Uniform Transfer Research Articles

Epoxy nanocomposites with dual filler system: Improving surface protection against wear and thermocyclic corrosion

This investigation explores the influence of dual nanofillers - multi-walled carbon nanotubes (MWCNT) and silicon nitride nanoparticles (SiN) - on the properties of epoxy (EP). Analyses of tribological characteristics show hybrid nanocomposite of 0.25/ 0.75 wt% of SiN/MWCNT filler system improves the wear resistance by 96 % compared to EP. Raman spectroscopy reveals a novel curing mechanism induced by SiN nanoparticles when incorporated into epoxy at room temperature, while DSC thermograms show SiN's role in enhancing the crosslinking density. Creep studies indicate that EP/SiN nanocomposites at 0.5 wt% loading reduced the creep rate by 99 % compared to EP over a 10-min duration at 60 °C. Dynamic mechanical analysis (DMA) illustrates a significant increase in storage modulus and a 13 °C increment in the glass transition temperature (Tg) for 0.5 wt% EP/SiN nanocomposites. High-resolution transmission electron microscopy (HR-TEM) ascertained the homogeneous dispersion of nanofillers in hybrid nanocomposites, suggesting improved and uniform stress transfer. SiN-based composites are more effective than MWCNT-based composites in protecting mild steel from corrosion with a coating efficiency of 87 %. The potential of SiN to reduce free amine groups responsible for the corrosion process is presented, while physisorption tests are conducted to evaluate pore size and volume in the corroded samples. Field emission scanning electron microscopy (FE-SEM) is employed to analyze worn-out and corroded surfaces comprehensively. In EMI shielding, SiN reduces reflectivity without affecting the absorptive capacity of MWCNTs, making them suitable for coatings in stealth applications.

Enhancement of friction and wear performance of polytetrafluoroethylene composites through the synergistic effect of hard fillers

AbstractThe Stirling engine is a high‐efficiency externally heating piston engine. The self‐lubricating properties of polytetrafluoroethylene (PTFE) are crucial for the operation of Stirling engines. Three PTFE composites filled with different contents of carbon fiber (CF), polyimide (PI) and nano‐zirconia (nano‐ZrO2) were prepared and their mechanical, friction and wear properties were investigated. The results showed that the density of CF‐containing PTFE composites was significantly reduced by 1.46% to 6.9% compared to neat PTFE. Meanwhile, the incorporation of fillers greatly enhanced the hardness by more than 21.4% over the hardness of neat PTFE. In addition, the friction coefficients of three PTFE composites were lower than those of neat PTFE, and the wear rate of these composites was three orders of magnitude lower than that of neat PTFE. In particular, the wear rate of PTFE filled with CF and PI at high pressure (2 MPa) and high velocity (4 m/s) was only 1.24 × 10–6 mm3/Nm. The wear morphology was also analyzed by scanning electron microscopy and energy‐dispersive x‐ray spectroscopy. It was found that the addition of CF and PI in PTFE has the most pronounced improvement on tribological performances. The synergistic effect of CF's mechanical reinforcement and PI's adhesive properties reduces the wear of the matrix, resulting in excellent wear resistance of PTFE composites.Highlights The compressive strength of PTFE was reinforced by CF and nano‐ZrO2. CF can lower the density and significantly enhance hardness of PTFE. Synergistic CF and PI enhance PTFE composites' friction & wear performance. Adhesive fillers & debris size key to forming uniform continuous transfer films.

Design and preparation of biomimetic "Hard-soft" functional scaffold with gradient irregular pore structure for bone repair

To treat critical-sized defects in long bones, a novel structure was proposed by introducing a Haversian biomimetic structure and trabecular-like irregular pore morphology (IPM) structure into functional gradient porous scaffolds (FGPS). The outer shell structure is a "hard" structure providing mechanical support, and the inner core is a "soft" structure with radial gradient distribution IPM structure to promote the ingrowth of bone tissue. In this study, different inner core continuous gradient FGPS (GIPM) and layered FGPS (IPM, and BCC structure), with different outer shell pore sizes (300, 500, and 700 μm) were designed and fabricated by selective laser melting. The results show the stiffness of those FGPS was between 20.0-28.7 kN/mm, which is similar to the native femur (with a stiffness ranging from 7.2-11.7 kN/mm) of similar size. The GIPM-500 has more uniform stress distribution and stress transfer, resulting in superior load-bearing efficiency. Moreover, GIPM-500 exhibited excellent fatigue durability, achieving excellent fatigue cycles of more than 1×106 cycles. Cell immunofluorescence shows that the GIPM-500 and IPM-500 are more suitable for cell attachment and growth due to the flexibility of the local porosity and curvature. Bone defect repair simulations showed that GIPM-500 can meet normal load-bearing requirements while having little impact on the normal stress-strain trajectory. This work provides a novel biomimetic scaffold design containing both cortical and trabecular bone components for repairing critical-size defects in long bones.

Insights into the pore structure effect on the mass transfer of fuel cell catalyst layer via combining machine learning and multiphysics simulation

Analysis of the catalytic layer (CL) pore structure and three-phase (electron phase, proton phase, and reactant phase) mass transfer in high-temperature polymer electrolyte membrane fuel cell (HT-PEMFC) is critical for improving concentration polarization and optimizing performance. However, there is a lack of studies on the pore structure’s impact on the catalytic layer three-phase mass transfer. In this work, the influence of pore structure on catalytic layer three-phase mass transfer and multiphysics distribution was investigated by combining machine learning and multiphysics simulation. Among many key factors investigated by machine learning that impact the performance of catalytic layer, porosity emerges as the primary influencing factor. Porosity accounts for 32.7 % of the electric potential drop, with macro/micro porosity contributing 27.6 % and 5.1 %, and 32.8 % of the current density, with macro/micro porosity contributing 15.6 % and 17.2 %. Furthermore, the macropore structure has a much greater influence on the performance of the catalytic layer compared to the micropore structure. Moreover, the simulation results demonstrated that porosity has a great influence on three-phase mass transfer, the oxygen molarity increases with increasing porosity. The electric potential difference increases exponentially as porosity increases. The relationship between current density and porosity is a volcanic relationship, which can be expressed as a quadratic polynomial function. The mesoscopic pore-scale model (PSM) with an εeff of 0.502 (εmic of 0.2 and εmac of 0.378) exhibits the highest mean current density at 619.526 mA/cm2@0.5 V, attributed to a more uniform and efficient three-phase transfer path. The accuracy of the mesoscopic pore-scale model and the polynomial equation is further confirmed through corresponding experiments. The experiment results show that the current density decreased as the εeff increased from 0.682 to 0.702, which aligns with the theoretical predictions of the PSM model and polynomial equation. These studies are valuable for comprehending the internal three-phase mass transfer behavior and optimizing the catalytic layer pore structure to enhance HT-PEMFC performance.

Multistage rigid and flexible structure-decorated basalt fibers for epoxy resin composites with synergistically enhanced strength and toughness

In this study, we report the construction of a multistage rigid and flexible structure using boron nitride (BN) and MXene (MX, Ti3C2Tx) nanosheets through the conjugation with (3-aminopropyl) triethoxysilane (APTES). The created structure is further utilized to modify basalt fibers (BFs) to obtain BF/epoxy resin (BF/EP) composites via a simple coating process. The rigid two-dimensional materials (2DMs), BN and MX, significantly enhance the roughness of the BF surface, while the silane (APTES) acts as a flexible bridge for linking BFs, BN, and MX. Consequently, the constructed multistage rigid and flexible structure synergistically enhances the strength and toughness of the composite through effective mechanical interlocking, chemical bonding, and multistage energy dissipation. Meanwhile, this complex structure prevents the stress concentration and promotes uniform stress transfer between BFs and EP. This study provides a promising strategy to construct an effective interface layer and achieve high-performance BF/EP composites by introducing 2DMs and a silane linker.

Micromechanical insights for enhancing the rebound resilience of sealing materials based on TPV

Thermoplastic vulcanizate (TPV) with fascinating high elasticity has been received the ongoing research attention in the application of sealing system for the engineering machine. However, there still exists one factor, the plastic strain of plastic matrix adjacent to rubber particles in equatorial direction, which has greatly inhibited the resilience improvement of TPV. Traditional in-situ online experiments could not accurately obtain and quantify the stress-strain evolution behavior of heterogeneous rubber-plastic materials, crucial for resilience. Herein, one kind of TPV based on polyamide thermoplastic elastomer (TPAE) and ethylene-propylene-diene monomer (EPDM) with outstanding rebound resilience has been fabricated via introducing the interfacial compatibilization reaction and reinforcing particles during the melt-reactive blending. One three-dimensional representative volume element (3D-RVE) model has been established to analyze the deformation mechanism of such designed TPV in this work compared with that for TPV based on polypropylene (PP) and EPDM. By analyzing the forces on the RVE mesh units, it could reveal that the TPAE matrix exhibited more uniform stress transfer behavior at the thin ligament, and the recovery behavior of TPV matrix mainly occurred at the thin ligament. This work would provide important value for the preparation of new high elastic TPV materials from a microscopic level.

Investigation on the effect of vertical baffle plate on droplet size distribution and mixing efficiency in Taylor Reactor

The Taylor reactor is a dynamic mixer based on the principles of Taylor vortex flow. However, traditional Taylor reactors feature smooth inner and outer cylinder surfaces, presenting challenges in achieving uniform mixing and efficient mass transfer. These limitations do not meet the requirements of modern chemical processes for highly efficient mixing equipment. This article introduces a novel Taylor reactor equipped with vertical baffle plates, designed to overcome these challenges. A comprehensive methodology combining CFD-PBM and experimental techniques was employed to investigate both droplet size distribution and mixing performance in the annular gap. Compared to traditional designs, the new device demonstrates significantly lower COV at 0.018 and Sauter mean diameter at 38.3 μm. Optimal mixing efficiency is achieved at rotating Reynolds number (Re) of 1.17 × 105 and inlet Reynolds number (Rei) of 2.65 × 103. Numerical simulation results suggest that vertical baffles effectively enhance liquid-liquid interactions including collision, interface contact, and droplet residence time within the annular gap. Moreover, increased turbulent stress in the flow field contributes to greater vorticity, turbulence intensity, and turbulent kinetic energy resulting in smaller droplet sizes and improved mixing efficiency. These findings provide a theoretical foundation for hydraulic structural optimization design as well as widespread application of Taylor reactors.

Transition from paediatric to adult health care in Poland – current problems and future challenges. Analysis of issues faced by patients with inborn errors of immunity

The health care system in Poland provides treatment for patients up to 18 years of age in paediatric health care facilities, whereas adult patients are treated in specialist health care facilities for adults. A critical moment for the continuity of permanent treatment for all people with chronic disease is the transition from paediatric care to adult care. Organisational, psychological, and social problems can disrupt this process, posing the risk of health deterioration, and in extreme cases, discontinuation of therapy and premature mortality among young adults. In Poland, there is no universal, coordinated, efficient, and successful model for patient transition. This article highlights potential factors contributing to the lack of fluidity in the transition process and the associated risks. Examples of models ensuring optimal transition of a paediatric patient to adult care are also presented. It seems that creating systematic, uniform patient transfer programmes is the only way to eliminate potential threats. The crucial elements in this process are postulated to include: 1) advance planning of the transition process, 2) efficient transfer of information about the patient’s condition and treatment between paediatric and adult centres, 3) patient awareness of their new role in the decision-making process. The article focus on patients with inborn errors of immunity, highlighting the current experience and potential reasons for failures in the patient transition process.

Computational Shape Design Optimization of Femoral Implants: Towards Efficient Forging Manufacturing

Total hip replacement is one of the most successful orthopedic operations in modern times. Osteolysis of the femur bone results in implant loosening and failure due to improper loading. To reduce induced stress, enhance load transfer, and minimize stress, the use of Ti-6Al-4V alloy in bone implants was investigated. The objective of this study was to perform a three-dimensional finite element analysis (FEA) of the femoral stem to optimize its shape and analyze the developed deformations and stresses under operational loads. In addition, the challenges associated with the manufacturing optimization of the femoral stem using large strain-based finite element modeling were addressed. The numerical findings showed that the optimized femoral stem using Ti-6Al-4V alloy under the normal daily activities of a person presented a strains distribution that promote uniform load transfer from the proximal to the distal area, and provided a mass reduction of 26%. The stress distribution was found to range from 700 to 0.2 MPa in the critical neck area of the implant. The developed computational tool allows for improved customized designs that lower the risk of prosthesis loss due to stress shielding.

Effect of raceway surface topography based on solid lubrication on temperature rise characteristics of HIPSN full ceramic ball bearings

PurposeThis study aims to understand the influence of raceway surface topography on the temperature rise characteristics of silicon nitride (Si3N4) full ceramic ball bearing and improve its service life.Design/methodology/approachThe arithmetic average height Sa, skewness Ssk and kurtosis Sku in the three-dimensional surface roughness parameters are used to quantitatively characterize the surface topography of the raceway after superfinishing. The bearing life testing machine is used to test the Si3N4 full ceramic ball bearing using polytetrafluoroethylene (PTFE) cage under dry friction conditions, and the self-lubricating full ceramic ball bearing heat generation model is established.FindingsWith the decrease of Sa and Ssk on the raceway surface and the increase of Sku, the average height of the raceway surface decreases, and the peaks and valleys tend to be symmetrically distributed on the average surface, and the surface texture becomes tighter. This kind of raceway surface topography is beneficial to form a thin and uniform filamentous PTFE transfer film with a wide coverage area on the raceway surface based on consuming less cage materials and improving the temperature rise characteristics of hot isostatic pressing silicon nitride full ceramic ball bearings.Originality/valueThe research results provide a theoretical basis for the reasonable selection of Si3N4 ring raceway processing technology and have important significance for improving the working characteristics and service life of Si3N4 full ceramic ball bearings under dry friction conditions.

Nano-Diamond Decorated Reduced Graphene Oxide: Improvement to Tribological Property of Polyimide and Its Molecular Dynamic Simulation

In this paper, the nano-diamond decorated reduced graphene oxide (Diamond-RGO) and its polyimide (PI) composite, by using in situ polymerization method, are synthesized, respectively. The tribological study of Diamond-RGO/PI composite exhibits super anti-wear properties under dry sliding and high load condition: the lowest wear rate of 4.9 × 10−8mm3N−1m−1, which is extraordinarily lower than that of pure PI and RGO/PI composite, is obtained under load 100 N. The tribological mechanism investigation shows that Diamond-RGO composite has a strong synergistic effect in the tribological process which contributes to form a uniform transfer film on the counterpart ring and thus significantly decrease the composite’s wear rate. Through molecular simulation, the shear behavior of the composite material indicates that the presence of the Diamond-RGO composite will obviously weaken the influence of the iron wall on the PI bulk phase molecular chain in the shear process. This confirms that the synergistic effect between nano-Diamond and RGO will improve its PI composite’s tribological performance on atomic level.

Investigation on activation performance of adhesive bonding connection between Fe-SMA and steel plates

Steel structures are extensively utilized in civil engineering because of their advantageous characteristics. However, cyclic loading can induce cracks in steel structures, resulting in a decline in mechanical properties and increased life cycle costs. In recent times, iron-based shape memory alloys (Fe-SMAs) have gained recognition as promising materials for structural reinforcement due to their distinct shape memory effect. The adhesive bonding connection between Fe-SMA and steel offers an efficient solution for reinforcing steel structures, enabling uniform stress transfer without introducing defects. This study investigates the influence of the geometric dimensions of Fe-SMA plates and the structural adhesive on the stress of steel plates through activation tests and finite element simulations. A multiple regression model has been proposed to describe the relationship between the size of Fe-SMA plates, structural adhesive, and the stress of steel plates. In addition, the temperature of the adhesive during activation is determined through activation tests. According to test results, a temperature distribution model for the adhesive has been developed, allowing for an accurate theoretical calculation of the adhesive softening length. The adhesive softening significantly impacts the stress distribution of the steel plate, making this model considerably valuable. This study provides valuable experimental data and a theoretical basis for the practical implementation of Fe-SMA in metal structural reinforcement.

Combined preparation and application of geopolymer pavement materials from coal slurry-slag powder-fly ash mining solid waste: A case study

The solid waste treatment problem generated in the process of coal mining has always been an important factor restricting safe and environmentally friendly production, and the coal slurry from the coal mine road surface is a new type of mine solid waste, so it is of great significance to treat and efficiently utilize the coal slurry. Currently, a common method of solid waste utilization is to add modifying reagents to prepare functional materials. Select coal slurry, slag powder and fly ash as raw materials, and sodium sulfate and sodium hydroxide were used as alkali exciters to prepare coal slurry based geopolymer pavement material (CSGPM). Response surface methodology was used to establish regression equations between the design optimization objectives (coagulation time, compressive strength) and the variables (mass fraction, mass ratio of slag powder to fly ash, mass ratio of sodium sulfate to sodium hydroxide). The effects of two-by-two interactions of the factors on the optimization objective were explored, and the use of different raw materials was obtained. Under the optimal proportioning parameters, the coagulation time of CSGPM was 33 min and the compressive strength of 24 h of curing was 11.20 MPa. In addition, the generation mechanism of AFt and C-S-H gel substances inside the specimen was explained with the help of microscopic scanning. CSGPM showed good mechanical properties in both load-bearing numerical simulations and acoustic emission tests. Numerical simulation was used to establish the relationship between the design objective of the roadbed (maximum subsidence of the roadbed after bearing) and the design variable (thickness of CSGPM paving). Comparative analyses yielded an optimal subgrade surface layer design thickness of 5 cm, with a maximum subsidence of 0.0033 m after bearing vehicles. Synchronization of roadbed material and concrete damage in combined specimen acoustic emission tests with uniform load transfer. The final coal mine pavement was successfully paved and the total cost of CSGPMD is 63.2 per cent of C30 concrete. Those results are important for the preparation of new pavement functional materials.

Study on the preparation and fretting behavior of bonded oriented MoS2 solid lubricant coating

The bonded MoS2 solid lubricant coating is an effective measure to mitigate the fretting wear of AISI 1045 steel. In this work, the amino functionalized MoS2 was protonated with acetic acid to make the MoS2 positively charged. The directional arrangement of protonated MoS2 in the coating was achieved by electrophoretic deposition under the electric field force. The bonded directionally aligned MoS2 solid lubricant coating showed high adaptability to various loads and excellent lubrication performance under all three working conditions. At a load of 10 N, the friction coefficient and wear volume of the coating with 5 wt% protonated MoS2 decreased by 20.0% and 37.2% compared to the pure epoxy coating, respectively, and by 0.07% and 16.8% than the randomly arranged MoS2 sample, respectively. The remarkable lubricating properties of MoS2 with directional alignment were attributed to its effective load-bearing and mechanical support, barrier effect on longitudinal extension of cracks, and the formation of a continuous and uniform transfer film.

In situ constructing fluorine/nitrogen-enriched interface on highly lithiophilic carbon fiber/MXene/ZnS skeleton for stable lithium anodes

Metallic lithium (Li) is an excellent electrode material for high-energy-density batteries; however, the continuous growth of Li dendrites and the poor deposited volume consistency of Li severely influence the stability of Li anodes. Herein, a LiF-Li3N/LiNxOy-enriched SEI is prepared in situ using a strongly lithiophilic 3D carbon fiber/MXene/ZnS (CMZ) skeleton. Multiscale in situ and ex situ characterizations reveal the mechanisms for Li nucleation and growth on the CMZ skeleton, proving that Li grows tightly over CMZ fibers. This behaviour is attributed to the CMZ skeleton, which provides abundant atomic-level active sites for the uniform and dense nucleation of Li. Electrochemical tests confirm that SEI enriched with LiF-Li3N/LiNxOy can effectively improve Li deposition kinetics, ensure uniform mass transfer and rapid migration of lithium ions in the SEI, and guarantee uniform growth of Li. Consequently, a half cell with a Li-CMZ electrode delivers a high Coulombic efficiency (99.83 %), an ultralong cycling life (17,860 h), and an excellent rate performance (30 mA cm−2). Moreover, full cells consisting of a Li-CMZ anode and different cathodes exhibit superior cycling stabilities. For Li-CMZ ‖ LiFePO4 pouch cell, 84 % capacity is maintained after 300 cycles at 1 C.

Pillar data-acquisition strategies for cryo-electron tomography of beam-sensitive biological samples.

For cryo-electron tomography (cryo-ET) of beam-sensitive biological specimens, a planar sample geometry is typically used. As the sample is tilted, the effective thickness of the sample along the direction of the electron beam increases and the signal-to-noise ratio concomitantly decreases, limiting the transfer of information at high tilt angles. In addition, the tilt range where data can be collected is limited by a combination of various sample-environment constraints, including the limited space in the objective lens pole piece and the possible use of fixed conductive braids to cool the specimen. Consequently, most tilt series are limited to a maximum of ±70°, leading to the presence of a missing wedge in Fourier space. The acquisition of cryo-ET data without a missing wedge, for example using a cylindrical sample geometry, is hence attractive for volumetric analysis of low-symmetry structures such as organelles or vesicles, lysis events, pore formation or filaments for which the missing information cannot be compensated by averaging techniques. Irrespective of the geometry, electron-beam damage to the specimen is an issue and the first images acquired will transfer more high-resolution information than those acquired last. There isalso an inherent trade-off between higher sampling in Fourier space and avoiding beam damage to the sample. Finally, the necessity of using a sufficient electron fluence to align the tilt images means that this fluence needs to be fractionated across a small number of images; therefore, the order of data acquisition is also a factor to consider. Here, an n-helix tilt scheme is described and simulated which uses overlapping and interleaved tilt series to maximize the use of a pillar geometry, allowing the entire pillar volume to be reconstructed asa single unit. Three related tilt schemes are also evaluated that extend the continuous and classic dose-symmetric tilt schemes for cryo-ET to pillar samples to enable the collection of isotropic information across all spatial frequencies. Afourfold dose-symmetric scheme is proposed which provides a practical compromise between uniform information transfer and complexity of data acquisition.

Tribological synergy of copper‐based metal–organic frameworks, carbon fibers and SiO2 in modifying the friction and wear properties of epoxy composites

AbstractCopper‐based metal–organic frameworks is anticipated to find applications in the field of friction materials owing to its plentiful surface‐active groups and distinctive framework structure. In this study, copper‐based metal–organic frameworks was synthesized through ultrasound‐assisted method and incorporated alone into carbon fiber reinforced epoxy composites or together with SiO2 nanoparticles towards the goal of improving the composites' friction and wear properties. It is revealed that copper‐based metal–organic frameworks alone cannot improve the friction and wear of carbon fiber reinforced epoxy composites simultaneously. The combination of copper‐based metal–organic frameworks and SiO2 nanoparticles was more effective in enhancing both the mechanical and tribological properties of studied composites. The composite material exhibits a friction coefficient of 0.104 under the specified test conditions of 10 MPa and 3.75 m/s. Additionally, the specific wear rate is impressively low, measuring only 5.64 × 10−7 mm3 N/m. Through morphological and chemical analysis on the worn surfaces and transfer films, the functioning mechanism of copper‐based metal–organic frameworks in modifying the mechanical and tribological properties was discussed. It was discovered that a tribological synergy exists between short carbon fibers, copper‐based metal–organic frameworks, and SiO2 fillers, leading to a shift in the wear mechanism of the composite materials from abrasive wear to adhesive wear. Concurrently, a shear‐prone transfer film forms on the surface of the counter steel surfaces. Findings of the present study pave a new route of designing high performance epoxy based tribo‐composites by using metal–organic frameworks.Highlights Cu‐BDC nanosheets were synthesized using ultrasound‐assisted techniques and incorporated as tribological fillers in EP composites. The combined use of Cu‐BDC, SiO2, and SCF fillers synergistically enhances the mechanical and tribological properties of EP composites. The composite material exhibits a friction coefficient of 0.104 under the specified test conditions of 10 MPa and 3.75 m/s, the specific wear rate is impressively low, measuring only 5.64 × 10−7 mm3N/m. During the sliding friction process of the composite materials, Cu‐BDC and SiO2 play a crucial role in reducing SCF pull‐out wear through their anchoring effect. The dynamic coordination bond structure of Cu‐BDC contributes to the formation of uniform and continuous transfer films on counter metal surfaces.

Experimental investigation of phase change material (PCM) thermal energy storages with and without metal foam at different temperatures

This paper presents an experimental investigation of phase change materials (PCM) thermal energy storage. The experimental unit consists of a square channel with a single flow stream having distilled water as a heat exchange fluid. RT-42 is used as a thermal energy storage and the overall system is designed in two configurations i.e. with and without aluminium metal foam having a porosity of 95%. Each configuration is analysed and compared for two temperature variations i.e. at 55 °C and 65 °C, respectively. The study reveals that the heat storage rate in metal foam (MF) integrated PCM thermal energy storage is enhanced to ~3-4 times as compared to the setup without metal foam. In metal foam PCM energy storage, the temperature distribution is uniform and heat transfer is due to conduction as well as convection, while in case of pure PCM, there exist a temperature gradient within the thermal storage and the heat transfer is slower due to convection phenomenon. It is also observed that the heat transfer rate for 65 °C is comparatively greater than that of 55 °C for both systems as the higher operating temperatures lead to higher heat flux. However, operating at high temperatures is less feasible as the setup is more prone to PCM leakages.

Gram-scale microwave-assisted synthesis of high-quality CsPbBr3 nanocrystals for optoelectronic applications

Fully inorganic halide perovskite nanocrystals (NCs) are promising candidates for optoelectronic applications due to their beneficial properties such as their amenability to solution processing, high absorption coefficients, and high quantum yields. Various methods have been developed to prepare perovskite CsPbX3 (X = Cl, Br, and I) NCs; however, large-scale synthesis with high-quality CsPbX3 NCs remains challenging. In the study, we report an advanced method for the gram-scale synthesis of all-inorganic perovskite NCs via specially designed microwave-assisted synthesis, which offers uniform reaction energy transfer, excellent reproducibility, and flexible parameter tuning. The composition, size and uniformity of the CsPbBr3 NCs have been optimized by controlling the surfactant ratio, precursor ratio, and reaction time. This systematic optimization leads to the production of gram-scale (> 0.165 g per a 100 ml reaction mixture for a single synthesis cycle) high-quality, phase-pure CsPbBr3 NCs with a uniform size of ∼ 10 nm. These optimized NCs exhibit a sharp photoluminescence peak centered at 515 nm with a photoluminescence quantum yield of 94 % and produce excellent radioluminescence under X-ray irradiation. To test the feasibility of these NCs for use in real optoelectronic devices, a photodetector consisting of CsPbBr3 NCs and monolayer MoS2 was fabricated, demonstrating enhanced photosensitivity and a faster response time compared with a pure MoS2-based photodetector. The proposed gram-scale microwave-assisted synthesis method thus has the potential to promote the commercialization of metal halide perovskite NCs through cost-effective mass production for use in many optoelectronic applications.

Preparation and Performance Study of Titanium‐Based Nanocomposites in Selective Laser Melting: Microstructure Regulation and Optimization of Mechanical Properties

This study focuses on exploring the application of selective laser melting (SLM) technology in the preparation of titanium‐based nanocomposite materials. By introducing 0.5 wt% graphene oxide (GO) and 7.0% nanomolybdenum (Mo) powder, an attempt is made to improve the microstructure and mechanical properties of titanium alloy materials. The experimental results indicate that the microstructure of the titanium‐based nanocomposite material undergoes significant crystal refinement and phase transition behavior, suggesting a positive role of introducing nanoreinforcing phases in crystal structure regulation. Simultaneously, the introduction of GO significantly improves the thermal conductivity of the material, contributing to more uniform energy transfer and temperature distribution, thereby optimizing the process control of laser melting. In terms of mechanical performance, through microhardness and tensile performance tests, the microhardness of TC4–0.5GO–7Mo increases by ≈30.8% compared with pure TC4. This strengthening effect is primarily attributed to the uniform distribution of GO and Mo powder in the matrix, effectively hindering lattice slip and dislocation movement, enhancing the hardness and tensile properties of the material. Through a comprehensive analysis of microstructure and mechanical properties, not only the mapping relationship between the microstructure and mechanical properties of titanium‐based nanocomposite materials is clarified but also the strengthening mechanism is revealed.