle in welding, contact (contact thermometer and thermocouples) and noncontact measurement methods (infrared thermography) were used

The extreme temperature fluctuations and the vacuum of the space environment make growing plants in outer space challenging. To simulate the temperature fluctuations and vacuum conditions associated with space environments, dry tomato seeds were placed in a thermal cycle simulator and vacuum simulator chamber of space systems, respectively. A Bradford method was used to determine the total protein content of each group of seeds. Sodium dodecyl-sulfate polyacrylamide gel electrophoresis was used to separate proteins. The seed of the thermal cycle group had the highest protein content (26 to 31 mg/ml), followed by control seeds (8-10 mg/ml) and the vacuum seeds (4-5.6 mg/ml). The molecular weights of the peptides ranged from 8 to 42 kDa. The intensity of the protein bands was significantly different in the thermal cycle group from the other two groups, and vacuum group had the lowest intensity. Water and oil released from seeds in the vacuum environment resulted in a reduction of protein content. In the thermal cycle group, the total protein content and the intensity of the bands were significantly higher than those treated with the control group, which can be attributed to the degradation of storage proteins involved in seed germination in the control group.

Background and objectives: To evaluate and compare the color stability and surface roughness of different composite resins after using different polishing systems and then submitting to accelerating artificial aging (AAA) and staining by black tea. Method: Twenty disk-shaped specimens (were compacted into the custom-made cylindrical plastic mold that had an internal diameter of 10 mm and a depth of 2 mm) were prepared for each composite resin type (3M Z350, Tokoyama Palfique, and Shofu Beautifil II) for a total of 60 specimens, each composite group was divided into two subgroups according to the polishing system (n=10) (Shofu super-snap polishing disks and Eve Diacomp Plus Twist wheel). Color parameters (L*, a*, and b*) and surface roughness were measured before and after accelerating artificial aging (2000–4000 thermal cycles) and staining. Results: It was observed that all resin-based materials showed an increase in color change value and surface roughness value after 2000 thermal cycles. while after 4000 thermal cycles, only the surface roughness value decreased in all resin-based materials. Conclusion: all resin-based materials showed clinically acceptable color stability (ΔΕ < 3.7) and surface roughness >0.2 µm) after (2000 thermal cycle) and staining.

In this research, a digital image correlation method was employed to measure the thermal strain of a metallized silicon nitride substrate subjected to multiple successive thermal cycles from −40 to 250°C. In all the thermal strain curves observed during the 1000 thermal cycles, consistent hysteresis loops were detected. At the beginning of the heating or cooling process, the curves display slopes nearly identical to the theoretical coefficient of the thermal expansion (CTE) of the metallized composite. Subsequently, the slope gradually decreased until the completion of heating or cooling and eventually reached the CTE of the plain silicon nitride substrate. However, as the number of thermal cycles increased, the deviation temperature from the theoretical CTE during heating increased, whereas the temperature decreased during cooling, but it did so to a lower temperature. The maximum expansion and contraction observed during each cycle increased equally between the initial thermal cycle and the 100th cycle, after which a saturation point was reached. The relationship between the increase, saturation, and cyclic hardening of copper plates on a metallized silicon nitride substrate is further discussed in this study, shedding light on the overall strain range over thermal cycles. [ABSTRACT FROM AUTHOR]

The bonding of cement mortar to the concrete substrate is crucial in buildings. In this study, cement mortar was prepared using manufactured sand (MS) instead of river sand (RS). The bonding strength between manufactured sand mortar (MSM) and concrete substrate was evaluated and the effects of curing age, water-to-cement ratio (w/c) and thermal cycling on the bonding strength were discussed and compared with those of the river sand mortar (RSM). The compressive strength of the MSM was consistently higher than that of the RSM, while the bonding strength of RSM was consistently higher than that of MSM, indicating that the bonding strength does not depend on the compressive strength of the mortar. As the number of thermal cycles increased, the pull-off strengths at the interface between the concrete and MSM or RSM at different w/c ratios all decreased, and the RSM experienced a larger reduction. After 400 cycles, the percentage decrease in bonding strength of MSM sample ranged from 18.62% to 30.86%. [ABSTRACT FROM AUTHOR]

The wind speed varies randomly over a wide range, causing the output wind power to fluctuate in large amplitude. An isobaric adiabatic compressed air energy storage system using a cascade of phase-change materials (CPCM-IA-CAES) is proposed to cope with the problem of large fluctuations in wind farm output power. When the input power is lower than the minimum energy storage power of the compressor, the gradient phase-change thermal energy storage is utilized to broaden the operating range of the system. Second, the system design method and operation rules are elaborated. The storage/release characteristic curve is obtained by constructing the system components and the overall variable operating condition model. A matching system scheme is designed according to the characteristics of a wind farm in a port in China. The case study shows that the wind farm configured with the CPCM-IA-CAES system reduces the wind abandonment rate by 5.7%, recovers 4,644.46 kW h of wind power abandonment, and improves the storage power index by 16.67% compared with that of IA-CAES. Meanwhile, the system efficiency is increased from 65.96% to 74.68%, and the energy storage density is increased from 8.69 to 9.89 kW h m-3. [ABSTRACT FROM AUTHOR]

Wire arc additive manufacturing (WAAM) based on cold metal transfer (CMT) technology is very suitable for additive manufacturing of light metals such as aluminum and magnesium alloys due to its low heat input. The temperature field in CMT additive manufacturing determines the microstructure evolution and mechanical properties. However, the mechanism of CMT-related process parameters affecting the thermal process and molten pool geometry in additive manufacturing is still unclear. The finite element analysis model of the CMT additive manufacturing process was established based on element birth and death technology, and the temperature field and molten pool shape in the CMT additive manufacturing process were quantitatively studied. The results show that with the increase in welding speed, the maximum temperature of the molten pool decreases, the length of the molten pool decreases, and the depth of the molten pool changes little. The effect of interlayer cooling on the temperature field of CMT additive manufacturing was quantitatively analyzed. The study found that without cooling between the deposited layers, heat accumulation will occur in the component of additive manufacturing, and the peak temperature will be higher. With the increase of the additive manufacturing layer number, the peak temperature of the additive manufacturing layer increases. With the increase of additive layer number and no cooling between sedimentary layers, the length of the molten pool increases obviously. The correctness of the model is verified by the experimental measurement of weld geometry in CMT additive manufacturing of AA5356 aluminum alloy. This study provides a theoretical basis for the optimization of the CMT additive manufacturing process of aluminum alloy. [ABSTRACT FROM AUTHOR]

The evolution of granite􀆳s mechanical characteristics with temperature is a contentious topic in the field of rock mechanics, and little research has been done on how its microstructures vary with temperature. The design of the constant amplitude temperature cycle and peak increasing temperature cycle loads was based on modern testing technology and experimental apparatus, with a particular emphasis on the generation and propagation law of granite microcracks under their action and a discussion of the influence of weathering degree. The results suggest that the peak temperature has a stronger influence on the formation of the fracture network than the total number of cycles. Temperature load can be slightly mitigated by weathering, but a thermal cycle with an increasing peak value can promote the growth of surface fracture. The understanding of the evolution of rock mechanical properties under temperature will be promoted in this study. [ABSTRACT FROM AUTHOR]

The aim of this study is to evaluate the color stability, translucency and hardness of eight different composite resins, after thermal cycling and immersion in beverages. Six light-cured dimethacrylate-based composite (Clearfil Majesty Esthetic, Clearfil Majesty Posterior, Grandio, Grandio Flow, Arabesk Top, Valux Plus), an ormocer (Admira) and a silorane-based composite (Filtek Silorane) were tested in this study. Fifteen samples (8x2 mm) from each composite were prepared. All samples were subjected to thermal cycling [(5.0 ± 0.5)~(55.0 ± 1.0) °C, 1000 cycles]. After thermal cycling, fifteen specimens in each group were divided into three subgroups (n = 5): distilled water (control), coffee, and red wine at 37°C for 30 days. With a spectrophotometer, the △E and Translucency Parameter (TP) were calculated against white and black backgrounds. Color, translucency and hardness of all samples were remeasured baseline, after thermal cycles and after immersion in beverages. The data were analyzed using repeated measured analysis of variance and Bonferroni multiple-comparison test (P3.3). The effect of thermal cycles on color and transluceny was not statistically significant (P>0.05). TP values generally decreased especially after immersion in red wine (P

The wind speed varies randomly over a wide range, causing the output wind power to fluctuate in large amplitude. An isobaric adiabatic compressed air energy storage system using a cascade of phase-change materials (CPCM-IA-CAES) is proposed to cope with the problem of large fluctuations in wind farm output power. When the input power is lower than the minimum energy storage power of the compressor, the gradient phase-change thermal energy storage is utilized to broaden the operating range of the system. Second, the system design method and operation rules are elaborated. The storage/release characteristic curve is obtained by constructing the system components and the overall variable operating condition model. A matching system scheme is designed according to the characteristics of a wind farm in a port in China. The case study shows that the wind farm configured with the CPCM-IA-CAES system reduces the wind abandonment rate by 5.7%, recovers 4,644.46 kW h of wind power abandonment, and improves the storage power index by 16.67% compared with that of IA-CAES. Meanwhile, the system efficiency is increased from 65.96% to 74.68%, and the energy storage density is increased from 8.69 to 9.89 kW h m−3.

Use of pervious concrete (PC) for permeable pavements can help avoid urban waterlogging and urban heat islands. However, PC typically has low strength and poor durability owing to its special porous structure. The purpose of this study was to understand the influence of aggregate size and water–cement ratio (w/c) on PC under different environmental conditions (freeze–thaw and thermal cycles). The experiment designed a PC made with five aggregate sizes (3–5 mm, 5–7 mm, 7–9 mm, 9–11 mm, 11–13 mm) and five w/c values (0.21, 0.25, 0.29, 0.33, 0.37). The mass loss, compressive strength and life of all mixtures were tested under freeze–thaw and thermal cycles. Results indicated that aggregate size and w/c were identified as important factors determining the properties of PC and were evaluated using survival analysis to determine the optimal mixture. As the number of freeze–thaw cycles increased, mass loss and risk of damage increased while compressive strength decreased. As the number of thermal cycles increased, mass loss increased and compressive strength first increased and then decreased. After thermal cycling, high w/c had better frost resistance, contrary to the results for direct freezing–thawing. [ABSTRACT FROM AUTHOR]

Currently, additive technologies, in particular, electric arc growth as the most universal and productive, are used to produce individual machine parts. The problem of studying the process of structure formation in alloys during electric arc additive growth to ensure the necessary parameters of the microstructure of a material and its mechanical properties is challenging. 09G2S steel samples for research are fabricated on a developed test bench implementing the technology of 3D printing by electric arc surfacing, microstructural studies on an optical microscope are used, and microhardness measurements are carried out. The features of structure formation in a 09G2S alloy during additive electric arc growth have been determined, and controlled parameters have been identified to ensure the necessary parameters of the structure and, consequently, the mechanical properties of the alloy. The heat input of the surfacing process and the temperature of a thermal cycle are found to play a significant role in the structure formation in the material. The conducted research and established dependences make it possible to control the structural state of 09G2S steel during cladding to ensure the required parameters of its microstructure and mechanical properties. [ABSTRACT FROM AUTHOR]