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Aerospace vehicles that undergo atmospheric re-entry require thermal protection systems (TPS) to protect them from the extreme environment. Currently, TPS production relies on hand layup techniques which are time-, cost-, and energy-intensive. A method to produce composite TPS via additive manufacturing (AM) is demonstrated, which uses a customdesigned formulation. Thermal characterization of the composite system showed that char yield values were comparable to ablative systems presently used in TPS. Printability was demonstrated by in situ deposition onto a rotating/tilting aluminum substrate. A five-axis printer system was developed/adapted to accommodate the contours of TPS substrates and to enable the extrudate to completely cover leading edges of vehicle control surfaces. [ABSTRACT FROM AUTHOR]

Given the critical threats to aviation safety induced by electromagnetic interference (EMI), fire hazards, and icing, high‐performance multifunctional materials integrating mechanical flexibility, EMI shielding, fire resistance, and thermal management capabilities are highly desired yet challenging. Herein, a synergistic strategy is developed involving defect engineering and graphitization to enhance EMI shielding and thermal management properties of SiBCNZr nanofiber fabrics. Initially, the SiBCNZr nanofiber fabrics demonstrate excellent mechanical flexibility and intrinsic ceramic fire resistance. Furthermore, after annealing at 1400 °C, t‐ZrO2 nanograins with various types of defects are precipitated from the amorphous matrix, accompanied by the formation of turbostratic graphite C. The synergistic effects of defect engineering of t‐ZrO2 nanograins and graphitization of turbostratic C enhance conductivity and polarization loss, leading to a specific shielding effectiveness (SSE/t) of 2718 dB cm2 g−1. Additionally, the fabrics also demonstrate remarkable electrothermal conversion capability with a rapid electrothermal response. This work provides valuable insights into designing multifunctional EMI shielding ceramic nanofiber fabrics for aviation safety. [ABSTRACT FROM AUTHOR]

MXene is a novel two-dimensional layered nanomaterial with a very large specific surface area and abundant surface functional groups, endowing it with unique physical and chemical properties. MXene can be compounded with other functional materials to significantly improve the performance of MXene composites or broaden their application scope. Meanwhile, with the development of flexible composite preparation technology, it has promoted the continuous expansion of its application fields. The introduction and combination of different materials can improve the performance of flexible composites and make them have a broader application prospect. In recent years, researchers have started preparing MXene materials as flexible composites for applications such as supercapacitors, sensors, electromagnetic shielding and thermal management. This paper gives a brief introduction to flexible composites and MXene materials, reviews the applications of MXene based flexible composites in various fields as well as the research progress, and provides an outlook on their future development direction. [ABSTRACT FROM AUTHOR]

We studied a candidate TPS (thermal protection system) material for reusable re-entry space vehicle applications. The material was based on a high-temperature-resistant material called Cerakwool. A total of six specimens were fabricated with substrate densities of 0.45 g/cm3, 0.40 g/cm3, and 0.35 g/cm3, with two specimens for each density. All specimens were coated with high-emissivity TUFI (toughened unpiece fibrous insulation), with coating thicknesses ranging from 445 to 1606 µm. The specimens were tested using an HVOF (high-velocity oxygen fuel) material ablation test facility. For each density specimen pair, one specimen was tested at 1 MW/m2 and the remaining one was tested at 0.65 MW/m2. The average stagnation point temperature for specimens tested at 1 MW/m2 was ~893 °C, approximately 200 °C higher than those tested at 0.65 MW/m2. This suggests a ~200 °C increase in stagnation point temperature for a 0.35 MW/m2 rise in incident heat flux. During the tests, internal temperatures were measured at three locations. For all tested specimens, regardless of heat flux test conditions and density, the temperature at ~40 mm from each specimen's stagnation point remained around or below 50 °C, well within the 180 °C design limit set for the TPS back face temperature. Post-test visual inspections revealed no signs of ablation or internal damage, confirming the material's reusability. [ABSTRACT FROM AUTHOR]

Soft X‐ray spectroscopy is an important technique for measuring the fundamental properties of materials. However, for measurements of samples in the sub‐millimetre range, many experimental setups show limitations. Position drifts on the order of hundreds of micrometres during thermal stabilization of the system can last for hours of expensive beam time. To compensate for drifts, sample tracking and feedback systems must be used. However, in complex sample environments where sample access is very limited, many existing solutions cannot be applied. In this work, we apply a robust computer vision algorithm to automatically track and readjust the sample position in the dozens of micrometres range. Our approach is applied in a complex sample environment, where the sample is in an ultra‐high vacuum chamber, surrounded by cooled thermal shields to reach sample temperatures down to 2.5 K and in the center of a superconducting split coil. Our implementation allows sample‐position tracking and adjustment in the vertical direction since this is the dimension where drifts occur during sample temperature change in our setup. The approach can be easily extended to 2D. The algorithm enables a factor of ten improvement in the overlap of a series of X‐ray absorption spectra in a sample with a vertical size down to 70 µm. This solution can be used in a variety of experimental stations, where optical access is available and sample access by other means is reduced. [ABSTRACT FROM AUTHOR]

Polymer-derived SiBCN ceramic aerogels have attracted extensive attention in recent years due to the excellent electromagnetic wave absorption and thermal insulation properties. With these merits, SiBCN aerogels are promising for the application of high-speed vehicles requiring thermal and electromagnetic shielding. However, the brittleness and poor mechanical property of SiBCN aerogel seriously hinder its practical applications. In this paper, SiBCN/SiBCN nf composite ceramic aerogels with enhanced mechanical property were prepared by combining electrospinning technique with simultaneous pyrolysis process of polyborosilane (PBS) fibers and precursor aerogels. The effect of varying fiber content on the density, mechanical property, thermal insulation as well as microwave absorption performance of the composite aerogel was investigated. In addition, the underlying toughness mechanism of the SiBCN/SiBCN nf composite ceramic aerogel was elucidated. The compressive strength of the SiBCN/SiBCN nf composite aerogel increased from 0.29 MPa to 1.62 MPa. Importantly, while the mechanical strength of the composite aerogel increased by about 5.5 times, SiBCN/SiBCN nf aerogel still exhibits low density of 0.105 g/cm³, low thermal conductivity of 0.048 W/mK and a minimum reflection loss (RL min) of −20 dB. Owing to the integration of electromagnetic wave (EMW) absorption and thermal insulation properties, SiBCN/SiBCN nf aerogels pave the way for the construction of thermal and electromagnetic shielding material for high-speed vehicles. [ABSTRACT FROM AUTHOR]

The Dragonfly mission has the scope of studying the surface of Titan, Saturn's largest moon, using a rotorcraft lander. A mission-critical event in the timeline involves Dragonfly's initial flight as it descends into Titan's atmosphere. The preparation for this initial flight involves releasing the heat shield and utilizing the lander's rotors to damp motion while still attached to the parachute-supported aeroshell to ensure a smooth release. The aerodynamics of this event are studied in Titan conditions using high-fidelity computational fluid dynamics (CFD). The CFD model is benchmarked using available experimental measurements relevant to subcomponents of the event and include: (1) an open backshell, (2) bluff bodies similar to the Dragonfly fuselage, and (3) a rotor-body interaction from a helicopter rotor. The CFD results correlate well with measurements to provide confidence in the present studies focused on Titan. The novel studies presented in this work focus on the rotor-based control of the lander–backshell combination and its ability to mitigate spinning about the main parachute support line. This effort finds that the relatively large fuselage combined with near-fuselage rotors (driven by aeroshell space limitations) drives an unexpected aerodynamic interaction between the rotor and fuselage. Specifically, we observe low-pressure zones on the fuselage adjacent to the rotor that create a "suction" force. This first-order force creates an unexpected aerodynamic interaction that demands careful attention. In this paper, this force is documented and solutions are proposed to mitigate undesirable control character. • Aerodynamics of the Dragonfly lander interacting with a parachute-supported backshell. • Efforts supported using high-fidelity numerical models backed with a series of experimental benchmarks. • Elucidation of rotors inducing a strong force on the lander that need special consideration. • Proposed solutions highlighted by careful consideration of rotor orientation. [ABSTRACT FROM AUTHOR]

Managing the metal's texture throughout the entire processing procedure is imperative for controlling the final properties of metal alloys. In the aerospace industry, α‐Ti alloys have been successfully utilized in applications such as aircraft skins, heat shields, and heat exchangers. However, inherent mechanical strength, fatigue sensitivity, and fracture toughness limitations have significantly restricted their wider adoption. On the other hand, β‐Ti alloys have received increasing attention in the biomedical field due to their lower elastic modulus. However, their actual application has been primarily restricted by the inability to match natural bone's Young's modulus sufficiently. Among these application limitations for both α‐Ti and β‐Ti alloys, texture is an essential factor affecting mechanical properties. Elucidating texture evolution on α‐Ti and β‐Ti alloys is crucial for enabling the expansion of their applications. This review summarizes detailed analyses of the intertwined evolution of texture and microstructure in α‐Ti and β‐Ti alloys during cold rolling, hot rolling, and annealing. Furthermore, based on these fundamental materials science insights, the resultant impact of texture and microstructure on achieving targeted mechanical properties is discussed. Finally, potential pathways are proposed to further guide texture and microstructure evolution in α‐Ti and β‐Ti alloys to meet application requirements. [ABSTRACT FROM AUTHOR]

Highlights: The large-scale, high-strength, super-tough, and multifunctional nacre-like heterocyclic aramid (HA)/MXene@polypyrrole (PPy) (HMP) nanocomposite papers were fabricated using the in-situ assembly of PPy onto the HA/MXene hydrogel template. The "brick-and-mortar" layered structure and abundant hydrogen-bonding interactions among MXene, PPy, and HA respond cooperatively to external stress and effectively increase the mechanical properties of HMP nanocomposite papers. The templating effect from HA/MXene was utilized to guide the assembly of conducting polymers, leading to high electrical conductivity and outstanding electromagnetic interference shielding performance. Robust, ultra-flexible, and multifunctional MXene-based electromagnetic interference (EMI) shielding nanocomposite films exhibit enormous potential for applications in artificial intelligence, wireless telecommunication, and portable/wearable electronic equipment. In this work, a nacre-inspired multifunctional heterocyclic aramid (HA)/MXene@polypyrrole (PPy) (HMP) nanocomposite paper with large-scale, high strength, super toughness, and excellent tolerance to complex conditions is fabricated through the strategy of HA/MXene hydrogel template-assisted in-situ assembly of PPy. Benefiting from the "brick-and-mortar" layered structure and the strong hydrogen-bonding interactions among MXene, HA, and PPy, the paper exhibits remarkable mechanical performances, including high tensile strength (309.7 MPa), outstanding toughness (57.6 MJ m−3), exceptional foldability, and structural stability against ultrasonication. By using the template effect of HA/MXene to guide the assembly of conductive polymers, the synthesized paper obtains excellent electronic conductivity. More importantly, the highly continuous conductive path enables the nanocomposite paper to achieve a splendid EMI shielding effectiveness (EMI SE) of 54.1 dB at an ultra-thin thickness (25.4 μm) and a high specific EMI SE of 17,204.7 dB cm2 g−1. In addition, the papers also have excellent applications in electromagnetic protection, electro-/photothermal de-icing, thermal therapy, and fire safety. These findings broaden the ideas for developing high-performance and multifunctional MXene-based films with enormous application potential in EMI shielding and thermal management. [ABSTRACT FROM AUTHOR]

The application of different glass materials in the area of radiation shielding and charge particle attenuation has necessitated a comprehensive study of glass materials doped with special elements to examine the impact of the special element on the microstructure and shielding capabilities of resultant glass materials. In this study, the optical absorption spectra of Mo3+ doped cadmium zinc lithium borate glasses (BCZLMx) was investigated using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopic methods to ascertain the suitability of BCZLMx glass microstructure to neutron and charge particle attenuation. Results show that the absorption cross-section is the dominant contributor to the total cross section for all samples, ranging from 110.9 cm−1 to 111.7 cm−1. BCZLM1 glass sample appears to be slightly more effective at removing fast neutrons from the beam while BCZLM5 glasses are effective at stopping electrons, protons, alpha particles, and carbon ions when compared to the other BCZLMx glasses samples. This implies that doping cadmium zinc lithium borate glasses with Mo3+ reduces fast and thermal neutrons shielding potential and increased charge particles interaction of the BCZLMx glass system. [ABSTRACT FROM AUTHOR]

Highlights: The introduction of MoS2 generates a "kill three birds with one stone" effect to the original binary MXene/ANF system: lubrication toughening mechanical performance; reduction in secondary reflection pollution of electromagnetic wave; and improvement in the performance of photothermal conversion. After the introduction of MoS2 into MXene/ANF (60:40), the strain and toughness were increased by 53.5% (from 18.3% to 28.1%) and 61.7% (from 8.9 to 14.5 MJ m−3), respectively. Fortunately, the SER decreases by 22.4%, and the photothermal conversion performance was increased by 22.2% from ~ 45 to ~ 55 °C. The design and fabrication of high toughness electromagnetic interference (EMI) shielding composite films with diminished reflection are an imperative task to solve electromagnetic pollution problem. Ternary MXene/ANF (aramid nanofibers)–MoS2 composite films with nacre-like layered structure here are fabricated after the introduction of MoS2 into binary MXene/ANF composite system. The introduction of MoS2 fulfills an impressive "kill three birds with one stone" improvement effect: lubrication toughening mechanical performance, reduction in secondary reflection pollution of electromagnetic wave, and improvement in the performance of photothermal conversion. After the introduction of MoS2 into binary MXene/ANF (mass ratio of 50:50), the strain to failure and tensile strength increase from 22.1 ± 1.7% and 105.7 ± 6.4 MPa and to 25.8 ± 0.7% and 167.3 ± 9.1 MPa, respectively. The toughness elevates from 13.0 ± 4.1 to 26.3 ± 0.8 MJ m−3 (~ 102.3%) simultaneously. And the reflection shielding effectiveness (SER) of MXene/ANF (mass ratio of 50:50) decreases ~ 10.8%. EMI shielding effectiveness (EMI SE) elevates to 41.0 dB (8.2–12.4 GHz); After the introduction of MoS2 into binary MXene/ANF (mass ratio of 60:40), the strain to failure increases from 18.3 ± 1.9% to 28.1 ± 0.7% (~ 53.5%), the SER decreases ~ 22.2%, and the corresponding EMI SE is 43.9 dB. The MoS2 also leads to a more efficient photothermal conversion performance (~ 45 to ~ 55 °C). Additionally, MXene/ANF–MoS2 composite films exhibit excellent electric heating performance, quick temperature elevation (15 s), excellent cycle stability (2, 2.5, and 3 V), and long-term stability (2520 s). Combining with excellent mechanical performance with high MXene content, electric heating performance, and photothermal conversion performance, EMI shielding ternary MXene/ANF–MoS2 composite films could be applied in many industrial areas. This work broadens how to achieve a balance between mechanical properties and versatility of composites in the case of high-function fillers. [ABSTRACT FROM AUTHOR]

Performance of Photovoltaic-double skin facade (Photovoltaic-DSF) system in summer has been critical. Owing to high solar ingress, cooling requirement of a building significantly increases. Photovoltaic-DSF system provides a shield and controls the heat gain through fenestration in the interior spaces. In the present article, mathematical correlations are developed for energy characterization of forced-ventilated Photovoltaic-DSF system in India's hot summer zone i.e. Jaipur. The Photovoltaic-DSF system has been installed and monitored for Jaipur's summer months (May to July). L25 Orthogonal array of design parameters (air cavity thickness, air velocity, and PV panel's transparency) and their respective levels have been developed using Taguchi design to perform experiments. Based on experimental results, multiple linear regression has been used to forecast solar heat gain coefficient, PVs electrical power and daylighting illuminance indoors as function of design factors. The statistical significance of mathematical relationships is sorted by variance analysis, which is found to be in good accord with field measurements (R² > 0.90). The proposed correlations are pragmatic in designing Photovoltaic-DSF systems for hot summer conditions. The Photovoltaic-DSF system with 30% transmittance and air velocity of 5 metres per second in 200 mm air cavity thickness achieved maximum energy performance in hot summers. [ABSTRACT FROM AUTHOR]

[Display omitted] The demand for flexible composite films with electromagnetic interference (EMI) shielding capabilities is rapidly increasing. Balancing high EMI performance with flexibility and portability has become a critical research focus in practical applications. In this study, an optimized strategy for aramid nanofibers (ANF) films was developed using spin-coating and sol–gel techniques. The resulting film features a smooth surface and excellent mechanical properties. ANF, initially an insulator, was transformed into a conductor through the in-situ polymerization of ion-doped polypyrrole (PPy). Leveraging a multilayer structural strategy, we prepared a symmetric composite film, ANF@PPy-(TA-MXene)-AgNWs-(TA-MXene)-ANF@PPy (PMA), using vacuum-assisted filtration and lamination hot pressing. This film, composed of ANF@PPy (PA) as the matrix, tannic acid (TA) modified MXene, and silver nanowires (AgNWs) as fillers, exhibited multiple shielding mechanisms as electromagnetic wave (EMW) passed through its various layers. This multilayer configuration provides significant flexibility in EMW shielding. Moreover, TA-modified MXene expands the lamellar spacing, enhancing the scattering efficiency of EMWs within the film, and serves as a medium connecting the upper and lower layers. This results in the efficient integration of the multilayer structure, synergistically improving both EMI shielding performance and mechanical properties. When the ratio of PA/MXene/AgNWs was 1:3:1, the film demonstrated optimal properties, including an EMI shielding effectiveness of 70.2 dB, thermal conductivity of 4.62 W/(m•K), and tensile strength of 50.2 MPa. Due to the exceptional EMI shielding and thermal properties of the PMA composite film, it holds great potential for applications in artificial intelligence, wearable heaters, and military equipment. [ABSTRACT FROM AUTHOR]

The widespread use of cellulose nanofiber (CNF)-based aerogels is hindered by their limited flame retardancy and mechanical properties. This study addresses these challenges by developing cellulose nanofiber/sodium alginate/fly ash (CNF/SA/FA) aerogel through a one-pot method, utilizing industrial waste fly ash (FA) as a reinforcing material. Various characterization and analytical techniques were employed to evaluate the properties of the CNF/SA/FA aerogel. The findings have revealed that resulting aerogel exhibited excellent thermal insulation performance, with a thermal conductivity of 0.485 W/(m·K), along with an impressive compressive strength of 88.4 kPa and favorable shape processability. Vertical combustion tests demonstrated a V-0 rating, indicating superior flame retardancy, and the aerogel achieved a remarkable 79.16% residual carbon, confirming their effective heat shielding capabilities. Notably, the incorporation of FA significantly enhanced both the thermal and mechanical properties of the composite aerogel, presenting a sustainable and effective solution to optimizing the properties of aerogel for thermal insulation. [ABSTRACT FROM AUTHOR]

Highlights Today, carbon fiber reinforced plastics (CFRPs) are materials of interest several industrial sectors because of their mechanical properties and low weight. However, applications in high‐temperature areas are limited because of thermal degradation. Thus, thin coatings acting as thermal shielding and ensuring the upkeep of CFRP structural stiffness are of high interest. This work presents an innovative approach to produce copper/graphene bilayer coatings through electrodeposition and electrophoretic deposition; it consists of laser pre‐treatment of the composite surface to remove the matrix layer exposing the carbon fibers, enabling the subsequent deposition. Bi‐layer graphene/copper coatings exhibit an enhancement in copper electrodeposition efficiency of more than 59% resulting in a 97% stiffness improvement compared to the single layer copper electroplating. All the obtained coatings were able to act as a thermal shield of the CFRPs, reducing the maximum temperature of the composite by more than 60%. In particular, due to the synergistic effect of copper and graphene, the GNPs‐Cu coating achieved the highest maximum temperature reduction (81%). Cross‐sectional analysis indicates severe delamination in uncoated CFRPs, whereas double‐layer coatings maintain structural integrity and prevent delamination even under high‐energy exposure. In addition, the coated composites exhibit a higher electrical conductivity compared to the laser cleaned CFRP, with the GNPs‐Cu coating that obtained a 90% enhancement because of the outstanding electrical properties of copper and graphene. The laser cleaning pretreatment allows the electrodepositions on CFRPs. The GNP‐Cu scenario achieves the highest deposition efficiency. A 97% stiffness improvement was achieved by GNPs‐Cu scenario. GNPs‐Cu coatings exhibit the utmost reduction in resistivity (98%). The GNPs‐Cu coating achieves the highest thermal shielding performance (81%). [ABSTRACT FROM AUTHOR]

High entropy alloys (HEAs) have attracted significant attention from researchers in academia and industry due to their various applications. They are effectively utilized in the manufacturing industry and find extensive use in nuclear technology to enhance radiation shielding properties. In this research article, a novel alloy composition called Co20Cr20Fe20Ni20Ag20 was fabricated using the mechanical milling process. Several characterization methods, such as Scanning and Transmission Electron Microscopy, Energy-Dispersive Spectroscopy, x-Ray Diffraction, and Differential Thermal Analysis Calorimetry, were employed. It was observed that the crystal size decreased as the alloying time increased, and the synthesized alloy exhibited thermal stability across a wide temperature range. Additionally, radiation shielding parameters were experimentally determined using a 137Cs source and a NaI(Tl) detector system. The obtained results indicate that HEAs possess excellent radiation shielding properties and hold promise for applications in the radiation industry. [ABSTRACT FROM AUTHOR]

In the era of 5 G, the rise in power density in miniaturized, flexible electronic devices has created an urgent need for thin, flexible, polymer-based electrically and thermally conductive nanocomposites to address challenges related to electromagnetic interference (EMI) and heat accumulation. However, the difficulties in establishing enduring and continuous transfer pathways for electrons and phonons using solid-rigid conductive fillers within insulative polymer matrices limit the development of such nanocomposites. Herein, we incorporate MXene-bridging-liquid metal (MBLM) solid-liquid bi-continuous electrical-thermal conductive networks within aramid nanofiber/polyvinyl alcohol (AP) matrices, resulting in the AP/MBLM nanocomposite with ultra-high electrical conductivity (3984 S/cm) and distinguished thermal conductivity of 13.17 W m−1 K−1. This nanocomposite exhibits excellent EMI shielding efficiency (SE) of 74.6 dB at a minimal thickness of 22 μm, and maintains high EMI shielding stability after enduring various harsh conditions. Meanwhile, the AP/MBLM nanocomposite also demonstrates promising heat dissipation behavior. This work expands the concept of creating thin films with high electrical and thermal conductivity. Composites of MXene-bridging-liquid metal (MBLM) networks in aramid nanofiber/polyvinyl alcohol matrices are developed, achieving high electrical and thermal conductivity, along with EMI shielding of 74.6 dB at 22 μm thickness [ABSTRACT FROM AUTHOR]

The low cooling efficiency of photovoltaic panels integrated into building façades restricts their electrical performance. The innovative approach of a dual-fluid photovoltaic-thermal system (BFPVT), incorporating bi-fluid cooling exchangers, appears to be a promising solution for jointly optimizing the electrical and thermal performance of PVT systems. However, despite the introduction of air heat shields to improve this performance, their limited efficiency makes them less competitive. We present a photovoltaic-thermal (PVT) system with a two-channel heat exchanger. The upper channel contains a stagnant fluid, which acts as a heat shield, while the lower, open channel ensures the continuous circulation or evacuation of heat transfer air. A copper metal plate separates the two channels. We examined the impact of various fluids employed as heat shields, including neon, argon, and xenon, in comparison to air, on the thermal and electrical performance of the collector. We employed numerical modeling of convective and conductive transfers to assess the average thermal efficiency of the BFPVT and the rise in PV temperature in the analyzed configuration. The equations were discretized using the implicit finite difference method and solved using the Thomas and Gauss-Seidel algorithms. The results demonstrated an 18% enhancement in thermal efficiency with the utilization of neon. In contrast, the employment of argon and xenon markedly reduced the mean temperature of photovoltaic cells by 4.82 °C and 4.87 °C, respectively. This led to an increase in their electrical efficiency by 0.33% in comparison to air. Thus, argon is regarded as the optimal choice for optimizing electrical efficiency, taking into account both economic and environmental considerations. [ABSTRACT FROM AUTHOR]

Heat management and color appearance are the key issues for the application of smart windows. Herein, a vibrant colored energy-saving polymer-dispersed liquid crystal (PDLC) film has been designed by combining dye-doping and the application of a heat shielding electrode. The LC droplet size could be varied by tuning the content of the dye. PDLC films featuring a low Disperse Orange 25 Azo dye concentration (0.06%) achieving an impressive contrast ratio of up to 101.5 with the transmittance reaching 79.17% at on state. Furthermore, indium tin oxide (ITO) and aluminum-doped zinc oxide (AZO) were chosen as the conductive layer materials, and the heat shielding properties of ITO and AZO/Ag/ITO (AAI) films were applied to PDLC devices and comparatively investigated. The AAI-based devices exhibited temperature reductions of 2 °C and 4 °C compared to the ITO-based devices at off and on states, respectively. This highlights the remarkable heat shielding performance and energy-saving capability of AAI-PDLC devices, as well as good flexibility and cycle stability. These AAI-based colored PDLC films exhibit substantial potential for smart window applications especially in buildings and automotive industry. [ABSTRACT FROM AUTHOR]

In order to prevent the body from overheating, a corresponding thermal protection device is usually designed on the inner wall of the combustion chamber. The working environment of this thermal protection device is very harsh, and it needs to withstand internal and external pressure loads and thermal radiation loads of the combustion chamber, especially at the connection between the cylinder and the support parts, the force is harsher. In order to avoid engine damage, causing unnecessary losses. In this article, the thermal–mechanical coupling analysis of the heat shield is carried out by finite element method to analyze the thermal stress and mechanical stress. According to the finite element simulation results, the initial cracks are inserted, respectively, at the stress concentration. Using linear elastic fracture mechanics and Forman–Newman–de Koning models, the crack growth lifetimes of cracks at different locations were calculated. The results of the study show that comparing the initial cracks at different locations, the cracks on the side near the edge of the heat shield have the largest reduction in crack growth life of 64.4% and the critical crack length of 52.0%. The linear superposition of thermal and mechanical stresses under different working conditions has different degrees of nonlinear effects on the crack growth life and critical crack length. The research work in this article can provide a basis for the evaluation of fatigue crack growth life of heat shield and can also provide a reference for engine maintenance. [ABSTRACT FROM AUTHOR]

The need for ceramic composites is increasing over a vast range of industrial applications, including energy and nuclear technology (structural materials for fission and fusion applications); space (thermal shields) or chemical sectors. Current finite element (FE) models are not able to reproduce the aleatory nature of crack generation and propagation through materials and interfaces. To tackle the shortcomings of FE models, a nonlocal bond‐based peridynamics model implemented in the Abaqus FE code has been updated to reproduce the behavior of interfaces between ceramic materials. Two‐ and three‐dimensional simulations have been used to simulate three‐point bend tests for a range of ceramic composites and compared with experiments available in the literature. The model reproduced most of the experimental failure loads, as well as correctly reproducing the failure modes and crack patterns. In particular, the model was able to predict two mechanisms for interface failure, cohesive failure, in which the two materials separate exactly at the interface, and cohesive failure of the substrate, in which a thin layer of the weaker material remains attached to the stronger material and a crack propagates in the weaker material, rather than at the interface. Both failure modes are experimentally observed and still difficult to reproduce with currently available FE simulations. [ABSTRACT FROM AUTHOR]

High-temperature conditions are harmful for carbon nanotube-based (CNT-based) composites, as CNTs are susceptible to oxidation. On the other hand, adding CNTs to ceramics with low electrical conductivity, such as 3YSZ, is beneficial because it allows the production of complex-shaped samples with spark plasma sintering (SPS). A shielding coating system may be applied to prevent CNT oxidation. In this work, the 8YSZ (yttria-stabilized zirconia) thermal shielding coating system was deposited by aerosol deposition (AD) to improve the composite's resistance to CNT degradation without the use of bond-coat sublayers. Additionally, the influence of the annealing process on the mechanical properties and microstructure of the composite was evaluated by nanoindentation, scratch tests, scanning electron microscopy (SEM), X-ray diffraction (XRD), flame tests, and light microscopy (LM). Annealing at 1200 °C was the optimal temperature for heat treatment, improving the coating's mechanical strength (the first critical load increased from 0.84 N to 3.69 N) and promoting diffusion bonding between the compacted powder particles and the substrate. The deposited coating of 8YSZ increased the composite's thermal resistance by reducing the substrate's heating rate and preventing the oxidation of CNTs. [ABSTRACT FROM AUTHOR]

Fabricating high-conductive composites and constructing highly conductive networks are crucial for high-performance electrothermal film. In this study, an Ag nanowires/graphene (Ag/G) composite synthesized by liquid-phase exfoliation and in-situ photoreduction is mixed with carbon black (CB) to form a composite conductive ink, and a CB/Ag/G composite electrothermal film with a point-line-plane three-dimensional microstructure is obtained via blade coating process. Both the addition of Ag nanowires and a subsequent compression rolling treatment induce the establishment of the effective conductive network in the film, endowing it with an outstanding conductivity of 399.4 S cm−1. The film reaches a Ts of 204 °C with an input voltage of 3.0 V, and is successfully applied in water heating and de-icing, demonstrating its extraordinary electrothermal performance and vast potential for practical applications. The film is also used as an electromagnetic shielding film and heat dissipation substrate, showing exceptional electromagnetic shielding (42.5 dB) and heat dissipation properties. [ABSTRACT FROM AUTHOR]

The utilization of ceramic aerogels is crucial in spacecraft thermal protection systems that necessitate exceptional high-temperature stability, mechanical robustness, and low thermal conductivity. The primary challenges hindering their implementation encompass inadequate mechanical robustness and high infrared radiation transparency. Herein, a biphasic nanorod encapsulation strategy is proposed to fabricate an Al 2 O 3 -TiO 2 nanorod aerogel (ATNA) with a hierarchical and anisotropic microstructure. The biphasic nanorod structure not only reduces the radiation heat transfer but also enhances the mechanical properties simultaneously. The primary compressive strain was borne by the intersecting Al 2 O 3 nanorods, while the interpenetrated TiO 2 nanorods served to reinforce and withstand partial stress at the joints. The ATNAs obtained exhibit an ultralow thermal conductivity (0.069 W·m−1·K−1 at 1100 °C), exceptional high stiffness (a specific compressive strength of 13.4 kN·m·kg−1), and remarkable thermal stability (1400 °C in air). The robust ATNAs can effectively meet the urgent demand for thermal insulation in high-temperature environments. • A biphasic nanorod encapsulation strategy is proposed to fabricate the Al2O3/ TiO2 ceramic aerogels. • Aerogels possessing the anisotropic and hierarchical structure. • The surface of Al2O3 nanorods is coated with TiO2 nanorods, which effectively absorb and reflect infrared heat radiation. • The derived aerogels exhibit high stiffness, low thermal conductivity and remarkable thermal stability. [ABSTRACT FROM AUTHOR]

MXene is a novel two-dimensional layered nanomaterial with a very large specific surface area and abundant surface functional groups, endowing it with unique physical and chemical properties. MXene can be compounded with other functional materials to significantly improve the performance of MXene composites or broaden their application scope. Meanwhile, with the development of flexible composite preparation technology, it has promoted the continuous expansion of its application fields. The introduction and combination of different materials can improve the performance of flexible composites and make them have a broader application prospect. In recent years, researchers have started preparing MXene materials as flexible composites for applications such as supercapacitors, sensors, electromagnetic shielding and thermal management. This paper gives a brief introduction to flexible composites and MXene materials, reviews the applications of MXene based flexible composites in various fields as well as the research progress, and provides an outlook on their future development direction. [ABSTRACT FROM AUTHOR]

In order to effectively protect personnel and equipment from radiation hazards and expand the application range of materials， the preparation and radiation shielding mechanism of lead boron polyethylene composite materials are studied. Preprocess and modify boron containing compounds， mix them with lead sand and polyethylene to prepare lead boron polyethylene composite materials. Select Cs radiation source and use Monte Carlo neutron photon transport program as the simulation program to verify the shielding mechanism. Construct a composite material model and Cs radiation source model， calculate the neutron shielding coefficient， consider the density and thickness of the composite material， and simulate the shielding performance of radiated X-rays under different radiation energies. The experimental results show that when the neutron coefficient decreases， increasing the density of the prepared composite material leads to an increase in the shielding thermal neutron coefficient； When the density of the composite material is 5. 9 g/cm3 and the thickness is 4. 5 cm， it can meet the requirements of radiation shielding mechanism [ABSTRACT FROM AUTHOR]

In order to investigate the most extreme conditions in which materials potentially applicable in reusable thermal shields can be operated, ultra-high-temperature ZrB2 ceramics with 20 vol.% MoSi2 were prepared using two different techniques, cold isostatic pressing (CIP) and robocasting (RC, an additive manufacturing technique), followed by consolidation using pressureless spark plasma sintering (SPS). The oxidation behavior of the resulting materials was analyzed in low-pressure dissociated air at three different temperatures, namely 1800, 2000 and 2200 K. Using XRD and surface and cross-section SEM (coupled with EDS), zirconia was found to form at all three temperatures, while silica was only present at 1800 K, with gaseous SiO forming at a higher temperature. The elaboration technique influences the density of the ceramic, and less dense materials undergo deeper oxidation. This investigation suggests that 2000 K is already beyond the maximum temperature threshold at which damage to ceramics is limited by the formation of protective silica. This study confirms that the selected material is a promising candidate for thermal protection applications. [ABSTRACT FROM AUTHOR]

This study focused on developing microstructural, thermal, and radiation shielding changes in Al50Si25B25 powders using mechanical alloying techniques. Based on the x‐ray powder diffraction data, the crystallite size and microstrain of the 100‐hours milled powder were calculated as 0.25 nm and 50.33 %, respectively. The solubility of silicon in the α‐aluminium matrix increased with longer mechanical alloying duration. Transmission electron microscope analyses further showed that the alloy particulates had an average size of 3 μm and an average grain size of 0.226 nm. The radiation shielding properties of the Al50Si25B25 powders indicated that the Linear Attenuation Coefficient value increased from 0.0554±0.1689 cm−1 to 1.0632±0.2425 cm−1 with an increase in the thickness of the Al50Si25B25 alloy. This work successfully demonstrated the potential of mechanical alloying techniques to enhance the microstructural and thermal properties of Al50Si25B25 powders. It highlighted their effectiveness in providing radiation shielding capabilities when varying the thickness of the alloy. [ABSTRACT FROM AUTHOR]

In this study, we devised a green and straightforward approach for fabricating carbon aerogels by heating dextrin, drawing inspiration from the popping mechanism of popcorn. The structure and morphology of the samples were intricately regulated through precise adjustments in the temperature and duration of the heat-treatment process, resulting in the formation of a carbon aerogel comprising nano-walls. Upon carbonisation at 2100 °C, the resultant carbon aerogel exhibited an exceptionally low density of approximately 0.029 g cm−3. Notably, the aerogel demonstrated excellent electromagnetic shielding performance, reaching a shielding effectiveness of approximately 57 dB and an impressive specific shielding effectiveness of 1965 dB cm3 g−1 with a thickness of 5 mm across the entire X band. Additionally, it displayed an ultra-low thermal conductivity of approximately 0.016 W m−1 K−1 and good thermal stability. These characteristics position carbon aerogels as promising materials with vast application potential in electromagnetic shielding and thermal insulation. [ABSTRACT FROM AUTHOR]

This research examines the flow of incompressible Casson fluid with gyrotactic microorganisms and thermophoretic particle deposition across a sheet, incorporating a nonlinear heat source and the convective boundary conditions. Our motivation stems from the need to optimize heat transfer in renewable energy systems and improve thermal regulation in aerospace engineering, which could inform advancements in heat shield design. The impact of this study extends to renewable energy, aiding heat transfer optimization, and in aerospace engineering, it may inform heat shield design. Medical imaging, chemical engineering and environmental remediation benefit from insights into the fluid behavior and particle transport. Based on heat source and thermophoretic particle deposition, this work investigates the concentration, temperature flow and microorganism distributions. Using suitable similarity variables, all equations for the proposed flow are converted into ODEs. The reduced equations are evaluated using the RKF45 method. The impacts of significant parameters on temperature, concentration, microbiological and flow profiles are determined with the support of graphs. The thermal and concentration distributions are improved with an increase in the thermal radiation, heat generation and magnetic parameter. This study enhances knowledge across disciplines including healthcare diagnostics, chemical engineering and ecological restoration by offering fresh perspectives on the dynamics of fluid movement and the transportation of particles. [ABSTRACT FROM AUTHOR]

Wire arc additive manufacturing (WAAM) is a direct energy deposition additive manufacturing technique. In this, the system comprises numerous variables that make a difference to the shape, morphology and mechanical behaviours of the WAAM processed Ti–6Al–4 V bead. The travel speed, wire feed speed, heat input and shielding gas flow rate are the most influential variables among them that can be found in the literature. WAAM is a material deposition technique that uses multiple thermal cycles or repeated heat treatments during the entire process. As a consequence of which, an uneven dissemination of microstructure, anisotropy in mechanical properties, high residual stresses and distortion of parts are some of the challenges during the implementation of WAAM on Ti–6Al–4 V. With the ongoing need to reduce the cost of manufacturing Ti–6Al–4 V parts, WAAM system should overcome these challenges to get the good part dimensions and qualities of the manufactured Ti–6Al–4V alloy components. This review presents an overview of the current and common issues that the WAAM system encounters while fabricating Ti–6Al–4 V parts. In addition, an attempt is made to discuss the existing possible solutions to these issues. The review begins by introducing the effect of different process parameters like travel speed, wire feed speed, heat input and shielding gas flow rate on the geometry of the deposited materials. In addition, the morphology and mechanical properties of the WAAM-manufactured Ti-6Al-4 V alloy components have been discussed, followed by the influence of different post-thermal treatments which try to optimise the microstructure and enhance the mechanical properties of the deposited materials. Moreover, distortions and residual stresses which are associated with the WAAM systems and the methods to minimise them are discussed. [ABSTRACT FROM AUTHOR]

Co/Mn co-substituted MgAl 2 O 4 pigments were spray pyrolysis, and their crystal structure and optical properties were characterized with changing the Co/Mn ratio and synthesis temperature. Regardless of the Co/Mn ratio, the resulting pigments showed spinel structured MgAl 2 O 4 phase without any impurity phase. The synthesized Mg 0.5 Co 0.5 Al 2 O 4 and Mg 0.5 Mn 0.5 Al 2 O 4 showed a dark blue and brown color due to the visible light absorption by the 4A 2 (F) → 4T 1 (P) transition of Co2+ and the d-d transition of Mn2+, respectively. The black colored pigment was achieved by simultaneous substituting Co2+ and Mn2+ in the Mg2+ tetrahedral site in MgAl 2 O 4. The optical band gap of the Mg 0.5 Co 0.5-x Mn x Al 2 O 4 pigment decreased linearly from 3.08 eV (x = 0) to 2.46 eV (x = 0.4) as the Mn2+ content increased. As a result, Mg 0.5 Co 0.1 Mn 0.4 Al 2 O 4 uniformly absorbed the entire visible light and had a black color (L* = 28.10, C* = 1.68). In terms of obtaining high near-infrared reflectance and good blackness, the optimal calcination temperature of Mg 0.5 Co 0.1 Mn 0.4 Al 2 O 4 was determined to be 900 °C. The optimized Mg 0.5 Co 0.1 Mn 0.4 Al 2 O 4 black pigment had a good LiDAR reflectance (38 % at 905 nm) and excellent chemical stability, and showed improved heat shielding performance compared to carbon black using in black vehicles. [ABSTRACT FROM AUTHOR]

This paper explores the optimization of critical parameters in the Czochralski (CZ) crystal growth process, a key technique in semiconductor device manufacturing. The CZ system involves the melting of high-purity polycrystalline silicon and controlled growth of a single-crystal ingot. This process relies on key variables such as the thermal shield thickness, shield gap size, cooling jacket length, crucible dimensions, and rotation speed. A computational model was applied to simulate heat transfer, fluid flow, and radiation heat exchange within the CZ system. The model was validated using experimental data, which demonstrated its precision in predicting crystal-front deflection and heater power. The results highlight the substantial impact of increasing the thermal shield thickness on the crystal-pulling speed and uniformity. Greater cooling jacket lengths increased the cooling rate, which increased the pulling speed, although more heater power was required. The shield gap size had negligible effects, and variations in the heater power ratio showed minimal impact. The optimal combination of parameters led to significantly improved crystal-pulling speed and reduced power consumption, making it a compelling choice for enhanced CZ crystal growth in semiconductor manufacturing. [ABSTRACT FROM AUTHOR]

Carbon-carbon composites are advanced materials known for their high strength, high-temperature stability, and superior thermal conductivity. Mechanical properties such as tensile strength, flexural strength, and compressive strength are examined, as well as thermal properties like the coefficient of thermal expansion and thermal conductivity, to understand the characteristics of the composite. Carbon-carbon composites are ideal for the aerospace industry's need for lightweight and high-performance materials. Tribological and surface properties are relevant to this discussion, given the use case of carbon-carbon composites in extreme conditions, the effect of exposing the composite to different fluids and the change in friction and wear properties. Coatings can protect the composite from environmental factors such as UV radiation, oxidation, and erosion. Self-healing composites that can repair themselves can increase the lifespan of structures while reducing maintenance costs. These have been used in aerospace applications such as airplane braking systems, rocket nozzles, and re-entry vehicle heat shields. Furthermore, researchers have recently addressed the problem of finishing and drilling without delamination and loss of properties, and this study looks into unconventional methods that can be adopted for the same. This study aims to provide an overview of the current state of carbon-carbon composite materials and their applications. [ABSTRACT FROM AUTHOR]

This research study concerns an experimental, budget-friendly, electricity-powered apparatus for bench-scale fire testing. The apparatus consists of various elements, of which the most important are ceramic heating pads, used to impose heat fluxes on exposed surfaces of specimens. The test method allows to control the heating pads' temperature and to adjust the distance between the heating pads and the specimen to obtain well-defined heat fluxes up to 50–60 kW/m2. Higher heat fluxes and temperatures can be obtained by setting the heating pads in full power mode, with or without the use of a thermal shield, which can lead to heat fluxes up to 150 kW/m2. The heating and thermal boundary conditions imposed by the apparatus are characterised and discussed, and the thickness of the convective boundary layer at the heating pads' surface is estimated significantly lower than in the case of gas-fired radiant panels. The performance of the apparatus is analysed for various conditions: controlling the temperature of the heating pads, in an open environment or with the presence of thermal shields, and in full power mode. A few examples of application of the apparatus to fire test typical construction materials (steel and glass) are also presented. These results emphasise the well-defined heating conditions in temperature-controlled mode. The study finally discusses the advantages and limitations of the apparatus, as well as many possibilities of future applications and improvement for future research studies. [ABSTRACT FROM AUTHOR]

The hypersonic flow around bodies of different geometries, made of composite materials, was investigated and different methods of decreasing the maximum temperatures of their surface were estimated. [ABSTRACT FROM AUTHOR]

CNF-PPy/MXene composite films with excellent electromagnetic interference (EMI) shielding and infrared thermal camouflage performance were fabricated by compounding cellulose nanofiber-polypyrrole (CNF-PPy) and MXene. CNF-PPy was prepared by the modified in-situ polymerization of pyrrole on the surfaces of CNFs and exhibited excellent dispersion stability and storage stability in aqueous phase. CNF-PPy films showed enhanced conductivity (~ 3.91 S/cm) and EMI shielding effectiveness (average ~ 28.1 dB in X-band). The composite films loaded with MXene exhibited even better EMI shielding performance (~ 45.8 dB on average in X-band) and good applicability in other bands (~ 44.7 dB in 26.5–40.0 GHz band). The sample CP3M3 presented excellent infrared thermal camouflage properties on the MXene side (45.0 °C at 100 °C) and exhibited different infrared thermal camouflage properties on the other side (84.4 °C at 100 °C on the CNF-PPy side). Given excellent electrical conductivity, dispersion and storage stability of CNF-PPy, enhanced electromagnetic shielding and adjustable infrared emissivity of CNF-PPy/MXene films, the resulting samples can be chosen according to the scenarios, providing a promising method to ensure the smooth operation of military equipment. [ABSTRACT FROM AUTHOR]

The thermal protection system (TPS) plays a major role in shielding solid rocket motors (SRMs) against structural failure from excessive heating. This study was directed at the recent innovation in flame‐retardant materials used for thermal insulation, with a particular focus on integrating metal–organic frameworks (MOFs) to bolster thermal stability. Three targeted transition metal‐BDC MOFs (MIL‐88(Fe), MOF‐71(Co), and MOF‐5(Zn)) were hydrothermally synthesized and the effect of incorporating these MOFs into nitrile butadiene rubber (NBR) composites was tracked. In general, the addition of the MOFs improved the interfacial compatibility and the processing of the composites. Additionally, experimental investigations have shown that all MOFs improved the mechanical properties of the NBR composite materials. Specifically, the addition of MOF‐5 has been found to increase the maximum tensile strength to 13 MPa, while MIL‐88 increased the elongation at break to 67.1%. In order to evaluate the thermal stability and ablative resistance of the prepared composites, the oxy‐acetylene flame test was utilized. Results showed that the efficiency of the composite as thermal insulation is highly dependent on the MOF type and the metal included. The impact of MOF‐71(Co) on thermal insulation displayed the least linear and mass ablation rates (0.0168 mm/s and 0.057 g/s, respectively) along with the lowest recorded back‐face temperatures, owing to the formation of a thick and compact char layer upon exposure to flames. [ABSTRACT FROM AUTHOR]

Thermal protection systems (TPS) are employed on space vehicles to protect against the heat fluxes faced upon re-entry to the Earth’s atmosphere. This work reports a method of 3D printing composite materials for TPS to reduce the time and cost associated with hand layup production methods. A phenolic resin system was tested to determine char yield, viscosity, cure behavior and cure evolutions. A commercial 3D printer was modified to move along two additional axes to accommodate the complex curves of typical heat shields on space vehicles. This technique can be scaled to produce full-sized TPS for industrial applications. [ABSTRACT FROM AUTHOR]

The paper presents and discusses the results of a study of the thermal properties of cement composites with different contents of magnetite aggregate (0%, 20%, 40% and 60% by volume). The effect of grain size on the evaluated thermal properties was also investigated. For this purpose, concrete containing 50% by volume of magnetite aggregate with four different fractions (1–2 mm, 2–4 mm, 4–8 mm and 8–16 mm) was used. Thermal parameters were evaluated on specimens fully saturated with water and dried to a constant mass at 65 °C. The series with varying grain sizes of magnetite achieved thermal conductivity values in the range of 2.76–3.03 W/(m·K) and 2.00–2.21 W/(m·K) at full water saturation and after drying to a constant mass, respectively. In the case of the series with 20% magnetite by volume, the thermal conductivity was 2.65 W/(m·K) and 1.99 W/(m·K) for the material fully saturated with water and dried to a constant mass, respectively. The series with a 60% volume share of magnetite obtained values of this parameter of 3.47 W/(m·K) and 2.66 W/(m·K), respectively, under the same assumptions. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) exhibits intriguing thermo-physical properties such as higher heat capacity and conductivity, as well as a lower density than Ti6Al4V(ELI). These properties make SiC a good candidate for the reinforcement of Ti6Al4V(ELI) with respect to its use as a heat shield in aero turbines to increase their efficiency. The traditional materials used in aircraft structures were required to have a combination of good mechanical properties such as strength, stiffness, and hardness and low weight, as well as low thermo-physical properties such as coefficient of thermal expansion (CTE) and thermal conductivity. The alloy Ti6Al4V(ELI) has a density of 4.45 g/cm3, which is lower than that of structural steel (7.4 g/cm3) and higher than that of aluminium (2.5 g/cm3). Lower density benefits light weighting. Aluminium is the lightest of the traditional materials used but has relatively low strength. The CTE of SiC of 4.6 × 10−6/K is lower than that of Ti6Al4V(ELI) of 8.6 × 10−6/K, while the density of SiC of 3.21 g/cm3 is lower than that of Ti6Al4V(ELI) of 4.45 g/cm3. Therefore, from the theory of composites, SiC/Ti6Al4V(ELI) composites are expected to have lower densities and CTEs than those of Ti6Al4V(ELI), thus providing for lightweighting and less thermal related buckling or separation at their joints with carbon/epoxy resin panels. The specific strength, stiffness, and Knoop hardness of SiC of 75–490 kNm/kg, 132 MNm/kg, and 600–3800 GPa, respectively, are generally larger than those of Ti6Al4V(ELI) of 211 KNm/kg, 24 MNm/kg, and 880 GPa, respectively. Therefore, investigating reinforcement of Ti6Al4V(ELI) with SiC particles is worthwhile as it will lead to the formation of composites that are stronger, stiffer, harder, and lighter, with lower values of CTE. For additive manufacturing, this requires initial studies to optimise the process parameters of laser power and scanning speed for single tracks. To print single tracks in the present work, different laser powers ranging from 100 W to 350 W and scanning speeds ranging from 0.3 m/s to 2.7 m/s were used for different SiC volume fraction values of values. To print single layers, different values of hatch distance were used together with the best values of laser power and scanning speed determined elsewhere by the authors for different volume fractions of SiC. Through optical microscopy, the built tracks and their cross sections were examined. By using laser power and scanning speeds of 200 W and 1.2 m/s, and 150 W and 0.8 m/s, respectively, the best tracks at 5% and 10% volume fractions were obtained, whereas the best tracks at 25% volume fraction were achieved using a laser power of 200 W and a scanning speed of 0.5 m/s. Furthermore, the results showed that the maximum SiC volume percentage of 30% resulted in limited or no penetration. Therefore, it is concluded from the study that parts with improved mechanical properties can be produced at SiC volume fractions ranging from 5% to 25%, while parts produced at the high volume fraction of 30% would have unacceptable mechanical qualities for the final part. [ABSTRACT FROM AUTHOR]

Conducting three-dimensional thermohydraulic analysis of an entire nuclear reactor poses significant challenges due to the considerable geometric volume and complex internal structures involved. The top reflector is one of the internal structures found in high-temperature pebble bed Small Modular Reactors (SMR). This structure serves several critical functions, including neutron reflection, control and distribution of helium inlet into the core, neutron and thermal shielding, among others. In this kind of system, the detailed representation of the top reflector includes the representation of more than 460 channels of 2.5cm of diameter. Considering that the reactor has almost a ten of meters then dimension scales of various orders must be represented, which is a challenge. In this sense, a three-dimensional Computational Fluid Dynamics (CFD) thermohydraulic analysis of the entry pattern to the core of a High Temperature SMR using ANSYS CFX has been done. This study presents a comparison between five coolant entry patterns into the core. Initially, two prototype models of 460xØ2.5cm, one with vertical channels and another with inclined channels, are modeled. Additionally, two prototype models of 20xØ12cm of equivalent area, with vertical and inclined channels are also included. Finally, a simplified porous media model with the same equivalent area is considered. The thermohydraulic behavior of the coolant before and after passing through the top reflector was then analyzed for these five patterns. An analysis of fuel elements temperature in the core was conducted. It is important to highlight that this study is qualitative and has the goal of identifying and characterizing the impact that the coolant entry pattern into the reactor core has on the main thermohydraulic parameters in this region. The study exposes a strong correlation between the porous media model and all prototype models in terms of the maximum fuel temperature, average fuel temperature, and helium velocity. In this study, the potential applicability of the porous media models for an integral full-scale reactor simulation in the future was demonstrated. As a benefit, the porous media model reduces the mesh quantity compared to a prototypic model. [ABSTRACT FROM AUTHOR]

Coal-fired power plants generate power by rotating turbines (TBNs). According to the high-temperature work exposure standard (KOSHA CODE 02), the turbine (TBN) building, where essential power-generation components, turbines (TBNs), are installed, contains various types of high-temperature equipment, creating a hazardous working environment for onsite employees. In addition, malfunctions from lubricant leaks occur at the moving parts of such power-generation equipment in the building, due to the high-temperature environment. In this study, we analyzed the heat concentration phenomenon in the turbine (TBN) building using computational fluid dynamics (CFD) software and made recommendations for its improvement. We examined options for installing automatic ventilation windows and additional heat exhaust fans on turbine (TBN) floors. We discovered that installing an automatic ventilation window and a heat exhaust fan on the deaerator floor can reduce the average temperature by 1.2 °C and 6.6 °C, respectively. In addition, the mezzanine floor, where the core heat-generating equipment is installed, is significantly affected by radiant heat. To mitigate the heat concentration phenomenon, we recommend installing additional radiant heat shields. [ABSTRACT FROM AUTHOR]

The rapid development of miniaturized, high-frequency, and highly integrated microelectronic devices has brought about critical issues in electromagnetic compatibility and thermal management. In recent years, there has been significant interest in lightweight polymer-based composites that offer both electromagnetic interference (EMI) shielding and thermal conductivity. One promising approach involves constructing three-dimensional (3D) interconnection networks using functional fillers in the polymer matrix. These networks have been proven effective in enhancing the thermal and electrical conductivity of the composites. This mini-review focuses on the preparation and properties of 3D network-reinforced polymer composites, specifically those incorporating metal, carbon, ceramic, and hybrid networks. By comparing the effects of different filler types and distribution on the composite materials, the advantages of 3D interconnected conductive networks in polymer composites are highlighted. Additionally, this review addresses the challenges faced in the field of multifunctional thermal management and electromagnetic protection materials and provides insights into future development trends and application prospects of 3D structured composites. [ABSTRACT FROM AUTHOR]