Enhancement Of Properties Research Articles

In-situ formed silicon oxycarbide nanowires into porous SiC(rGO) PDCs enable balanced enhancement of robustness and thermal management

With ongoing development of rocket combustion and hypersonic vehicles, urgent needs are created on thermal structures, protection and thermal insulating materials, particularly balanced enhancement of mechanical and antioxidant properties. Herein, we propose a design strategy to construct continuous in-situ formed SiOC nanowires (SiOCnws)-toughened self-healing SiOx coatings into porous SiC(rGO) PDCs. The key production technique is re-pyrolyzing coassembled flexible precursors/SiC(rGO)p/graphite blends, followed by decarbonization and silica sol impregnation-sintering (SIS) process. Well-distributed hierarchical pores are built to heighten thermal insulation properties by the integrated decarburization of graphite coupled with free carbon. High-yield SiOCnws, with high surface activity, are first cultivated via graphite-assisted vapor-solid (VS) mechanism without transition metal catalysts. They interconnect to form intricate 3D meshwork by graphite-assisted melt-spinning and have good compatibility with ceramic matrix and SiOx coatings by carbothermal reaction. Hierarchically porous SiOCnws/SiC(rGO)40% PDCs after once SIS exhibit favorable thermal conductivity of 0.27 W‧m−1‧K−1 and exceptional high robustness (compressive strength: 39.02 MPa, hardness: 10.27 GPa). Such composites display low reflection loss of −48.14 dB at 11.22 GHz and even good structural stability at about 1300 °C as burned by a butane blowtorch for 3600 s, shedding light on competitive components for uses in thermal protection fields.

Evaluation of Mechanical Properties of Composite Material with a Thermoplastic Matrix Reinforced with Cellulose Acetate Microfibers.

Low-density polyethylene (LDPE) has been widely used in various applications due to its flexibility, lightness, and low production cost. However, its massive use in disposable products has raised environmental concerns, prompting the search for more sustainable alternatives. This study aims to investigate the mechanical properties achievable in a composite material utilizing low-density polyethylene (LDPE), potato starch (PS), and cellulose microfibrils (MFCA) at loadings of 0.05%, 0.15%, and 0.30%. Initially, the cellulose acetate microfibrils (MFCA) were produced via an electrospinning process. Subsequently, a dispersive mixture of the aforementioned materials was created through the extrusion and pelletizing process to form pellets. These pellets were then molded by injection molding to produce test specimens in accordance with ASTM D 638, the standard for tensile strength testing. The evaluation of the properties was conducted through mechanical tensile tests (ASTM D638), hardness tests (ASTM D 2240), melt flow index (ASTM D1238), and scanning electron microscopy (SEM). This study determined the influence of cellulose acetate microfibril loadings below 0.3% as reinforcement within a thermoplastic LDPE matrix. It was demonstrated that these microfibrils, due to their length-to-diameter ratio, contribute to an enhancement in the mechanical properties.

Enhancement of Mechanical Properties of NiCo Alloy Induced by Inhomogeneous Gradient of Solute Element Segregation

Inhomogeneous gradient nanocrystals have better mechanical properties than uniform gradient nanocrystals. The segregation of solute elements in inhomogeneous gradient nanocrystals is expected to induce the re‐enhancement of mechanical properties of alloys. Herein, solute element segregation structures of inhomogeneous gradient structure nanocrystalline NiCo alloy are established, simulating tensile deformation via molecular dynamics. The results show that the segregation of solute elements in the inhomogeneous gradient structure of nanocrystals can improve the mechanical properties of the alloy, especially the structure of the intragranular segregation. The intragranular segregation of solute elements induces the decrease of grain boundary energy and greatly enhances the stability of grain boundaries. In addition, the segregation of solute elements within grains can hinder the dislocation movement to a certain extent, and the hindering effect on dislocation movement of stable grain boundaries induced by intragranular segregation of solute elements further enhances the mechanical properties of nanocrystalline alloys. This strategy of combining heterogeneous gradient structure and solute element segregation structure provides a positive and interesting perspective for the design of advanced alloys with excellent properties.

Theoretical and experimental studies on 2D β-NiS battery-type electrodes for high-performance supercapacitor

Recently, quirky features and eccentric structures of transition metal sulfides have grasped great attention to remove roadblocks and unwrap fresh avenues for electrodes in energy storage devices. Herein, we developed a 2D beta phase nickel sulfide nanosheets (2D β-NiS NSs) electrode with remarkable enhancement in charge storage properties. When served as active electrodes for electrochemical tests, 2D NiS NSs exhibited ultra-high capacitance of 2693 Fg−1 at 1 mVs−1 and specific capacity of 219 mAhg−1 at 1 Ag−1. The symmetric battery type solid-state supercapacitor device comprising 2D β-NiS NSs electrodes exhibits specific capacity of 83.43 mAhg−1at 2 Ag−1 over broad potential range of 0.7V with good cycling performance, and energy and power density of 28.9 Whkg−1 (@ 2 Ag−1) and 21 kWkg−1 (@ 6 Ag−1) respectively. Complementary first-principles density functional theory (DFT) calculations accomplished to explore the electrolyte ion interactions with nickel sulfide nanostructures defining 2D NiS NSs as a potential candidate for real-time applications.

Polydopamine‐coated iron‐nickel alloy and epoxy composites for electromagnetic interference shielding

AbstractWith the development of electronic devices and wireless communication technology, the quality of human life has improved. However, shielding from electromagnetic interference (EMI) is required due to device malfunctions and harmful effects on human health. Polymer‐based shielding materials getting much attention due to their light weight, flexibility, good processability, and other desirable traits. However, achieving consistent dispersion of conductive fillers and optimizing the balance between electrical, mechanical, and thermal properties remain challenges despite the advantages of polymer‐based materials. Especially, epoxy resins are promising polymer materials for EMI shielding applications due to their excellent mechanical strength, chemical resistance, and excellent adhesive properties. Additionally, epoxy resin exhibits remarkable processability allowing for various fabrication techniques such as casting, molding, and three‐dimensional printing. However, one of the significant drawbacks of epoxy resin is the difficulty in achieving uniform dispersion of conductive fillers within the epoxy matrix. In this study, we propose an iron‐nickel alloy (FeNi) embedded in an epoxy matrix (FeNi/Epoxy) for EMI shielding material. It is manufactured by facile fabrication process due to the advantages of epoxy, which has excellent processability. EMI shielding effectiveness at 12 GHz is enhanced from 9.12 to 17.86 dB by the increase of FeNi concentrations. Furthermore, thermal and mechanical properties were improved by the increase of FeNi concentration. Thermal conductivity for efficient heat dissipation is increased from 0.63 to 1.49 Wm−1 K−1. Moreover, polydopamine (PDA) was employed as a surface coating material for FeNi to overcome the non‐uniform dispersion of FeNi particles in the epoxy matrix. Surface coating by PDA significantly enhanced the dispersion uniformity and strengthened the adhesion between the filler and matrix. Elastic modulus is greatly increased from 83.03 MPa to 1.29 GPa by the surface coating. The enhancement of mechanical properties is derived from the chemical bonds between the filler and matrix.

Application of biomineralisation for enhancement of interfacial properties of rice husk ash blended concrete

The present study is comprehensive research on application of biocementation to enhance the properties of concrete including rice husk ash (RHA) as a supplementary cementitious material (SCM). RHA has a large potential to be used as SCM because it has high silica content which eventually forms C–S–H gel by reacting with calcium and water, which increases strength of the cementitious material. However, using high doses of RHA causes a decrease in concrete strength because excessive silica is available to react with calcium hydroxide, forming silica clumps within the concrete matrix, which reduce the bonds within the concrete constituents causing micro cracks. Hence to mitigate this problem, enzyme induced calcium carbonate precipitation (EICCP) process was used to treat the micro cracks, and enhance the mechanical and durability properties of RHA blended concrete. Results showed that EICCP process enhanced the strength of the mix at each replacement level and 10% replacement level exhibited optimum results. with nearly 29% increment in compressive strength. This mix also exhibited enhanced durability as compared to the control specimens. Since concrete constitutes a significant portion of embodied carbon footprint, using greener concrete mixes like “Experimental Mix” has the potential to considerably decrease the carbon footprint of construction.

Enhancement of mechanical properties in coral concrete via seawater and sea-sand: Experimental insights into the use of dual plastic fibers

The South China Sea contains many coral reefs, and there is a lot of discussion about the best way to dispose of them. Finding ways to use these materials effectively in marine engineering could help address the shortage of natural aggregates in coastal engineering. One potential solution is using coral concrete, which offers cost-effective and enhanced properties. A type of coral fiber concrete using sea sand is created by combining coral rock, sea sand, seawater, PVA fiber, and PP fiber. The findings indicate that by utilizing the optimal ratio of the two fibers (3 kg PVA + 1 kg PP and 2 kg PVA + 2 kg PP), the cubic and axial compressive strength of the new concrete can be increased by 10 % and 20 %, respectively compared to ordinary coral concrete. Furthermore, incorporating these fibers can also reduce axial displacement, resulting in an elastic modulus that is 30–50 % higher than non-fiber variants while enhancing axial toughness. Finally, this study examines stress-strain curves at three different stages through analysis of macroscopic and microscopic failure mechanisms. It was found that there exists a correlation exceeding 0.9 between two mathematical models and measured stress-strain curves from this study. The effective use of composite plastic fiber significantly enhances concrete material performance while providing valuable data support for marine economic facilities construction.

Enhanced charge storage in supercapacitors using carbon nanotubes and N-doped graphene quantum dots-modified (NiMn)Co2O4

The integration of ternary metal oxides into carbon materials is anticipated to significantly boost the electrochemical performance of supercapacitor electrodes. This article synthesized carbon nanotubes (CNT)/(NiMn)Co2O4 composite materials using a straightforward hydrothermal method and subsequently prepared composite thin films of CNT/P-(NiMn)Co2O4@NGQD by phosphating and incorporating nitrogen-doped graphene quantum dots (NGQD). These films served as the functional electrode material for supercapacitors, enhancing their performance capabilities. The specific capacity of CNT/P-(NiMn)Co2O4@NGQD was measured at 2172.0 F g−1 at a current density of 1 A g−1, maintaining a capacitance of 1954.0 F g−1 at 10 A g−1, thus demonstrating excellent rate performance. Electrochemical impedance spectroscopy (EIS) further revealed enhancements in electrolyte flow dynamics and capacitance behavior post-NGQD introduction. The energy density of the composite material reached 94.4 Wh kg−1 at power density of 800 W kg−1, demonstrating superior electrochemical performance. The enhancement in these electrochemical properties is attributed to the high specific surface area and active sites of CNT/P-(NiMn)Co2O4@NGQD films, along with the synergistic effects of NGQD and metal ions facilitating rapid electrons and charge transfer. This work provides new insights into developing high-performance supercapacitors.

Enhanced mechanical properties of the additively manufactured IN738LC superalloy through thermal history management during the laser powder bed fusion process

IN738LC superalloy, as one of the hard-to-weld Ni-based superalloys, is relatively difficult to be produced by laser powder bed fusion (LPBF) due to its high cracking susceptibility. In this study, local heat accumulation based on substrate preheating and chessboard scanning strategy modification was proposed to reduce the thermal stress and promote the dynamic precipitation of IN738LC superalloy during LPBF process, which contributes to the crack inhibition and mechanical property enhancement. The as-built IN738LC superalloy exhibited superior room temperature tensile yield strength (YS) of 1011 ± 7 MPa, ultimate tensile strength (UTS) of 1400 ± 12 MPa, and good ductility of 17.4 ± 2.9 %. The superior mechanical performance was achieved mainly due to the successful elimination of micro-cracks, the formation of hierarchical microstructure composed of columnar γ grains, cellular dislocation network, especially in-situ formation of carbide precipitates. The formation of micro-cracks was fully eliminated due to the reduced temperature gradient and residual stress. In-situ formation of carbide precipitates was enabled by well-controlling the thermal history during the LPBF process. The use of a chessboard scanning strategy and substrate preheating was found to be beneficial for achieving a larger melting pool size, coarser dendrite/cellular arm spacing, and a larger volume of carbide precipitates due to enhanced heat accumulation during the LPBF process, which was verified by finite element analysis. This work provides insights into the effects of thermal profiles inherent to LPBF processes on the performance of LPBF-processed IN738LC superalloy.

Characterization of a copper matrix composite reinforced with nano/submicron-sized boron fabricated via spark plasma sintering

The addition of various reinforcing phases can improve the mechanical properties of copper. This study investigates the enhancement of the mechanical properties of copper by adding boron, focusing on overcoming the challenges associated with the homogeneous distribution of submicron/nanoscale secondary phases in metal matrix composites. Employing a combination of mechanical alloying and spark plasma sintering, a copper-boron composite containing 3 wt% boron was prepared. Scanning electron microscopy equipped with an electron backscatter diffraction detector and energy-dispersive X-ray spectroscopy was utilized to characterize the structure of the sintered samples and mechanically alloyed powder. A two-phase structure containing nano/submicron-sized boron distributed uniformly in the copper matrix was formed in the sintered sample. Instrumented micro-indentation tests were performed to characterize the mechanical behavior of the samples. The sintered composite sample exhibits significantly higher hardness than the sintered copper. The enhanced mechanical performance of the composite is primarily attributed to grain boundary strengthening and microstructural refinement, where nano/submicron-sized boron particles prevent grain growth and refine the microstructure, enhancing hardness and strength. Additionally, dispersion strengthening from hard boron particles and the presence of a high density of twin boundaries within the copper matrix increase resistance to dislocation motion and deformation, and further improving the material's mechanical properties. On the other hand, the composite sample exhibits increased electrical resistivity due to the boron’s role as electron scattering centers. Overall, this study provides a valuable strategy for the design and optimization of advanced copper-based composites with tailored mechanical and electrical properties.

Densification and network structural changes in binary aluminosilicate glass via cold sintering process

Binary aluminosilicate glasses containing 20–50 wt% Al2O3 were successfully densified through a cold sintering process (CSP) using 1–10 M NaOH solutions. The investigation focused on densification and structural unit changes in the cold-sintered binary aluminosilicate glasses. Specifically, the binary aluminosilicate glass with 40 wt% Al2O3, cold-sintered at 180 °C using 1–10 M NaOH solutions, achieved a relative density of up to 90 % at 10 M NaOH. This was attributed to an enhanced dissolution-precipitation process facilitated by an increased concentration of the NaOH solution. In aluminosilicate glasses with 20–50 wt% Al2O3, the relative densities approached 90 % after CSP at 180 °C using a 10 M NaOH solution. Al(OH)3 formation in the cold-sintered glasses was confirmed, particularly at higher concentrations of NaOH solution (>10 M) and higher contents of Al2O3 (>40 wt%). Changes in Si structural units were observed during CSP, with Al-rich Si units becoming dominant as the concentration of the NaOH solution increased. The higher substitution of Si-O-Si bonds by Si-O-Al bonds led to the precipitation of Al(OH)3, as well as an increased Vickers hardness and biaxial flexural strength of the cold-sintered glasses. These findings demonstrate that the Al2O3 content and NaOH concentration play important roles in the densification and enhancement of the mechanical property in the cold-sintered alumina-rich binary aluminosilicate glasses and offer insights into the optimal conditions for obtaining desirable aluminosilicate materials through CSP.

Electrochemical and structural properties of binder-free iron-based bifunctional catalyst for aqueous Zinc-Oxygen batteries

Global warming necessitates efficient new batteries, with Zn-O2 batteries standing out due to their high theoretical energy density, safety, and long cycle life, making them ideal for large-scale use. However, their industrial application faces challenges such as rapid energy density decline after initial cycles, limited cathode efficiency, and high overpotential between discharge and charge. This study focuses on synthesizing and characterizing ceramic iron compounds as catalysts for the cathode of Zn-O2 aqueous batteries. The findings revealed that obtained catalysts presented surface active areas beyond 220 m2/g after calcination at 800 °C, which removed organic templates. Various thermal treatments have been analysed to measure their impact on the final product. XRD, FTIR, and Raman spectroscopy confirmed sample nitridation, while SEM showed macro–meso-porosity. The electrochemical evaluation demonstrated a significant enhancement in the material's catalytic properties for ORR/OER in alkaline Zn-O2 batteries, surpassing 140 h of satable cyling with catalytic activity for ORR and OER. This improvement, coupled with optimized electrode design, resulted in a substantial increase in the batteries' operational life, achieving stable cycling for over 120 h.

Enhanced soft magnetic properties with high frequency stability of pure iron powder cores via high-pressure compaction – An environment and cost saving solution as a prospective alternative to soft magnetic composites

The paper presents the analysis of the magnetic behaviour of soft magnetic powder compacts vs. the increasing compacting pressure. An unexpectedly positive result was obtained at a pressure of 1500 MPa, as the pure iron compact without coating of powder particles and without subsequent heat treatment showed very good magnetic properties compared to the class of soft magnetic composites (SMCs). In particular, the effective relative permeability of μeff ∼120, stable up to a frequency f ∼200 kHz, the maximum total relative permeability of μtotmax ∼700, and the specific electrical resistivity of ρR ∼10−5 Ω m. This phenomenon was explained on the basis of analyses of the samples microstructure, the magnetic and electrical properties, magnetization processes, inner demagnetizing fields, Barkhausen noise and thermal diffusivity. It was found that the grain size refinement inside iron particles occurs at certain elevated compaction pressure because the deformation bands gradually rise and break up with compaction pressure, leading to a higher resistivity of the compact thus to its SMC-like behaviour, despite the counteracting effect of increasing number of iron-iron bridges among neighbouring particles. The grain size refinement causes also the refinement of magnetic domain structure, which facilitates the magnetization reversal, although, the increased internal stresses and microstructural defects affect domain wall mobility negatively. The most favourable combination of the mentioned factors influences, finally resulting in the soft magnetic properties enhancement, appeared at 1500 MPa. Due to high-pressure compaction, the high density (above ∼95 % of iron density) of a compact was achieved, ensuring sufficient mechanical properties. The presented material can serve as a potential supplanter of SMCs in many applications as it provides evident advantages, such as its easy production with minimum chemical waste (because any additional chemical processes and substances needed for particle coatings in conventional SMCs are completely omitted), as well as easy recycling process, which makes it eco-friendly and cost-effective, nevertheless, maintaining the advantages of SMCs.

Enhancement of energy storage and pyroelectric properties of (Na0.5Bi0.5)TiO3-SrTiO3-BaTiO3 ceramics by addition of (Ba0.9B0.1)TiO3 glass-phase

The present study introduces a novel analysis of the effect of the glass phase on the energy storage and the pyroelectric properties of 0.65(Bi0.5Na0.5)TiO3-0.25SrTiO3–0.1BaTiO3 (abbreviate NBT-ST-BT) lead-free ceramics. The glass phase was prepared by melt-quenching of (Ba0.9B0.1)TiO3 (BBT) calcined powder. Different content of BBT glass phase was introduced into the ceramic matrix [(1-x)(NBT-ST-BT)—x(BBT)] (x = 0.0, 2.5, 5, 7.5 and 10%) solid solution. The crystal structure shows rhombohedral and orthorhombic coexistence phases, increasing the R-phase volume fraction by increasing BBT glass content. The grain size was suppressed to a sub-micrometer by increasing the BBT glass amount, denoting the enhanced dielectric breakdown strength (BDS). The most significant recoverable energy storage density (Wrec = 2.5 J cm−3) with the highest energy storage efficiency (η ∼ 87%) has been obtained at 200 kV cm−1 of BBT 5%. The variation in Wrec of the optimum sample is less than 4% from 25 °C to 150 °C, indicating the high thermal stability of energy storage properties. The pyroelectric coefficient (PE) was estimated using an approximate numerical method of differentiating remnant polarization Pr concerning temperature. Adding the BBT glass phase enhanced the pyroelectric properties and figure of merit (FOM). The FOM increased from 7 × 10−10 to 8 × 10−10 C/cm2. °C at T = 150 °C when glass content increased from 0.0 to 0.1. These results prove that the addition of the BBT glass phase resolves the difference between high energy storage properties and lower sintering temperatures of ceramic materials, enhancing the pyroelectric properties for practical applications.

Multi-scale microstructure and its synergetic strengthening effect in stress rupture life of Inconel 718 fabricated by high-deposition-rate laser directed energy deposition

Superior elevated temperature properties are critical for the application of Inconel 718 in hot-end components. The utilization of high-deposition-rate laser directed energy deposition (HDR-LDED) increases the microstructural diversity of Inconel 718, which accordingly provides more opportunities for properties improvement. Herein, Inconel 718 alloy with a multi-scale microstructure were fabricated by HDR-LDED followed by customized heat treatment. The coarser columnar grains (width ∼300 μm) were obtained with γ" phase (diameter ∼33.74 nm and volume fraction ∼15.16 %) distributed homogeneously in the grain and the fine Laves phases (length ∼3.69 μm; width ∼1.94 μm; aspect ratio ∼1.99 and volume fraction ∼1.55 %) in the inter-dendritic region. This multi-scale microstructure possesses an excellent stress rupture life of 342.9 h with the elongation of 13 % at 650 °C, which far exceeds that of the forging (106 h, 4.2 %), It is attributed to the reduced number of transverse grain boundaries, the finer Laves phase accommodating many dislocations, and γ" phase promoting the formation of stacking faults, Lomer-Cottrell locks and nanotwins. The findings demonstrate the great potential of additively manufactured microstructure in properties enhancement, and may be enlightening for the development of novel customized high-temperature alloys.

The change in thermal-induced interchain distance boosts the gas barrier property of PEI-derived hollow fiber membranes

In order to fulfill diverse special applications (e.g. food packaging, anticorrosion coatings, flame retardant coatings, biomedical industry and lighter-than air applications), the superior gas barrier property is principal requirement. Based on previous researches, the gas barrier property of membranes could be improved to some extent by changing their component, chemical structure, physical property, fabrication parameters or incorporating impermeable fillers. The above-mentioned approaches provide the enhanced gas barrier property owing to increment in resistance for diffusion of tested gas. That implies the intrinsic factors of the membrane such as free volume fraction of membrane are determined effect on permeability to gas. Accordingly, present work investigated the impact of thermal treatment on enhancement of gas barrier property by manipulating the temperature in the range of 200 °C to 240 °C to adjust the orientation of molecular structure. Based on a series of analysis as well as pure gas measurement, the hydrogen permeability of as-treated membrane decreased by almost 2700 times than that of neat membrane, which is due to the absence of amorphousity. The exceptional gas barrier properties of resultant membrane exhibited great potential for special applications and paved the feasible way for other amorphous precursor to prepare the gas barrier membrane.

Enhancement in the Mechanical Properties of Newly Developed Ceramic Reinforced Al-Based Syntactic Foams: Analysis of Microstructure, Mechanical Response, and Energy Absorption Properties

Enhancement in the Mechanical Properties of Newly Developed Ceramic Reinforced Al-Based Syntactic Foams: Analysis of Microstructure, Mechanical Response, and Energy Absorption Properties

A Design Strategy for Highly Active Oxide Electrocatalysts by Incorporation of Oxygen-Vacancies.

Using both density functional theory (DFT+U) simulations and experiments, we show that the incorporation of an ordered array of oxygen-vacancies in a perovskite oxide can lead to enhancement of the electrocatalytic activity for the oxygen-evolution reaction (OER). As a benchmark, LaCoO3 was investigated, where the incorporation of oxygen-vacancies led to La3Co3O8 (LaCoO2.67), featuring a structural transformation. DFT+U simulations demonstrated the effect of oxygen-vacancies on lowering the potential required to achieve negative Gibbs Free Energy for all steps of the OER mechanism. This was also confirmed by experiments, where the vacancy-ordered catalyst La3Co3O8 (LaCoO2.67) showed a remarkable enhancement of electrocatalytic properties over the parent compound LaCoO3 that lacked vacancies. We also synthesized and studied an intermediate system, with a smaller degree of oxygen-vacancies, which showed intermediate electrocatalytic activity, lower than La3Co3O8 and higher than LaCoO3, confirming the expected trend and the impact of oxygen-vacancies. Furthermore, we employed additional DFT+U calculations to simulate a hypothetical material with the same formula as La3Co3O8 but without the vacancy-order. We found that the gap between centers of Co d and O p bands, which is considered an OER descriptor, would be significantly greater for a hypothetical disordered material compared to an ordered system.

Nanostructural Modification of Fe2O3 Nanoparticles: Carbon Coating for Enhanced Magnetic Behavior

In this study, the enhancement of magnetic properties in Fe2O3 nanoparticles through nanostructural modification via carbon coating is investigated. Fe2O3 and carbon‐coated Fe2O3 nanoparticles are synthesized using the solvothermal method. Structural, morphological, optical, and magnetic properties are comprehensively analyzed. The results demonstrate a significant reduction in particle size upon carbon coating, effectively mitigating agglomeration. Furthermore, carbon‐coated nanoparticles exhibit substantial enhancement in coercivity, remanence, and saturation magnetization suggesting improved magnetic behavior in comparison to their uncoated counterparts. This enhancement is attributed to the prevention of spin misalignment at the nanoparticle surface by the carbon coating, as well as the formation of distinct magnetic domains due to the reduced particle size. The observed improvements underscore the effectiveness of carbon coating in tailoring the magnetic properties of Fe2O3 nanoparticles for applications in magnetic devices and biomedical systems, such as magnetic hyperthermia and drug delivery systems, where precise control over magnetic behavior is crucial.

Enhancing Mechanical Properties of Cast Ingot Al6061 Alloy Using ECAP Process

AbstractGrain refinement and mechanical property enhancement of cast ingot aluminum 6061 alloy were achieved using equal-channel angular pressing (ECAP) at room temperature, employing route A and route R types. Analytical, finite element and experimental methods were utilized to investigate the alloy’s deformation behavior under the ECAP process. The tensile tests conducted at room temperature demonstrated a significant increase in strength with an increasing number of pressings, reaching 44.23, 53.19, and 56.7% for 1-pass, route A, and route R types 2-passes of the ECAP process, respectively. However, ductility, as indicated by elongation, gradually decreased after the first pressing. Electron backscatter diffraction was employed to reveal submicrometer grain sizes resulting from the ECAP process. The grain structure showed substantial improvement under route A and route R types at a 2-passes ECAP process. Wear tests conducted under loads of 10 and 25 N showed an increase in the coefficient of friction within the minimum wear loss intervals. Rockwell hardness also exhibited a significant increase of 119.3, 176.3, and 164.8% at 1-pass and 2-passes using routes R and A, respectively. As part of the evaluation, analytical models were computed using Python, and finite element simulations were performed using ABAQUS software. The results from analytical and finite element simulations demonstrated good agreement with the experimental data.