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12 pages, 1309 KiB

Open AccessEditor’s ChoiceArticle

CO₂ and CH₂ Adsorption on Copper-Decorated Graphene: Predictions from First Principle Calculations

by Oleg Lisovski, Sergei Piskunov, Dmitry Bocharov, Yuri F. Zhukovskii, Janis Kleperis, Ainars Knoks and Peteris Lesnicenoks

Crystals 2022, 12(2), 194; https://doi.org/10.3390/cryst12020194 - 28 Jan 2022

Cited by 9 | Viewed by 3440

Abstract

Single-layer graphene decorated with monodisperse copper nanoparticles can support the size and mass-dependent catalysis of the selective electrochemical reduction of CO

_{2}

to ethylene (C

_{2}

H

_{4}

). In this study, various active adsorption sites of nanostructured Cu-decorated graphene have been calculated [...] Read more.

Single-layer graphene decorated with monodisperse copper nanoparticles can support the size and mass-dependent catalysis of the selective electrochemical reduction of CO

_{2}

to ethylene (C

_{2}

H

_{4}

). In this study, various active adsorption sites of nanostructured Cu-decorated graphene have been calculated by using density functional theory to provide insight into its catalytic activity toward carbon dioxide electroreduction. Based on the results of our calculations, an enhanced adsorption of the CO

_{2}

molecule and CH

_{2}

counterpart placed atop of Cu-decorated graphene compared to adsorption at pristine Cu metal surfaces was predicted. This approach explains experimental observations for carbon-based catalysts that were found to be promising for the two-electron reduction reaction of CO

_{2}

to CO and, further, to ethylene. Active adsorption sites that lead to a better catalytic activity of Cu-decorated graphene, with respect to general copper catalysts, were identified. The atomic configuration of the most selective CO

_{2}

toward the reduction reaction nanostructured catalyst is suggested. Full article

(This article belongs to the Special Issue Fabrication of Carbon and Related Materials/Metal Hybrids and Composites)

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14 pages, 7798 KiB

Open AccessArticle

A Theoretical Modeling of Adaptive Mixed CNT Bundles for High-Speed VLSI Interconnect Design

by Abu Bony Amin, Syed Muhammad Shakil and Muhammad Sana Ullah

Crystals 2022, 12(2), 186; https://doi.org/10.3390/cryst12020186 - 27 Jan 2022

Cited by 6 | Viewed by 2791

Abstract

The aroused quest to reduce the delay at the interconnect level is the main urge of this paper, so as to come across a configuration of carbon nanotube (CNT) bundles, namely, squarely packed bundles of mixed CNTs. The demonstrated approach in this paper [...] Read more.

The aroused quest to reduce the delay at the interconnect level is the main urge of this paper, so as to come across a configuration of carbon nanotube (CNT) bundles, namely, squarely packed bundles of mixed CNTs. The demonstrated approach in this paper makes the mixed CNT bundle adaptable to adopt for high-speed very-large-scale integration (VLSI) interconnects with technology shrinkage. To reduce the delay of the proposed configuration of the mixed CNT bundle, the behavioral change of resistance (R), inductance (L), and capacitance (C) has been observed with respect to both the width of the bundle and the diameter of the CNTs in the bundle. Consequently, the performance of the modified bundle configuration is compared with a previously developed configuration, namely, squarely packed bundles of dimorphic MWCNTs in terms of propagation delay and crosstalk delay at local-, semiglobal-, and global-level interconnects. The proposed bundle configuration is, ultimately, enacted as the better one for 32-nm and 16-nm technology nodes, and is suitable for 7-nm nodes as well. Full article

(This article belongs to the Special Issue Fabrication of Carbon and Related Materials/Metal Hybrids and Composites)

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13 pages, 4316 KiB

Open AccessArticle

Extrusion Dwell Time and Its Effect on the Mechanical and Thermal Properties of Pitch/LLDPE Blend Fibres

by Salem Mohammed Aldosari and Sameer Rahatekar

Crystals 2021, 11(12), 1520; https://doi.org/10.3390/cryst11121520 - 05 Dec 2021

Cited by 2 | Viewed by 2808

Abstract

Mesophase pitch-based carbon fibres have excellent resistance to plastic deformation (up to 840 GPa); however, they have very low strain to failure (0.3) and are considered brittle. Hence, the development of pitch fibre precursors able to be plastically deformed without fracture is important. [...] Read more.

Mesophase pitch-based carbon fibres have excellent resistance to plastic deformation (up to 840 GPa); however, they have very low strain to failure (0.3) and are considered brittle. Hence, the development of pitch fibre precursors able to be plastically deformed without fracture is important. We have previously, successfully developed pitch-based precursor fibres with high ductility (low brittleness) by blending pitch and linear low-density polyethylene. Here, we extend our research to study how the extrusion dwell time (0, 6, 8, and 10 min) affects the physical properties (microstructure) of blend fibres. Scanning electron microscopy of the microstructure showed that by increasing the extrusion dwell from 0 to 10 min the pitch and polyethylene components were more uniformly dispersed. The tensile strength, modulus of elasticity, and strain at failure for the extruded fibres for different dwell times were measured. Increased dwell time resulted in an increase in strain to failure but reduced the ultimate tensile strength. Thermogravimetric analysis was used to investigate if increased dwell time improved the thermal stability of the samples. This study presents a useful guide to help with the selection of mixes of linear low-density polyethylene/pitch blend, with an appropriate extrusion dwell time to help develop a new generation of potential precursors for pitch-based carbon fibres. Full article

(This article belongs to the Special Issue Fabrication of Carbon and Related Materials/Metal Hybrids and Composites)

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14 pages, 6671 KiB

Open AccessArticle

Preparation and Evaluation of Cu-Zn-GNSs Nanocomposite Manufactured by Powder Metallurgy

by A. T. Hamed, E. S. Mosa, Amir Mahdy, Ismail G. El-Batanony and Omayma A. Elkady

Crystals 2021, 11(12), 1449; https://doi.org/10.3390/cryst11121449 - 24 Nov 2021

Cited by 2 | Viewed by 1889

Abstract

Room-temperature ball milling technique has been successfully employed to fabricate copper-zinc graphene nanocomposite by high-energy ball milling of elemental Cu, Zn, and graphene. Copper powder reinforced with 1-wt.% nanographene sheets were mechanically milled with 5, 10, 15, and 20 wt.% Zn powder. The [...] Read more.

Room-temperature ball milling technique has been successfully employed to fabricate copper-zinc graphene nanocomposite by high-energy ball milling of elemental Cu, Zn, and graphene. Copper powder reinforced with 1-wt.% nanographene sheets were mechanically milled with 5, 10, 15, and 20 wt.% Zn powder. The ball-to-powder weight ratio was selected to be 10:1 with a 400-rpm milling speed. Hexane and methanol were used as a process control agent (PCA) during composite fabrication. The effect of PCA on the composite microstructure was studied. The obtained composites were compacted by a uniaxial press under 700 MPa. The compacted samples were sintered under a controlled atmosphere at 1023 K for 90 min. The microstructure, mechanical, and tribological properties of the prepared Cu-Zn GrNSs nanocomposites were studied. All results indicated that composites using hexane as PCA had a uniform microstructure with higher densities. The densities of sintered samples were decreased gradually by increasing the Zn percent. The obtained composite contained 10 wt.% Zn had a more homogeneous microstructure, low porosity, higher Vickers hardness, and compression strength, while the composite contained 15 wt.% Zn recorded the lowest wear rate. Both the electrical and thermal conductivities were decreased gradually by increasing the Zn content. Full article

(This article belongs to the Special Issue Fabrication of Carbon and Related Materials/Metal Hybrids and Composites)

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8 pages, 2048 KiB

Open AccessArticle

Silica Microspheres for Economical Advanced Solar Applications

by Maha M. Khayyat

Crystals 2021, 11(11), 1409; https://doi.org/10.3390/cryst11111409 - 18 Nov 2021

Viewed by 1187

Abstract

Solar cells made of silicon nanowires (Si-NWs) have several potential benefits over conventional bulk Si ones or thin-film devices related primarily to light absorption and cost reduction. Controlling the position of Si-NWs without lithography using silica microspheres is indeed an economical approach. Moreover, [...] Read more.

Solar cells made of silicon nanowires (Si-NWs) have several potential benefits over conventional bulk Si ones or thin-film devices related primarily to light absorption and cost reduction. Controlling the position of Si-NWs without lithography using silica microspheres is indeed an economical approach. Moreover, replacing the glass sheets with polycarbonates is an added advantage. This study employed the Nanoscale Chemical Templating (NCT) technique in growing Si-NWs seeded with Al. The growth was undertaken at the Chemical Vapor Deposition (CVD) reactor via the original growth process of vapor–liquid–solid (VLS). The bottom-up grown nanowires were doped with aluminum (Al) throughout the growth process, and then the p–n junctions were formed with descent efficiency. Further work is required to optimize the growth of Si-NWs between the spun microspheres based on the growth parameters including etching time, which should lead to more efficient PV cells. Full article

(This article belongs to the Special Issue Fabrication of Carbon and Related Materials/Metal Hybrids and Composites)

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20 pages, 4667 KiB

Open AccessArticle

Direct Observation of Induced Graphene and SiC Strengthening in Al–Ni Alloy via the Hot Pressing Technique

by Omayma A. Elkady, Hossam M. Yehia, Aya A. Ibrahim, Abdelhalim M. Elhabak, Elsayed. M. Elsayed and Amir A. Mahdy

Crystals 2021, 11(9), 1142; https://doi.org/10.3390/cryst11091142 - 18 Sep 2021

Cited by 12 | Viewed by 2652

Abstract

In this study, Al/5 Ni/0.2 GNPs/x SiC (x = 5, 10, 15, and 20 wt%) nanocomposites were constituted using the powder metallurgy–hot pressing technique. The SiC particles and GNPs were coated with 3 wt% Ag using the electroless deposition technique then mixed with [...] Read more.

In this study, Al/5 Ni/0.2 GNPs/x SiC (x = 5, 10, 15, and 20 wt%) nanocomposites were constituted using the powder metallurgy–hot pressing technique. The SiC particles and GNPs were coated with 3 wt% Ag using the electroless deposition technique then mixed with an Al matrix and 5% Ni using ball milling. The investigated powders were hot-pressed at 550 °C and 600 °C and 800 Mpa. The produced samples were evaluated by studying their densification, microstructure, phase, chemical composition, hardness, compressive strength, wear resistance, and thermal expansion. A new intermetallic compound formed between Al and Ni, which is aluminum nickel (Al₃Ni). Graphene reacted with the Ni and formed the nickel carbide Ni₃C. Additionally, it reacted with the SiC and formed the nickel–silicon composite Ni31Si12 at different percentages. A proper distribution for Ni, GNs, and SiC particles and excellent adhesion were observed. No grain boundaries between the Al matrix particles were discovered. Slight increases in the density values and quite high convergence were revealed. The addition of 0.2 wt% GNs to Al-5Ni increased the hardness value by 47.38% and, by adding SiC-Ag to the Al-5Ni-0.2GNs, the hardness increased gradually. The 20 wt% sample recorded 121.6 HV with a 56.29% increment. The 15 wt% SiC sample recorded the highest compressive strength, and the 20 wt% SiC sample recorded the lowest thermal expansion at the different temperatures. The five Al-Ni-Gr-SiC samples were tested as an electrode for electro-analysis processes. A zinc oxide thin film was successfully prepared by electrodeposition onto samples using a zinc nitrate aqueous solution at 25 °C. The electrodeposition was performed using the linear sweep voltammetric and potentiostatic technique. The effect of the substrate type on the deposition current was fully studied. Additionally, the ohmic resistance polarization values were recorded for the tested samples in a zinc nitrate medium. The results show that the sample containing the Al-5 Ni-0.2 GNs-10% SiC composite is the most acceptable sample for these purposes. Full article

(This article belongs to the Special Issue Fabrication of Carbon and Related Materials/Metal Hybrids and Composites)

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17 pages, 7171 KiB

Open AccessArticle

Influence of High-Concentration LLDPE on the Manufacturing Process and Morphology of Pitch/LLDPE Fibres

by Salem Mohammed Aldosari, Muhammad A. Khan and Sameer Rahatekar

Crystals 2021, 11(9), 1099; https://doi.org/10.3390/cryst11091099 - 09 Sep 2021

Cited by 5 | Viewed by 2436

Abstract

A high modulus of elasticity is a distinctive feature of carbon fibres produced from mesophase pitch. In this work, we expand our previous study of pitch/linear low-density polyethylene blend fibres, increasing the concentration of the linear low-density polyethylene in the blend into the [...] Read more.

A high modulus of elasticity is a distinctive feature of carbon fibres produced from mesophase pitch. In this work, we expand our previous study of pitch/linear low-density polyethylene blend fibres, increasing the concentration of the linear low-density polyethylene in the blend into the range of from 30 to 90 wt%. A scanning electron microscope study showed two distinct phases in the fibres: one linear low-density polyethylene, and the other pitch fibre. Unique morphologies of the blend were observed. They ranged from continuous microfibres of pitch embedded in linear low-density polyethylene (occurring at high concentrations of pitch) to a discontinuous region showing the presence of spherical pitch nodules (at high concentrations of linear low-density polyethylene). The corresponding mechanical properties—such as tensile strength, tensile modulus, and strain at failure—of different concentrations of linear low-density polyethylene in the pitch fibre were measured and are reported here. Thermogravimetric analysis was used to investigate how the increased linear low-density polyethylene content affected the thermal stability of linear low-density polyethylene/pitch fibres. It is shown that selecting appropriate linear low-density polyethylene concentrations is required, depending on the requirement of thermal stability and mechanical properties of the fibres. Our study offers new and useful guidance to the scientific community to help select the appropriate combinations of linear low-density polyethylene/pitch blend concentrations based on the required mechanical property and thermal stability of the fibres. Full article

(This article belongs to the Special Issue Fabrication of Carbon and Related Materials/Metal Hybrids and Composites)

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23 pages, 7997 KiB

Open AccessArticle

Synthesis and Characterization of Antibacterial Carbopol/ZnO Hybrid Nanoparticles Gel

by Sameh H. Ismail, Ahmed Hamdy, Tamer Ahmed Ismail, Heba H. Mahboub, Walaa H. Mahmoud and Walid M. Daoush

Crystals 2021, 11(9), 1092; https://doi.org/10.3390/cryst11091092 - 07 Sep 2021

Cited by 29 | Viewed by 5396

Abstract

This study recommends Carbopol/zinc oxide (ZnO) hybrid nanoparticles gel as an efficient antibacterial agent against different bacterial species. To this end, ZnO nanoparticles were synthesized using chemical precipitation derived from a zinc acetate solution with ammonium hydroxide as its precipitating agent under the [...] Read more.

This study recommends Carbopol/zinc oxide (ZnO) hybrid nanoparticles gel as an efficient antibacterial agent against different bacterial species. To this end, ZnO nanoparticles were synthesized using chemical precipitation derived from a zinc acetate solution with ammonium hydroxide as its precipitating agent under the effect of ultrasonic radiation. The synthesized ZnO nanoparticles were stabilized simultaneously in a freshly prepared Carbopol gel at a pH of 7. The chemical composition, phase identification, particle size and shape, surface charge, pore size distribution, and the BET surface area of the ZnO nanoparticles, as well as the Carbopol/ZnO hybrid Nanoparticles gel, were by XRD, SEM, TEM, AFM, DLS, Zeta potential and BET instruments. The results revealed that the synthesized ZnO nanoparticles were well-dispersed in the Carbopol gel network, and have a wurtzite-crystalline phase of spherical shape. Moreover, the Carbopol/ZnO hybrid nanoparticles gel exhibited a particle size distribution between ~9 and ~93 nm, and a surface area of 54.26 m²/g. The synthesized Carbopol/ZnO hybrid nanoparticles gel underwent an antibacterial sensitivity test against gram-negative K. pneumonia (ATCC 13883), Bacillus subtilis (ATCC 6633), and gram-positive Staphylococcus aureus (ATCC 6538) bacterial strains, and were compared with ampicillin as a reference antibiotic agent. The obtained results demonstrated that the synthesized Carbopol/ZnO hybrid nanoparticles gel exhibited a compatible bioactivity against the different strains of bacteria. Full article

(This article belongs to the Special Issue Fabrication of Carbon and Related Materials/Metal Hybrids and Composites)

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15 pages, 4824 KiB

Open AccessArticle

Analysis of Microstructure and Mechanical Properties of Bi-Modal Nanoparticle-Reinforced Cu-Matrix

by Fadel S. Hamid, Omayma A. Elkady, A. R. S. Essa, A. El-Nikhaily, Ayman Elsayed and Ashraf K. Eessaa

Crystals 2021, 11(9), 1081; https://doi.org/10.3390/cryst11091081 - 06 Sep 2021

Cited by 3 | Viewed by 1998

Abstract

Bi-modal particles are used as reinforcements for Cu-matrix. Nano TiC and/or Al₂O₃ were mechanically mixed with Cu particles for 24 h. The Cu-TiC/Al₂O₃ composites were successfully produced using spark plasma sintering (SPS). To investigate the effect of [...] Read more.

Bi-modal particles are used as reinforcements for Cu-matrix. Nano TiC and/or Al₂O₃ were mechanically mixed with Cu particles for 24 h. The Cu-TiC/Al₂O₃ composites were successfully produced using spark plasma sintering (SPS). To investigate the effect of TiC and Al₂O₃ nanoparticles on the microstructure and mechanical properties of Cu-TiC/Al₂O₃ nanocomposites, they were added, whether individually or combined, to the copper (Cu) matrix at 3, 6, and 9 wt.%. The results showed that titanium carbide was homogeneously distributed in the copper matrix, whereas alumina nanoparticles showed some agglomeration at Cu grain boundaries. The crystallite size exhibited a clear reduction as a reaction to the increase of the reinforcement ratio. Furthermore, increasing the TiC and Al₂O₃ nanoparticle content in the Cu-TiC/Al₂O₃ composites reduced the relative density from 95% for Cu-1.5 wt.% TiC and 1.5 wt.% Al₂O₃ to 89% for Cu-4.5 wt.% TiC and 4.5 wt.% Al₂O₃. Cu-9 wt.% TiC achieved a maximum compressive strength of 851.99 N/mm². Hardness values increased with increasing ceramic content. Full article

(This article belongs to the Special Issue Fabrication of Carbon and Related Materials/Metal Hybrids and Composites)

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11 pages, 4302 KiB

Open AccessEditor’s ChoiceArticle

Crystalline Silicon Spalling as a Direct Application of Temperature Effect on Semiconductors’ Indentation

by Maha M. Khayyat

Crystals 2021, 11(9), 1020; https://doi.org/10.3390/cryst11091020 - 25 Aug 2021

Viewed by 2068

Abstract

Kerf-less removal of surface layers of photovoltaic materials including silicon is an emerging technology by controlled spalling technology. The method is extremely simple, versatile, and applicable to a wide range of substrates. Controlled spalling technology requires a stressor layer, such as Ni, to [...] Read more.

Kerf-less removal of surface layers of photovoltaic materials including silicon is an emerging technology by controlled spalling technology. The method is extremely simple, versatile, and applicable to a wide range of substrates. Controlled spalling technology requires a stressor layer, such as Ni, to be deposited on the surface of a brittle material; then, the controlled removal of a continuous surface layer can be performed at a predetermined depth by manipulating the thickness and stress of the Ni layer, introducing a crack near the edge of the substrate, and mechanically guiding the crack as a single fracture front across the surface. However, spalling Si(100) at 300 K (room temperature RT) introduced many cracks and rough regions within the spalled layer. These mechanical issues make it difficult to process these layers of Si(100) for PV, and in other advanced applications, Si does not undergo phase transformations at 77 K (Liquid Nitrogen Temperature, LNT); based on this fact, spalling of Si(100) has been carried out. Spalling of Si(100) at LNT improved material quality for further designed applications. Mechanical flexibility is achieved by employing controlled spalling technology, enabling the large-area transfer of ultrathin body silicon devices to a plastic substrate at room temperature. Full article

(This article belongs to the Special Issue Fabrication of Carbon and Related Materials/Metal Hybrids and Composites)

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14 pages, 2681 KiB

Open AccessArticle

Paraffin Wax [As a Phase Changing Material (PCM)] Based Composites Containing Multi-Walled Carbon Nanotubes for Thermal Energy Storage (TES) Development

by Norah Hamad Almousa, Maha R. Alotaibi, Mohammad Alsohybani, Dominik Radziszewski, Saeed M. AlNoman, Bandar M. Alotaibi and Maha M. Khayyat

Crystals 2021, 11(8), 951; https://doi.org/10.3390/cryst11080951 - 15 Aug 2021

Cited by 14 | Viewed by 4131

Abstract

Thermal energy storage (TES) technologies are considered as enabling and supporting technologies for more sustainable and reliable energy generation methods such as solar thermal and concentrated solar power. A thorough investigation of the TES system using paraffin wax (PW) as a phase changing [...] Read more.

Thermal energy storage (TES) technologies are considered as enabling and supporting technologies for more sustainable and reliable energy generation methods such as solar thermal and concentrated solar power. A thorough investigation of the TES system using paraffin wax (PW) as a phase changing material (PCM) should be considered. One of the possible approaches for improving the overall performance of the TES system is to enhance the thermal properties of the energy storage materials of PW. The current study investigated some of the properties of PW doped with nano-additives, namely, multi-walled carbon nanotubes (MWCNs), forming a nanocomposite PCM. The paraffin/MWCNT composite PCMs were tailor-made for enhanced and efficient TES applications. The thermal storage efficiency of the current TES bed system was approximately 71%, which is significant. Scanning electron spectroscopy (SEM) with energy dispersive X-ray (EDX) characterization showed the physical incorporation of MWCNTs with PW, which was achieved by strong interfaces without microcracks. In addition, the FTIR (Fourier transform infrared) and TGA (thermogravimetric analysis) experimental results of this composite PCM showed good chemical compatibility and thermal stability. This was elucidated based on the observed similar thermal mass loss profiles as well as the identical chemical bond peaks for all of the tested samples (PW, CNT, and PW/CNT composites). Full article

(This article belongs to the Special Issue Fabrication of Carbon and Related Materials/Metal Hybrids and Composites)

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14 pages, 5060 KiB

Open AccessArticle

A New Approach to Direct Friction Stir Processing for Fabricating Surface Composites

by Abdulla I. Almazrouee, Khaled J. Al-Fadhalah and Saleh N. Alhajeri

Crystals 2021, 11(6), 638; https://doi.org/10.3390/cryst11060638 - 02 Jun 2021

Cited by 9 | Viewed by 2409

Abstract

Friction stir processing (FSP) is a green fabrication technique that has been effectively adopted in various engineering applications. One of the promising advantages of FSP is its applicability in the development of surface composites. In the current work, a new approach for direct [...] Read more.

Friction stir processing (FSP) is a green fabrication technique that has been effectively adopted in various engineering applications. One of the promising advantages of FSP is its applicability in the development of surface composites. In the current work, a new approach for direct friction stir processing is considered for the surface fabrication of aluminum-based composites reinforced with micro-sized silicon carbide particles (SiC), eliminating the prolonged preprocessing stages of preparing the sample and filling the holes of grooves. The proposed design of the FSP tool consists of two parts: an inner-threaded hollow cylindrical body; and a pin-less hollow shoulder. The design is examined with respect to three important tool processing parameters: the tilt angle of the tool, the tool’s dispersing hole, and the tool’s plunge depth. The current study shows that the use of a dispersing hole with a diameter of 6 mm of and a plunge depth of 0.6 mm, in combination with a tilting angle of 7°, results in sufficient mixing of the enforcement particles in the aluminum matrix, while still maintaining uniformity in the thickness of the composite layer. Metallographic examination of the Al/SiC surface composite demonstrates a uniform distribution of the Si particles and excellent adherence to the aluminum substrate. Microhardness measurements also show a remarkable increase, from 38.5 Hv at the base metal to a maximum value of 78 Hv in the processed matrix in the surface composites layer. The effect of the processing parameters was also studied, and its consequences with respect to the surface composites are discussed. Full article

(This article belongs to the Special Issue Fabrication of Carbon and Related Materials/Metal Hybrids and Composites)

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19 pages, 8911 KiB

Open AccessArticle

Effect of Copper Addition on the AlCoCrFeNi High Entropy Alloys Properties via the Electroless Plating and Powder Metallurgy Technique

by Mohamed Ali Hassan, Hossam M. Yehia, Ahmed S. A. Mohamed, Ahmed Essa El-Nikhaily and Omayma A. Elkady

Crystals 2021, 11(5), 540; https://doi.org/10.3390/cryst11050540 - 12 May 2021

Cited by 20 | Viewed by 3300

Abstract

To improve the AlCoCrFeNi high entropy alloys’ (HEAs’) toughness, it was coated with different amounts of Cu then fabricated by the powder metallurgy technique. Mechanical alloying of equiatomic AlCoCrFeNi HEAs for 25 h preceded the coating process. The established powder samples were sintered [...] Read more.

To improve the AlCoCrFeNi high entropy alloys’ (HEAs’) toughness, it was coated with different amounts of Cu then fabricated by the powder metallurgy technique. Mechanical alloying of equiatomic AlCoCrFeNi HEAs for 25 h preceded the coating process. The established powder samples were sintered at different temperatures in a vacuum furnace. The HEAs samples sintered at 950 °C exhibit the highest relative density. The AlCoCrFeNi HEAs model sample was not successfully produced by the applied method due to the low melting point of aluminum. The Al element’s problem disappeared due to encapsulating it with a copper layer during the coating process. Because the atomic radius of the copper metal (0.1278 nm) is less than the atomic radius of the aluminum metal (0.1431 nm) and nearly equal to the rest of the other elements (Co, Cr, Fe, and Ni), the crystal size powder and fabricated samples decreased by increasing the content of the Cu wt%. On the other hand, the lattice strain increased. The microstructure revealed that the complete diffusion between the different elements to form high entropy alloy material was not achieved. A dramatic decrease in the produced samples’ hardness was observed where it decreased from 403 HV at 5 wt% Cu to 191 HV at 20 wt% Cu. On the contrary, the compressive strength increased from 400.034 MPa at 5 wt% Cu to 599.527 MPa at 15 wt% Cu with a 49.86% increment. This increment in the compressive strength may be due to precipitating the copper metal on the particles’ surface in the nano-size, reducing the dislocations’ motion, increasing the stiffness of produced materials. The formability and toughness of the fabricated materials improved by increasing the copper’s content. The thermal expansion has increased gradually by increasing the Cu wt%. Full article

(This article belongs to the Special Issue Fabrication of Carbon and Related Materials/Metal Hybrids and Composites)

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19 pages, 4822 KiB

Open AccessArticle

Green Synthesis and Biomedical Applications of ZnO Nanoparticles: Role of PEGylated-ZnO Nanoparticles as Doxorubicin Drug Carrier against MDA-MB-231(TNBC) Cells Line

by Madiha Batool, Shazia Khurshid, Walid M. Daoush, Sabir Ali Siddique and Tariq Nadeem

Crystals 2021, 11(4), 344; https://doi.org/10.3390/cryst11040344 - 28 Mar 2021

Cited by 22 | Viewed by 4342

Abstract

The present study aimed to develop the synthesis of zinc oxide nanoparticles (ZnO-NPs) using the green method, with Aloe barbadensis leaf extract as a stabilizing and capping agent. In vitro antitumor cytotoxic activity, as well as the surface-functionalization of ZnO-NPs and their drug [...] Read more.

The present study aimed to develop the synthesis of zinc oxide nanoparticles (ZnO-NPs) using the green method, with Aloe barbadensis leaf extract as a stabilizing and capping agent. In vitro antitumor cytotoxic activity, as well as the surface-functionalization of ZnO-NPs and their drug loading capacity against doxorubicin (DOX) and gemcitabine (GEM) drugs, were also studied. Morphological and structural properties of the produced ZnO-NPs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersion X-ray diffraction (EDX), UV-Vis spectrophotometry, Fourier-transform infrared analysis (FTIR), and X-ray diffraction (XRD). The prepared ZnO-NPs had a hexagonal shape and average particle size of 20–40 nm, with an absorption peak at 325 nm. The weight and atomic percentages of zinc (50.58% and 28.13%) and oxygen (26.71% and 60.71%) were also determined by EDAX (energy dispersive x-ray analysis) compositional analysis. The appearance of the FTIR peak at 3420 m^–1 confirmed the synthesis of ZnO-NPs. The drug loading efficiency (LE) and loading capacity (LC) of unstabilized and PEGylated ZnO-NPs were determined by doxorubicin (DOX) and gemcitabine (GEM) drugs. DOX had superior LE 65% (650 mg/g) and higher LC 32% (320 mg/g) than GEM LE 30.5% (30 mg/g) and LC 16.25% (162 mg/g) on ZnO-NPs. Similar observation was observed in the case of PEG-ZnO-NPs, where DOX had enhanced LE 68% (680 mg/g) and LC 35% (350) mg/g in contrast to GEM, which had LE and LC values of 35% (350 mg/g) and 19% (190 mg/g), respectively. Therefore, DOX was chosen to encapsulate nanoparticles, along with the untreated nanoparticles, to check their in vitro antiproliferative potential against the triple-negative breast cancer (TNBC) cell line (MDA-MB-231) through the MTT (3-(4,5-Dimethylthiazol-2-Yl)-2,5-Diphenyltetrazolium Bromide) assay. This drug delivery strategy implies that the PEGylated biogenically synthesized ZnO-NPs occupy an important position in chemotherapeutic drug loading efficiency and can improve the therapeutic techniques of triple breast cancer. Full article

(This article belongs to the Special Issue Fabrication of Carbon and Related Materials/Metal Hybrids and Composites)

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15 pages, 4158 KiB

Open AccessArticle

Development of Red Clay Ultrafiltration Membranes for Oil-Water Separation

by Saad A. Aljlil

Crystals 2021, 11(3), 248; https://doi.org/10.3390/cryst11030248 - 28 Feb 2021

Cited by 6 | Viewed by 2045

Abstract

In this study, a red clay/nano-activated carbon membrane was investigated for the removal of oil from industrial wastewater. The sintering temperature was minimized using CaF₂ powder as a binder. The fabricated membrane was characterized by its mechanical properties, average pore size, and [...] Read more.

In this study, a red clay/nano-activated carbon membrane was investigated for the removal of oil from industrial wastewater. The sintering temperature was minimized using CaF₂ powder as a binder. The fabricated membrane was characterized by its mechanical properties, average pore size, and hydrophilicity. A contact angle of 67.3° and membrane spore size of 95.46 nm were obtained. The prepared membrane was tested by a cross-flow filtration process using an oil-water emulsion, and showed a promising permeate flux and oil rejection results. During the separation of oil from water, the flux increased from 191.38 to 284.99 L/m² on increasing the applied pressure from 3 to 6 bar. In addition, high water permeability was obtained for the fabricated membrane at low operating pressure. However, the membrane flux decreased from 490.28 to 367.32 L/m²·h due to oil deposition on the membrane surface; regardless, the maximum oil rejection was 99.96% at an oil concentration of 80 NTU and a pressure of 5 bar. The fabricated membrane was negatively charged, as were the oil droplets, thereby facilitating membrane purification through backwashing. The obtained ceramic membrane functioned well as a hydrophilic membrane and showed potential for use in oil wastewater treatment. Full article

(This article belongs to the Special Issue Fabrication of Carbon and Related Materials/Metal Hybrids and Composites)

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16 pages, 11177 KiB

Open AccessArticle

Syntheses and Step-by-Step Morphological Analysis of Nano-Copper-Decorated Carbon Long Fibers for Aerospace Structural Applications

by Walid M. Daoush, Turki S. Albogmy, Moath A. Khamis and Fawad Inam

Crystals 2020, 10(12), 1090; https://doi.org/10.3390/cryst10121090 - 28 Nov 2020

Cited by 8 | Viewed by 2650

Abstract

Carbon long fiber/copper composites were prepared using electroless and electroplating methods with copper metal for potential aerospace applications. Carbon fibers were heat-treated at 450 °C followed by acid treatment before the metallization processes. Three different methods of metallization processes were applied: electroless silver [...] Read more.

Carbon long fiber/copper composites were prepared using electroless and electroplating methods with copper metal for potential aerospace applications. Carbon fibers were heat-treated at 450 °C followed by acid treatment before the metallization processes. Three different methods of metallization processes were applied: electroless silver deposition, electroless copper deposition and electroplating copper deposition. The metallized carbon fibers were subjected to copper deposition via two different routes. The first method was the electroless deposition technique in an alkaline tartrate bath using formaldehyde as a reducing agent of the copper ions from the copper sulphate solution. The second method was conducted by copper electroplating on the chemically treated carbon fibers. The produced carbon fiber/copper composites were extensively investigated by Field-Emission Scanning Electron Microscopy (FE-SEM) supported with an Energy Dispersive X-Ray Analysis (EDAX) unit to analyze the size, surface morphology, and chemical composition of the produced carbon long fiber/copper composites. The results show that the carbon fiber/copper composites prepared using the electroplating method had a coated type surface morphology with good adhesion between the copper coated layer and the surface of the carbon fibers. However, the carbon fiber/copper composites prepared using the electroless deposition had a decorated type morphology. Moreover, it was observed that the metallized carbon fibers using the silver method enhanced the electroless copper coating process with respect to the electroless copper coating process without silver metallization. The electrical conductivity of the carbon fiber/copper composites was improved by metallization of the carbon fibers using silver, as well as by the electrodeposition method. Full article

(This article belongs to the Special Issue Fabrication of Carbon and Related Materials/Metal Hybrids and Composites)

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The Development of Graphene/Silica Hybrid Composites: A Review for Their Applications and Challenges

by Murni Handayani, Nurin Nafi’ah, Adityo Nugroho, Amaliya Rasyida, Agus Budi Prasetyo, Eni Febriana, Eko Sulistiyono and Florentinus Firdiyono

Crystals 2021, 11(11), 1337; https://doi.org/10.3390/cryst11111337 - 01 Nov 2021

Cited by 11 | Viewed by 4130

Abstract

Graphene and silica are two materials that have wide uses and applications because of their unique properties. Graphene/silica hybrid composite, which is a combination of the two, has the good properties of a combination of graphene and silica while reducing the detrimental properties [...] Read more.

Graphene and silica are two materials that have wide uses and applications because of their unique properties. Graphene/silica hybrid composite, which is a combination of the two, has the good properties of a combination of graphene and silica while reducing the detrimental properties of both, so that it has promising future prospects in various fields. It is very important to design a synthesis method for graphene/silica composite hybrid materials to adapt to its practical application. In this review, the synthesis strategies of graphene, silica, and hybrid graphene/silica composites such as hydrothermal, sol-gel, hydrolysis, and encapsulation methods along with their results are studied. The application of this composite is also discussed, which includes applications such as adsorbents, energy storage, biomedical fields, and catalysts. Furthermore, future research challenges and futures need to be developed so that hybrid graphene/silica composites can be obtained with promising new application prospects. Full article

(This article belongs to the Special Issue Fabrication of Carbon and Related Materials/Metal Hybrids and Composites)

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