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14 pages, 4650 KiB

Open AccessArticle

Mechanocaloric Effects Characterization of Low-Crystalline Thermoplastic Polyurethanes Fiber

by Jiongjiong Zhang, Yilong Wu, You Lv, Guimei Zhu and Yuan Zhu

Polymers 2024, 16(23), 3360; https://doi.org/10.3390/polym16233360 - 29 Nov 2024

Cited by 1 | Viewed by 918

Mechanocaloric cooling/heat pumping with zero carbon emission and high efficiency shows great potential for replacing traditional refrigeration with vapor compression. Mechanocaloric prototypes that are developed using shape memory alloys (SMAs) face the problems of a large driving force and high cost. In this [...] Read more.

Mechanocaloric cooling/heat pumping with zero carbon emission and high efficiency shows great potential for replacing traditional refrigeration with vapor compression. Mechanocaloric prototypes that are developed using shape memory alloys (SMAs) face the problems of a large driving force and high cost. In this work, we report a low-crystalline thermoplastic polyetherurethane (TPU) elastomer fiber with a low actuation force and good mechanocaloric performance. We fabricate the TPU fiber and develop a multifunctional mechanical tester to measure both the elastocaloric and twistocaloric effects. In the experiments, the applied stress required to induce mechanocaloric effects of the TPU fiber is only 10~30 MPa, which is much lower than that of widely used NiTi elastocaloric SMAs (600~1200 MPa). The TPU fiber produces a maximum twistocaloric adiabatic temperature change of 10.2 K, which is 78.9% larger than its elastocaloric effect of 5.7 K. The wide-angle X-ray scattering (WAXS) results show that the strain-induced amorphous chain alignment and associated configurational entropy change are the main causes of the good mechanocaloric effects of the TPU fiber, rather than the strain-induced crystallization. This work demonstrates the potential of achieving low-force heat-efficient mechanocaloric cooling using thermoplastic elastomer fibers. Full article

(This article belongs to the Special Issue Thermal Properties Analysis of Polymers)

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19 pages, 12338 KiB

Open AccessArticle

Mechanical Properties of Ultra-High-Performance Concrete with Amorphous Alloy Fiber: Surface Modification by Silane Coupling Agent KH-550

by Dawei Wang, Runqing Liu, Song Wang and Xin Ma

Materials 2024, 17(16), 4037; https://doi.org/10.3390/ma17164037 - 14 Aug 2024

Cited by 1 | Viewed by 1606

Abstract

Amorphous alloy fiber has the advantages of high tensile strength and high corrosion resistance compared with steel fiber, but its interfacial bonding with cement matrix is poor and requires surface modification treatment. In this study, the surface modification of amorphous alloy fiber was [...] Read more.

Amorphous alloy fiber has the advantages of high tensile strength and high corrosion resistance compared with steel fiber, but its interfacial bonding with cement matrix is poor and requires surface modification treatment. In this study, the surface modification of amorphous alloy fiber was carried out by using silane coupling agent KH-550 solution, and its effect on the mechanical properties of ultra-high-performance concrete was investigated. The results showed that the amorphous alloy fibers modified with 15% concentration silane coupling agent KH-550 solution can effectively improve the mechanical properties of the ultra-high-performance concrete, where the interfacial bond strength with the cement matrix reached 3.29 MPa and the roughness reached 3.85. The compressive strength, flexural strength, tensile strength, and peak stress of the ultra-high-performance concrete mixed with modified amorphous alloy fibers could reach up to 133.6 MPa, 25.5 MPa, 8.32 MPa, and 114.26 MPa, respectively, which were 2.9%, 6.3%, 10.9%, and 4.3% higher than those of the ultra-high-performance concrete with unmodified amorphous alloy fibers. As the surface of the fiber was modified, its properties changed and the bonding effect with the cement matrix was better, which in turn improved the mechanical properties of the ultra-high-performance concrete. Full article

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11 pages, 3462 KiB

Open AccessArticle

Magnetocaloric Properties of Melt-Extracted Medium Entropy Gd₃₃Co₃₃Al₃₄ Microfibers

by Ning Zhang, Hongxian Shen, Lin Luo, Jingshun Liu, Zijian Zhao, Lunyong Zhang, Jianfei Sun and Manh-Huong Phan

Metals 2024, 14(8), 880; https://doi.org/10.3390/met14080880 - 30 Jul 2024

Cited by 1 | Viewed by 1252

Abstract

In this paper, a new medium entropy alloy with nominal composition of Gd₃₃Co₃₃Al₃₄ was designed and fabricated into microfibers by a melt-extraction method. The microstructure, thermophysical parameters, and magnetocaloric properties of the obtained fibers were systematically analyzed. The [...] Read more.

In this paper, a new medium entropy alloy with nominal composition of Gd₃₃Co₃₃Al₃₄ was designed and fabricated into microfibers by a melt-extraction method. The microstructure, thermophysical parameters, and magnetocaloric properties of the obtained fibers were systematically analyzed. The results showed that the as-cast fibers show an amorphous matrix with embedded in situ nano crystals. The fibers show a good magnetocaloric effect with the maximum magnetic entropy change of ~6 J/kg·K for a field change of 5 T. Notably, the fibers show excellent cooling efficiencies with an RCP and RC of ~611.72 and ~487.38 J/kg, respectively. Though the as-cast fibers possess an amorphous/nanocrystal bi-phase structure, they still exhibit a second-order transition near a Curie temperature of ~96 K. Our findings provide a promising pathway towards developing new magnetocaloric materials with good magnetocaloric performances. Full article

(This article belongs to the Special Issue Microstructural, Mechanical and Magnetic Properties of Metallic Microwires)

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14 pages, 8292 KiB

Open AccessArticle

Highly Conducting Surface-Silverized Aromatic Polysulfonamide (PSA) Fibers with Excellent Performance Prepared by Nano-Electroplating

by Ruicheng Bai, Pei Zhang, Xihai Wang, Hengxin Zhang, Hao Wang and Qinsi Shao

Nanomaterials 2024, 14(1), 115; https://doi.org/10.3390/nano14010115 - 2 Jan 2024

Cited by 4 | Viewed by 2070

Abstract

In this work, bilayer nanocoatings were designed and constructed on high-performance aromatic polysulfonamide (PSA) fibers for robust electric conduction and electromagnetic interference (EMI) shielding. More specifically, PSA fibers were first endowed with necessary electric conductivity via electroless nickel (Ni) or nickel alloy (Ni-P-B) [...] Read more.

In this work, bilayer nanocoatings were designed and constructed on high-performance aromatic polysulfonamide (PSA) fibers for robust electric conduction and electromagnetic interference (EMI) shielding. More specifically, PSA fibers were first endowed with necessary electric conductivity via electroless nickel (Ni) or nickel alloy (Ni-P-B) plating. Afterward, silver electroplating was carried out to further improve the performance of the composite. The morphology, microstructure, environmental stability, mechanical properties, and EMI shielding performance of the proposed cladded fibers were thoroughly investigated to examine the effects of electrodeposition on both amorphous Ni-P-B and crystalline Ni substrates. The acquired results demonstrated that both PSA@Ni@Ag and PSA@Ni-P-B@Ag composite fibers had high environment stability, good tensile strength, low electric resistance, and outstanding EMI shielding efficiency. This indicates that they can have wide application prospects in aviation, aerospace, telecommunications, and military industries. Furthermore, the PSA@Ni-P-B@Ag fiber configuration seemed more reasonable because it exhibited smoother and denser silver surfaces as well as stronger interfacial binding, leading to lower resistance (185 mΩ cm⁻¹) and better shielding efficiency (82.48 dB in the X-band). Full article

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17 pages, 4627 KiB

Open AccessArticle

Fiber Laser Alloying of Additively Manufactured 18Ni-300 Maraging Steel Part Surface: Effect of Processing Parameters on the Formation of Alloyed Surface Layer and Its Properties

by Jelena Škamat, Kęstutis Bučelis, Olegas Černašėjus and Simonas Indrišiūnas

Materials 2023, 16(13), 4732; https://doi.org/10.3390/ma16134732 - 30 Jun 2023

Cited by 3 | Viewed by 1478

Abstract

The development of new efficient, economical, and safe methods for strengthening the working surfaces of parts is an important task in the field of improving the reliability and resourcefulness of critical equipment and structures. In the present paper, laser boronizing is investigated as [...] Read more.

The development of new efficient, economical, and safe methods for strengthening the working surfaces of parts is an important task in the field of improving the reliability and resourcefulness of critical equipment and structures. In the present paper, laser boronizing is investigated as an alternative method for improving the wear resistance of maraging steel parts manufactured by laser powder bed fusion (LPBF). After LPBF, the specimens’ surface was covered with an amorphous boron paste (0.03–0.6 mm) and laser processed with a continuous-wave fiber laser in melting mode (λ—1070 nm; power—300 W; spot Ø—1.0 mm) at 500–1500 mm/min laser beam scanning speeds. Scanning electron microscopy, X-ray microanalysis, Knoop hardness, and dry sliding wear tests were applied to investigate the geometry, microstructure, hardness and its distribution, heat-affected zones, wear resistance, and wear mechanism of the alloyed layers. The boronized layers of thickness ~280–520 µm with microstructure from hypoeutectic to borides’ mixture were obtained, whose hardness varied from ~490 to ~2200 HK0.2. With laser boronizing, the wear resistance was improved up to ~7.5 times as compared with aged LPBF samples. In further method development, the problem of thermal cracking and softening of the heat-affected zone should be solved. Full article

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29 pages, 12644 KiB

Open AccessReview

Metallic Glass-Reinforced Metal Matrix Composites: Design, Interfaces and Properties

by Konstantinos Georgarakis, Dina V. Dudina and Vyacheslav I. Kvashnin

Materials 2022, 15(23), 8278; https://doi.org/10.3390/ma15238278 - 22 Nov 2022

Cited by 17 | Viewed by 3443

Abstract

When metals are modified by second-phase particles or fibers, metal matrix composites (MMCs) are formed. In general, for a given metallic matrix, reinforcements differing in their chemical nature and particle size/morphology can be suitable while providing different levels of strengthening. This article focuses [...] Read more.

When metals are modified by second-phase particles or fibers, metal matrix composites (MMCs) are formed. In general, for a given metallic matrix, reinforcements differing in their chemical nature and particle size/morphology can be suitable while providing different levels of strengthening. This article focuses on MMCs reinforced with metallic glasses and amorphous alloys, which are considered as alternatives to ceramic reinforcements. Early works on metallic glass (amorphous alloy)-reinforced MMCs were conducted in 1982–2005. In the following years, a large number of composites have been obtained and tested. Metallic glass (amorphous alloy)-reinforced MMCs have been obtained with matrices of Al and its alloys, Mg and its alloys, Ti alloys, W, Cu and its alloys, Ni, and Fe. Research has been extended to new compositions, new design approaches and fabrication methods, the chemical interaction of the metallic glass with the metal matrix, the influence of the reaction products on the properties of the composites, strengthening mechanisms, and the functional properties of the composites. These aspects are covered in the present review. Problems to be tackled in future research on metallic glass (amorphous alloy)-reinforced MMCs are also identified. Full article

(This article belongs to the Special Issue Powder Metallurgy: Materials and Processing)

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10 pages, 5020 KiB

Open AccessArticle

Magnetocaloric Properties of Melt-Extracted Gd-Co-Al Amorphous/Crystalline Composite Fiber

by Fan Chen, Kun Han, Meng Gao, Yan Zhang, Wei Xu, Juntao Huo, Changjiang Zhang, Lijian Song and Jun-Qiang Wang

Metals 2022, 12(8), 1367; https://doi.org/10.3390/met12081367 - 18 Aug 2022

Cited by 5 | Viewed by 2141

Abstract

In this work, a series of Gd-based amorphous/crystalline composite fibers (ANCFs) were prepared by regulating the Gd content in Gd-Co-Al alloys using the melt-extracted method. Compared to the amorphous alloy, the ANCFs display excellent magnetic refrigeration capacity (RC). Among them, Gd [...] Read more.

In this work, a series of Gd-based amorphous/crystalline composite fibers (ANCFs) were prepared by regulating the Gd content in Gd-Co-Al alloys using the melt-extracted method. Compared to the amorphous alloy, the ANCFs display excellent magnetic refrigeration capacity (RC). Among them, Gd₈₅Co₅Al₁₀ ANCF had the largest RC (841 J kg⁻¹) and the widest working temperature range (245 K). Compared with Gd₇₀Co₁₀Al₂₀, RC and working temperature range increased by 56% and 119%, respectively. This superior property is attributed to the ideal coupling between the amorphous phase and the crystalline. This result opens a new door to optimize the magnetic refrigeration capacity by controlling the amorphous crystalline composite structure. Full article

(This article belongs to the Special Issue Development and Application of Microscale Metallic Fibers)

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14 pages, 5468 KiB

Open AccessArticle

Penetration Gain Study of a Tungsten-Fiber/Zr-Based Metallic Glass Matrix Composite

by Feng Zhou, Chengxin Du, Zhonghua Du, Guangfa Gao, Chun Cheng and Xiaodong Wang

Crystals 2022, 12(2), 284; https://doi.org/10.3390/cryst12020284 - 18 Feb 2022

Cited by 13 | Viewed by 2998

Abstract

A tungsten fiber/Zr-based bulk metallic glass matrix composite (Wf/Zr-MG) is a potential penetrator material. To compare and analyze the penetration behavior of Wf/Zr-MG and a tungsten heavy alloy (WHA), a penetration experiment into the 30CrMnMo homogeneous armor target plate (RHA) is conducted in [...] Read more.

A tungsten fiber/Zr-based bulk metallic glass matrix composite (Wf/Zr-MG) is a potential penetrator material. To compare and analyze the penetration behavior of Wf/Zr-MG and a tungsten heavy alloy (WHA), a penetration experiment into the 30CrMnMo homogeneous armor target plate (RHA) is conducted in the present paper, by using a 37 mm smooth bore artillery with an impact velocity of 1550 ± 40 m/s. Unlike the penetrator made of WHA, the self-sharpening phenomenon was observed in the nose of the Wf/Zr-MG rod. The experimental results indicate that the penetration ability of Wf/Zr-MG rod is approximately 10% higher than that of the WHA rod when the impact velocity is 1550 ± 40 m/s. The combined findings on the microscopic morphology, composition, hardness distribution around the crater, and the macroscopic structure of the penetrator residual show that under this impact velocity, the Wf/Zr-MG material shows amorphous gasification. The Wfs outside the rod shows bending and backflow, resulting in the maintenance of the self-sharpening nose of the penetrator during the penetration process. Moreover, the hardness peak around the crater formed by the Wf/Zr-MG rod is lower, and the penetration crater is straighter, indicating that the Wf/Zr-MG rod has a stronger slag removal ability, lower penetration resistance, and higher penetration efficiency. It is an ideal penetrator material. Full article

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12 pages, 2479 KiB

Open AccessArticle

Catalytic Decomposition of 2% Methanol in Methane over Metallic Catalyst by Fixed-Bed Catalytic Reactor

by Ali Awad, Israr Ahmed, Danial Qadir, Muhammad Saad Khan and Alamin Idris

Energies 2021, 14(8), 2220; https://doi.org/10.3390/en14082220 - 16 Apr 2021

Viewed by 2116

Abstract

The structure and performance of promoted Ni/Al₂O₃ with Cu via thermocatalytic decomposition (TCD) of CH₄ mixture (2% CH₃OH) were studied. Mesoporous Cat-1 and Cat-2 were synthesized by the impregnation method. The corresponding peaks of nickel oxide and [...] Read more.

The structure and performance of promoted Ni/Al₂O₃ with Cu via thermocatalytic decomposition (TCD) of CH₄ mixture (2% CH₃OH) were studied. Mesoporous Cat-1 and Cat-2 were synthesized by the impregnation method. The corresponding peaks of nickel oxide and copper oxide in the XRD showed the presence of nickel and copper oxides as a mixed alloy in the calcined catalyst. Temperature program reduction (TPR) showed that Cu enhanced the reducibility of the catalyst as the peak of nickel oxide shifted toward a lower temperature due to the interaction strength of the metal particles and support. The impregnation of 10% Cu on Cat-1 drastically improved the catalytic performance and exhibited 68% CH₄ conversion, and endured its activity for 6 h compared with Cat-1, which deactivated after 4 h. The investigation of the spent carbon showed that various forms of carbon were obtained as a by-product of TCD, including graphene fiber (GF), carbon nanofiber (CNF), and multi-wall carbon nanofibers (MWCNFs) on the active sites of Cat-2 and Cat-1, following various kinds of growth mechanisms. The presence of the D and G bands in the Raman spectroscopy confirmed the mixture of amorphous and crystalline morphology of the deposited carbon. Full article

(This article belongs to the Section A5: Hydrogen Energy)

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