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Boron carbide (B4C) is an essential material in various high-performance applications due to its light weight and hardness. In this work, B4C-based composites were fabricated via a powder route consisting of powder mixing, precursor preparation, and hot-pressing under vacuum. The composites' mechanical properties and microstructure were analyzed to investigate the effect of adding minor second-phase particles. In addition to homogenizing the grain size, the addition of SiC (≤10 wt%) to B4C increased its strength and improved its fracture toughness, with values reaching 551 MPa and 3.22 MPa m1/2, respectively. Meanwhile, the addition of TiB2 (≤10 wt%) significantly improved the strength and fracture toughness only, with values reaching 548 MPa and 3.92 MPa m1/2, respectively, with only a minimal decrease in hardness. Microstructural analysis revealed that the second-phase particles were uniformly distributed and reduced the average grain size, contributing to the increase in strength. Additionally, the TiB2 particles impeded crack propagation and induced crack deflection at the interface, indicating the formation of an intergranular fracture mode. On the contrary, the addition of SiC primarily resulted in transgranular fracture behavior, though it still improved the toughness of the B4C. These results suggest that small amounts of SiC and TiB2 can effectively enhance the mechanical properties of B4C ceramics while maintaining the lightweight characteristics critical for military and aerospace applications. [ABSTRACT FROM AUTHOR]

Nb-Si based ultrahigh-temperature alloys with the composition of Nb-22Ti-15Si-5Cr-3Al (atomic percentage, at. %) were prepared by hot press sintering (HPS) at 1250, 1350, 1400, 1450 and 1500 °C. The effects of HPS temperatures on the microstructure, room temperature fracture toughness, hardness and isothermal oxidation behavior of the alloys were investigated. The results showed that the microstructures of the alloys prepared by HPS at different temperatures were composed of Nbss, βTiss and γ(Nb,X)5Si3 phases. When the HPS temperature was 1450 °C, the microstructure was fine and nearly equiaxed. When the HPS temperature was lower than 1450 °C, the supersaturated Nbss with insufficient diffusion reaction still existed. When the HPS temperature exceeded 1450 °C, the microstructure coarsened obviously. Both the room temperature fracture toughness and Vickers hardness of the alloys prepared by HPS at 1450 °C were the highest. The alloy prepared by HPS at 1450 °C exhibited the lowest mass gain upon oxidation at 1250 °C for 20 h. The oxide film was mainly composed of Nb2O5, TiNb2O7, TiO2 and a small amount of amorphous silicate. The formation mechanism of oxide film is concluded as follows: TiO2 forms by the preferential reaction of βTiss and O in the alloy; after that, a stable oxide film composed of TiO2 and Nb2O5 forms; then, TiNb2O7 is formed by the reaction of TiO2 and Nb2O5. [ABSTRACT FROM AUTHOR]

Impact by hailstone, volcanic rock, bird strike, or also dropping tools can cause damage to aircraft materials. For maximum safety, the goal is to increase Charpy impact strength (auc) of a carbon-fiber-reinforced thermoplastic polyphenylene sulfide polymer (CFRTP-PPS) composite for potential application to commercial aircraft parts. The layup was three cross-weave CF plies alternating between four PPS plies, [PPS-CF-PPS-CF-PPS-CF-PPS], designated [PPS]4[CF]3. To strengthen, a new process for CFRP-PPS was employed applying homogeneous low voltage electron beam irradiation (HLEBI) to both sides of PPS plies prior to lamination assembly with untreated CF, followed by hot press under 4.0 MPa at 573 K for 8 min. Experimental results showed a 5 kGy HLEBI dose was at or near optimum, increasing auc at each accumulative probability, Pf. Optical microscopy of 5 kGy sample showed a reduction in main crack width with significantly reduced CF separation and pull-out; while, scanning electron microscopy (SEM) and electron dispersive X-ray (EDS) mapping showed PPS adhering to CF. Electron spin resonance (ESR) of a 5 kGy sample indicated lengthening of PPS chains as evidenced by a reduction in dangling bond peak. It Is assumed that 5 kGy HLEBI creates strong bonds at the interface while strengthening the PPS bulk. A model is proposed to illustrate the possible strengthening mechanism. [ABSTRACT FROM AUTHOR]

The widespread use of synthetic composite materials has raised environmental concerns due to their non-biodegradability and energy-intensive production. This paper explores the potential of natural composites, specifically flax–polypropylene, as a sustainable alternative to traditional composites for semi-structural applications. In fact, the mechanical properties of flax–polypropylene composites are similar to synthetic ones (such as those made with E-glass fibers). However, processing challenges related to fiber–matrix interaction and material degradation necessitate suited process parameters for this sustainable type of material. For this reason, this review highlights the importance of optimizing existing manufacturing processes, such as hot press molding, to better accommodate the specific characteristics of polypropylene–flax composites. By refining the parameters and techniques involved in hot press molding, researchers should overcome current limitations and fully capitalize on its potential to produce composite materials of optimal quality. Therefore, a comprehensive literature assessment was conducted to analyze the properties and processing challenges of flax–polypropylene composites. Key process parameters affecting the material's performance are identified and discussed. By optimizing process parameters for flax–polypropylene composites, it is possible to develop a sustainable and high-performance material with a reduced environmental footprint. Further research is needed to scale up production and explore different applications for this sustainable composite material. [ABSTRACT FROM AUTHOR]

The current practice in aluminum recycling plants is to change the waste into molten metal through the conventional recycling (CR) manufacturing process. However, the CR technique is so energy-intensive that it also poses an indirect threat to the environment. This paper presents a study on meltless direct recycling hot press forging (DR-HPF) as an alternative sustainable approach that has fewer steps with low energy consumption, as well as preventing the generation of new waste. A laboratory experiment was conducted to study the mechanical properties and surface integrity of AA7075 aluminum alloy by employing a hot press forging (HPF) process under different temperatures (380, 430, and 480 °C) and holding times (0, 60, and 120 min). It was found that as the parameter increased, there was a positive increase in ultimate tensile strength (UTS), elongation to failure (ETF), density, and microhardness. The recycled chips exhibit the best mechanical properties at the highest parameters (480 °C and 120 min), whereas the UTS = 245.62 MPa and ETF = 6.91%, while surface integrity shows that the calculated microhardness and density are 69.02 HV and 2.795 g/cm3, respectively. The UTS result shows that the highest parameters of 480 °C and 120 min are comparable with the Aerospace Specification Metals (ASM) Aluminum AA7075-O standard. This study is a guide for machinists and the manufacturing industry to increase industry sustainability, to preserve the earth for future generations. [ABSTRACT FROM AUTHOR]

Meltless recycling technique has been utilized to overcome the lack of primary resources, focusing on reducing the usage of energy and materials. Hot press was proposed as a novel direct recycling technique which results in astoundingly low energy usage in contrast with conventional recycling. The aim of this study is to prove the technical feasibility of this approach by characterizing the recycled samples. For this purpose, AA6061 aluminium chips were recycled by utilizing hot press process under various operating temperature (Ts = 430, 480, and 530 °C) and holding times (ts = 60, 90, and 120 min). The maximum mechanical properties of recycled chip are Ultimate tensile strength (UTS) = 266.78 MPa, Elongation to failure (ETF) = 16.129%, while, for surface integrity of the chips, the calculated microhardness is 81.744 HV, exhibited at Ts = 530 °C and ts = 120 min. It is comparable to theoretical AA6061 T4-temper where maximum UTS and microhardness is increased up to 9.27% and 20.48%, respectively. As the desired mechanical properties of forgings can only be obtained by means of a final heat treatment, T5-temper, aging after forging process was employed. Heat treated recycled billet AA6061 (T5-temper) are considered comparable with as-received AA6061 T6, where the value of microhardness (98.649 HV) at 175 °C and 120 min of aging condition was revealed to be greater than 3.18%. Although it is quite early to put a base mainly on the observations in experimental settings, the potential for significant improvement offered by the direct recycling methods for production aluminium scrap can be clearly demonstrated. This overtures perspectives for industrial development of solid state recycling processes as environmentally benign alternatives of current melting based practices. [ABSTRACT FROM AUTHOR]

Solid-state recycling, which involves the direct recycling of scrap metal into bulk material using severe plastic deformation, has emerged as a potential alternative to the conventional remelting and recycling techniques. Hot press forging has been identified as a sustainable direct recycling technique that has fewer steps and maintains excellent material performance. An experimental investigation was conducted to explore the hardness and density of a recycled aluminum-based metal matrix composite by varying operating temperature and holding time. A mixture of recycled aluminum, AA6061, and aluminum oxide were simultaneously heated to 430,480, and 530 °C and forged for 60, 90, and 120 min. We found a positive increase in microhardness and density for all composites. The hardness increased approximately 33.85%, while density improved by about 15.25% whenever the temperature or the holding time were increased. Based on qualitative analysis, the composite endures substantial plastic deformation due to the presence of hardness properties due to the aluminum oxide embedded in the aluminum matrix. These increases were significantly affected by the operating temperature; the holding time also had a subordinate role in enhancing the metal matrix composite properties. Furthermore, in an effort to curb the shortage of primary resources, this study reviewed the promising performance of secondary resources produced by using recycled aluminum and aluminum oxide as the base matrix and reinforcement constituent, respectively. This study is an outline for machining practitioners and the manufacturing industry to help increase industry sustainability with the aim of preserving the Earth for our community in the future. [ABSTRACT FROM AUTHOR]

This research investigates the performance of medium density fiberboard (MDF) with respect to hot press parameters. The performance of the board, type of glue, and production efficiency determine the optimum temperature and pressure for hot pressing. The actual temperature of the hot press inside the MDF board determines the properties of the final product. Hence, the optimal hot press parameters for the desired product are experimentally obtained. Moreover, MDF is experimentally investigated in terms of its vertical density profile, bending, and internal bonding under the various input parameters of temperature, pressure, cycle time, and moisture content during the manufacturing process. The experimental study is carried out by varying the temperature, pressure, cycle time, and moisture content in the ranges of 200–220 °C, 145–155 bar, 260–275 s, and 8–10%, respectively. Consequently, the optimum input parameters of a hot-pressing temperature of 220 °C, pressure of 155 bar, cycle time of 256 s, and moisture content of 8% are identified for the required internal bonding (0.64 N/ mm 2 ), bending (32 N/ mm 2 ), and increase in both the core and peak density of the vertical density profile as per the ASTM standard. [ABSTRACT FROM AUTHOR]

Solid-state batteries (SSBs) are gaining attention as they promise to provide better safety and a higher energy density than conventional liquid electrolyte batteries. Solid polymer electrolytes (SPEs) are promising candidates due to their flexibility providing better interfacial contact between electrodes and the electrolyte. However, SPEs exhibit very low ionic conductivity at ambient temperatures, which prevents their practical use in batteries. Herein, a simple and effective technique of hot press rolling is demonstrated to improve ionic conductivity and, hence, the performance of polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP)-based solid polymer electrolyte. Applying hot press rolling to the electrolyte membrane induced structural changes in the grain boundaries, which resulted in a reduction in the crystallinity of the material and, hence, an increase in the amorphous phase of the material, which eased the movement of the lithium ions within the material. This technique also improved the surface of the membrane, making it homogeneous and smoother, which resulted in better interfacial contact between the electrodes and electrolyte. Electrochemical tests were carried out on electrolyte membranes treated with and without hot press rolling to evaluate the effect of the treatment. The hot pressed electrolyte membrane showed significant improvements in its ionic conductivity and transference number. The cycling performance of the LFP/Li batteries using a hot press rolled electrolyte was also evaluated, which gave a specific discharge capacity of 134 mAh/g at 0.1 C. These results demonstrate that hot press rolling can have a significant effect on the electrochemical performance of solid polymer electrolytes. [ABSTRACT FROM AUTHOR]

To promote the development of the 'Bamboo as a Substitute for Steel' proposal, rotary cut bamboo veneers were applied to prepare a kind of high-strength laminated bamboo composite, which was achieved through the hot press molding method in this study. Orthogonal experiments of L9 (33) were performed, with hot-pressing temperature, pressure, and time considered as three influencing factors. Physical properties like density and moisture content, and mechanical properties like modulus of rupture (MOR), modulus of elasticity (MOE), shear strength, and compressive strength were tested for the samples. It can be obtained from the results of range analysis and ANOVA that higher density and lower moisture content were correlated with higher mechanical strength. Within the selected range of tested factors, a hot-pressing temperature and time of 150 °C and 10 min can contribute to higher density and lower moisture content, and the combination of 150 °C and 50 MPa can produce greater mechanical strength. In the thickness direction, the laminated bamboo composites displayed a notable compressed structure. [ABSTRACT FROM AUTHOR]

Our study mainly focused on diffusible hydrogen in aluminum–silicon-coated hot-stamped boron steel during a hot press forming process and in pre-treatment sequential lines of the automotive manufacturing process using a thermal desorption spectroscopy (TDS) technique. First, in the hot stamping procedure, as the soaking time increased in the heating furnace at a specific dew point when austenitizing, a high concentration of diffusible hydrogen was absorbed into the hot-stamped boron steel. Based on the TDS analysis of hydrogen absorbed from hot stamping, the activation energy value of hydrogen trapping in 1.8 GPa grade steel is lower than that of 1.5 GPa grade steel. This means that diffusible hydrogen can be more easily diffused into defective sites of the microstructure at a higher level of the tensile strength grade. Second, in sequential pre-treatment lines of the automotive manufacturing process, additional hydrogen did not flow into the surface, and an electro-deposition process, including a baking procedure, was effective in removing diffusible hydrogen, which was similar to the residual hydrogen of the as-received state (i.e., initial cold rolled blank). Based on these results, the hydrogen absorption was facilitated during hot press forming, but the hydrogen was sequentially desorbed during automotive sequential lines on aluminum-coated hot-stamped steel parts. [ABSTRACT FROM AUTHOR]

The applications of pure multi-walled carbon nanotubes (MWCNTs) buckypapers are still limited due to their unavoidable micro/nano-sized pores structures. In this work, polyvinyl alcohol (PVA) was added to a uniform MWCNTs suspension to form MWCNT/PVA buckypapers by vacuum infiltration combined with a hot press method. The results showed an improvement in the thermal, electrical, and electromagnetic interference (EMI) shielding properties due to the formation of dense MWCNTs networks. The thermal and electrical properties rose from 1.394 W/m·k to 2.473 W/m·k and 463.5 S/m to 714.3 S/m, respectively. The EMI performance reached 27.08 dB. On the other hand, ABAQUS finite element software was used to simulate the coupled temperature-displacement performance. The electronic component module with buckypapers revealed a homogeneous temperature and thermal stress distribution. In sum, the proposed method looks promising for the easy preparation of multi-functional nanocomposites at low-cost. [ABSTRACT FROM AUTHOR]

Ecological manageability in manufacturing these days is a dire and exceptional issue and the principle concerns are identified with increasingly proficient utilization of energy and materials. Recycling can save a large amount greenhouse gas emissions, particularly in the case of aluminum. The parameter on the innovative technique on the direct recycling was investigated by employing design of experiments, via hot press forging process (DR-HPF). Thus, reutilizing of aluminum chips AA6061 with full factorial 32 design of experiment comprising a variety of working temperature and holding time were employed. Central composite design (CCD) was applied to outline the experiments towards evaluating the influences of the hot press forging parameters to the three responses; ultimate tensile strength (UTS), elongation to failure (ETF), and global warming potential (GWP). In conjunction with this, the environmental impacts associated with DR-HPF process are evaluated alongside the resultant conventional recycling (CR) by using re-melting route as indication. Experimental measurements, literature analysis and industrial data were merged to acquire the analysis of aluminum recycling life cycle. Clear conclusions were successfully drawn through the attained results on the outlook proposed by solid state direct recycling for the purpose of reducing the environmental effects by taking material and energy conservation as one of the most essential impacting factor. The global warming potential of a DR-HPF route gives a significant environmental impact where it is reduced up to 69.2% in comparison to the conventional (melting) routes. [ABSTRACT FROM AUTHOR]

Carbon fiber (CF) reinforced thermoplastic composites have gradually become increasingly popular in composite production owing to their lower hazard level, good structural flexibility and recyclability. In this work, a multilayered carbon–fabric/polycarbonate laminate (multi-CFPL) was fabricated by a two-step hot-press process, mainly based on the thermoplastic properties of its polycarbonate (PC) matrix. Different from the conventional one-step method, the two-step hot-press process was composed of two separate procedures. First, a unit-hot-press operation was introduced to prepare a single-layered carbon–fabric/PC laminate (simplified as unit-CFPL). Subsequently, a laminating-hot-press was employed to compress several as-prepared unit-CFPLs bonded together. This combined process aims to reduce the hot-press temperature and pressure, as well as facilitate the structure designability of this new composite. Several mechanical investigations were conducted to analyze the effect of the hot-press parameters and unit-CFPL numbers on the performance of this multi-CFPL material, including flexural, uniaxial tensile and impact tests. The results reveal that the multi-CFPL exhibits a good stability of flexural and tensile properties in terms of strength and modulus. Furthermore, during impact tests, the multi-CFPL presents an accelerated growth of peak force and energy absorption capability with increasing unit-CFPL layers. [ABSTRACT FROM AUTHOR]

Melting aluminium waste to produce a secondary bulk material is such an energy-intensive recycling technique that it also indirectly threatens the environment. Hot press forging is introduced as an alternative. Mixing the waste with another substance is a proven practice that enhances the material integrity. To cope with the technology revolution, a finite element is utilised to predict the behaviour without a practical trial. Utilising commercial software, DEFORM 3D, the conjectures were demonstrated scientifically. The flow stress of the material was modified to suit the material used in the actual experiment. It is acknowledged that the stress–strain had gradually increased in each step. Due to the confined forming space, the temperature decreased by ~0.5% because the heat could not simply vacate the area. A reduction of ~10% of the flesh observed in the simulation is roughly the same as in the actual experiment. Above all, the simulation abides by the standards and follows what has been done previously. Through the finite element utilisation, this study forecasted the performance of the recycled composite. The results presented may facilitate improvement of the recycling issue and conserve the environment for a better future. [ABSTRACT FROM AUTHOR]

Porous liquid-phase-sintered SiC (L-SiC) ceramics were successfully fabricated by hot press sintering (HP) at 1800 °C in argon, using Al2O3 and Y2O3 as oxide additions. By varying the starting coarse SiC particle size, the relationships between pore microstructures and flexural strength as well as gas permeability of porous L-SiC were examined. All the as-sintered samples possessed homogeneous interconnected pores. The porosity of porous L-SiC decreased from 34.0% to 25.9%, and the peak pore size increased from 1.1 to 3.8 μm as the coarse SiC particle sizes increased. The flexural strengths of porous L-SiC ceramics at room temperature and 1000 °C were as high as 104.3 ± 7.3 MPa and 78.8 ± 5.1 MPa, respectively, though there was a decrease in accordance with their increasing pore sizes and particle sizes. Moreover, their gas permeability increased from 1.4 × 10−14 m2 to 4.6 × 10−14 m2 with the increase of pore size in spite of their decreased porosity. [ABSTRACT FROM AUTHOR]

The Fe/FeAl2O4 cermet was prepared with Fe-Fe2O3-Al2O3 powder by a hot press sintering method at 1400 °C. The raw materials for the powder particles were respectively 2 µm (Fe), 0.5 µm (Fe2O3), and 0.5 µm (Al2O3) in diameter, the sintering pressure was 30 MPa, and the holding time was 120 min. The effects of different Fe mass ratios on the microstructure and mechanical properties of Fe/FeAl2O4 cermet were studied. The results showed that a new ceramic phase FeAl2O4 could be formed by an in situ reaction during the hot press sintering. When the Fe mass ratio was increased, the microstructure and mechanical properties of the Fe/FeAl2O4 cermet showed a change law that initially became better and then became worse. The best microstructure and mechanical properties were obtained in the S2 sample, where the mass ratio of Fe-Fe2O3-Al2O3 was 6:1:2. In this Fe mass ratio, the relative density was about 94%, and the Vickers hardness and bending strength were 1.21 GPa and 210.0 MPa, respectively. The reaction mechanism of Fe in the preparation process was the in situ synthesis reaction of FeAl2O4 and the diffusion reaction of Fe to FeAl2O4 grains. The increase of the Fe mass ratio improved the wettability of Fe and FeAl2O4, which increased the diffusion rate of Fe to FeAl2O4 grains, which increased the influence on the structure of FeAl2O4. [ABSTRACT FROM AUTHOR]

Nanocellulose (NC) has been spotlighted as a new building block of future materials since it has many advantages, such as being lightweight and environment-friendly and having high mechanical properties and heat resistance. However, the use of NC requires an upscale manufacturing process to maintain its advantageous properties. Herein, the process of assembling NC into a macro-scale bulk material was developed through a combination of steam treatment and hot press molding. The steam treatment was applied to an NC paste to energize the hydroxyl groups in the cellulose, followed by two stages of hot press molding, which helped in the self-assembly of NC without adhesives. Cellulose nanocrystals were used as the NC, and circular disk shape specimens were prepared. The mechanical properties of the prepared bulk material were higher than typical engineering plastics. In addition, an end mill machining test of the NC bulk material showed its machinability. This paper showed the processing feasibility of NC bulk material, which can substitute plastics. [ABSTRACT FROM AUTHOR]

All-cellulose composites (ACCs) are manufactured using only cellulose as a raw material. Biobased materials are more sustainable alternatives to the petroleum-based composites that are used in many technical and life-science applications. In this study, an aquatic NaOH-urea solvent system was used to produce sustainable ACCs from wood-based woven textiles with and without the addition of TEMPO-oxidized nanocellulose (at 1 wt.-%). This study investigated the effects of dissolution time, temperature during hot press, and the addition of TEMPO-oxidized nanocellulose on the mechanical and thermal properties of the composites. The results showed a significant change in the tensile properties of the layered textile composite at dissolution times of 30 s and 1 min, while ACC elongation was the highest after 2 and 5 min. Changes in hot press temperature from 70 °C to 150 °C had a significant effect: with an increase in hot press temperature, the tensile strength increased and the elongation at break decreased. Incorporating TEMPO-oxidized nanocellulose into the interface of textile layers before partial dissolution improved tensile strength and, even more markedly, the elongation at break. According to thermal analyses, textile-based ACCs have a higher storage modulus (0.6 GPa) and thermal stabilization than ACCs with nanocellulose additives. This study highlights the important roles of process conditions and raw material characteristics on the structure and properties of ACCs. [ABSTRACT FROM AUTHOR]

During industrial and laboratory processes involving material grinding, the grinding media endure prolonged high-collision and friction environments, resulting in substantial wear. Consequently, this study adopts the hot-pressing sintering technique in powder metallurgy to prepare SiC-reinforced Fe-based wear-resistant composite grinding media, aiming to increase wear performance. For this purpose, Fe with 10 wt% SiC powders were milled for the fabrication of the composite. Then, sintering was performed by hot press at 1100 °C in a furnace. Scanning electron microscopy (SEM) and X-ray diffraction were employed to investigate the microstructures and phase of SiC-reinforced Fe-based matrix composite. Subsequently, comparative performance evaluations of the newly developed grinding media and traditional chromium-based media were conducted in terms of wear rate and grinding efficiency. The wear resistance tests revealed that the SiC-reinforced composite media displayed significantly superior wear resistance across various abrasives compared to the chromium-containing alternatives. Specifically, the composite media achieved a wear rate reduction of 2.9 times against standard sand over 1 h, and 2.3 and 2.4 times against sandstone and iron slag, respectively. Moreover, extended grinding for 3 hours further enhanced these reductions to 3.1, 2.4, and 2.7 times, respectively. Additionally, efficiency assessments indicated that at a 1:1 material ratio, the composite media outperformed the chromium-containing media in grinding efficiency by 7.5%, 12.5%, and 10.3% for standard sand, sandstone, and iron slag, respectively. Further increasing the material ratio to 3:1 resulted in efficiency improvements of 7.4%, 17.5%, and 11.3%, correspondingly. [ABSTRACT FROM AUTHOR]

This study presents an analysis of films which consist of two layers; one layer is PVDF as the matrix, along with fillers BaTiO3 (BT), and the second is one bacterial nanocellulose (BNC) filled with Fe3O4. The mass fraction of BT in PVDF was 5%, and the samples were differentiated based on the duration of the mechanical activation of BT. This innovative PVDF laminate polymer with environmentally friendly fillers aligns with the concept of circular usage, resulting in a reduction in plastic content and potential improvement of the piezoelectric properties of the entire composite. This work presents new, multifunctional "green" packaging materials that potentially could be a good alternative to specific popular materials used for this purpose. The synthesis of the films was carried out using the hot press method. Tensile tests, water vapor permeability examination, and structural analyses using SEM-EDS and FTIR have been conducted. The sample PVDF/BT20/BNC/Fe3O4 exhibited the best barrier properties (impermeability to water vapor), while the highest tensile strength and toughness were exhibited by the PVDF/BT5/BNC/Fe3O4 sample. [ABSTRACT FROM AUTHOR]

This study aims to achieve in situ-formed pure Ti and Ti6Al4V coatings on 316L stainless steel through hot pressing and examine their wear and corrosion properties thoroughly in two simulated body fluids: physiological serum (0.9% NaCl) and Hanks' solution. The sintering and diffusion bonding process was conducted at 1050 °C under a uniaxial pressure of 40 MPa for 30 min in a vacuum environment of 10−4 mbar. Following sintering, in situ-formed pure Ti and Ti6Al4V coatings, approximately 1000 µm thick, were produced on 316L substrates approximately 3000 µm in thickness. The mean hardness of 316L substrates, pure Ti, and Ti6Al4V coatings are around 165 HV, 170 HV, and 420 HV, respectively. The interface of the stainless steel substrate and the pure Ti and Ti6Al4V coatings exhibited no microstructural defects, while the interface exhibited significantly higher hardness values (ranging from 600 to 700 HV). The coatings improved corrosion resistance in both electrolytes compared to the 316L substrate. Wet wear tests revealed reduced friction coefficients in 0.9% NaCl relative to Hanks' solution, highlighting the chemical interactions between the material surface and the electrolyte type and the significance of tribocorrosion in biocoatings. [ABSTRACT FROM AUTHOR]

The cooling performance of a slice die is studied numerically and experimentally. The slice die is designed to improve the cooling performance compared to that of a conventional die that is generally used in the Hot Press Forming (HPF) process by modifying the cooling channel layout and arrangement. In order to understand the physical phenomenon of the slice die cooling performance, the cooling performance of the conventional die is also simulated and their results are compared with the slice die results. From the results of the maximum temperature of the blank and die and the temperature distribution of the blank, the slice die has considerably improved cooling performance. To validate the simulation results, the slice die is prototyped and a blank is produced by the HPF process. Blank temperatures are measured by a thermal imaging camera at several holding times. The simulation and experimental results of the blank temperatures are compared and agree with the error rate of 3%. In order to verify the quality of the produced blank, ultimate tensile stress, yield stress, and elongation tests are conducted for specimens that are extracted from the blank and are compared with existing literature results. [ABSTRACT FROM AUTHOR]

This study investigates the influence of a hot press process on the properties of hemp fiber-reinforced organo sheets. Plain-woven fabric made from hemp staple fiber yarns is used as textile reinforcement, together with a recycled poly-lactic acid (PLA) matrix. Process pressure and temperature are considered with three factor levels for each parameter. The parameter influence is examined based on the B-factor model, which considers the temperature-dependent viscosity of the polymer, as well as the process pressure for the calculation of a dimensionless value. Increasing these parameters theoretically promotes improvements in impregnation. This study found that the considered recycled polymer only allows a narrow corridor to achieve adequate impregnation quality alongside optimal bending properties. Temperatures below 170 °C impede impregnation due to the high melt viscosity, while temperature increases to 185 °C show the first signs of thermal degradation, with reduced bending modulus and strength. A comparison with hemp fiber-reinforced virgin polypropylene, manufactured with identical process parameters, showed that this reduction can be mainly attributed to polymer degradation rather than reduction in fiber properties. The process pressure should be at least 1.5 MPa to allow for sufficient compaction of the textile stack, thus reducing theoretical pore volume content to a minimum. [ABSTRACT FROM AUTHOR]

Recently, natural silk nonwoven fabrics have attracted attention in biomedical and cosmetic applications because of their excellent biocompatibility, mechanical properties, and easy preparation. Herein, silk nonwoven fabrics were prepared by carding silk filaments to improve their productivity, and the effect of sericin content on the structure and properties of silk nonwoven fabrics was investigated. Owing to the binding effect of sericin in silk, a natural silk nonwoven fabric was successfully prepared through carding, wetting, and hot press treatments. Sericin content affected the structural characteristics and properties of the silk nonwoven fabrics. As the sericin content increased, the silk nonwoven fabrics became more compact with reduced porosity and thickness. Further, with increasing sericin content, the crystallinity and elongation of the silk nonwoven fabrics decreased while the moisture regain and the maximum stress increased. The thermal stability of most silk nonwoven fabrics was not affected by the sericin content. However, silk nonwoven fabrics without sericin had a lower thermal decomposition temperature than other nonwoven fabrics. Regardless of the sericin content, all silk nonwoven fabrics exhibited optimal cell viability and are promising candidates for cosmetic and biomedical applications. [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC) is a biodegradable, non-toxic, natural substance that can be obtained by culturing bacteria. It can be approached in various ways from physical, chemical, and biological points. BC nanoparticles have been applied as lubricating additives to improve the load capacity, anti-wear, and friction. The microcellular foaming process was created using a technology based on the saturation of the polymer by supercritical CO2 and rapid decompression. An increase in saturation pressure leads to an increase in the molecular potential energy of CO2, which can be more easily compressed into the cellulose matrix. Moreover, the high crystallinity and water content combination contribute to thermal stability. Specimen membranes produced by Komagataeibacter xylinus prepared with a thickness of 2 mm were saturated in supercritical condition, 10 MPa of CO2 for 4 h, and foamed at a temperature of 120 °C in a hot press. After the foaming process, we used dry ice to cool the BC. Before foaming, the friction coefficient continuously increased with the increase in cycles, and after foaming, a stable friction coefficient of 0.3 or less was secured despite the increase in the cycle. The microcellular foaming process significantly reduced and made BC's coefficient of friction stable. [ABSTRACT FROM AUTHOR]

This study involves performing direct and indirect hot press forming on ultra-high-strength steel (UHSS) boron steel sheets to determine formability. The indirect hot press process is performed as a cold deep drawing process, while the direct hot press process is performed as a hot deep drawing process. The initial blank temperature and the blank holding force are set as parameters to evaluate the performance of the direct and indirect deep drawing processes. The values of punch load and forming depth curve were obtained in the experiment. In addition, the hardness and microstructure of the boron steel sheets are examined to evaluate the mechanical properties of the material. The forming depth, maximum punch load, thickness, and thinning rate according to blank holding force were examined. The result shows that a larger blank holding force has a more significant effect on the variation of the thickness and thinning rate of the samples during the drawing process. Furthermore, the thinning rate of the deep drawing part in with and without fracture boundary was respectively examined. [ABSTRACT FROM AUTHOR]

Biobased and biodegradable polyhydroxyalkanoates (PHAs) are currently gaining momentum. Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) polymer has a useful processing window for extrusion and injection molding of packaging, agricultural and fishery applications with required flexibility. Processing PHBHHx into fibers using electrospinning or centrifugal fiber spinning (CFS) can further broaden the application area, although CFS remains rather unexplored. In this study, PHBHHx fibers are centrifugally spun from 4–12 wt.% polymer/chloroform solutions. Beads and beads-on-a-string (BOAS) fibrous structures with an average diameter (ϕav) between 0.5 and 1.6 µm form at 4–8 wt.% polymer concentrations, while more continuous fibers (ϕav = 3.6–4.6 µm) with few beads form at 10–12 wt.% polymer concentrations. This change is correlated with increased solution viscosity and enhanced mechanical properties of the fiber mats (strength, stiffness and elongation values range between 1.2–9.4 MPa, 11–93 MPa, and 102–188%, respectively), though the crystallinity degree of the fibers remains constant (33.0–34.3%). In addition, PHBHHx fibers are shown to anneal at 160 °C in a hot press into 10–20 µm compact top-layers on PHBHHx film substrates. We conclude that CFS is a promising novel processing technique for the production of PHBHHx fibers with tunable morphology and properties. Subsequent thermal post-processing as a barrier or active substrate top-layer offers new application potential. [ABSTRACT FROM AUTHOR]

In engineering application, the hot press assembly technology is often used to improve the stability of the rotor structure, but the conventional design methods cannot effectively evaluate the influence of this process on the rotor strength, which easily causes the rotor strength to exceed its safety margin range, and seriously it will lead to the failure of the rotor structure. This paper takes the cylindrical magnet surface-mounted high-speed permanent magnet synchronous motor rotor as the research object. Firstly, the influence of the assembly pressing force on the rotor stresses and interference is analyzed; then, comprehensively considering the assembly pressing force, speed and temperature, the rotor strength's design method with high structural stability is proposed. Finally, based on the proposed method, the rotor strength of a 100 kW/30,000 rpm high-speed motor is designed, and the feasibility of the design is verified by over-speed experiment. [ABSTRACT FROM AUTHOR]

Half Heusler materials are promising thermoelectric materials with potential application in generators at medium range temperatures. Solid solutions are typically prepared by arc melting, presenting interesting properties. In this work, the effect of Hf incorporation and the formation of solid solutions is discussed. More specifically, Ti1−xHfxNiSn and (Ti0.4Zr0.6)1−yHfyNiSn half Heusler materials were synthesized via mechanical alloying and consolidated via hot press sintering. Hf incorportation in the lattice strongly affected the lattice thermal conductivity due to the large mass fluctuation. The power factor and thermoelectric figure of merit was optimized via Sb doping the values of 34 μ W/cmK2 and 38 μ W/cmK2; 0.72 and 0.76 at 762 K for Ti0.4Hf0.6NiSn0.985Sb0.015 and (Ti0.4Zr0.6)0.7Hf0.3NiSn0.98Sb0.02, respectively, were reached. [ABSTRACT FROM AUTHOR]

The rapid development of electric vehicles has generated a recent demand for high energy density lithium-ion batteries (LIBs). One simple, effective way to enhance energy density of LIBs is to increase the thickness of electrodes. However, the conventional wet process used to fabricate thick electrodes involves the evaporation of large amounts of organic solvents, which causes an inhomogeneous distribution of conductive additives and binders. This weakens the mechanical and electrochemical network between active materials, resulting in poor electrochemical performance and structural degradation. Herein, we introduce a new strategy to produce homogeneous thick electrodes by using a dry, solvent-free process. Instead of using a conventional PVDF (polyvinylidene fluoride) binder, we employed a phenoxy resin as the binder in dry process for the first time. This thermoplastic binder exhibits better ductile properties than PVDF in the way that it generates a uniform network structure that connects the active materials during the hot press process. This enables the production electrochemically stable electrodes without using organic solvents, which record capacity retention rates of 73.5% over 50 cycles at a 40 mg/cm2 of thick electrodes. By contrast, thick electrodes produced with a PVDF binder via wet processing only have a capacity retention rate of 21.8% due to rapid structural degradation. [ABSTRACT FROM AUTHOR]

Closed-cell metal syntactic foam is a new material consisting of hollow spheres embedded in metal matrix syntactic foams. These foams have good physical and mechanical properties and are increasingly used worldwide in industrial and high-tech fields. Magnesium matrix syntactic foams containing hollow Al2O3 spheres ((Al2O3hs)/AZ91D) were successfully fabricated by hot press sintering at different temperatures. The fabrication of Al2O3hs/AZ91D and the effect of sintering temperature on the microstructure and properties are reported in this paper. Additionally, sandwiched magnesium matrix syntactic foams were prepared by placing magnesium plates on both sides of the syntactic foam. Some Al2O3hs particles became filled with matrix particles during preparation. Thus, the actual density was greater than the theoretically calculated value and increases with increasing sintering temperature. Above 723 K, a brittle phase MgAl2O4 formed in Al2O3hs/AZ91D. The quasistatic and dynamic compressive strengths of Al2O3hs/AZ91D first increased and then decreased with increasing sintering temperature, and the maximums were 162 MPa and 167.87 MPa, respectively. Thus, this paper reports a new strategy for the controlled preparation of metal matrix syntactic foams with predetermined porosity. The results show that this strategy improved the performance of lightweight and high-strength syntactic foam materials and shows potential for further research. [ABSTRACT FROM AUTHOR]

One-way water transport is a predominant feature of comfortable textiles used in daily life. However, shortcomings related to the textiles include their poor breathability and durability. In this study, low-cost and eco-friendly PLA/low-melt (polylactic acid) LMPLA-thermoplastic polyurethane (TPU) membranes were fabricated through a needle punch/hot press and electrospinning method. The micro-/nano-channels, used for the first time, endowed the composite membranes with robust, breathable, moisture-permeable, and abrasion-resistant performance. By varying the nano- layer thickness, the resulting 16–40 μm membranes exhibited excellent one-way water transport, robust breathability and moisture permeability, and good abrasion resistance. Nano-layer thickness was found to be a critical performance factor, balancing comfort and protection. These results may be useful for developing low-cost, eco-friendly, and versatile protective products for medical application. [ABSTRACT FROM AUTHOR]

An efficient way to improve the properties of metal–diamond composites (mechanical strength, wear resistance, thermal conductivity) is the preliminary modification of the diamond surface to improve its wettability by the metal matrix. In the present work, Mo2C-containing coatings were deposited on the diamond crystals under different conditions: hot pressing (atmosphere of argon), spark plasma sintering (forevacuum), and annealing in air. The influence of the sintering parameters on the morphology and phase composition of the coatings deposited on diamond was studied. Mo2C-containing coatings were selectively deposited on the facets of synthetic diamond microcrystals by annealing of the latter with a molybdenum powder. Experiments were carried out to deposit coatings under different conditions: during hot pressing (argon atmosphere), spark plasma sintering (forevacuum), and annealing in air. The process parameters were the temperature, holding time, and concentration of molybdenum in the initial mixture. Experiments with a pre-oxidized molybdenum powder were also conducted. The coated diamond crystals were investigated by X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. The deposition was enabled by the gas phase transport of molybdenum dioxide, MoO2, contained in the starting powder. The following sequence of the coating formation stages was proposed. First, MoO2 sublimes and is adsorbed mainly on the {100} facets of diamond. Then, it is reduced to metallic molybdenum by carbon of the diamond, which further reacts with carbon to form the Mo2C carbide phase. These processes occurred during treatment of the mixtures in the hot press and the spark plasma sintering facility. When the mixture was annealed in air, no selective deposition was observed. During annealing, MoO3 particles adhered to the diamond surface. [ABSTRACT FROM AUTHOR]

In this study, natural silk web and natural silk non-woven fabric were prepared mechanically using the binding character of the sericin in silk. The effect of process variables on the preparation, structure, and properties of the silk web and the non-woven fabric was examined. The reeling velocity affected the morphology and mechanical properties of the web but had almost no influence on the crystalline structure of the silk. From the viewpoint of reel-ability and the mechanical properties (work of rupture) of silk web, a reeling velocity of 39.2 m/min represented the optimal processing velocity. The porosity and swelling ratio of the silk web decreased slightly with increasing reeling velocity. Furthermore, the reeling bath temperature had a significant effect on the reel-ability of silk filaments from a silkworm cocoon. Bath temperatures ≥50 °C yielded good reel-ability (>900 m reeling length). The porosity, swelling ratio in water, and mechanical properties of the silk web and silk non-woven fabric changed only slightly with the reeling bath temperature but changed significantly with the hot press treatment. The hot-pressed silk web (i.e., silk non-woven fabric) exhibited higher tensile strength as well as lower elongation at break, porosity, and swelling ratio than the silk web. [ABSTRACT FROM AUTHOR]

To improve the properties of additively manufactured parts to be used in high-end applications, intrinsic defects occurring during the printing process need to be minimized. Defects such as void can significantly degrade the mechanical properties of the resulted parts. The presence of void is more evident in composite printed parts due to the inhomogeneity of the specimen. In this study, composite rectangular coupons printed with a Markforged Mark Two printer were manufactured with different fiber orientations and stacking sequences. A void content reduction/consolidation process, consisting of applying pressure at different temperature levels, was developed and implemented to remove the voids in form of air bubbles trapped in the specimen. A two-part mold with female and male components with the same dimensions as the rectangular specimen was designed and machined to be used in a hot press process. The success of the approach was evaluated by calculating the density of the specimen pre- and post-consolidation. The void content reduction results were highly dependent on fiber orientation; however, the density increased for all tested specimens, confirming the reduction in porosity. [ABSTRACT FROM AUTHOR]

The purpose of this study is to investigate the natural weathering properties of unmodified and acetylated veneer overlaid wood‒plastic composites (vWPCs) manufactured by one-step hot press molding. The results show that the water absorption and thickness swelling of vWPC with acetylated veneer were lower than those of unmodified vWPC. In addition, the surface tensile strength of vWPC increased with increasing weight gain of acetylated veneer, and the flexural properties of vWPC were not significantly different. Furthermore, the results of natural weathering demonstrated that not only the photostability but also the modulus of elasticity (MOE) retention ratio and surface tensile strength of vWPC with acetylated veneer were significantly higher than those of vWPC with unmodified veneer. Thus, better dimensional stability, surface tensile strength, and weathering properties can be achieved when the vWPC is made with acetylated veneer, especially those containing veneers with a higher weight percent gain. [ABSTRACT FROM AUTHOR]

In this paper, a fuzzy failure mode and effects analysis (FMEA) method is proposed by combining fault theory and a failure analysis method. The method addresses the problem of board thickness control failure and the problem of thickness deviation defect blanking, which can occur during continuous hot pressing (CHP) process, which is one of the most important processes in the production of medium-density fiberboard (MDF). The method combines the fault analysis with the Hamming code method and using the Hamming code to calculate and represent the cylinder array of the continuous hot-pressed thickness control execution unit to analyze and process the potential fixed thickness failure modes in MDF hot press production, and then summarizes the decision rules for controlling the board thickness and the level of sheet deviation. By combining the fuzzy FMEA method of the Hamming code and the logical OR operation of the experimental analysis, the method of thickness deviation and recognition control fault information for the CHP of MDF, which is proposed in this paper, permits the increase of the number of error levels, which makes optimization for controller more convenient and improves the efficiency to recognize errors. [ABSTRACT FROM AUTHOR]

In recent years, W-Cu composite systems have become very interesting subjects due to good electrical and thermal conductivity, high-temperature strength, certain plasticity, and excellent radiation resistance. W-Cu composites are a very important class of materials in applications like PFM (plasma facing materials), functional graded materials (FGM), electronic packaging materials, high-voltage electrical contacts, sweating materials, shaped charge liners, electromagnetic gun-rail materials, kinetic energy penetrators, and radiation shielding/protection. There is no possibility of forming a crystalline structure between these two materials. However, due to the unique properties these materials possess, they can be used by preparing them as a composite. Generally, W-Cu composites are prepared via the conventional powder metallurgy routes, i.e., sintering, hot pressing, hot isostatic pressing, isostatic cold pressing, sintering and infiltration, and microwave sintering. However, these processes have certain limitations, like the inability to produce bulk material, they are expensive, and their adoptability is limited. Here, in this review, we will discuss in detail the fabrication routes of additive manufacturing, and its current progress, challenges, trends, and associated properties obtained. We will also explain the challenges for the additive manufacturing of the composite. We will also compare W-Cu composites to other materials that can challenge them in terms of specific applications or service conditions. The solidification mechanism will be explained for W-Cu composites in additive manufacturing. Finally, we will conclude the progress of additive manufacturing of W-Cu composites to date and suggest future recommendations based on the current challenges in additive manufacturing. [ABSTRACT FROM AUTHOR]

There are many factors that determine the performance parameters of piezoelectric ceramics, but the process of preparing ceramics plays a decisive role in their properties. By improving the preparation process, significant improvements in ceramic properties can be achieved. In order to meet the growing demand for improvement in the performance of piezoelectric ceramics, various crystal preparation methods such as Template Crystal Growth (TGG), Reflected Template Growth (RTGG), and Oriented Curding (OCAP) techniques have been used for the preparation of piezoelectric ceramics. This article first introduces the performance parameters of piezoelectric ceramics, then summarizes the influence of various preparation processes on the performance of piezoelectric ceramics, and finally summarizes the parameters of high-tech ceramics reported this year, and predicts the future of the preparation of high-tech ceramic materials. [ABSTRACT FROM AUTHOR]

In the automobile industry, carbon fiber reinforced thermoplastics (CFRTP) have attracted attention as potential materials to reduce the weight of the automobile body. In order to apply CFRTP to mass-produced automobile parts, it is necessary to develop the reduction of molding time and the impregnation method into the carbon fiber (CF) for the thermoplastic resin, which has relatively high viscosity. Although the conventional hot press molding uses only the heat transfer from the mold to the molding materials, it is expected to develop a new molding method for CFRTP using heat generation of the materials themselves to overcome these issues. As a method of heating the carbon fiber, there is a direct resistance heating method, in which carbon fiber is directly energized and heated by Joule heat. We have developed resistance welding methods in which carbon nanotube (CNT) grafted carbon fiber (CNT-CF) is used for the heating elements, and revealed that the higher welded strength is obtained by using CNT-CF instead of CF. Therefore, the carbon nanofilaments (CNF) grafted carbon fiber (CNF-CF) including CNF-CF is expected not only to be used as a resistance heating medium at the time of joining but also as a reinforcing fiber and as a self-heating member at the time of molding. In this study, we develop the CFRTP molding method by using direct resistance heating to CNF-CF in the hot press molding. CFRTP ([0°]20) with the volume fractions (Vf) of 40% are molded by conventional hot press and hot press with direct resistance heating to reinforcing fiber. CF or CNF-CF is used for reinforcement. CFRTP molded by hot press with direct resistance heating to CNF-CF indicated lower void content than CFRTP molded by hot press with direct resistance heating to CF. Compared to CFRTP molding by only hot press, hot press molding with direct resistance heating to CNF-CF can mold CFRTP with low void content. [ABSTRACT FROM AUTHOR]

The thin-walled hyperbolic structures made from titanium alloy primarily encompass two typical forms: hyperbolic convex and hyperbolic concave (saddle). This paper addresses the technical challenges associated with the forming processes that frequently result in ripples or wrinkles in these configurations. Specifically, it investigates precision control techniques for the hot forming process of thin-walled hyperbolic skins from TC4 titanium alloy. The present study examines the relationship between the instability characteristics and defect features of the thin-walled hyperbolic skins, establishing a constitutive model for TC4 titanium alloy and conducting uniaxial tensile tests. For the hyperbolic convex skin and the hyperbolic saddle skin, small-margin coupled hot pressing and curved edge forming processes are employed, respectively. Results are analyzed to identify the forms and distribution patterns of forming defects across different geometries. Furthermore, the surface accuracy following the forming processes is compared, culminating in a summary of the relationship between the ratio of the sum of chord heights to the sum of chord lengths and the occurrence of ripples and wrinkles. [ABSTRACT FROM AUTHOR]

The development of wheat straw boards utilizing intrinsic bonding mechanisms not only facilitates the high-value utilization of agricultural solid waste but also diminishes the reliance on synthetic adhesives. In this study, using wheat straw as the primary substrate, we investigated the effects of mechanical smashing combined with pretreatment using inorganic acids or alkalis on the properties of hot-pressed boards, as well as the relationship between the properties of hot-pressed boards and the physical properties and chemical composition of wheat straw raw materials. These selective pretreatments effectively degraded lignin, hemicellulose, and other components, thereby promoting fiber reorientation and resulting in a denser microstructure with improved self-bonding capabilities. The optimal board was fabricated with a granularity of 0.3 mm and underwent alkali pretreatment, achieving a tensile strength of 11.564 MPa, an internal bonding strength of 0.556 MPa, and bending strength and modulus of 24.306 MPa and 2.766 GPa, respectively. These findings have significant implications for advancing manufacturing processes and conceptualizing binder-free boards derived from agricultural residues. [ABSTRACT FROM AUTHOR]

Elastocaloric cooling is recognized as a promising alternative to modern vapor-compression cooling systems, which often rely on environmentally hazardous refrigerants. Natural rubber (NR), a well-known renewable resource, stands out among elastomers exhibiting elastocaloric behavior due to a peculiar combination of nontoxicity, low cost, softness, long-life fatigue and high caloric power. Despite these properties, research on the refrigeration potential of NR is still in its early stages, and several aspects require attention. This work investigates, for the first time, the effect of crosslinking density on the elastocaloric properties of NR. Samples with three different crosslinking densities (2.9, 4.0 and 5.2 mol·10−4/cm3) were produced by internal compounding and hot pressing, and thermo-mechanically characterized. The assessment of the elastocaloric effect of the produced samples revealed that reducing the crosslinking degree significantly enhanced the elastocaloric properties. To compare the cooling capacity of the samples, a qualitative coefficient of performance (COPmat) was evaluated as the ratio between extracted thermal energy and deformational work per unit volume. The results highlight that the least crosslinked sample achieved the higher COPmat, equal to 2.4. These results underscore the significance of crosslinking density as one of the primary factors to be considered to enhance the refrigeration potential of NR. [ABSTRACT FROM AUTHOR]

This study fabricated (Al63Cu25Fe12)99Ce1 quasicrystal-enhanced aluminum matrix composites using the hot-pressing method to investigate their interfacial reaction traits. Microstructure analysis revealed that at 490 °C for 30 min of hot-pressing, the interface between the matrix and reinforcement was clear and intact. Chemical diffusion between the I-phase and aluminum matrix during sintering led to the formation of Al7Cu2Fe, AlFe, and AlCu phases, which, with their uniform and fine distribution, significantly enhanced the alloy's overall properties. Regarding compactness, it first increased and then decreased with different holding times, reaching a maximum of about 98.89% at 490 °C for 30 min. Mechanical property analysis showed that compressive strength initially rose and then fell with increasing sintering temperature. After 30 min at 490 °C, the reinforcement particles and matrix were tightly combined and evenly distributed, with a maximum compressive strength of around 790 MPa. Additionally, the diffusion dynamics of the transition layer were simulated. The reaction rate of the reaction layer increased with hot-pressing temperature and decreased with holding time. Selecting a lower temperature and appropriate holding time can control the reaction layer thickness to obtain composites with excellent properties. This research innovatively contributes to the preparation and property study of such composites, providing a basis for their further application. [ABSTRACT FROM AUTHOR]

The objective of this research was to develop a mathematical model of the hot-pressing process for making flat-pressed wood–polymer composites (FPWPCs). This model was used to calculate and predict the temperature and time required for FPWPC pressing. The model's performance was analysed using the experimental results of hot pressing FPWPCs. It was found that an increase in the content of wood particles led to a rapid increase in the pressing time. The model and experiment showed that the core temperature of the wood–polymer mat remained nearly constant for the first 20–30 s of the hot-pressing process. After this period, this temperature increased rapidly until it reached 100 °C, after which the rate of increase began to decelerate sharply. This transition was more distinct in FPWPCs with a high wood-particle content, while in those with a high thermoplastic-polymer content, it was smoother. Increasing the pressing temperature contributed to a reduction in the time required to heat the FPWPC, as confirmed by both experimental data and the modelling of the hot-pressing process. A decrease in the predicted density of the FPWPC resulted in a directly proportional increase in the time required to heat the mat. Validation of the mathematical model revealed a mean absolute percentage error (MAPE) of only 2.5%, confirming its high precision and reliability. The developed mathematical model exhibited a high degree of accuracy and can be used for further calculations of the time required for FPWPC pressing, considering variable parameters such as pressing temperature, wood–polymer ratio, mat thickness, and density. [ABSTRACT FROM AUTHOR]

TiCx particle-reinforced Cu-matrix composites were prepared in the Cu-Ti-C system by thermal explosion and hot press. Extracted TiCx particles with various shapes of in situ TiCx particles in the Cu-Ti-C system were observed through the Field Emission Scanning Electron Microscope (FESEM). It was found that octahedral and close-to-spherical, spherical or cubic TiCx could be fabricated by changing the C/Ti molar ratio and Cu content. Then, the effect of the C/Ti molar ratio and constituent element concentrations on the shape of in situ TiCx particles was determined: the shape of TiCx particles is octahedral at a C/Ti ratio of 0.4-0.6 with the presence of 70 vol% Cu; or spherical and close-to-spherical at 0.8-1.0 with the presence of 70 vol% Cu; or cubic at C/Ti ratios ≥1.0 with the presence of Cu from 80 vol%-90 vol% and even at C/Ti ratios >1.0 with the presence of 70 vol% Cu. The shape-controlled synthesis of TiCx particles in the Cu-Ti-C system is realized. [ABSTRACT FROM AUTHOR]

With the increasing demand for Nd-Fe-B magnets across various applications, the cost-effective substitution of Ce has garnered significant interest. Many studies have been conducted to achieve the high magnetic properties of Nd-Ce-Fe-B hot deformation magnets in which Nd is replaced with Ce. We propose a method to improve magnetic properties of the Ce-substituted Nd-Ce-Fe-B hot-deformed magnets by optimizing the hot-pressing process. This study investigates the microstructure and properties following hot deformation of Ce-substituted Nd-Ce-Fe-B magnets fabricated at a constant temperature and different pressures (100–300 MPa) during the hot-pressing process. The results highlight the influence of pressure from previous hot-pressing processes on grain alignment and microstructure during hot deformation. Magnets subjected to hot pressing at 200 MPa followed by hot deformation achieved superior magnetic properties, with Hci = 8.9 kOe, Br = 12.2 kG, and (BH)max = 31 MGOe with 40% of Nd replaced with Ce. Conversely, precursors prepared at 100 MPa exhibited low density due to high porosity, resulting in poor microstructure and magnetic properties after hot deformation. In magnets using precursors prepared at 300 MPa, coarsened grains and a condensed h-RE2O3 phase were observed. Incorporating Ce into the magnets led to insufficient formation of RE-rich phases due to the emergence of REFe2 secondary phases, disrupting grain alignment and hindering the homogeneous distribution of the RE-rich phase essential for texture formation. Precursors prepared under suitable pressure exhibited uniform distribution of the RE-rich phase, enhancing grain alignment along the c-axis and improving magnetic properties, particularly remanence. In conclusion, our findings present a strategy for achieving the ideal microstructure and magnetic properties of hot-deformed magnets with high Ce contents. [ABSTRACT FROM AUTHOR]

An Fe/FeAl2O4 composite was prepared with Fe-Fe2O3-Al2O3 powder by a hot press sintering method. The mass ratio was 6:1:2, sintering pressure was 30 MPa, and holding time was 120 min. The raw materials for the powder particles were respectively 1 µm (Fe), 0.5 µm (Fe2O3), and 1 µm (Al2O3) in diameter. The effect of sintering temperature on the microstructure and mechanical properties of Fe/FeAl2O4 composite was studied. The results showed that Fe/FeAl2O4 composite was formed by in situ reaction at 1300 °C–1500 °C. With the increased sintering temperature, the microstructure and mechanical properties of the Fe/FeAl2O4 composite showed a change law that initially became better and then became worse. The best microstructure and optimal mechanical properties were obtained at 1400 °C. At this temperature, the grain size of Fe and FeAl2O4 phases in Fe/FeAl2O4 composite was uniform, the relative density was 96.7%, and the Vickers hardness and bending strength were 1.88 GPa and 280.0 MPa, respectively. The wettability between Fe and FeAl2O4 was enhanced with increased sintering temperature. And then the densification process was accelerated. Finally, the microstructure and mechanical properties of the Fe/FeAl2O4 composite were improved. [ABSTRACT FROM AUTHOR]