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In this paper, it shows the microstructure and mechanical properties of 7050 aluminum alloy during semisolid compression at 610-680 °C for 5-20 min were investigated. The results display that the semisolid near-spherical structure can be obtained during the compression process. It also can be found that Cu is enriched at the grain boundary, while Mg and Zn are depleted at the grain boundary obviously. The increase in the material temperature and dislocation movement during compression will lead to the diffusion of solute, resulting in the growth and overlap of precipitated phases, and affect the performance. Therefore, yield strength decreases at semisolid temperature and increases with increasing temperature. [ABSTRACT FROM AUTHOR]

The traditional 70 MPa liquid hydrogen (LH 2) refueling stations (HRSs) require LH 2 pumps with high outlet pressures, leading to high initial investment, energy consumption, and difficulty in developing an LH 2 pump meeting requirements. Existing LH 2 HRSs using thermal compression eliminate the need for pressurization equipment but result in significant waste due to low-pressure hydrogen venting. Therefore, we have pioneered a novel pump-thermal synergistic pressurization process for an efficient LH 2 HRS system. The process utilizes a 45 MPa LH 2 pump and an electric heating method, allowing easily controllable heat input. This study constructs a thermodynamic model for this system that includes the dynamic operational processes of all core components. Based on the established model, the outlet parameters of the LH 2 pump, characteristic parameters of the pressure vessel, the refueling process, and the operation of the entire system are investigated. By dynamic simulation of the whole HRS system with pump and thermal compression, it is found that the specific energy consumption for hydrogen refueling is reduced to 0.55 kWh/kg, with the pump consuming 0.2 kWh/kg while thermal compression consuming 0.35 kWh/kg. After optimizing control strategies, the cycle venting of the pressure vessel and the residual hydrogen gas after re-heating and pressurization account for only 11.6%, and further utilization through the pump pressurization cycle can achieve high utilization with no residuals. This system effectively reduces the initial investment and energy consumption for LH 2 HRSs. It simplifies the structure, facilitating the retrofit of existing stations and promoting the construction and application of HRSs. [Display omitted] • An advanced hydrogen refueling station with pump and thermal compression is proposed. • A simulation model is developed for HRS with pump and thermal compression. • Thermodynamic analysis of HRS with pump and thermal compression is conducted. [ABSTRACT FROM AUTHOR]

Nickel-based superalloys have been widely used in the aerospace industry, and regulating the reinforcing phases is the key to improving the high-temperature strength of the alloy. In this study, a series of aging treatments (650 °C, 750 °C, 850 °C and 950 °C for 8 h) were designed to study different thermal deformation behaviors and microstructure evolutions for a novel nickel-based superalloy. Among the aged samples, the 950 °C aged sample achieved the peak stress of ~323 MPa during the thermal deformation and the highest microhardness of ~315 HV after thermal compression, which were the greatest differences compared to before deformation. In addition, the grains of the 950 °C sample exhibit deformed fibrous shapes, and the grain orientation is isotropic, while the other samples exhibited isotropy. In the 850 °C and 950 °C high-temperature aging samples, the γ′ precipitate (about 20 nm in size) is gradually precipitated, which inhibits the movement of dislocation in the grain during compression, thus inhibiting the occurrence of dynamic recrystallization and improving the high-temperature mechanical properties of the alloy. [ABSTRACT FROM AUTHOR]

In this study, hot compression experiments were conducted on cast TC21 titanium alloy using a Gleeble-1500D thermal simulation compression tester, and the hot-compressed specimens were heat-treated. The data obtained after analyzing the thermal compression of cast TC21 titanium alloy were analyzed to construct a thermal machining diagram with a strain of 0.8 and to optimize the machining window. This study investigated the microstructure of the alloy after hot pressing experiments and heat treatment, applying the study of the microstructure evolution law of cast TC21 titanium alloy. The analysis of the tissue evolution law established the dynamic and static recrystallization volume fraction as a function of heat deformation parameters. The results show that the optimal processing window for cast TC21 titanium alloy is a deformation temperature in the range of 1373 K–1423 K and a strain rate of 0.1 s−1. The increase in deformation volume and deformation temperature both favor recrystallization and make the recrystallization volume fraction increase, but the increase in strain rate will inhibit the increase in the recrystallization degree to some extent. The dynamic and static recrystallization equations for the cast TC21 titanium alloy at different temperatures were constructed. The experimental measurements of recrystallization volume fraction are in good agreement with the predicted values. [ABSTRACT FROM AUTHOR]

In this paper, the dynamic precipitation and dynamic recrystallization (DRX) behaviors of Mg-7Gd-2Nd-0.5Zr (wt.%) alloy during thermal compression were investigated by optical microscopy (OM), scanning electron microscope (SEM) and transmission electron microscopy (TEM). The hot compression tests were performed at 350–500 °C with strain rates of 0.003–1 s−1 and a strain of 0.7. The results indicate that dynamic precipitation and DRX occur in the deformed region under appropriate conditions, and that dynamic precipitation precedes DRX. Elevated deformation temperature and strain rate facilitate DRX but weaken dynamic precipitation. The dynamic precipitates were β (Mg5Gd) phases and were mainly located at the grain boundaries in the deformed regions. DRX can be promoted when the size of the granular precipitates is larger than 200 nm. The second phase particles located at the grain boundaries of the recrystallized grains can pin the grain boundaries to refine the recrystallized grains. There are three mechanisms of recrystallization nucleation: grain boundary bowing nucleation, dislocation pile-up induced nucleation, and particle-stimulated nucleation (PSN). Moreover, a critical strain model and a kinetic model for the DRX of the alloy were developed.

The energy consumption of conventional 70-MPa hydrogen refueling stations (HRS) with liquid hydrogen (LH 2) pumps remains at a high level due to the low efficiency of LH 2 pumps working at extremely high pressures, up to nearly 90 MPa. This paper presents a novel HRS with significantly lower energy consumption, based on a step-by-step compression strategy enabled by a highly-efficient 50-MPa LH 2 pump for low-pressure compression and a subsequent thermal compression module for high-pressure compression driven by thermal energy. The performance of the cryogenic pressure vessels in the HRS process is analyzed via a numerical model, and then several improvements to the HRS process are proposed for large-scale refueling requirements. Finally, the techno-economic performance of the HRS is compared with the conventional HRSs and the HRS with pure thermal compression. Compared to the conventional HRSs with 90-MPa LH 2 pumps, the capital cost of the proposed 400-kg/day HRS is reduced to $1.52M from $1.80M, while its energy consumption is reduced to 0.3 kWh/kg H2 from 1.3 kWh/kg H2. This work provides a new solution for low-energy-consumption hydrogen refueling which would be beneficial for reducing the overall cost of the hydrogen supply chain. [Display omitted] • A novel hydrogen refueling station with pump and thermal compression is proposed. • The reliability of this HRS is higher in the high-temperature environment. • A pump can supply more refueling units to increase the capacity of the HRS. • Capital cost of the HRS is $1.52 M, which is much lower than conventional HRS. • Power consumption of the HRS with 50-MPa pump is only 0.3 kWh/kg of hydrogen. [ABSTRACT FROM AUTHOR]

Incoloy 800H alloy has excellent high-temperature mechanical properties and broad application prospects. However, the dynamic recrystallization (DRX) behavior of this alloy at different deformations has been little studied. The thermal deformation characteristics and DRX mechanisms of Incoloy 800H alloy are studied by thermal compression tests. Quantitative analysis of grain size, DRX fraction, misorientation distribution, and twin boundaries under different deformation degrees is conducted using electron-backscattered diffraction. Furthermore, the evolution characteristics of dislocations and grains are observed through transmission electron microscopy. It is found that the proportion of DRX improves with increasing deformation significantly. In the DRX process, discontinuous DRX (DDRX) is the main nucleation mechanism, while continuous DRX (CDRX) serves as an auxiliary nucleation mechanism. As the deformation increases, the CDRX þ DDRX mechanisms can also be observed simultaneously in the high-density dislocation region near the grain boundary. In addition, the ratio of Σ3 boundaries first decreases and then increases as the deformation increases. The initial twins gradually disappear due to the increase in deformation, and new twins are formed within the DRX grains. Twins can promote grain boundary bulging, provide more nucleation sites for DRX, and have a significant promoting effect on DRX. [ABSTRACT FROM AUTHOR]

A novel two-stage refrigeration cycle with deep intercooling and series-parallel integration of thermal and mechanical compression is proposed. Its mechanical energy consumption can be reduced by supplementing it with low-grade non-large-scale heat sources. Firstly, to show the advantages of the proposed cycle, the comparison with a two-stage refrigeration cycle with series integration of thermal and mechanical compression as well as the cascade system driven by heat and power is implemented. Secondly, the effects of the major operating parameters affecting the performance such as inter-stage pressure, inlet quality of high-pressure stage mechanical compressor and thermal compressor flow rate are analyzed. Finally, the near-optimal operating parameters for different working conditions are proposed. It is exhibited that the ECOP of the proposed layout increases by 19.4–43.7% as compared to the traditional system layouts. It is recommended that the inlet quality of 0.9 in the high-pressure mechanical compressor serves as a good guide for different operational conditions. The results show that the proposed system has a clear potential of lowering the energy consumption of cold storage refrigeration systems by supplementing with available low-grade heat. It is believed that the proposed cycle promotes a more sustainable development of fresh produce e-commerce logistics. [ABSTRACT FROM AUTHOR]

Incoloy 800H alloy has excellent high‐temperature mechanical properties and broad application prospects. However, the dynamic recrystallization (DRX) behavior of this alloy at different deformations has been little studied. The thermal deformation characteristics and DRX mechanisms of Incoloy 800H alloy are studied by thermal compression tests. Quantitative analysis of grain size, DRX fraction, misorientation distribution, and twin boundaries under different deformation degrees is conducted using electron‐backscattered diffraction. Furthermore, the evolution characteristics of dislocations and grains are observed through transmission electron microscopy. It is found that the proportion of DRX improves with increasing deformation significantly. In the DRX process, discontinuous DRX (DDRX) is the main nucleation mechanism, while continuous DRX (CDRX) serves as an auxiliary nucleation mechanism. As the deformation increases, the CDRX + DDRX mechanisms can also be observed simultaneously in the high‐density dislocation region near the grain boundary. In addition, the ratio of ∑3 boundaries first decreases and then increases as the deformation increases. The initial twins gradually disappear due to the increase in deformation, and new twins are formed within the DRX grains. Twins can promote grain boundary bulging, provide more nucleation sites for DRX, and have a significant promoting effect on DRX.During thermal compression, the change in deformation amount can well reflect the process of dynamic recrystallization (DRX) from nucleation to growth. Herein, the DRX mechanism and ∑3n boundaries of Incoloy 800H alloy are explored. With the increase of deformation, the grain size is more uniform. The ∑3n boundary has a significant promotion effect on DRX. [ABSTRACT FROM AUTHOR]

High-temperature plastic deformation is one of the main methods for the fabrication of titanium-based alloys. Accurate determination of the mechanical constitutive relation is pivotal for the design, optimization, as well as the prediction of the mechanical behavior of materials. In this study, finite element simulations were carried out to simulate the Gleeble thermal compression experiment of titanium alloy samples, focusing on different thermocouple design parameters, including thermocouple material and wire diameter, etc. The results show that the heat dissipation of the thermocouple distorted the local temperature field of the contact point between the sample and the thermocouple, resulting in a deviation of the measured temperature. Through finite element method (FEM) simulation and analysis of the changes caused by various factors and comparison with the metallographic morphology of titanium alloy samples from relevant heat treatment experiments, it was shown that the material and wire diameter of the thermocouple, the thermal conductivity coefficient of sample, and the testing temperature of the sample all affected the measurement results. The thermal conductivity of sample had the largest influence on the measurement accuracy. Based on the finite element simulation and experimental comparison, the corresponding correction method and correction formula are proposed. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Science & Engineering (1673-2812) is the property of Journal of Materials Science & Engineering Editorial Office 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 this study, hot compression experiments were conducted on cast TC21 titanium alloy using a Gleeble-1500D thermal simulation compression tester, and the hot-compressed specimens were heat-treated. The data obtained after analyzing the thermal compression of cast TC21 titanium alloy were analyzed to construct a thermal machining diagram with a strain of 0.8 and to optimize the machining window. This study investigated the microstructure of the alloy after hot pressing experiments and heat treatment, applying the study of the microstructure evolution law of cast TC21 titanium alloy. The analysis of the tissue evolution law established the dynamic and static recrystallization volume fraction as a function of heat deformation parameters. The results show that the optimal processing window for cast TC21 titanium alloy is a deformation temperature in the range of 1373 K–1423 K and a strain rate of 0.1 s−1. The increase in deformation volume and deformation temperature both favor recrystallization and make the recrystallization volume fraction increase, but the increase in strain rate will inhibit the increase in the recrystallization degree to some extent. The dynamic and static recrystallization equations for the cast TC21 titanium alloy at different temperatures were constructed. The experimental measurements of recrystallization volume fraction are in good agreement with the predicted values.

The one-dimensional thermo-mechanical behaviour of two peats was investigated through consolidation tests, including incremental loadings and constant-rate-of-strain loadings, under a variety of temperature-stress conditions. As an appropriate expression of highly compressible materials, the natural strain was employed instead of conventional engineering strain, which eliminates the apparent stress dependency of the compression index and the coefficient of secondary compression. Test results suggest the applicability of an isotach approach to the two peats used in this study. The temperature dependency of the coefficient of secondary compression defined with natural strain, λ*α, is very small. All the results summarized on the effective stress-strain plane show that there exists a unique Normal Compression Line (NCL) corresponding to each combination of temperature and strain rate. The NCLs are parallel to each other. Finally, in an attempt to construct a constitutive model, the temperature dependency of the NCL was quantified by introducing a constant, λ*T. By using the two parameters, λ*α and λ*T, which describe the strain rate- and temperature-dependent characteristics, respectively, a 1-D thermo-mechanical behaviour observed in this study will be modelled in a simple manner.

Ferrite rolling is generally used to produce deep-drawn steel sheets, which can replace cold rolling to achieve short-flow production. Realizing low-cost production of deep-drawn steel. However, the deep-drawn performance of ferrite rolling products is not as good as the deep-drawn performance of cold rolled products. Of which dynamic recrystallization microstructure have a great effect on the deep-drawn performance. In the present study, ferrite steel was compressed at different deformation parameters (including deformation temperatures and strain rates) in a thermo-mechanical testing system to simulate the deformation behavior during the ferrite regions. The flow behavior of the ferrite steel was studied, and processing maps of the ferrite steel were plotted. The relationship between the Zener-Hollomon parameter and the dynamic recrystallization mechanisms of the ferrite steel was studied in this paper. The microstructure evolution in the steel was characterized by optical microstructure, electron backscatter diffraction, and transmission electron microscopy. The results show that both dynamic recovery and dynamic recrystallization happened during deformation process. The main softening mechanism was dynamic recovery. Discontinuous dynamic recrystallization, continuous dynamic recrystallization and geometric dynamic recrystallization were found in ferrite steel. Meanwhile, it was found that a corresponding relationship between dynamic recrystallization mechanisms and ln Zener-Hollomon values. At high ln Zener-Hollomon value, the dynamic recrystallization mechanism was discontinuous dynamic recrystallization. At middle ln Zener-Hollomon value, the dynamic recrystallization mechanism was continuous dynamic recrystallization. At low ln Zener-Hollomon value, the dynamic recrystallization mechanism in addition to continuous dynamic recrystallization and geometric dynamic recrystallization.

High-temperature plastic deformation is one of the main methods for the fabrication of titanium-based alloys. Accurate determination of the mechanical constitutive relation is pivotal for the design, optimization, as well as the prediction of the mechanical behavior of materials. In this study, finite element simulations were carried out to simulate the Gleeble thermal compression experiment of titanium alloy samples, focusing on different thermocouple design parameters, including thermocouple material and wire diameter, etc. The results show that the heat dissipation of the thermocouple distorted the local temperature field of the contact point between the sample and the thermocouple, resulting in a deviation of the measured temperature. Through finite element method (FEM) simulation and analysis of the changes caused by various factors and comparison with the metallographic morphology of titanium alloy samples from relevant heat treatment experiments, it was shown that the material and wire diameter of the thermocouple, the thermal conductivity coefficient of sample, and the testing temperature of the sample all affected the measurement results. The thermal conductivity of sample had the largest influence on the measurement accuracy. Based on the finite element simulation and experimental comparison, the corresponding correction method and correction formula are proposed.

Copyright of Rare Metals is the property of Springer Nature 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 objective of this study was to investigate the gloss of different types of commercially manufactured varnish systems, including water-based (WB), polyurethane (PUR) and UV-cured (UV), applied on veneered MDF panels with sanded and thermally densified alder and birch wood veneers. The varnishes were applied at various numbers of layers on veneered panels. The gloss was measured at three angles of incident light: 20°, 60° and 85°. Statistical analysis showed that the type of varnish, the number of layers, the pre-treatment process, the wood species and direction of wood fibers significantly affect gloss of the coatings of veneered MDF panels. The type of varnish had a dominant effect on gloss. The highest gloss values were measured for the UV-varnished surface, and the lowest for WB- and PUR-varnished surfaces. Gloss was enhanced with an increase in the number of layers. Birch veneer provided higher gloss values compared to alder veneer. The gloss values measured along the wood fibers were higher than those measured across the fibers. No significant differences were found between the coatings created on sanded and thermally densified veneers for the average gloss values measured along the fibers at angles 60° and 85°. This study could have practical applications for producing value-added furniture elements using low-value wood species pre-treated by thermal compression. [ABSTRACT FROM AUTHOR]

Surface roughness is an important factor during the processes of wood gluing and finishing. This study proposed a new approach for the preparation of wood veneer surfaces before varnishing through the use of thermal compression instead of sanding. The quality of the pre-treated surface was examined using surface roughness measurements. In the experiment, a wood veneer of black alder and birch, before varnishing, was subjected to sanding with a sandpaper of 180 grit size, and thermal compression at temperatures of 180 and 210 °C. Three different types of commercially manufactured varnishes (water-based (WB), polyurethane (PUR) and UV-cured (UV)) were applied to the prepared veneer surfaces with various numbers of varnish layers. Seven roughness parameters such as Ra, Rz, Rq, Rp, Rv, Rsk, and Rku were determined for the sanded and thermally densified unvarnished and varnished surfaces. The profile surface was recorded with a portable surface roughness tester along and across the wood fibers. It was found that there was no difference between the surface roughnesses of the surfaces that had been sanded and the surface roughnesses of those that had been thermally densified at a temperature of 210 °C. The research suggests that thermal compression at a temperature of 210 °C is enough to obtain smoother surfaces with a UV varnish system, and this process can be recommended as a replacement for sanding before varnishing as the most labor-intensive and expensive operations in woodworking industry. Applying two layers of varnish along with intermediate sanding was also sufficient to obtain a satisfactory finish. [ABSTRACT FROM AUTHOR]

The study aimed to investigate the effect of thermal compression on the properties of 8-year-old waru gunung wood. Wood specimens with the dimension of 25 mm100 mm150 mm in thickness, width and length, respectively were heated at 180 ˚C and 200 ˚C for 4 h. During the heating process, the specimens were subsequently compressed at 2.452 N mm-2 for 40 mins at each temperature. Changes in the wood chemical structure were examined using the pyrolysis-gas chromatography-mass spectrometry, the wood physical properties were tested according to ASTM D143-94, the wood surface hardness was tested using a Universal Testing Machine and the wood discoloration was examined using the CIELab method. The changes in crystallinity degree was examined using x-ray diffraction and cell structure were collected as supporting data. Results showed that the thermal compression at 180 ˚C and 200 ˚C caused severe degradation on the specimen carbohydrate but less for lignin. The sum effect of thermal compression on the specimens also consecutively increased the density by 34.24% and 41.87% and surface hardness by 52.78% and 63.09% and decreased the swelling thickness by 38.54% and 47.03% and the equilibrium moisture content by 36.53% and 38.59% at 180 ˚C and 200 ˚C, respectively. Thermally compressed specimens also had darker colours, glossier surfaces and smoother texture compared to non-thermally compressed specimens. [ABSTRACT FROM AUTHOR]

Edge cracking, a common issue encountered during the rolling of magnesium alloys, holds substantial importance in determining the success of subsequent finishing processes. It serves as a pivotal parameter for evaluating the formability of rolled plates. In this particular investigation, researchers concentrated on understanding the behavior of edge cracks within the solid solution magnesium alloy designated as Mg-10Gd-3Y-2Ag-0.4Zr (expressed in weight percentage as GWQ1032K). To support this analysis, one delved into the thermal rheological characteristics of the magnesium alloy and established a mathematical relationship connecting rheological stress, strain rate, and temperature. This served as the foundation for a constitutive model tailored to the alloy. Furthermore, practical rolling experiments were conducted to examine how reductions in thickness influenced the morphology of edge cracks in rolled plates. The study also explored shifts in stress–strain behavior and microstructural changes during the deformation process. The results highlighted the substantial impact of compression levels on the magnesium alloy’s anisotropic behavior, subsequently influencing the shape of the resultant plate and the stress–strain characteristics observed during deformation. Significantly, as the rolling reduction increased, a notable increase in heat generation due to the plastic deformation of the magnesium alloy plate was observed. This heightened heat played a key role in dynamic recrystallizationand and facilitating the formation of the brittle Mg _5 (RE, Ag) phase. Consequently, minimizing the generation of this brittle phase emerged as a critical factor in effectively managing and controlling edge cracks in the rolling process.

Copyright of Wood Industry / Drvna Industrija is the property of Drvna Industrija 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 effects of the glass transition and the operating process on the hardness of thermally compressed maltodextrin were investigated. The hardness of compressed maltodextrin increased significantly when it was compressed above the glass transition temperature (Tg). Maltodextrin compressed before heating showed much higher fractural stress than that compressed after heating due to the difference in force required for constant deformation. There was no effect of the decompression temperature being above or below Tg. Furthermore, the effect of crystalline additives (NaCl, monosodium glutamate monohydrate, sucrose, lactose monohydrate, lauric acid, and stearic acid) on the hardness of maltodextrin compressed above Tg was investigated. The hardness of compressed maltodextrin decreased with increasing crystalline additives except for hydrate crystals at a low-additive fraction. Since crystalline additives existed as dispersions in amorphous maltodextrin, the compressed maltodextrin became fragile by the addition of crystalline materials. In the case of hydrate crystals, it is thought that the hydrate crystals melted at the interface, releasing water molecules that formed an intermolecular binding layer. Stearic acid formed a solid by itself. Stearic acid has an intrinsically much lower melting temperature than the other crystals, and interfacial melting would have occurred in the compressed stearic acid itself. [ABSTRACT FROM AUTHOR]

The Gleeble-3800 thermal simulation machine was used to perform hot compression experiments on a new type of β alloy, Ti-6Mo-5V-3Al-2Fe (wt.%), at temperatures of 700–900 °C, strain rates of 5 × 10−1 to 5 × 10−4 s−1, and total strain of 0.7. Transmission and EBSD techniques were used to observe the microstructure. The results show that the deformation activation energy of the alloy was 356.719 KJ/mol, and dynamic recrystallization occurred during the hot deformation. The higher the deformation temperature was, the more obvious the dislocations that occurred and the more sufficient the dynamic recrystallization that occurred, but the effect of strain rate was the opposite. When the deformation temperature was higher than the phase transition point, the recrystallized grains clearly grew up. The calculated strain rate sensitivity index of the alloy was 0.14–0.29. The constitutive equation of hot deformation of Ti-6Mo-5V-3Al-2Fe alloy was established by using the Arrhenius hyperbolic sine equation. The dynamic DMM hot working diagram with the strain of 0.7 was constructed. The relatively good hot working area of the alloy was determined to be the deformation temperature of 700–720 °C and 0.0041–0.0005 s−1.

Abstract Background Inadvertent perioperative hypothermia (IPH) leads to surgical complications and increases length of stay. IPH rates are high with the current standard of care, forced air warming (FAW). Our hypothesis is that a prototype thermal compression device that heats the popliteal fossa and soles of the feet, with lower leg compression, increases perioperative temperatures and reduces IPH compared to the current standard of care. Methods Thirty six female breast surgery patients, at a tertiary academic hospital, were randomized to the device or intraoperative FAW (stage I) with a further 18 patients randomized to the device with a single heating area only (stage II, popliteal fossa or sole of the feet). Stage I: 37 patients recruited (final 36). Stage II: 18 patients recruited (final 18). Inclusion criteria: general anesthesia with esophageal monitoring for over 30 min, legs available and able to fit the device and no contraindications to leg heating or compression. The intervention was: Stage I: Investigational prototype thermal compression device (full device group) or intraoperative FAW. Stage II: Device with only a single heating location. Primary outcomes were perioperative temperatures and incidence of IPH. Secondary outcomes were local skin temperature, general and thermal comfort scores and presence of perioperative complications, including blood loss. Results Mean temperatures in the full device group were significantly higher than the FAW group in the pre-operative (36.7 vs 36.4 °C, p

The aim of this study was finding out the effect of the thermal compression process on the roughness and color properties of Poplar (Populus spp.) solid wood as a fast-growing species. The clear samples were thermally compressed along 45min. with four combinations of different pressure (1 and 2 MPa) and temperature (150°C and 170°C) values. Each group and untreated samples were compared to each other. Roughness properties were determined at both parallel and perpendicular to grain with a profilemeter. Color properties were measured according to the CIE L*a*b system by using a spectrophotometer. The results showed that surface roughness results changed significantly with thermal compression. Especially pressure had an important effect that all values in all directions. On the other hand, the temperature didn't affect the roughness of samples at the same pressure levels. When the color values were evaluated; the treatment changed the wood appearance at high levels and the samples became darker after treatments. The results of this research showed that thermal compression method which is used generally for surface densification to increase fast-growing species, significantly changed of some roughness and color properties of Poplar wood with especially at the 170°C and 2 MPa parameters. [ABSTRACT FROM AUTHOR]

Enhancement of energy delivery of a carbon dioxide (CO2) Brayton cycle without compression work liability is achievable using low grade heat for thermal compression. The limitation of the expansion ratios of a single stage adsorption thermal compression is obviated by opting for pressure build up in two stages. Despite the use of a large number of adsorbers, it is shown that, specific work output can be augmented substantially with no undue penalty on the overall cycle efficiency albeit with a marginal shortfall in work output per unit mass of adsorbent. These features are elucidated through an activated carbon based thermal compression of CO2 yet limiting high side pressures to 80 bar and the principal heat source at a temperature equal to or less than 300 °C in tandem with another low grade source at 100 °C for thermal compression. The net outcome is a substantial reduction in the size of the power block and heat exchangers resulting from enhancement of the expansion ratio and reduction in the mass flow rate in the circuit. [ABSTRACT FROM AUTHOR]

Abstract This study described the effect of water content on the glass transition temperature (T g) of a soup powder and the hardness of a soup solid compressed at various temperatures above and below the T g. Although differential scanning calorimetry showed indistinct glass transition, thermal rheological analysis revealed a clear mechanical glass transition. The mechanical T g decreased as water activity (or water content) increased because of a water-plasticizing effect. Since X-ray diffraction showed peaks reflecting crystalline NaCl, lactose, and sucrose, the amorphous region in the soup powder likely consisted mainly of vegetable, yeast, beef, and chicken extracts. The fractural stress of the thermally compressed soup solid increased with water activity of the samples, compressed height (density), and temperature. The results showed that the fractural stress of the soup solid increased dramatically when it was compressed at a temperature above the mechanical T g. Highlights • T g of the soup powder samples could be evaluated by thermal rheological analysis. • DSC thermograms showed endothermic peaks due to the melting of fat. • X-ray diffraction identified crystalline NaCl, lactose and sucrose. • Fractural stress of the soup solid increased when it was compressed above the T g. • Fractural stress of the soup solid increased with sample density. [ABSTRACT FROM AUTHOR]

The thermal compression experiment of GH984G18 alloy was carried out using thermal-mechanical testing machines Gleeble3800. Based on the stress-strain curves obtained from the experiments, the processing maps of the GH984G18 alloy were established according to the dynamic materials model (DMM), then the hot working process window of alloy was built, and the influence of temperature and strain on the dynamic recrystallization of the experimental alloy was also analyzed. The results show that when the strain is small(ε≤0.2), the optimum deformation temperature is in the temperature range of 1030-1090℃ and strain rate range of 0.01-0.18s-1; with the increase of strain(ε≥0.3), the optimum deformation temperature moves to the high temperature range of 1180-1200℃ and strain rate range of 0.056-0.25s-1; and at the strain rate of 1s-1, dynamic recrystallization does not occur and dynamic recovery dominates when the temperature is lower than 900℃; and partial dynamic recrystallization occurs at the temperature of 1000℃ and the strain of 30%; and then the complete dynamic recrystallization occurs at the temperature of 1000℃ and strain of 60%.

2219 aluminum alloy is a kind of high-strength Al-Cu-Mn alloy that can be strengthened by heat treatment. Its mechanical property parameters and forming properties are greatly affected by the deformation rate, temperature and strain. Taking 2219 aluminum alloy extruded bar as the research object, the Gleeble-3500 thermomechanical simulator was used to analyze the thermal compression deformation behavior of 2219 aluminum alloy under different temperatures and strain rates. The results show that the deformation behavior of 2219 aluminum alloy under high temperatures is greatly influenced by the deformation temperature and strain rate, and the flow stress is the result of high-temperature softening, strain hardening and deformation rate hardening. According to the experiment results, the Arrhenius constitutive model and the exponential constitutive model considering the influence of temperature and strain rate, respectively, were established, and the predicted results of the two constitutive models were in good agreement with the test results. On this basis, the processing map of 2219 aluminum alloy was established. Under the same strain rate condition with an increase of the deformation temperature, the power dissipation efficiency increases gradually, and the driving force of 2219 aluminum alloy to change its microstructure increases gradually. At the same deformation temperature, the lower the strain rate, the less possibility of plastic instability.

Highlights • Thermal compression – alternative method of the preparation of the wood substrate. • Adhesion strength of compressed and varnished samples is higher than of control samples. • The lacquer performed well on thermally compressed wood surfaces. Abstract The objectives of this work was to evaluate the adhesion strength of thermally compressed and varnished veneer used as overlay on medium density fibreboard (MDF) panels. Rotary cut birch veneer sheets were compressed at temperature levels of 150 °C, 180 °C and 210 °C before they were bonded MDF substrate. The varnish was applied to the surface of the samples at various layers and spread rates. Based on the findings of this study compression temperature significantly influences overall adhesion strength of the samples. Since thermal compression process resulted in uniform surface quality of both loose and tight sides no significant difference between them regarding their adhesion strength characteristics was determined. It was also determined that adhesion strength values of compressed and varnished samples had higher values than those of control samples. [ABSTRACT FROM AUTHOR]

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Currently, greater environmental awareness promotes research and development advances in biodegradable materials; they represent an alternative that decreases the environmental impact caused by traditional synthetic plastics. This study consists of the development and characterization of thermoplastic corn starch-based composites, reinforced with barley straw particles made by thermal compression. The study materials were prepared by using three particle concentrations (5, 10, and 15 %), while the matrix (0 %) was used as a reference. A mechanical evaluation of all samples was carried out, as well as that of their water absorption properties. They were also characterized by scanning electron microscopy (SEM), infrared spectroscopy (FTIR), X-ray diffraction (XRD), and flammability tests. The inclusion of straw in the thermoplastic matrix increased water absorption and quickened carbon formation, although it also increased its tensile strength (7 MPa) and the Young’s modulus of activity (MOE) (420 MPa) with a 15 % reinforcement. The FTIR analysis highlights the presence of a carbonyl signal (1720 cm-1) caused by a thermal breakdown (caramelization) linked to barley particles. Moreover, X-ray diffraction demonstrated a VA-type crystallinity pattern (anhydrous) within the biocomposites and an increase of the crystallinity index, through incorporating barley particles in the thermoplastic corn starch-based matrix. [ABSTRACT FROM AUTHOR]

The conditions are determined, and the parameters for the onset of the mode of dimeric molecular association in the water system are estimated. The characteristics of dimeric associates of molecules are determined. The region of anomalous thermal compression water is increased from T ≤ 4°C to T ≤ 66.4°C by introducing the temperature equivalent T0 of the energy of proton transition from molecule to molecule into the parameter of resonant interaction of atoms of different molecules. The time of transfer of excitation energy correlates with the periods of the valence and deformation vibrations of the molecules. Therefore, a molecule that performs valence vibrations “has time” to store an excitation energy sufficient to provide a parallel orientation of the spins of the nuclei of the hydrogen atoms in the molecules. Molecules that perform deformation vibrations have zero spins because of the smallness of the frequencies of such vibrations. [ABSTRACT FROM AUTHOR]

The present work inspects the preparation of bio-composites of cassava starch with particles of eucalyptus wood through the application of a novel method of thermal compression. Bio-composites with different amounts of wood particles (5 to 30%), with particle sizes of 4 and 8 mm, were obtained. Chemical and mechanical evaluation of these samples was carried out using optical microscopy, infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and the moisture absorption effect. The effect of the amount and size of the wood particles was tested by comparison with a thermoplastic matrix sample. Results from these evaluations demonstrated that the thermo-compression method produced bio-composites with a distribution of particles in the matrix that contributed to an increase in their tensile strength. This mechanical property is also enhanced by interfacial adhesion between the matrix and particles, as confirmed by SEM. Furthermore, the maximum amount of particles in the bio-composites (30%) showed the maximum resistance to moisture absorption. Temperature and time parameters contributed to the formation of diffraction patterns VH and EH as a consequence of the structural disruption of native starch. Finally, FTIR showed the chemical compatibility between the starch, glycerol, and wood particles.

In this work, hot compression experiments of 300M steel were performed at 900−1150 °C and 0.01−10 s−1. The relation of flow stress and microstructure evolution was analyzed. The intriguing finding was that at a lower strain rate (0.01 s−1), the flow stress curves were single-peaked, while at a higher strain rate (10 s−1), no peak occurred. Metallographic observation results revealed the phenomenon was because dynamic recrystallization was more complete at a lower strain rate. In situ compression tests were carried out to compare with the results by ex situ compression tests. Hot working maps representing the influences of strains, strain rates, and temperatures were established. It was found that the power dissipation coefficient was not only related to the recrystallized grain size but was also related to the volume fraction of recrystallized grains. The optimal hot working parameters were suggested. This work provides comprehensive understanding of the hot workability of 300M steel in thermal compression.

Background: Inadvertent perioperative hypothermia (IPH) leads to surgical complications and increases length of stay. IPH rates are high with the current standard of care, forced air warming (FAW). Our hypothesis is that a prototype thermal compression device that heats the popliteal fossa and soles of the feet, with lower leg compression, increases perioperative temperatures and reduces IPH compared to the current standard of care. Methods: Thirty six female breast surgery patients, at a tertiary academic hospital, were randomized to the device or intraoperative FAW (stage I) with a further 18 patients randomized to the device with a single heating area only (stage II, popliteal fossa or sole of the feet). Stage I: 37 patients recruited (final 36). Stage II: 18 patients recruited (final 18). Inclusion criteria: general anesthesia with esophageal monitoring for over 30 min, legs available and able to fit the device and no contraindications to leg heating or compression. The intervention was: Stage I: Investigational prototype thermal compression device (full device group) or intraoperative FAW. Stage II: Device with only a single heating location. Primary outcomes were perioperative temperatures and incidence of IPH. Secondary outcomes were local skin temperature, general and thermal comfort scores and presence of perioperative complications, including blood loss. Results: Mean temperatures in the full device group were significantly higher than the FAW group in the pre- operative (36.7 vs 36.4 °C, p < 0.001), early intraoperative (36.3 vs 35.9 °C, p < 0.001), intraoperative (36.6 vs 36.2 °C, p < 0.001) and postoperative periods (36.8 vs 36.5 °C, p < 0.001). The incidence of IPH in the device group was also significantly lower (16.7% vs 72.0%, p = 0.001). Thermal comfort scores were significantly higher in the full device group and hypothermia associated wound complications were higher in the FAW group. Conclusions: The thermal compression device is feasible and has efficacy over the FAW. Further studies are recommended to investigate clinically significant outcomes. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effects of thermally compressed veneer laminating on some of the physical and mechanical properties of particleboard. Oriental beech (Fagus orientalis Lipsky) veneers were compressed under various press conditions. Commercially produced particleboard samples were laminated with such compressed veneer sheets. The density, 2-h and 24-h water absorption (WA) and thickness swelling (TS), bending strength (MOR), and modulus of elasticity (MOE) in the parallel and perpendicular directions to grain orientation were measured. The results showed that all of the particleboards laminated with compressed veneer had higher MOR and MOE values compared to unlaminated particleboard and particleboard laminated with non-compressed veneer. In the sandwiched panels, particleboards laminated with veneer sheets and compressed at a pressure of 4 MPa and a temperature of 150 oC had the highest MOR and MOE values. The MOR and MOE values decreased with increasing temperatures higher than 150 oC. The TS value for 2-h and 24-h immersion times decreased with increasing press temperature. The findings of this work could provide some insight in producing sandwich-type panels with improved properties. It appears that compressed veneer using different press temperatures and pressures could be considered as an alternative way of developing sandwich-type products with satisfactory structural properties.

Effects of temperature and press pressure on the anatomical structure of solid-wood panels produced by using Pinus sylvestris L. (Scotch pine) wood were evaluated. Solid wood panels with dimensions of 250 by 500 by 18 mm were hot-pressed using a laboratory hot press at a temperature of either 120°C or 150°C and pressure of either 5 or 7 MPa for 1 h. Microscopic investigations conducted by Light Microscopy (LM) and Scanning Electron Microscopy (SEM) showed that the highest deformation occurred in earlywood regions of all growth rings for each process condition and the distribution of deformation was not uniform in growth rings. Cell-wall thickness was observed to be an important factor in wood behavior during thermal compressing processes. The results showed clearly that the impact of pressure in wood structure is promoted by increased temperature. Significant densification was observed at the maximum temperature and maximum pressure condition employed in the study, and almost all earlywood layers showed cell collapse. The study revealed that a homogenous structure of growth rings with the uniform earlywood and latewood widths throughout the wood samples plays a major role in prevention of cell collapse. The results indicated that both process conditions and anatomical structure of the wood have an interaction.

• Effect of pressing parameters on thermally compressed (TC) coconut wood properties is explored. • Increasing pressing temperature improved the dimensional stability of TC coconut wood. • Thermal degradation did not affect the bending stiffness but decreased the strength properties. • Bonding performance of cross- and parallel-laminated TC coconut wood was studied. • Surface sanding appeared unnecessary from the wood failure percentage perspective. Previous research on thermally compressed (TC) coconut wood has shown potential for structural applications. However, its dimensional stability needed to be improved. This study aimed to improve the dimensional stability of TC coconut wood for further use in laminated products by using relatively high pressing temperatures to make it more hydrophobic. TC specimens with a target compression ratio of 55 % were manufactured from low-density (LD, 332 ± 25 kg/m3) wood, and TC specimens with a target compression ratio of 25 % were manufactured from medium-density (MD, 514 ± 28 kg/m3) wood. Two pressing temperatures (170 °C and 200 °C) and three pressing times (1 h, 2 h and 3 h) were applied. Chemical changes, dimensional stability, physical and mechanical properties, and bonding performance of the specimens were examined. Thermal degradation of the LD specimens was higher than that of the MD specimens. Differences in chemistry between the surface and the interior could explain bonding behavior. Pressing temperature had a greater impact on wood degradation than the pressing time. Dimensional stability could be achieved at 200 °C pressing temperature. Most physical and mechanical properties of the TC specimens had decreased due to thermal degradation. However, compressive strength parallel to the grain and modulus of elasticity were not affected at the chosen pressing parameters. Bonding performance determined by block shear tests was dependent on the original material, panel assembly, and the sanding process. Longitudinally laminated panels made from MD specimens with sanded surfaces provided the highest block shear strength. [ABSTRACT FROM AUTHOR]

For the first time, the thermal compression method is applied to effectively enhance the electrical conductivity of carbon nanotube thin films (CNTFs). With the assistance of heat and pressure on the CNTFs, the neighbor multiwalled carbon nanotubes (CNTs) start to link with each other, and then these separated CNTs are twined into a continuous film while the compression force, duration, and temperature are quite enough for the reaction. Under the compression temperature of 400°C and the compression force of 100 N for 50 min, the sheet resistance can be reduced from 17 to 0.9 k Ω/sq for the CNTFs with a thickness of 230 nm. Moreover, the effects of compression temperature and the duration of thermal compression on the conductivity of CNTF are also discussed in this work. [ABSTRACT FROM AUTHOR]

The present work inspects the preparation of bio-composites of cassava starch with particles of eucalyptus wood through the application of a novel method of thermal compression. Bio-composites with different amounts of wood particles (5 to 30%), with particle sizes of 4 and 8 mm, were obtained. Chemical and mechanical evaluation of these samples was carried out using optical microscopy, infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and the moisture absorption effect. The effect of the amount and size of the wood particles was tested by comparison with a thermoplastic matrix sample. Results from these evaluations demonstrated that the thermocompression method produced bio-composites with a distribution of particles in the matrix that contributed to an increase in their tensile strength. This mechanical property is also enhanced by interfacial adhesion between the matrix and particles, as confirmed by SEM. Furthermore, the maximum amount of particles in the bio-composites (30%) showed the maximum resistance to moisture absorption. Temperature and time parameters contributed to the formation of diffraction patterns VH and EH as a consequence of the structural disruption of native starch. Finally, FTIR showed the chemical compatibility between the starch, glycerol, and wood particles. [ABSTRACT FROM AUTHOR]