| 1. |
- Abutalib, M. M., et al.
(författare)
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Fe3O4/Co3O4-TiO2 S-scheme photocatalyst for degradation of organic pollutants and H-2 production under natural sunlight
- 2022
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Ingår i: Journal of Materials Research and Technology. - : Elsevier Editora Ltda. - 2238-7854 .- 2214-0697. ; 20, s. 1043-1056
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Tidskriftsartikel (refereegranskat)abstract
- Sunlight responsible mono-and co-doped TiO2 nanoparticles (Con+ and Fen+) were prepared via sol-gel technique. The X-ray diffraction (XRD) results showed no phase change of TiO2 was observed after the addition of Con+ and Fen+ ions. Diffuse reflectance spectra (DRS) results showed a significant red-shift of the absorption edge after doping TiO2 by Co(n )and Fen+ and the band gap energy reduced sharply from 3.10 to 1.72 eV. X-ray photoelectron spectroscopy (XPS) results emphasized the existence of multivalent states of Co2+, Co3+, Fe2+ and Fe3+. The results of ultraviolet photoelectron spectroscopy (UPS), work function, electron spin resonance (ESR) illustrated the Fe3O4/Co3O4-TiO2 formed of ternary hetero-junctions. The photocatalytic performance of the prepared photocatalysts was determined for photodegradation of tetracycline (TC) and phenol (Pl) and production of hydrogen. The results illustrated the existence of multivalent states of Fe and Co ions (Co2+, Co3+, Fe2+ and Fe3+) together improved the solar light absorption, inhibited the recombination of photo -generated charges and consequently enhanced the photocatalytic efficiency of TiO2 compared with mono-doped TiO2 (Co3O4/TiO2 and Fe3O4/TiO2). The sample with 5%Fe3O4/ Co(3)O(4)4-TiO2 showed the highest photoactivity. The mineralization (TOC), photodegradation mechanism and reusability of prepared photocatalysts were also studied. The Fe3O4/Co3O4-TiO2 nanoparticles showed high photoactivity and stability and can be adopted as a promising materials for different environmental and H-2 production applications. (C) 2022 The Author(s). Published by Elsevier B.V.
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| 2. |
- Ahmed, Hesham, et al.
(författare)
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Effect of carbon concentration and carbon bonding type on the melting characteristics of hydrogen- reduced iron ore pellets
- 2022
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Ingår i: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854 .- 2214-0697. ; 21, s. 1760-1769
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Tidskriftsartikel (refereegranskat)abstract
- Decarbonization of the steel industry is one of the pathways towards a fossil-fuel-free environment. The steel industry is one of the top contributors to greenhouse gas emissions. Most of these emissions are directly linked to the use of a fossil-fuel-based reductant. Replacing the fossil-based reductant with green H2 enables the transition towards a fossil-free steel industry. The carbon-free iron produced will cause the refining and steelmaking operations to have a starting point far from today's operations. In addition to carbon being an alloying element in steel production, carbon addition controls the melting characteristics of the reduced iron. In the present study, the effect of carbon content and form (cementite/graphite) in hydrogen-reduced iron ore pellets on their melting characteristics was examined by means of a differential thermal analyser and optical dilatometer. Carburized samples with a carbon content 2 wt%, the molten fraction is higher in the case of carburized samples, which is indicated by the amount of absorbed melting heat.
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| 3. |
- Ahmed, Hesham, et al.
(författare)
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Injection of H2-rich carbonaceous materials into the blast furnace : devolatilization, gasification and combustion characteristics and effect of increased H2–H2O on iron ore pellets reducibility
- 2020
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Ingår i: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854 .- 2214-0697. ; 9:6, s. 16029-16037
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Tidskriftsartikel (refereegranskat)abstract
- Increasing the share of hydrogen in reduction of iron oxide in the blast furnace iron making will directly reduce the share of blast furnace greenhouse gas emissions. In the present study, injection of H2-rich biomass and plastic materials was studied in terms of its devolatilization, gasification and combustion characteristics. The released gases were identified using mass spectroscopy attached to a thermogravimetric analyzer and the corresponding kinetics parameters were estimated.The devolatilization was found to occur through two or more steps. The first step is always associated with the release of CO2, CO, H2, H2O and hydrocarbons while only CO and H2 were detected during the later steps. Combustion and gasification starting temperatures of char of H2-rich carbonaceous materials were lower than that of pulverized coal char by ≥ 100 °C. The estimated activation energies suggested that, under the present conditions, devolatilization, gasification and combustion were chemically controlled. Carbon reactivity of the char of the studied H2-rich carbonaceous materials were higher than that of pulverized coal. Moreover, increased H2–H2O content in the blast furnace gas, due to injected H2-rich carbonaceous materials, was found to improve the iron ore pellets reduction kinetics.
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| 4. |
- Alghamdi, Haifa Mohammed, et al.
(författare)
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Modification and development of high bioactivities and environmentally safe polymer nanocomposites doped by Ni/ZnO nanohybrid for food packaging applications
- 2022
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Ingår i: Journal of Materials Research and Technology. - : ELSEVIER. - 2238-7854 .- 2214-0697. ; 19, s. 3421-3432
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to develop a sodium alginate (50%NaAlg)/polyethylene oxide (50%PEO) blend-based film loaded with nickel and zinc oxide nanoparticles (Ni/ZnO NPs) as a rein-forcing and antibacterial agent. The Ni/ZnO NPs as nanohybrid were synthesized via the sol-gel method at different concentrations (0.0, 5.0, 10.0, 15.0, 20.0 wt.%). The solution cast approach was utilized to create polymer nanocomposites samples from NaAlg/PEO/Ni/ZnO NPs for application in bioactive food packaging. The films were characterized using various procedures in detail. With the addition of Ni/ZnO, the XRD confirms the expansion of amorphous nature within NaAlg/PEO. The crystallinity degree of NaAlg/PEO-Ni/ZnO nanocomposite were decreased from 47 to 25%. The interactions between the compo-nents of NaAlg/PEO and Ni/ZnO NPs are revealed by FTIR findings. The bio-degradable nanocomposites dielectric behavior, electrical conductivity as well as mechanical prop-erties, were investigated. With the addition of Ni/ZnO NPs, the dielectric and AC conduc-tivity properties of the nanocomposites improved with the increase in the concentrations of Ni/ZnO NPs. The loading of Ni/ZnO nanoparticles increased the mechanical character-istics of the nanocomposite, such as tensile strength increased from 30.18 to 72.34, stiff-ness increased from 18.78 to 38.42, and Youngs Modulus increased from 8.24 to 29.76. The antibacterial activity of nanocomposites films was examined against Gram-negative (Escherichia coli), Gram-positive (Staphylococcus aureus), Aspergillus niger (fungus) and Candida albicans (yeast). Though the tested NaAlg/PEO blend did not indicate any activity against the microbial strains, when Ni/ZnO NPs were added, activity against E. coli, S. aureus, fungus and yeast was enhanced. The water solubility of nanocomposites films reduced from 65.5% to 9.81% with increasing of Ni/ZnO NPs content. The present study shown that NaAlg/PEO-Ni/ZnO films were more effective in inhibiting bacteria growth than pure NaAlg/PEO film, confirming the nanocomposites films potential application as anti-microbial food packaging.(c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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| 5. |
- Alhourani, A., et al.
(författare)
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Thermal modeling of friction stir welding of thick high-density polyethylene plates
- 2024
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Ingår i: Journal of Materials Research and Technology. - : Elsevier BV. - 2238-7854 .- 2214-0697. ; 28, s. 4186-4198
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Tidskriftsartikel (refereegranskat)abstract
- The process temperatures in the friction stir welding of thick polymer plates play a significant role in the joint's quality since the process is characterized by mixed solid and viscous flow states. The heat generation mechanism in each state is fundamentally different, with heat being generated by friction in the solid-state and by viscous shear flow in the viscous state. In this study, the heat generation and dissipation in the friction stir welding of 14 mm thick high-density polyethylene plates were studied numerically through solving the direct heat conduction problem. Two models of heat generation were used in the numerical solution and the effect of the pin rotational speed on the process temperatures was investigated. It was shown that the utilization of a mixed heat generation model consisting of both the solid state and the viscous shear flow considerably improves the numerical model predictions. The temperature predictions were validated through welding experiments and showed a temperature difference of 3 %. Furthermore, it was found that the welding process stabilizes at rotational speeds higher than 800 rpm, where no considerable change occurs in the volume of the viscous flow region and the welding power requirement. The numerical results based on the combined solid-viscous heat model were in good agreement with the experimental thermal histories.
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| 6. |
- Almessiere, M. A., et al.
(författare)
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Effects of Ce-Dy rare earths co-doping on various features of Ni-Co spinel ferrite microspheres prepared via hydrothermal approach
- 2021
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Ingår i: Journal of Materials Research and Technology. - : Elsevier BV. - 2238-7854 .- 2214-0697. ; 14, s. 2534-2553
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Tidskriftsartikel (refereegranskat)abstract
- The effects of Ce-Dy co-doping on the crystal structure, optical, dielectric, magnetic properties, and hyperfine interactions of Ni-Co spinel ferrite microspheres synthesized hydrothermally have been studied. A series of ferrites with the general formula Ni0.5-Co0.5CexDyxFe2-2xO4 were synthesized with x values ranging from 0.00 to 0.10. The phase, crystallinity, and morphology of ferrite microspheres were analyzed by X-ray powder diffractometry (XRD), scanning and transmission electron microscopes (SEM and TEM), respectively. The structural analyses of the synthesized ferrite microspheres confirmed their high purity and cubic crystalline phase. The Diffuse reflectance spectroscopic (DRS) measurements were presented to calculate direct optical energy band gaps (E-g) and is found in the range 1.63 eV - 1.84 eV. Fe-57 Mossbauer spectroscopy showed that the hyperfine magnetic field of tetrahedral (A) and octahedral (B) sites decreased with the substitution of Dy3+-Ce3+ ions that preferrentially occupy the B site. The impact of the rare-earth content (x) on the magnetic features of the prepared NiCo ferrite microspheres was investigated by analyzing M-H loops, which showed soft ferrimagnetism. The magnetic features illustrate a great impact of the incorporation of Ce3+-Dy3+ ions within the NiCo ferrite structure. The saturation magnetization (M-s), remanence (M-r), and coercivity (H-c) increased gradually with increasing Ce-Dy content. At x = 0.04, M-s, M-r, and H-c attain maximum values of about 31.2 emu/g, 11.5 emu/g, and 512.4 Oe, respectively. The Bohr magneton (n(B)) and magneto-crystalline anisotropy constant (K-eff) were also determined and evaluated with correlation to other magnetic parameters. Further increase in Ce3+-Dy3+ content (i.e., x >= 0.06) was found to decrease M-s, M-r, and H-c values. The variations in magnetic parameters (M-s, M-r, and H-c) were largely caused by the surface spins effect, the variations in crystallite/particle size, the distribution of magnetic ions into the different sublattices, the evolutions of magneto-crystalline anisotropy, and the variations in the magnetic moment (n(B)). The squareness ratios were found to be lower than the predicted theoretical value of 0.5 for various samples, indicating that the prepared Ce-Dy substituted NiCo ferrite microspheres are composed of NPs with single-magnetic domain (SMD). Temperature and frequency-dependent electrical and dielectric measurements have been done to estimate the ac/dc conductivity, dielectric constant, and tangent loss values for all the samples. The ac conductivity measurements confirmed the power-law rules, largely dependent on Ce-Dy content. Impedance analysis stated that the conduction mechanisms in all samples are mainly due to the grains-grain boundaries. The dielectric constant of NiCo ferrite microspheres give rise to normal dielectric distribution, with the frequency depending strongly on the Ce-Dy content. The observed variation in tangential loss with frequency can be attributed to the conduction mechanism in ferrites, like Koop's phenomenological model.
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| 7. |
- Arafa, Salaheddin, et al.
(författare)
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Investigation into the permeability and strength of pervious geopolymer concrete containing coated biomass aggregate material
- 2021
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Ingår i: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854 .- 2214-0697. ; 15, s. 2075-2087
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Tidskriftsartikel (refereegranskat)abstract
- Waste palm oil products can be recycled in the production of pervious geopolymer concrete (PGC) for long-term sustainable development. PGC is a non-slip porous pavement concrete that allows water to pass through. Biomass aggregate (BA) is produced by burning palm oil biomass and is introduced as a replacement for natural aggregate (NA). BA is mixed with fly ash (FA) and alkaline liquid (AL) and heated in an oven at 80 °C for 24 h to produce coated biomass aggregate (CBA). PGC containing CBA is commonly used as a cement substitute in concrete. This study aims to develop and evaluate the effect of rainfall intensity on the ability of PGC to reduce stormwater runoff. Coating BA with geopolymer paste resulted in improved properties, better Aggregate crushing value (ACV), Aggregate impact value (AIV), water absorption and higher compressive strength compared with BA. Results indicated, a PGC with a FA/CBA ratio of 1:7, CBA of 5–10 mm, NaOH molarity of 10 M, Na2SiO3/NaOH ratio of 2.5, and AL/FA ratio of 0.5 when cured in an oven for 24 h at 80 °C, gave the optimum ratio for compressive strength of 13.7 MPa and water permeability of 2.1 cm/s. Both BA and CBA revealed a viable alternative aggregates for producing PGC and that the compressive strength of PGC made with CBA was 51% greater than cement pervious concrete containing NA. The results also showed that the reduction in runoff was due to the permeable concrete and decreased runoff with the increased rainfall intensity.
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| 8. |
- Arya, Pradyumn Kumar, et al.
(författare)
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Development of high strength and lightweight Ti6Al4V5Cr alloy : Microstructure and mechanical characteristics
- 2024
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Ingår i: Journal of Materials Research and Technology. - : Elsevier Editora Ltda. - 2238-7854 .- 2214-0697. ; 28, s. 3526-3540
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Tidskriftsartikel (refereegranskat)abstract
- This article explains development of high strength and lightweight Ti6Al4V5Cr alloy by μ-plasma powder additive manufacturing (μ-PPAM) process for automotive, aerospace, military, dies and moulds, and other similar applications. Microstructure, formation of phases, porosity, microhardness, tensile properties, abrasion resistance, and fracture toughness of multi-layer deposition of Ti6Al4V5Cr alloy are studied and compared with Ti6Al4V alloy. Results reveal that the presence of chromium in Ti6Al4V5Cr alloy refined the grains of its β-Ti and α-Ti phases, increased volume % of β-Ti phase, and promoted formation of its equiaxed grains. It also increased tensile strength, microhardness, abrasion resistance, and fracture toughness of Ti6Al4V5Cr alloy. It enhanced solid solution strengthening and formed higher hardness imparting intermetallic Cr2Ti phase and changed fracture mode to mixed ductile and brittle mode with larger size dimples, cleavage facets, and micropores. But it decreased formation temperature of β-Ti phase and % elongation as compared to Ti6Al4V alloy. Chromium and vanadium content in β-Ti phase of Ti6Al4V5Cr alloy is 7 % and 2.1 % more than its α-Ti phase. This study demonstrates that inclusion of limited amount of chromium content to Ti6Al4V5Cr alloy by μ-PPAM process is very beneficial to enhance microstructure, mechanical properties, crack propagation resistance, and abrasive wear resistance of the Ti6Al4V5Cr alloy. It makes Ti6Al4V5Cr alloy very useful in many commercial applications that require higher strength than Ti6Al4V alloy along with lightweight requirement.
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| 9. |
- Aslam, Marryam, et al.
(författare)
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Physical characteristics of CdZrO3 perovskite at different pressure for optoelectronic application
- 2020
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Ingår i: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854 .- 2214-0697. ; 9:5, s. 9965-9971
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Tidskriftsartikel (refereegranskat)abstract
- A comprehensive investigation of the physical characteristics of any material provides beneficial information regarding its application viewpoint in different industries. Herein, we report the tunable mechanical and optoelectronic properties of cubic CdZrO3 under variable pressure up to 80 GPa using density functional theory (DFT). The pressure-induced band gap engineering reveals a fantastic fact of transformation of the indirect to direct band gap with increasing pressure. The dielectric response disclosed that optical parameters dragged towards higher energy with an increase of pressure, which unveiled the potential of CdZrO3 for optoelectronic applications. Effective change in optoelectronic is attributed to indirect to direct band gap transition. This study provides a gateway to how the optoelectronic properties of cubic CdZrO3 could be tuned by employing external pressure.
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| 10. |
- Atefi, S., et al.
(författare)
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A study on microstructure development and mechanical properties of pure copper subjected to severe plastic deformation by the ECAP-Conform process
- 2022
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Ingår i: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854 .- 2214-0697. ; 21, s. 1614-1629
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Tidskriftsartikel (refereegranskat)abstract
- Commercially pure copper rod was successfully subjected to severe plastic deformation by applying the continuous equal channel angular pressing (ECAP-Conform) method at room temperature. Microstructural characterizations of copper rod samples at various stages of plastic deformation were carried out by optical microscopy and electron backscatter diffraction methods. X-ray diffractometry and Kernal average misorientation were used for dislocation density estimations. Microstructural evaluations revealed grain size change of 30 mm for the initial annealed copper rod to less than 5 mm and even 100 nm for severely deformed samples. Mechanical behaviors of samples after different deformation stages were characterized using tensile and hardness tests. The ultimate tensile strength of the severely deformed copper rod was increased threefold by ECAP-Conform while elongation halved in comparison to the initial annealed copper. Low-temperature annealing of severely plastic deformed samples led to bi-modal grain size distribution and lowering of strength accompanied by the increase of elongation. Tensile properties of severely deformed and then annealed copper samples showed around a 40% increase in both ultimate tensile strength and elongation in comparison to the initial annealed copper rod.
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