International Journal of Mechanical and Materials Engineering最新文献

The increasing demand for clean and affordable energy in developing countries highlights the need to utilize abundant agricultural residues through sustainable technologies. This study investigates the production, optimization, and economic feasibility of biomass briquettes developed from sorghum stalks and groundnut husks using cow dung as a natural binder. Response Surface Methodology (RSM) was applied to evaluate the effects of particle size, binder proportion, and feedstock mixing ratio on key fuel properties, including density, shatter index, and calorific value. The optimized composite briquette exhibited a calorific value of 24.36 MJ·kg⁻1, density of 1.202 g·cm⁻3, and shatter index of 96.19%, outperforming single-feedstock briquettes. Proximate analysis revealed low moisture (3.16%), low ash (3.63%), and high volatile matter (≈80%), while ultimate analysis indicated favorable elemental composition with 51.56% carbon, 6.30% hydrogen, and negligible nitrogen and sulfur, suggesting low emission potential. Economic evaluation demonstrated strong investment viability, with a positive Net Present Value (NPV), a payback period of 2.25 years, and profitable break-even capacity under typical local market conditions. Overall, the findings confirm that sorghum stalk and groundnut husk residues can be efficiently converted into high-quality briquettes with promising economic returns, offering a sustainable alternative to traditional biomass fuels and contributing to improved energy security and environmental conservation in Ethiopia.

This paper presents a comparative study of dysprosium-doped di-barium magnesium disilicate (Ba₂MgSi₂O₇: Dy³⁺) phosphors. We synthesized these materials using a combustion method, employing two distinct fuels as reducing and stabilizing agents: aloe vera (a biofuel) and urea (an organic fuel). Our investigation involved a comprehensive characterization of these phosphors. We used Powder X-ray Diffraction (PXRD) to confirm the formation of monoclinic phases in both aloe vera and urea-prepared Ba2​MgSi2​O7​: Dy³⁺ nanoparticles (NPs). Scanning Electron Microscopy (SEM) provided insights into their morphology, while Fourier Transform Infrared (FTIR) spectroscopy helped analyze their chemical bonds. Crucially, we examined their luminescence properties. The thermoluminescence (TL) and photoluminescence (PL) behavior were studied after exposure to gamma rays. Our findings indicate that aloe vera proved to be the more effective "green" fuel, yielding higher quality Ba₂MgSi₂O₇: Dy³⁺ ​ NPs. Optical absorption studies revealed that the bandgap of these Ba₂MgSi₂O₇: Dy³⁺ NPs is significantly influenced by the synthesis method and the type of fuel used. Interestingly, the highest bandgap of 4.40 eV was observed for NPs fabricated with urea, while the lowest, 4.20 eV, was found for those prepared with aloe vera. Further Photoluminescence (PL) and Electron Spin Resonance (ESR) analyses confirmed the presence of Schottky and Frenkel surface defects, along with self-trapped excitons and oxygen vacancies, within these Ba₂MgSi₂O₇: Dy³⁺ NPs. The TL glow curves of Ba₂MgSi₂O₇: Dy³⁺ phosphors (with 1–4 mol% doping) showed distinct thermally activated trap centers depending on the fuel. Urea-based phosphors exhibited a TL glow curve with two peaks at 368.29 K and 563.93 K, whereas samples prepared with aloe vera gel displayed more intense peaks at a higher temperature of 375.35 K and 572.16 K. This suggests that aloe vera-derived phosphors possess enhanced trap depths and greater TL sensitivity. Finally, the phosphors demonstrated low fading behavior, a critical characteristic that confirms their promising suitability for various dosimetric applications.

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Tin oxide (SnO₂) nanoparticles were synthesized followed by the preparation of SnO₂–graphene oxide (GO) composites in different proportion ratios by a facile two-step hydrothermal method. Obtained nanomaterials were intensively evaluated employing various analyzing techniques. X-ray diffraction (XRD) patterns confirmed the formation of SnO₂ in the tetragonal rutile phase, with decreasing crystallite size (10.35 to 2.78) observed as GO content increased in the nanocomposites. Fourier transform infrared (FTIR) spectroscopy revealed the presence of Sn–O and Sn–O–Sn bonding around 636 cm^− 1, with broadened peaks upon GO addition indicative of strong interactions between SnO₂ and GO. Field-emission scanning electron microscopy (FESEM) & Transmission electron microscopy (TEM) demonstrated the average particle size of SnO₂ is 20–60 nm and its uniform distribution with reduced aggregation when supported on GO sheets. Energy-dispersive X-ray spectroscopy (EDS) analyses confirmed the quantification of elemental composition in pure SnO₂ and (%Sn:79.36–58.46, %O:20.64–20.96, %C:7.17–20.58) composites with GO. UV-Visible spectroscopy showed a notable reduction in the bandgap from 3.80 eV to 1.98 eV for the SnO₂-GO composites than SnO₂ by enhancing visible light absorption. Photocatalytic degradation studies highlighted the superior photocatalytic efficiency (99%) of the nanocomposites, achieving highly efficient dye degradation under UV-visible light irradiation. Raman spectroscopy revealed A_1g, B_2g, and E_g vibrational modes in SnO₂, as well as S₁ and S₂ peaks associated with oxygen vacancies. In the SnO₂–GO (1:1) nanocomposite, prominent D and G bands were observed at 1347 cm^− 1 and 1615 cm^− 1, respectively, with an I_D /I_G ratio of 1.17, indicating a high level of defects. These structural defects and oxygen vacancies along with charge transfer mechanism confirmed from Photoluminescence (PL) analysis conducted on SnO₂, GO and SnO₂-GO nanocomposites play a major role in enhancing photocatalytic degradation. Electrical conductivity measurements indicated improvement (238.99 S/m for SnO₂ to 14598.32 S/m for SnO₂-GO 1:1) with addition of graphene oxide. These findings suggest that SnO₂–GO composites are promising materials for advanced functional applications and environmental remediation through photocatalytic degradation.

The purpose of this study is to report a low-cost electroless deposition (EN) process of Ni-P thin films using a wet-chemical process on flexible polyimide substrate (Kapton^® 300HN DuPont™), comprising surface functionalization with NaOH, nucleation with Sn and Pd, and acceleration with HCl. The pretreatment performed on the polyimide surface was investigated using a contact angle system and Fourier-transform infrared spectroscopy (FTIR). Structural, morphological and electrical characterization of the Ni-P film were performed by X-ray diffraction (XRD), stylus scan profiler, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and four-point probe measurements. The results showed that the pretreatment of the flexible polyimide enables a faster EN process, with lower thermal expenses, delivering a compact, spherical shaped Ni-P film -free of holes, scratches, and flaws, with particle size ranging from 380 to 780 nm.

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The improper disposal of municipal solid waste incineration fly ash (MSWI-FA) presents serious environmental and health risks due to its toxic constituents, highlighting the urgent need for sustainable treatment and reuse strategies. This study aims to evaluate the potential of non-traditional cementitious materials in the stabilization/solidification (S/S) of MSWI-FA, thereby offering a low-carbon alternative to conventional methods. The research involves a comprehensive review and analysis of the chemical and physical characteristics of MSWI-FA, with a particular focus on the leaching behavior of heavy metals and the effectiveness of various pretreatment techniques. The scope includes an in-depth investigation of magnesium-based cement, alkali-activated binders, and calcium-aluminate cement, assessing their performance in immobilizing hazardous components of MSWI-FA. Furthermore, the study examines the incorporation of treated MSWI-FA into concrete and assesses its impact on mechanical strength, durability, and microstructural properties. Results from the literature suggest that these alternative binders can effectively stabilize MSWI-FA, reduce environmental risks, while contributing to circular construction practices. The study concludes that non-traditional cementitious materials hold significant promise for integrating waste valorization into sustainable building practices. It recommends further experimental studies, long-term leaching assessments, and standardization of treatment protocols to support the safe and widespread adoption of MSWI-FA in construction materials.

The conventional flat rolling (FR) process suffers from low bonding strength and significant edge cracks when preparing Mg/Al laminates. This paper proposes a Lattice Severe Deformation Pre-Rolling (LSDPR) corrugated interface scheme and compares it with the FR process. The forming characteristics of Mg/Al laminates prepared using the LSDPR process were investigated through experimental and simulation methods. The results show that the bonding interface of Mg/Al laminates prepared by LSDPR exhibits an obvious three-dimensional network of corrugations. Compared to the FR process, the bonding area at the interface increases, and multiple cross-shear bands are formed. This accelerates the cracking of metal oxide film, the forming of the hardened layer at the interface and the diffusion of elements. Furthermore, the waveform structure provides a mechanical interlocking effect, significantly enhancing the bonding strength. The trough positions of Mg/Al laminates prepared by LSDPR exhibit the highest shear strength, with values of 58.81 MPa and 55.93 MPa along the transverse direction (TD) and rolling direction (RD), respectively. These values are 52.5% and 78.4% higher than the shear strengths of 38.56 MPa and 31.34 MPa in the FR process. Additionally, the LSDPR process helps suppress edge cracks in the magnetism alloy plate. The corrugated structure along the TD inhibits the inward propagation of edge cracks, and the structure along the RD distributes the damage, making the edge damage at the peak lower than that at the trough, which effectively prevents the initiation and expansion of edge cracks. The proposed LSDPR process provides a valuable reference for the roll forming of high-quality metal laminates.

Trimetallic copper-cobalt-iron nanoparticles supported on nitrogen-doped carbon (CuCoFe@N–C) were synthesized via the pyrolysis of Cu dopped ZIF-67/Fe₃O₄ composites, producing a magnetically recoverable catalyst with hierarchical micro and mesoporous structure. This work advances MOF-derived trimetallic catalysts by addressing key limitations of prior systems, such as poor metal dispersion and instability, through ZIF-67’s structural precision and Fe₃O₄’s dual role as a Fe precursor and magnetic support. Comprehensive characterization using FT-IR, XRD, BET, EDX, TGA, VSM, FE-SEM, TEM, ICP-OES, and XPS confirmed a robust N-doped carbon matrix with well-dispersed Cu, Co, and Fe active sites. CuCoFe@N–C exhibited exceptional catalytic performance in Ullmann C–N coupling (up to 94% yield, 110 °C, 12 h) and Biginelli multicomponent reactions (up to 95% yield, reflux, 30 min), surpassing monometallic (Cu@N–C, Co@N–C) and bimetallic analogs (CuCo@N–C, CoFe@N–C) due to synergistic metal interactions and hierarchical porosity enabling substrate accessibility. The catalyst maintained over 90% activity after five cycles with negligible metal leaching (< 0.5 ppm) as verified by ICP-OES and leaching tests, outperforming conventional trimetallic catalysts in stability and recyclability. This work highlights a straightforward and highly efficient approach to designing MOF-derived trimetallic catalysts for impactful, recyclable chemical transformations.

Friction is a critical factor in metal forming processes, influencing material flow, surface quality, tool life, and overall production efficiency. This comprehensive review explores the experimental methods employed to evaluate friction behavior in metal forming, including pin-on-disk tests, ring compression tests, stretch forming tests, and tribometers. The integration of advanced measurement technologies such as infrared thermography, digital image correlation, and high-speed imaging has significantly improved the accuracy of friction assessments. Furthermore, the review highlights the key parameters affecting friction, including lubrication conditions, material pairings, surface roughness, and process temperature. Surface engineering strategies, such as coatings and texturing, are also discussed as effective approaches to control friction. The insights provided aim to support researchers and practitioners in selecting suitable evaluation techniques and in developing optimized surface treatments for enhanced metal forming performance.

The polyacrylonitrile (PAN)/ TiO₂ nanofiber and PAN/TiO₂/curcumin nanofiber mat containing various concentrations of TiO₂ and curcumin was fabricated using the electrospinning method and tested for its antibacterial performance. The PAN/TiO₂ and PAN/TiO₂/curcumin samples were characterized for structural and morphological analysis. The FT-IR analysis showed the presence of TiO₂ nanoparticles incorporated into PAN nanofibers. The maximum antimicrobial inhibition zone against E. coli are 17 mm and 27 mm for optimized concentrations of PAN/TiO₂ and PAN/TiO₂/curcumin samples. This investigation revealed that adding curcumin and TiO₂ NPs in the PAN nanofibers significantly enhances the antibacterial performance. The synergistic effect between curcumin and TiO₂ NPs contributes to this enhanced antibacterial performance, making the nanofibers potential candidates. Hence, our study indicates that low-cost nanofiber-based materials would be excellent modifications real-life antibacterial applications.

This dip coating research investigates the hydrophobic properties of aluminium oxide coatings on carbon fiber sheets using ethanol, polyvinyl alcohol (PVA), and acetone at varying ratios. The dip coating technique applies Al₂O₃ coatings to carbon fiber sheets. At 5%, 10%, and 15%, ethanol is combined with Al₂O₃. These amounts of PVA and acetone are also produced by combining Al₂O₃ with PVA and ethanol. Samples are heat-treated in a hot air oven at 250℃ to 350℃ after 48 h of drying. The contact angle measurements reveal that increasing Al₂O₃ concentrations enhances hydrophobicity. The coatings lack diffraction peaks, indicating that they are amorphous. No Al₂O₃ diffraction peaks in epoxy–Al₂O₃ coatings suggest a homogeneous dispersion of alumina nanoparticles in the epoxy matrix. XRD (X-ray diffraction) analysis of the 5 wt% Al₂O₃ coating shows uniformity, no particle agglomeration, and an amorphous nature. There is a single peak at ~ 20°, corresponding to the (002) crystallographic plane of the carbon substrate. No distinguishable Al₂O₃ peaks are found, indicating homogeneous dispersion. The untreated carbon fiber sheet has a contact angle of 37°, whereas the coated sample has contact angles of 98.80°, 102.80°, and 103.80° for Al₂O₃ + Ethanol, PVA, and Acetone, respectively. Each sample’s coating was 10 mm x 50 mm, and the solution volume was constant, but the weight % of aluminium oxide fluctuated.