Low-cost Process Research Articles

Studies of Quantum Dots in Light-Emitting Diodes

Quantum dots are regarded as a revolutionary material especially in display and lighting applications due to their excellent optical properties. Their high quantum efficiency, high color purity, low-cost solution processability, and tunable emission wavelength, facilitate the realization of their potential for display applications. Therefore, researchers have made a lot of effort in the development and characterization of quantum dot light-emitting diodes (QD-LEDs) to achieve high color purity and brightness in light-emitting devices. Meanwhile, with the aim of commercialization, inefficiency, instability, and cost seem to be inevitable challenges that need to be faced. Progression and challenges of using quantum dots in light-emitting diodes are two aspects that are concentrated on in this review. It also affords methods to tackle these challenges. Lastly, the potential applications of QD-LEDs in displays and lighting are investigated. Their potential to revolutionize various industries are also highlighted. By overcoming current limitations and capitalizing on emerging opportunities, QD-LEDs technology will have further applications. This work will help promote in-depth research on QD-LEDs.

Toward High-Performance Li-Rich Mn-Based Layered Cathodes: A Review on Surface Modifications.

Lithium-rich manganese-based layered oxides (LRMOs) have received attention from both the academic and the industrial communities in recent years due to their high specific capacity (theoretical capacity ≥250 mAhg-1), low cost, and excellent processability. However, the large-scale applications of these materials still face unstable surface/interface structures, unsatisfactory cycling/rate performance, severe voltage decay, etc. Recently, solid evidence has shown that lattice oxygen in LRMOs easily moves and escapes from the particle surface, which inspires significant efforts on stabilizing the surface/interfacial structures of LRMOs. In this review, the main issues associated with the surface of LRMOs together with the recent advances in surface modifications are outlined. The critical role of outside-in surface decoration at both atomic and mesoscopic scales with an emphasis on surface coating, surface doping, surface structural reconstructions, and multiple-strategy co-modifications is discussed. Finally, the future development and commercialization of LRMOs are prospected. Looking forward, the optimal surface modifications of LRMOs may lead to a low-cost and sustainable next-generation high-performance battery technology.

Pyrene‐Based Self‐Assembled Monolayer with Improved Surface Coverage and Energy Level Alignment for Perovskite Solar Cells

AbstractRecently, the efficiency of p‐i‐n perovskite solar cells drastically increased, a pivotal factor being the incorporation of self‐assembled monolayers (SAMs) as a hole‐transporting layer (HTL). SAMs offer many advantages over conventional HTLs, including minimal material requirements, low cost, and facile processing. Current research is mainly focused on the development of carbazole‐derived SAMs. However, the versatility of organic chemistry allows for the design of SAMs with alternative organic cores that may possess specific benefits. In this study, three novel SAMs are incorporated in p‐i‐n perovskite solar cells, each based on an aromatic core commonly used in organic semiconductors. The novel SAMs vary in their energy level alignment with the perovskite active layer. Optimal alignment is achieved with a pyrene‐based SAM (4PAPyr), resulting in solar cells that outperform the commercially available 2PACz. Moreover, due to improved surface coverage, the use of 4PAPyr leads to a significantly higher number of working solar cell devices when compared to 2PACz, which is of particular interest with regard to upscaling. After device optimization, a power conversion efficiency of 22.2% is achieved with 4PAPyr. This research underlines the importance of diversifying SAMs to unlock further advancements in perovskite solar cell efficiency and scalability.

Development of scalable processes to prepare a key chiral, nonracemic intermediate en route to LpxC inhibitors for gram-negative infections

Deaths resulting from drug-resistant gram-negative bacterial infections are a growing public health concern. Pyridone methylsulfone hydroxamic acid LpxC inhibitors, such as 1, are being developed for the treatment of serious gram-negative infections. Carboxylic acid 2 is a key intermediate in the synthesis of analogs of type 1. The current synthesis of 2 is unsuitable as a manufacturing process due to safety concerns and high cost. Two scalable and potentially lower cost processes have been developed, one based on chromatographic resolution of a novel intermediate and a second based on a classical resolution of the key intermediate 3. The advantages of these new chemical approaches are illustrated in the process details described in this letter.

Cu-TiO2/Zeolite/PMMA Tablets for Efficient Dye Removal: A Study of Photocatalytic Water Purification

In this study, Cu-doped TiO2 combined with natural zeolite (ZT) was synthesized and applied as a fixed powder layer on poly(methyl methacrylate) (PMMA) tablets. The material’s morphology, structural, and chemical properties were characterized using high-resolution scanning electron microscopy, Raman spectroscopy, and Brunauer–Emmett–Teller analysis. The antioxidant capacity was evaluated by assessing the neutralization of hydroxyl radicals and iron (III) ions. For the first time, tablets with Cu-TiO2 and ZT deposited on PMMA as the carrier were investigated for removing two dyes, methyl orange (MO) and methylene blue (MB), from water under simulated solar (SS) and UVC irradiation. Under SS irradiation, the Cu-TiO2/PMMA and Cu-TiO2/ZT/PMMA tablets achieved about 21% degradation of MB after 240 min. This result is particularly noteworthy because SS radiation provides lower energy compared with UVC, making the process more economically efficient. Furthermore, the photocatalysts are immobilized on a stable carrier, which enhances the method’s cost-effectiveness by reducing material loss and simplifying recovery. In the presence of ZT/PMMA tablets, 69% of MB was removed by adsorption after 240 min. Additionally, we explored the mechanism of degradation, revealing that the enhanced generation of hydroxyl radicals plays a pivotal role in the effective degradation of MB. At the same time, photogenerated holes contribute to the removal of MO. The overall results suggest that the tablets obtained are a promising solution for water purification due to their effectiveness, simplicity, and low processing cost.

Facile nanofabrication and simultaneous color-and-Raman hybrid mechanism of economic SERS substrate with tunable structure color for high enhancement factor

The conventional SERS technique utilizing metal nanoparticles (MNPs) is a powerful optical sensing method, relying on the inelastic collision between incident light and the analyte. However, the development of traditional color-tunable MNP-SERS substrates remains limited to two separate components of the color supporter for generating structure color and followed by the MNPs coating to generate the localized surface plasmonic resonance for SERS sensing. Here, a novel color-tunable SERS substrate without MNPs based on the economic one-step anodic aluminum oxide (AAO) coated with nanoporous Pt films was proposed to generate the color-and-Raman hybrid effect for high enhancement factor. This novel SERS substrate employs an economic method, that is a facile and low-cost one-step anodization process to fabricate the AAO with tunable structure color, enabling adaptation to excitation of laser sources. The substrate with the lowest reflectance to laser light exhibits the highest enhancement factor due to the coupling between the laser and the substrate. The resultant SERS substrate demonstrates a high enhancement factor (EF) of 5.27x105 to methylene blue with a good uniformity of the relative standard deviation (RSD) of 6.35 %. In a practical application, one of preservative, benzoic acid, was detected with a low concentration of 1 ppm in the extraction solution of tapioca balls. This innovative approach promotes limitations associated with traditional color-tunable SERS substrates and offers a promising path for sensitive and versatile trace substance detection.

Optical and Amplified Spontaneous Emission Properties of 4H-Pyran-4-Ylidene-2-Cyanoacetate Fragment Containing 2-Cyanoacetic Acid Derivative in PVK, PSU, or PS Matrix

Organic solid-state lasers are highly promising devices known for their low-cost fabrication processes and compact sizes and the tunability of their emission spectrum. These lasers are in high demand across various industries including biomedicine, sensors, communications, spectroscopy, and military applications. A key requirement for light-emitting materials used in a light-amplifying medium is a low threshold value of the excitation energy of the amplified spontaneous emission (ASE). A newly synthesized non-symmetric red-light-emitting laser dye, Ethyl 2-(2-(4-(bis(2-(trityloxy)ethyl)amino)styryl)-6-tert butyl-4H-pyran-4-ylidene)-2-cyanoacetate (KTB), has shown great promise in meeting this requirement. KTB, with its attached bulky trityloxyethyl groups, has the ability to form amorphous thin films from a solution using a wet-casting method. Recent experiments have demonstrated that KTB exhibits a low ASE threshold value. This study focused on investigating the optical and amplified spontaneous emission properties of KTB in poly(N-vinylcarbazole) (PVK), polysulfone (PSU), and polystyrene (PS) matrices at various concentrations. The results showed that as the concentration of the dye increased, a redshift of the photoluminescence and ASE spectra occurred due to the solid-state solvation effect. The lowest ASE threshold value of 9 µJ/cm2 was achieved with a 20 wt% concentration of KTB in a PVK matrix, making it one of the lowest excitation threshold energies reported to date.

Evaluating antenna phase center variation effects on tropospheric delay retrieval using a low-cost dual-frequency GNSS receiver

Abstract This study examines the impact of Phase Center Variation (PCV) corrections on Zenith Wet Delay (ZWD) accuracy using a low-cost U-blox ZED-F9P receiver paired with three different antenna configurations: the high-grade TRM57971 antenna, the moderate-grade AS-ANT3BCAL antenna, and the low-cost ANN-MB-00 antenna. Among the three antennas evaluated, the low-cost antenna exhibited the largest PCV magnitude and a pronounced elevation angle dependence. In contrast, the other two antennas demonstrated lower levels of PCV variation. Without PCV corrections, the low-cost antenna showed significant ZWD biases compared to reference values. Applying PCV corrections significantly improved its accuracy, reducing bias and RMS by 88% and 79%, respectively. Moderate- and high-grade antennas experienced minimal improvement with correction. All antennas exhibited remarkable day-to-day repeatability in their residual patterns, despite variations observed in the RMS of phase residuals. This observed repeatability is likely attributable to the presence of unmodeled multipath contributions. The variations in RMS, in turn, can be primarily ascribed to inherent differences in multipath resistance among the antenna designs. This study highlights the critical role of PCV corrections for accurate ZWD estimation with low-cost GNSS receivers. Future research should prioritize the acquisition of manufacturer-provided calibration data for low-cost antennas to streamline and enhance the accuracy of PCV correction applications. Moreover, efforts should be directed toward developing innovative solutions, such as low-cost, multipath-resistant antennas or advanced signal processing algorithms, to mitigate the impact of multipath errors. By addressing these areas, low-cost GNSS solutions can become more reliable and cost-effective tools for tropospheric delay estimation.

Numerical optimization of inorganic p-Sb2Se3/n-ZrS2 heterojunction solar cells: achieving high efficiency through SCAPS-1D simulation

p-Sb2Se3 and n-ZrS2 materials show strong potential for cost-effective photovoltaic applications. This study presents a detailed numerical analysis of p-Sb2Se3/n-ZrS2 heterojunction solar cells using SCAPS-1D, focusing on how key parameters such as layer thickness, doping density, and bandgap have affected device performance. Critical photovoltaic metrics, such as built-in voltage (Vbi), carrier lifetime, depletion width (Wd), recombination rates, and photogenerated current, were examined. Our findings demonstrate that optimizing the p-Sb2Se3 absorber layer with a 1.0 eV bandgap, 5000 nm thickness, and doping density of 1020 cm−3 leads to a maximum efficiency of 32.14%, with a fill factor (FF) of 84.57%, short-circuit current density (Jsc) of 47.61 mA cm−2, and open-circuit voltage (Voc) of 0.792 V. For the ZrS2 buffer layer, the best performance was achieved with a 1.2 eV bandgap, 200 nm thickness, and doping density below 1 × 1020 cm−3. These optimized parameters significantly enhanced carrier separation and minimized recombination losses, leading to improved power conversion efficiency. In addition to theoretical optimization, this study emphasizes the practical potential of these materials for real-world applications. The combination of Sb2Se3 and ZrS2 offers a low-cost fabrication process suitable for scalable commercial solar cell production while maintaining high efficiency. These results underscore the viability of p-Sb2Se3/n-ZrS2 heterojunctions as promising candidates for next-generation clean energy solutions.

Unlocking the efficiency potential of all-perovskite tandem solar cells: Insights from photoelectric coupling simulations

All-perovskite tandem solar cells (TSCs) have garnered widespread attention due to their high-efficiency potential and low-cost fabrication processes. However, a significant efficiency gap remains between all-perovskite TSCs (30.1%) and their Shockley-Queisser limit (∼44%), primarily due to a lack of comprehensive understanding of the working mechanisms and design principles for TSCs. Here, we develop rigorous photoelectric coupling simulation models and systematically explore the device physics and working mechanisms of all-perovskite TSCs. Through in-depth simulations, we find that: 1) TSC performance is more sensitive to the interface defects in current-limited sub-cells, while bulk defects in both wide-bandgap and narrow-bandgap perovskites are crucial in limiting TSC performance, regardless of current-matching conditions. 2) The interface defects of perovskite/functional layers (FLs) near intermediate recombination layers (IRLs) have a substantial effect on TSC efficiency, which, however, can be mitigated by a double-layer FL design. 3) The work function of the IRL and the energy levels of adjacent FLs should be well-controlled to balance carrier transport barriers at FL/perovskite and FL/IRL interfaces. Based on these principles, we propose a detailed roadmap to enhance the efficiency of all-perovskite TSCs to 34.15% through collaborative optimization strategies. This study provides valuable guidance for designing high-efficiency all-perovskite TSCs.

Designing Contact Independent High-Performance Low-Cost Flexible Electronics.

Organic semiconductors enable low-cost solution processing of optoelectronic devices on flexible substrates. Their use in contemporary applications, however, is sparse due to persistent challenges in achieving the requisite performance levels in a reliable and reproducible manner. A critical bottleneck is the inefficiency associated with charge injection. Here, large-scale simulations are employed to identify operational windows where key device parameters that are difficult to control experimentally, such as the contact resistance, become less consequential to overall device functionality. This design methodology overcomes injection barrier limitations in organic field-effect transistors (OFETs), leading to high charge carrier mobility and significantly expanding the range of suitable electrode materials. Leveraging this new understanding, all-organic, solution-deposited OFETs are successfully fabricated on flexible substrates. These devices incorporate printed contacts and showcase mobilities exceeding 5cm2Vs-1. These results provide a route for accessing the fundamental limits of material properties even in the absence of ideal contacts - a critical step in establishing reliable structure/property relationships and optimal material design paradigms. While reducing the injection barrier and contact resistance remains critical for achieving high OFET performance, this work demonstrates a path toward consistently achieving high charge carrier mobility through device geometry design, ultimately reducing processing complexity and cost.

Up-conversion materials for solid-state lighting

AbstractConventional phosphor-converted white LEDs (WLEDs), using (Stokes) down-conversion light emission, suffer from a red deficiency that increases the Color Temperature towards “cool white light” above 5000 K. The present work describes a phosphor-Up-converted WLED approach that wishes to overcome this issue by achieving white light generation (WLG) through Up-conversion photoluminescence (UCPL), without energy losses due to Stokes shift and excited by a 980 nm LED instead of the more expensive blue LEDs. The UC materials include thin films of lanthanide (Ln)-doped aluminosilicate glass multilayers, alternating (Ln)-doped aluminosilicate and titania films in the form of 1-D photonic crystals and Ln ion-implanted materials. Sol-gel (SG) processing has been used as a low-cost high purity processing method to prepare titania, as well as aluminosilicate films containing Er3+, Tm3+ and Yb3+, for WLG and possible application as WLED materials. The total Ln content varied from a high of 22 mol% to as low as 5.8 mol%. The materials prepared have been characterized by UV-Vis-NIR (using a variable angle specular reflection accessory), plus FTIR and UCPL spectroscopies. The UC light emission was analyzed with the help of CIE chromaticity diagrams. Graphical abstract

Multi-Response Optimization of Single Point Incremental Forming of Al 6061 Sheet Through Grey-Based Response Surface Methodology

The single point incremental forming process (SPIF) is materialized to form the desired shapes in low-cost sheet metal processing and well suited for low batch components and customized designs. Many modifications have been attempted in recent years to maximize the formability, geometric accuracy and quality of the SPIF formed parts. In this work, an attempt has been made to analyse the influence of process parameters namely ball tool diameter, step size, spindle speed and sheet thickness on final wall thickness, forming force and surface roughness. The optimized results exhibit the desirable formability when the roller ball tool diameter of the tool is 12 mm. The results also project that formability of the sheet metal is minimized when the spindle speed is increased and the ball diameter maximizes the accuracy and surface roughness. Also minimizing the step size increases the product quality features. Upon conducting this multi-response optimization by grey based response surface methodology (RSM) technique It is identified that 12 mm ball diameter of the tool, 0.25 mm step size, 2445 rpm spindle speed, and 2 mm sheet thickness are the obtained optimized SPIF process parameters as confirmed through confirmation experiments.

Fabrication of Low-Cost Porous Carbon Polypropylene Composite Sheets with High Photothermal Conversion Performance for Solar Steam Generation.

The development of absorber materials with strong light absorption properties and low-cost fabrication processes is highly significant for the application of photothermal conversion technology. In this work, a mixed powder consisting of NaCl, polypropylene (PP), and scale-like carbon flakes was ultrasonically pressed into sheets, and the NaCl was then removed by salt dissolution to obtain porous carbon polypropylene composite sheets (P-CPCS). This process is simple, green, and suitable for the low-cost, large-area fabrication of P-CPCS. P-CPCS has a well-distributed porous structure containing internal and external connected water paths. Under the dual effects of the carbon flakes and porous structure, P-CPCS shows excellent photothermal conversion performance in a broad wavelength range. P-CPCS-40 achieves a high temperature of 128 °C and a rapid heating rate of 12.4 °C/s under laser irradiation (808 nm wavelength, 1.2 W/cm2 power). When utilized for solar steam generation under 1 sun irradiation, P-CPCS-40 achieves 98.2% evaporation efficiency and a 1.81 kg m-2 h-1 evaporation rate. This performance means that P-CPCS-40 outperforms most other previously reported absorbers in terms of evaporation efficiency. The combination of carbon flakes, which provide a photothermal effect, and a porous polymer structure, which provides light-capturing properties, opens up a new strategy for desalination, sewage treatment, and other related fields.

Impact of early continuous positive airway pressure in the delivery room (DR-CPAP) on neonates < 1500 g in a low-resource setting: a protocol for a pilot feasibility and acceptability randomized controlled trial

BackgroundPreterm birth is the leading cause of childhood mortality, and respiratory distress syndrome is the predominant cause of these deaths. Early continuous positive airway pressure is effective in high-resource settings, reducing the rate of continuous positive airway pressure failure, and the need for mechanical ventilation and surfactant. However, most deaths in preterm infants occur in low-resource settings without access to mechanical ventilation or surfactant. We hypothesize that in such settings, early continuous positive airway pressure will reduce the rate of failure and therefore preterm mortality.MethodsThis is a mixed methods feasibility and acceptability, single-center pilot randomized control trial of early continuous positive airway pressure among infants with birthweight 800–1500 g. There are two parallel arms: (i) application of continuous positive airway pressure; with optional oxygen when indicated; applied in the delivery room within 15 min of birth; transitioning to bubble continuous positive airway pressure after admission to the neonatal unit if Downes Score ≥ 4 (intervention), (ii) supplementary oxygen at delivery when indicated; transitioning to bubble continuous positive airways pressure after admission to the neonatal unit if Downes Score ≥ 4 (control). A two-stage consent process (verbal consent during labor, followed by full written consent within 24 h of birth) and a low-cost third-party allocation process for randomization will be piloted.We will use focus group discussions and key informant interviews to explore the acceptability of the intervention, two-stage consent process, and trial design. We will interview healthcare workers, mothers, and caregivers of preterm infants. Feasibility will be assessed by the proportion of infants randomized within 15 min of delivery; the proportion of infants in the intervention arm receiving CPAP within 15 min of delivery; and the proportion of infants with primary and secondary outcomes measured successfully.DiscussionThis pilot trial will enhance our understanding of methods and techniques that can enable emergency neonatal research to be carried out effectively, affordably, and acceptably in low-resource settings. This mixed-methods approach will allow a comprehensive exploration of parental and healthcare worker perceptions, experiences, and acceptance of the intervention and trial design.Trial registrationThe study is registered on the Pan African Clinical Trials Registry (PACTR) PACTR202208462613789. Registered 08 August 2022. https://pactr.samrc.ac.za/TrialDisplay.aspx?TrialID=23888.

Stability Challenges in Industrialization of Perovskite Photovoltaics: From Atomic‐Scale View to Module Encapsulation

AbstractPerovskite photovoltaics have attracted significant attention in both academia and industry, benefiting from the superiorities of high efficiency, low cost, and simplified fabrication process. Importantly, long‐term stability is essential for practical industrialization; however, the stability challenge remains a significant impediment. Notably, stability is an essential prerequisite for practical applications. Unfortunately, as the device area increases, even to the module level, the efficiency gradually diminishes, and the stability deteriorates. This review summarizes the advances in perovskite photovoltaic technology stability from comprehensive perspectives, including the atomic‐scale, grain boundary, film morphology, interface, charge transport layer, electrode, laser etching, and module encapsulation. First, the review highlights the ongoing importance of stability in the industrialization of perovskite photovoltaics. Then, the review presents the stability challenge and explores the relationship between efficiency and stability in large‐area photovoltaic modules, shedding light on the stability issue. Later, the review explains the stability issue in terms of structure, chemistry, interfaces, device design, operation, and external environment, and proposes stability strategies ranging from the atomic‐scale to module encapsulation. Finally, the review emphasizes various improvement strategies, particularly multilevel synergistic optimization, offering fundamental guidance for the industrialization of perovskite photovoltaics.

Gold Nanoparticles Decoration of Zinc Oxide Nanowalls on Flexible Substrates

Metal oxide nanostructures decorated with noble metal nanoparticles are hybrid structures with a special interface that combines the unique properties of those two materials. Noble metal nanoparticles exhibit useful catalytic properties, and they can be functionalized with biomaterials. In this work, we use gold nanoparticles that can be functionalized using thiolated molecules bound to the metal surface. Zinc oxide nano-walls (NWs) are a high surface-to-volume ratio wide-bandgap semiconductor nanostructures that, due to their biocompatibility and non-toxicity characteristics, can be used in biosensing applications that involve contact with tissues and cells. ZnO nano-walls can be deposited from aqueous solutions at low temperatures, both on rigid and flexible substrates, using a simple and low-cost process that can be upscaled to high-volume production. In this work, we study the nucleation and growth of the ZnO nano-walls and we describe the gold nanoparticles decoration at three different schemes of surface functionalization. Among these schemes, we found that the process where ZnO nano-walls were deposited on polyimide substrates followed by activation using a self-assembled monolayer, resulted in a decoration with uniform size and distribution of gold nano-particles. That process was studied as a function of the growth temperature, solution concentration, and time. The morphology of the ZnO nano-walls was studied by Scanning Electron microscope imaging and the crystal structure was studied by X-ray diffraction.

Boric Acid Removal from Water with Alginate Based Beads and Films as Adsorbents

High levels of boron cause harmful effects on humans, animals and plants. While boron is an important auxiliary nutrient for plants, excessive amounts cause toxic effects. The removal of boron in wastewater from chemical processes, industrial processes and agriculture is an important field of study. One of the most widely used methods for boron removal is adsorption method due to its low cost and ease of processing. In this study, adsorption method and sodium alginate microcapsules and sodium alginate-carbon nanotube film adsorbents were used as adsorbents for boric acid removal. In adsorption studies, sodium alginate-carbon nanotube film adsorbents with 42.11% boron removal were more efficient than sodium alginate microcapsules As a result of kinetic studies, it was found that the study was consistent with the pseudo-first order kinetic model.

Optimisation of Beam Member Loading

Introduction. The I-beams are deemed to have the highest load-bearing capacity. However, in practice, due to wide spreading and affordability of pipe-rolling products, the tubular beams are being used quite often. The load-bearing capacity of these beams should be compared under the condition of their equal mass per running meter. An I-beam according to the GOST R 57837-2017 with the mass of running meter equal to 194 kg and a pipe according to the GOST 33228-2015 with the mass of 194 kg/m have been compared. The load-bearing capacity of an I-beam was almost twice as high as that of a tubular beam. The data about the concrete filled steel tubular (CFST) beams, including the ones with the prestressed concrete core at the bottom, is also provided. In such beams, a steel pipe works as an external reinforcement — exo-reinforcement. The load-bearing capacity of the CFST beams is quite considerable taking into account their low cost and good processability. The present research aims at increasing the load-bearing capacity of the tubular beams, which will expand the range of the construction products.Materials and Methods. The geometric optimisation and mental experiment methods have been used. The idea of using the fluid filling material for a tubular beam is based on the well-known property of fluid — its almost complete incompressibility. The maximum volume of a geometric long body with the rectilinear generatrix of lateral surface (for a given lateral surface) is reached if its cross-section has the shape of a circle, which corresponds to a round pipe.Results. A tubular beam with the fluid filling material (a hydraulic beam) is a round pipe blanked off at both ends, completely filled with fluid (without air pockets). When a hydraulic beam is loaded, its lateral surface tends to deform. Consequently, the internal volume of the pipe tends to decrease. However, since fluid is incompressible, its volume doesn’t decrease, which, in turn, prevents the pipe from deformation.Discussion and Conclusion. In a hydraulic beam, due to fluid, the entire load is distributed relatively evenly over the whole internal surface of a beam. The load-bearing capacity of a hydraulic beam has been estimated, which is five times higher than that of an I-beam and ten times higher than that of a tubular beam.

Multi-physics coupling numerical simulation of variable porosity in reactive melt infiltration process

Abstract The hypersonic craft necessitates significant advancements in thermal shielding to safeguard against the extreme aero-thermal environments encountered during flight at hypersonic speeds in near space or upon reentry from space. Carbon fiber-reinforced ceramic matrix composites (FRCMCs) have attracted increasingly interesting attention as advanced structural materials for application in thermal protection. The reactive melt infiltration (RMI) process is preferred for the preparation of FRCMCs because of its low cost and short processing time. However, the RMI process includes the complex interplay of melt flow, reaction dynamics, and thermal fields, with existing models failing to accurately predict these processes due to their uncoupled nature and neglect of pore structure changes. This study introduces a coupled model that integrates mass transfer flow, chemical reaction, and heat transfer, incorporating variable pore structures to more accurately evaluate the RMI process. This approach allows for a comprehensive assessment of internal pressure, temperature, and porosity changes during silicon infiltration into porous media, marking an improvement over the previous model. The model has been validated for use in predicting the exotherm of RMI processes. In conclusion, this coupled model presents a promising avenue for enhancing the fabrication of FRCMCs, either considering the melt infiltration from multiple locations in the RMI process or adjusting the pore structure at the infiltration location to larger pores.