Thermal Resistance Research Articles

Stabilization Effect of Interfacial Solute Segregation on θ′ Precipitates in Al-Cu Alloys

The effects of Sc, Mg and Si elements in an Al-Cu alloy have been studied by means of hardness tests and transmission electron microscopy analysis. The experimental results show that additions of Sc, Mg and Si can improve the heat resistance of the Al-Cu alloy. The Sc/Mg/Si segregation-sandwiched structure is the most stable, when compared with Sc segregation or Si/Sc co-segregation at the interface of θ′/Al. The additions of Si and Mg promote the aging–hardening response of the Al-Cu alloy. Mg is a micro-alloying element with great potential in stabilizing the size of θ′ phases, which further promotes the number density greatly. Consequently, the Al-Cu alloy achieves a high strength, matched with excellent thermal stability, due to the microalloying of Sc/Mg/Si solutes.

Effect of Polycarbosilane (PCS) on the High-Temperature Properties of Phenolic Resin (Phen) Films and Quartz Fiber/Phen-PCS Composites

In this study phenolic resin (Phen)-loaded PCS (Phen-PCS) films were prepared and quartz fiber/Phen-PCS composites based on the resin films were also prepared. The quartz fiber/Phen-PCS composites were prepared by impregnating 2.5 Dimension (2.5D was an arrangement of fibers) quartz fibers using the resin film infusion (RFI) process. The properties of the composites were investigated. The study demonstrated that the density of the composites, after curing gradually increased with the increase in PCS. The flexural strength of the composites exhibited a trend of increasing and then decreasing after curing and pyrolysis at 1100 °C under an N2 atmosphere. The flexural strength of the composites reached 13.73 MPa when the addition of PCS was 30% of the phenolic resin, representing an increase of 74.23% compared to that of the composites without PCS. The porosity was found to be as low as 2.3% after curing and 2.1% after pyrolysis. X-ray diffraction (XRD) analysis and infrared spectroscopy tests demonstrated that ceramicization products, such as SiO2 and SiC, were produced after pyrolysis of the composites containing PCS. This transformation significantly enhanced the ablation resistance of the composites. Butane flame tests were performed, and the lowest line and mass ablation rates were 0.026 mm/s and 0.196 mg/s after curing. The results of the study revealed the potential of PCS as a precursor to improve the mechanical properties and heat resistance of composites, which offers promising material options for high-temperature applications.

СТРЕССОУСТОЙЧИВЫЙ, С ХОРОШИМ КОМПЛЕКСОМ ОСНОВНЫХ ХОЗЯЙСТВЕННЫХ ПРИЗНАКОВ СОРТ ПШЕНИЦЫ ОЗИМОЙ ТЕРСИНКА

A new variety of soft winter wheat, Tersinka, has been developed in the North Caucasus Federal Scientific Agrarian Center of the Stavropol Region. The objective of research is to create adaptive, stress-resistant genotypes of universal wheat with a set of economic traits for cultivation using intensive and medium-intensive technologies in the conditions of the North Caucasus, Lower Volga and Central Black Earth regions of Russia. New varieties are bred using modern methods of classical, haploid and marker selection. It is based on intraspecific, complex, stepwise hybridization and, starting from the third generation of hybrids (F3), continuous, targeted, individual selection of new genotypes is carried out based on the traits of the model of universal wheat varieties of varying intensity that we have developed. The experiment was carried out on fallow, the method of variety placement was systematic. In the last crossing, the Don 95 variety was used as the maternal form, the Verta variety served as the paternal form. The Tersinka variety belongs to the Erythrospermum variety. During the years of study (2021–2023), the new variety always reliably exceeded the Grom standard in grain yield. On average, this excess over the standard was 1.67 t/ha. According to the growing season, Tersinka belongs to mid-season varieties. The new variety has a higher productive tillering. It is distinguished by high drought and heat resistance and reliably exceeds the standard in terms of resistance to these stresses. According to flour-baking indicators, it belongs to strong wheat improvers. It is distinguished by high field resistance to biotic stressors and a complex of major diseases.

Cost-effective preparation of pre-oxygenated PAN fiber composite SiO2 aerogel felt with excellent mechanical and thermal insulation properties

Silica aerogel is an attractive thermal insulation material due to its low thermal conductivity, light weight and non-combustible inorganic properties, but its inherent brittleness and high production cost hinder its practical application on a large scale. Herein, the high-performance pre-oxidized polyacrylonitrile fiber composite silica aerogel felt (PPAF-SiO2) was successfully prepared by a cost-effective combustion drying technique for the first time. The results show that the PPAF-SiO2 has the feature of lightweight, good flexibility, and its heat resistance, hydrophobicity, and specific surface area are significantly improved. Due to the further polymerization of fiber structure molecules caused by combustion, the tensile strength of the PPAF-SiO2 is increased by 81.9% to 1.71MPa. More importantly, due to the high proportion of silica aerogel in felt, its thermal conductivity can be reduced to 0.02W/(m·K), which is lower than most aerogel composite materials. Moreover, the thermal insulation performance of the PPAF-SiO2 was further confirmed by the infrared thermal imager from room temperature to 300 ℃. In addition, the innovative drying mechanism based on the combustion flame model was proposed. Finally, compared with traditional physical drying technologies in terms of drying time and drying conditions, the combustion drying technology shows great advantages in drying efficiency, energy consumption and equipment investment, which greatly reduces production costs. The combustion drying technology opens up a promisingly method for high efficiency, low energy consumption, and low cost preparation of silica aerogel composites.

Radio frequency‐assisted zirconium carbide matrix deposition for continuous fiber‐reinforced ultra high temperature ceramic matrix composites

AbstractZirconium carbide (ZrC) is considered to be a potential candidate for ultra high temperature applications due to its high melting point, good chemical inertness, and ablation resistance, but the monolithic form suffers from low fracture toughness and hence poor thermal shock resistance. Reinforcing it using continuous carbon fibers (Cf) to create an ultra high temperature ceramic matrix composite is an obvious solution, however densifying ZrC requires the use of very high temperatures combined with significant pressure, such as obtained by using hot pressing or spark plasma sintering, which risks damaging fibers. In the present work, radio frequency‐assisted chemical vapor infiltration (RF‐CVI) has been investigated with a view to forming Cf/ZrC composites. These initial experiments revealed the ability to deposit pure, nano‐grained, and near stoichiometric ZrC with deposition occurring preferentially from the center of the sample due to the nature of the inverse temperature profile developed. The deposited ZrC grains were in the range of 4–9 nm in size and had a lattice parameter of 0.4750 nm. The work also showed that the use of RF‐CVI enabled the minimization of early pore sealing, a common problem for conventional CVI.

Photopolymerization initiated by p-diethylene glycol monomethyl ether cinnamyl formamide-based disulfide under 455 nm LED with minimized volume shrinkage

This study introduces a novel p-diethylene glycol monomethyl ether cinnamyl formamide-based disulfide monomer, N,N′-(disulfanediylbis(2,1-phenylene)) bis(4-(4-(2-(2-methoxyethoxy)ethoxy) phenyl)-2-oxobut-3-enamide) (Mp-BSCF), designed to reduce the volume shrinkage of photosensitive resins and initiate monomer polymerization under 455 nm LED light irradiation. The photochemical properties and photoinitiation efficiency of Mp-BSCF are systematically investigated using UV–vis absorption spectroscopy, electron paramagnetic resonance (EPR) and real-time infrared spectroscopy. Although its weak absorption around 455 nm, Mp-BSCF can generate arylthiyl radicals under 455 nm LED irradiation, and then effectively initiate the polymerization of triethylene glycol dimethacrylate (TEGDMA)/A glycerolate dimethacrylate (Bis-GMA) system. Increasing Mp-BSCF addition enhances the final double bond conversion and maximum polymerization rate of the TEGDMA/Bis-GMA system, reaching up to 82.0 % and 2.02 % s−1, respectively. Notably, Mp-BSCF significantly reduces the volume shrinkage of the photopolymerization system, with the addition of 10 % Mp-BSCF resulting in a 50 % reduction compared to the control system. This reduction is attributed to the dynamic reversible nature of the SS bond “breaking-recovery” and the intermolecular hydrogen bond interaction. Additionally, Mp-BSCF improves the thermal stability, friction resistance, and hardness of the TEGDMA/Bis-GMA photopolymerization system.

Correlation of heat transport mechanism and structural properties of GaN high electron mobility transistors

Grain sizes, impurities, and layer thicknesses in the nm-range affect the heat transport and, hence, hinder proper heat dissipation of GaN-based devices. To obtain a clear picture of heat dissipation, the mechanisms of heat transport must be linked to the structural properties of the nitride-based materials in the device. In this paper, a systematic investigation of the typical layers of GaN high-electron mobility transistor stacks was conducted by time-domain thermoreflectance analysis and Raman measurements. The analyzed layers are the AlN nucleation layer, the Al0.3Ga0.7N transition layer, the AlGaN/AlN superlattice, the C-doped GaN back-barrier, and the uid GaN layer. The results were interpreted using the Born–van Karman model, including the suppression function approach to describe the governing heat transport mechanisms. Investigation of this AlN nucleation layer showed that its phonon scattering is dominated by impurity and grain boundary scattering. The Al0.3Ga0.7N transition layer was shown to have a reduced thermal conductivity not only due to alloy scattering but also because of grain boundary scattering. The AlGaN/AlN superlattice showed a thermal conductivity lower than the Al0.3Ga0.7N transition layer, especially at higher temperatures (7.2 ± 0.2 W/mK vs 14.1 ± 0.4 W/mK at 300 °C). Caused by the enhanced AlGaN/AlN interface density, the thermal conductance was found to be 2 GW/m2 K. The AlGaN/AlN superlattice indicated an anisotropic thermal transport with a factor of ∼1.5. The C-doped GaN layers were analyzed in terms of their size-dictated thermal conductivity, resulting in a reduction of ∼66% from 1 μm to 250 nm at 30 °C. Raman spectroscopy revealed that the thicker the GaN layer, the higher the compressive stress in GaN, which additionally results in a higher thermal transport. The investigations of the heat transport depending on the structural properties enabled an accurate determination of the thermal conductivity of the layer stack. These thermal conductivities served as input parameters for 3D simulation to extract the temperature, in terms of the thermal resistance, of such high-electron mobility transistor stacks. This simulation shows the importance of the GaN layer in terms of thermal management. This work uncovers the thermal transport in GaN-based transistor stacks with the aim to improving the thermal design.

Simultaneous close-contact melting on two asymmetric surfaces: Demonstration, modeling and application to thermal storage

The present study deals with melting in a geometry suitable for Latent-Heat Thermal Energy Storage (LHTES) systems, which are of importance for future industrial installations utilizing solar energy or waste heat. The intrinsically high thermal resistance of phase-change materials (PCM) can be remedied by taking advantage of close contact melting (CCM), where the solid phase is separated from a hot surface by only a thin liquid layer. The basic CCM takes place on a horizontal flat surface, but during the last decade its application in various finned LHTES units has been demonstrated experimentally and analyzed numerically.Specifically, the configuration studied in the present work is relevant to a horizontal double-pipe concentric storage unit with a longitudinally finned inner tube. While this rather simple geometry has been extensively studied in the past, the present work is completely novel in its demonstration and analysis of simultaneous close-contact melting on two generally asymmetric surfaces created by the longitudinal fins. A unique experimental apparatus is introduced, based on the so-called 'Mercedes' configuration of the fins. It is designed transparent, allowing for real-time observation of melting sequences. Close-contact melting is achieved by supplying heat to the outer shell of the unit: the solid phase is detached from the shell and moves, by translation and rotation, in the liquid phase. The results from these experiments demonstrate the feasibility of CCM on two asymmetric walls within this system, hinting at the potential for optimizing the melting rate by utilizing a larger portion of the extended surface for CCM.A key component of this study is the development of a reliable numerical approach, which goes beyond the limitations of widely-applied enthalpy-porosity method and combines the general enthalpy formulation, convective heat transfer and general rigid body motion that includes rotation. Therefore, a new numerical model has been devised, using an in-house code realized in MATLAB. A full set of the governing conservation equations is solved using a finite-difference framework, integrated with advanced numerical methods for the fluid-solid interaction and an enthalpy formulation for the phase change process. The model is validated carefully, and then numerical studies are conducted to elucidate the melting process.The present paper presents a further proof of the special role that close-contact melting (CCM) can play in properly designed thermal energy storage units and finned systems in general. It is demonstrated that the fins, when properly designed and oriented, can induce CCM in their vicinity, contributing to a very significant increase in the melting rate, which reflects charging of the unit.

Exploring the Impact of Visual Heat Conduction Paths on Thermal Conductivity of Polymer Composites and the Practical Applications.

The theory of heat conduction paths has been widely recognized and widely studied in the research about the thermal conductivity of thermal conductive polymer composites at present. Encapsulating polymer pellets with thermally conductive fillers and processing them into thermally conductive polymer composites is a simple and effective method for constructing heat conduction paths. It is meaningful to investigate the related heat conduction mechanism of this method. Otherwise, this approach can significantly preserve the performance of the polymer substrate, making it highly valuable for practical material applications. In this work, polyethylene-octene elastomer (POE) pellets were encapsulated with thermal conductive fillers by physical absorption. Subsequently, the composite films containing heat conduction paths were fabricated using the encapsulated POE pellets through a heating press. Alumina (Al2O3), boron nitride (BN), and alumina/boron nitride hybrid (Al2O3/BN) fillers were used to prepare Al2O3@POE, BN@POE, and BN/Al2O3@POE composite films to investigate the influence of filler shapes on heat conduction path construction. The influence of the constitute and density of heat conduction paths on the thermal conductivity of composite films was analyzed by infrared thermal imaging, finite element analysis, and thermal resistance theory in detail. Owing to the reserved good adhesion and flexibility of the POE substrate, the composite films could be directly used as thermal interface materials for chip cooling, which presented a good heat dissipation effect. Furthermore, a series of integrated composite materials were prepared by the combination of encapsulated pellets with various functional films (copper foil, aluminum foil, and graphite sheet) through a one-pot heating press, exhibiting a good electromagnetic shielding effect. The performance of the composites and the corresponding preparation method demonstrate the strong significance of this research for practical applications.

Highly Stable Polyimide Composite Nanofiber Membranes with Spectrally Selective for Passive Daytime Radiative Cooling.

Passive radiative cooling technology without electric consumption is an emerging sustainability technology that plays a key role in advancing sustainable development. However, most radiative cooling materials are vulnerable to outdoor contamination and thermal/UV exposure, which leads to decreased performance. Herein, we report a hierarchically structured polyimide/zinc oxide (PINF/ZnO) composite membrane that integrates sunlight reflectance of 91.4% in the main thermal effect of the solar spectrum (0.78-1.1 μm), the mid-infrared emissivity of 90.0% (8-13 μm), UV shielding performance, thermal resistance, and ideal hydrophobicity. The comprehensive performance enables the composite membrane to yield a temperature drop of ∼9.3 °C, compared to the air temperature, under the peak solar irradiance of ∼800 W m-2. In addition, the temperature drop of as-obtained composite membranes after heating at 200 °C for 6 h in a nitrogen/air atmosphere can be well maintained at ∼9.0 °C, demonstrating their ideal radiative cooling effect in a high-temperature environment. Additionally, the PINF/ZnO composite membrane shows excellent chemical durability after exposure to the outdoor environment. This work provides a new strategy to integrate chemical durability and thermal resistance with radiative cooling, presenting great potential for passive radiative cooling materials toward practical applications in harsh environments.

Use of modified polycaprolactone polymer in food packaging applications: a review

Objective: Plastic production in the world is constantly increasing and plastics have been degraded in nature for many years. This situation turns into a major environmental disaster that people and living organisms will encounter. In addition, packaging films that can be applied to foods safely and extend the shelf life of foods with their functional properties are needed. Polycaprolactone (PCL) is a biodegradable polymer produced by synthetic processes and has been frequently investigated in food packaging studies in recent years. Due to its flexibility, biocompatibility and thermoplasticity, the use of PCL and its copolymers in packaging film applications is becoming widespread. Disadvantages such as low mechanical and thermal resistance can be eliminated by adding fillers, mixing with other polymers or using multi-layers. This study aims to compile recent studies on the use of PCL polymer modified by various methods as food packaging. Conclusion: In the literature, there are many interesting studies on the making composite of PCL with different methods. Nanoclays to improve mechanical and gas barrier properties; nanometals and plant materials to impart antimicrobial properties; innovative additives such as oxygen scavengers, photosynthesizing agents, antimicrobial peptides are used in the modification of PCL. In this review, it was revealed that the modifications contribute to PCL polymer in terms of stiffness and gas barrier properties and add antimicrobial and antioxidant character to the polymer.

Temperature calibration of sample rods for neutron diffraction apparatus in the range of 6–473 K

Abstract Internal stresses play a crucial part in determining a material’s properties, which emphasizes the significance of accurate stress measurement and analysis. Neutron diffraction technology is a very promising approach to studying the complex microstructural properties of many materials, especially with the growing demand for cryogenic studies. This new device has a robust load capacity of 50 kN and works smoothly in a wide temperature range of 6 K–473 K. Furthermore, the diffraction angle is 47 degrees broader. Regardless of the samples, we observed that a thermal balance point existed close to 180 K. Importantly, thermal resistance was eliminated by the use of an analytical method, which has an extraordinarily small error of 2%. Using this exact calibration methodology ensures that the sample temperature is accurate during the experiments. This work presents a crucial apparatus for investigating the complexity of internal stresses in materials and offers an effective method for estimating and managing sample temperatures while doing research.

Integrated transcriptomics and metabolomics provides insights into the Nicotiana tabacum response to heat stress.

Heat stress is a prevalent factor that significantly damages crops, especially with the ongoing global warming and increasing frequency of extreme weather events. Tobacco is particularly sensitive to temperature fluctuations, experiencing reduced yield and quality under high temperatures. However, the underlying molecular mechanisms of heat resistance in tobacco remain poorly understood. This study comprehensively analyzed biochemical, transcriptomic, and metabolomic responses to heat stress on the root and shoot of the tobacco cultivar K326 compared to control conditions. Heat stress significantly increased the activities of antioxidant enzymes (CAT, POD, and SOD) and levels of osmotic mediators (soluble sugars, sucrose, and proline) in the shoot. Furthermore, transcriptome analysis identified 13,176 differentially expressed genes (DEGs) in the root (6,129 up-regulated and 7,047 down-regulated) and 12,283 DEGs (6,621 up-regulated and 5,662 down-regulated) in the shoot. The root had 24 enriched KEGG pathways, including phenylpropanoid metabolism, while the shoot had 32 significant pathways, such as galactose metabolism and MAPK signaling. The metabolomic data identified 647 metabolites in the root and 932 in the shoot, with carbohydrates and amino acids being the main categories. The root had 116 differentially abundant metabolites (DAMs) (107 up-regulated and 9 down-regulated), and the shoot contained 256 DAMs (251 up-regulated and 5 down-regulated). Joint transcriptome and metabolome analysis showed that galactose metabolism and starch and sucrose metabolism were co-enriched in both tissues. In contrast, amino sugar and nucleotide sugar metabolism was enriched in the root, and purine metabolism in the shoot. The purine metabolic pathway in the shoot can modulate the expression of MYB transcription factors by influencing ABA synthesis and signaling, thereby controlling the accumulation of HSPs, raffinose, sucrose, and trehalose to enhance heat tolerance. Furthermore, NtMYB78, an MYB transcription factor, enhances tolerance for heat stress in tobacco. This research offers a foundational framework for investigating and implementing heat-resistant genes and metabolic pathways in the root and shoot of tobacco seedlings.

Thermally conductive silver adhesive enhanced by MXene@AgNPs with excellent thermal conductivity for thermal management applications

The Thermal Conductive Silver Adhesive (TCSA) efficiently transfers heat from electronic components to heat dissipation components, preventing overheating and extending device lifespan. Despite the effectiveness of commercial sintered nano TCSA, high production costs necessitate a more affordable, high-performance preparation method. This study presents a strategy for preparing ultra-high thermal conductivity (TC) TCSA using multidimensional thermal conductive fillers and low-temperature sintering of silver nanoparticles (AgNPs). MXene@AgNPs particles are synthesized via in-situ reduction of AgNPs on MXene surfaces. These particles, combined with silver microflakes (AgMFs) as primary fillers and epoxy (EP), undergo low-temperature heat treatment to form the AgMFs-MXene@AgNPs/EP composite. Characterization and computational models show that filler-filler interface thermal resistance (ITRf-f) is critical for TC. Adding MXene alone is insufficient, but using MXene@AgNPs particles as secondary fillers allows AgNPs to interconnect fillers, effectively reducing the ITRf-f. The resulting composite achieves an ultra-high TC of 65.51 Wm−1K−1 with 63 wt% total filler content (60 wt% AgMFs, 3 wt% MXene@AgNPs). This study advances the development of low-cost, high-performance TCSA for thermal management applications.

Significant improvement in sensitivity of an anomalous Nernst heat flux sensor by composite structure

Heat flux sensors (HFS) have attracted significant interest for their potential in managing waste heat efficiently. A recently proposed HFS, which works on the basis of the anomalous Nernst effect (ANE), offers several advantages in its simple structure leading to easy fabrication, low cost, and reduced thermal resistance. However, enhancing sensitivity through traditional material selection is now challenging due to a small number of materials satisfying the required coexistence of a large transverse thermopower and low thermal conductivity. In this study, by utilizing composite structures and optimizing the device geometry, we have achieved a substantial improvement in the sensitivity of an ANE-based HFS. We developed composite structures comprised of a plastic substrate with an uneven surface and three-dimensional (3D) uneven TbCo films, fabricated using nanoimprint techniques and sputtering. This approach resulted in a sensitivity that is approximately four times greater than that observed in previous studies. Importantly, this method is independent of the material properties and can significantly enhance the sensitivity. Our findings could lead to the development of highly sensitive HFS devices and open avenues for the fabrication of 3D devices.

Research on temperature field and thermal deformation characteristics of casting rollers in twin-roll casting process

The twin-roll casting (TRC) process is considered a revolutionary technology in the metallurgical field and has garnered significant attention and research in recent years. The casting rollers used in the TRC process are crucial for achieving the desired shape of the casting strip. This study investigates the temperature distribution and thermal deformation of casting rollers in the TRC process using numerical simulation. A novel model for predicting the thermal resistance distribution at the circumferential interface between the casting roller and the molten pool has been introduced. The study examined the effects of various factors including casting roller diameter, water channel position, number, and diameter on temperature, thermal deformation, and heat flux. The findings reveal that increasing the casting roller diameter from 460 mm to 500 mm or augmenting the distance from the water channel to the casting roller surface from 35 mm to 55 mm resulted in a 37 % and 30 % increase in the maximum surface temperature of the casting roller, respectively. Additionally, an increase in the number of water channels from 30 to 50 and a growth in their diameter from 20 mm to 28 mm resulted in the average heat flux of the casting roller remaining stable, with fluctuations less than 1 MW/m2. Leveraging the insights gained from the thermal deformation behavior of the casting roller and the ideal shape of the casting strip, a comprehensive control approach for the casting roller profile was developed. The outcomes of this research provide a valuable theoretical framework for enhancing the design of casting roller structures in the TRC process.

Multifunctional, efficient, and durable composites of conductive PMIA/Ag membrane

Developing high-efficiency electromagnetic interference (EMI) shielding composite membranes along with additional functionalities to extend the application scenarios is highly desirable for the next generation electronic devices. Here, we report an ultrathin and flexible EMI shielding materials with sensitive Joule heating and outstanding infrared stealth performance was fabricated from poly-m-phenylene isophthalamide (PMIA) and Ag nanoparticles (AgNPs) through an innovation and simplicity method of electrospinning and electroless plating. Profiting from a continuous three-dimensional (3D) conductive network, the final membrane achieves an outstanding EMI shielding effectiveness (SE) of 100.51 dB (in X-band), a remarkable Joule heating properties with a fast thermal response and low driving voltage (<0.5 V), and an outstanding infrared stealth with a low infrared emissivity (0.28). Meanwhile, the prepared composite membrane demonstrates stable EMI SE even after water washing, continuous bending, and heating treatment. This work integrates high-performance fiber PMIA, characterized by high heat resistance, flame retardancy, self-extinguishing properties, and chemical resistance, with functions such as EMI shielding, infrared stealth, and autonomous thermal management. It has great development potential if utilized in specialized combat uniforms under harsh conditions.

Effect of moisture content in polyether-ether-ketone (PEEK) filament on 3D printed parts

Polyether-ether-ketone (PEEK) is a recently commonly used high-performance thermoplastic material with high heat resistance, high chemical resistance, high water resistance, and high wear resistance. Polyether-ether-ketone products with complex structures manufactured through the 3D printing process of fused filament fabrication (FFF) are emerging in the medical field. However, similar to other plastics, PEEK materials are also hygroscopic. This may have an impact on 3D printed products. The effect of storage time of filament on 3D printed PEEK products under specific temperature and humidity conditions has not been further explored. This study is mainly to explore the moisture absorption of PEEK filament for different storage time and the effect of moisture absorption on the performance of 3D printed PEEK products. The correlation between storage time and moisture absorption is verified by experiment. It is found that moisture will affect the surface quality of PEEK products. In addition, the mechanical test results show that the increase in the amount of water absorbed leads to the decrease of material properties, such as tensile strength, density, and hardness. Therefore, it is recommended to store unused or leftover PEEK filaments under vacuum drying conditions. For PEEK filaments that are being printed, it should be ensured to replace them every less than 24 h.

Influence of varying matrix/fiber concentration on mechanical properties of bi-directional carbon fiber reinforced polymer composite

The polymer composites comprising bi-directional carbon fabric incorporated in the epoxy matrix have been developed for various advanced applications in the field of automobile and aerospace sectors. The distinct advantages of using epoxy material with hardener are good adhesion, high tensile, compression and bending strengths, good corrosion, and heat resistance properties. Using carbon fiber enhances the stiffness, reduces the weight, and improves the chemical resistance apart from possessing high thermal conductivity and low coefficient of thermal expansion. Considering all the above aspects, the present work proposes to investigate the mechanical properties of carbon-reinforced epoxy composites with fiber matrix ratios of 40:60, 50:50, and 60:40 by wt% as these particular combinations have been limitedly addressed so far. The well-known hand lay-up technique has produced the laminates and the test samples prepared from the laminate are subjected to tensile, flexural, hardness, and impact strength properties. Based on the experimental work of the composites made in the laboratory, the fiber matrix ratio of 60:40 has revealed the best attributes in terms of higher mechanical strengths compared to the composites with fiber matrix ratio of 40:60 and 50:50 and the data obtained have been substantiated using scanning electron microscope analysis.

High Strength and Heat Resistance of Low-RE-Containing Mg Alloy Achieved via Substantial Dynamic Precipitates

High Strength and Heat Resistance of Low-RE-Containing Mg Alloy Achieved via Substantial Dynamic Precipitates