Materials

13 pages, 25274 KiB

Open AccessArticle

Ab Initio Simulation of Structure and Properties in Ni-Based Superalloys: Haynes282 and Inconel740

by Wai-Yim Ching, Saro San, Caizhi Zhou and Ridwan Sakidja

Materials 2023, 16(2), 887; https://doi.org/10.3390/ma16020887 - 16 Jan 2023

Cited by 2 | Viewed by 1646

The electronic structure, interatomic bonding, and mechanical properties of two supercell models of Ni-based superalloys are calculated using ab initio density functional theory methods. The alloys, Haynes282 and Inconel740, are face-centered cubic lattices with 864 atoms and eleven elements. These multi-component alloys have [...] Read more.

The electronic structure, interatomic bonding, and mechanical properties of two supercell models of Ni-based superalloys are calculated using ab initio density functional theory methods. The alloys, Haynes282 and Inconel740, are face-centered cubic lattices with 864 atoms and eleven elements. These multi-component alloys have very complex electronic structure, bonding and partial-charge distributions depending on the composition and strength of the local bonding environment. We employ the novel concept of total bond order density (TBOD) and its partial components (PBOD) to ascertain the internal cohesion that controls the intricate balance between the propensity of metallic bonding between Ni, Cr and Co, and the strong bonds with C and Al. We find Inconel740 has slightly stronger mechanical properties than Haynes282. Both Inconel740 and Haynes282 show ductile natures based on Poisson’s ratio. Poisson’s ratio shows marginal correlation with the TBOD. Comparison with more conventional high entropy alloys with equal components are discussed. Full article

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15 pages, 3493 KiB

Open AccessEditor’s ChoiceReview

Prediction of Novel Ultrahard Phases in the B–C–N System from First Principles: Progress and Problems

by Vladimir L. Solozhenko and Samir F. Matar

Materials 2023, 16(2), 886; https://doi.org/10.3390/ma16020886 - 16 Jan 2023

Cited by 11 | Viewed by 1587

Abstract

The modern synthesis of superhard and, especially, ultrahard phases is a fascinating area of research that could lead to the design of new, industrially important materials. Computational methods built within the well-established quantum mechanics framework of density functional theory (DFT) play an important [...] Read more.

The modern synthesis of superhard and, especially, ultrahard phases is a fascinating area of research that could lead to the design of new, industrially important materials. Computational methods built within the well-established quantum mechanics framework of density functional theory (DFT) play an important role in the search for these advanced materials and the prediction of their properties. The close relationship between the physical properties of carbon and boron nitride has led to particular interest in the B–C–N ternary system, characterized by the small radii of the elements, resulting in short interatomic distances and reduced volumes—the parameters being ‘recipes’ for very high hardness in three-dimensional structures. The purpose of this review is to provide a brief outline of recent developments and problems in predicting novel ultrahard carbon allotropes as well as binary and ternary compounds of the B–C–N system with particular emphasis on the analysis of the models used to evaluate the hardness of the theoretically predicted structures. Full article

(This article belongs to the Special Issue Advances in Density Functional Theory (DFT) Studies of Solids (Second Volume))

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24 pages, 8606 KiB

Open AccessArticle

Indirect Induction Sintering of Metal Parts Produced through Material Extrusion Additive Manufacturing

by Manuel Ortega Varela de Seijas, Andreas Bardenhagen, Thomas Rohr and Enrico Stoll

Materials 2023, 16(2), 885; https://doi.org/10.3390/ma16020885 - 16 Jan 2023

Cited by 7 | Viewed by 3970

Abstract

Avoiding loose powders and resins, material extrusion additive manufacturing is a powerful technique to produce near-net shape parts, being a cheap and safe alternative for developing complex industrial-grade products. Filaments embedded with a high packing density of metallic or ceramic granules are being [...] Read more.

Avoiding loose powders and resins, material extrusion additive manufacturing is a powerful technique to produce near-net shape parts, being a cheap and safe alternative for developing complex industrial-grade products. Filaments embedded with a high packing density of metallic or ceramic granules are being increasingly used, resulting in almost fully dense parts, whereby geometries are shaped, debinded and sintered sequentially until the completion of the part. Traditionally, “brown” debinded geometries are transported to conventional furnaces to densify the powder compacts, requiring careful tailoring of the heating profiles and sintering environment. This approach is decoupled and often involves time-consuming post-processing, whereby after the completion of the shaping and debinding steps, the parts need to be transported to a sintering furnace. Here, it is shown that sintering via indirect induction heating of a highly filled commercially available filament embedded with stainless steel 316L powder can be an effective route to densify Fused Filament Fabricated (FFF) parts. The results show that densities of 99.8% can be reached with very short soaking times, representing a significant improvement compared to prior methods. A hybrid machine is proposed, whereby a custom-built machine is integrated with an induction heater to combine FFF with local indirect induction sintering. Sintering in situ, without the need for part transportation, simplifies the processing of metal parts produced through material extrusion additive manufacturing. Full article

(This article belongs to the Special Issue Materials Processing and Emerging Technologies)

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20 pages, 6234 KiB

Open AccessArticle

Testing and Analysis of Uniaxial Mechanical Fatigue, Charpy Impact Fracture Energy and Microhardness of Two Low-Carbon Steels

by Josip Brnic, Sebastian Balos, Marino Brcic, Miroslav Dramicanin, Sanjin Krscanski, Mladomir Milutinovic, Biao Ding and Zeng Gao

Materials 2023, 16(2), 884; https://doi.org/10.3390/ma16020884 - 16 Jan 2023

Cited by 1 | Viewed by 1941

Abstract

The paper presents and analyzes the results of experimental tests performed on two non-alloy low carbon steels (1.1141 and 1.0122) in cases of their exposure to impact fracture energy and uniaxial high cyclic mechanical stress-controlled fatigue. The experimental results provide insight into the [...] Read more.

The paper presents and analyzes the results of experimental tests performed on two non-alloy low carbon steels (1.1141 and 1.0122) in cases of their exposure to impact fracture energy and uniaxial high cyclic mechanical stress-controlled fatigue. The experimental results provide insight into the changes in the Charpy impact fracture energy of the V-notched test specimen that occur as a result of temperature changes. The experimental results also provide insight into the mechanical response of the tested materials to mechanical uniaxial high-cycle fatigue at room temperature in an air atmosphere and at different applied stress ratios. Material fatigue tests refer to symmetric (R = −1), asymmetric (R = −0.5) and pulsating tensile (R = 0) cycles. The test results are shown in the S–N diagrams and refer to the highest applied stresses in relation to the number of failures at a given stress ratio. Using the modified staircase method, the fatigue limit (endurance limit) was calculated for both tested materials at each prescribed stress ratio. For both tested steel alloys, and at prescribed stress ratios, the fatigue limit levels (σ_f) are shown as follows: for steel C15E+C (1.1141)

\to σ_{f} [{250.8}_{R = - 1}; {345.4}_{R = - 0.5}; 527_{R = 0}] (MPa);

and for steel S235JRC+C (1.0122)

\to

σ_{f}

[

202_{R = - 1}; 310_{R = - 0.5}; 462_{R = 0}] (MPa)

. All uniaxial fatigue tests were performed on unnotched, smooth, highly-polished specimens. The microhardness of both materials was also tested. Full article

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19 pages, 8584 KiB

Open AccessArticle

Molecular Dynamics Study on Crack Propagation in Al Containing Mg–Si Clusters Formed during Natural Aging

by Sangjun Lee, Heon Kang and Donghyun Bae

Materials 2023, 16(2), 883; https://doi.org/10.3390/ma16020883 - 16 Jan 2023

Cited by 2 | Viewed by 1521

Abstract

The crack propagation behavior of Al containing Mg–Si clusters is investigated using molecular dynamics (MD) simulations to demonstrate the relationship between the natural aging time in Al–Si–Mg alloys and ductility. Experimental results show that the elongation at failure decreases with natural aging. There [...] Read more.

The crack propagation behavior of Al containing Mg–Si clusters is investigated using molecular dynamics (MD) simulations to demonstrate the relationship between the natural aging time in Al–Si–Mg alloys and ductility. Experimental results show that the elongation at failure decreases with natural aging. There are few studies on the relationship between natural aging and ductility because of the difficult observation of Mg–Si clusters. To solve the difficulty, cracked Al containing Mg–Si clusters of varying sizes are assumed for the MD simulations. A larger Mg–Si cluster in Al results in earlier crack opening and dislocation emission. Moreover, as the Mg–Si cluster size increases, the stress near the crack tip becomes more concentrated. This causes rapid crack propagation, a similar effect to that of crack tip sharpening. As a result of long-term natural aging, the cracks expand rapidly. The influence of geometry is also investigated. Crack lengthening and thickness reduction negatively impact the fracture toughness, with the former having a larger impact than the latter. Although there are several discrepancies in the practical deformation conditions, the simulation results can help to more thoroughly understand natural aging in Al–Si–Mg alloys. Full article

(This article belongs to the Special Issue Numerical Simulation Methods for Analyzing Fatigue and Fracture Behavior in Metallic Materials)

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10 pages, 13274 KiB

Open AccessArticle

Improvement of Mechanical Properties of Composites with Surface Modified B₄C for Precision Machining

by Jun Ding, Jintao Wang, Hao Yang, Zhenglong Liu, Chao Yu, Xiangcheng Li, Chengji Deng and Hongxi Zhu

Materials 2023, 16(2), 882; https://doi.org/10.3390/ma16020882 - 16 Jan 2023

Cited by 2 | Viewed by 1394

Abstract

In order to solve the problem of difficult sintering and high brittleness of B₄C-based ceramics, B₄C@ZrB₂-TiB₂ composite powder was synthesized by molten salt method, and B₄C–(Zr, Ti)B₂ composite ceramics were successfully prepared by [...] Read more.

In order to solve the problem of difficult sintering and high brittleness of B₄C-based ceramics, B₄C@ZrB₂-TiB₂ composite powder was synthesized by molten salt method, and B₄C–(Zr, Ti)B₂ composite ceramics were successfully prepared by spark plasma sintering. The effects of different raw material ratios on the composition, microstructure, and mechanical properties of the prepared composite ceramics were characterized by XRD, XPS, SEM, and TEM. The results show that ZrB₂ and TiB₂ were grown on the surface of B₄C by template mechanism to form a dense nanocrystalline coating, and the original surface of B₄C was exposed gradually with the decrease of the ratio of metal powder. When the composite powders were sintered at 1700 °C, ZrB₂ and TiB₂ formed a solid solution, which can refine grains and improve strength. When the raw material ratio is n(B₄C): n(Zr): n(Ti) = 12:1:1, the composite ceramics have excellent comprehensive properties, the Vickers hardness reaches 41.2 GPa. Full article

(This article belongs to the Special Issue Feature Papers in Refractories and Ceramics: Microstructure, Properties and Applications)

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13 pages, 2490 KiB

Open AccessArticle

Temperature during Repetitive Short-Term Operation of a Brake with Functionally Graded Friction Element

by Aleksander Yevtushenko, Katarzyna Topczewska and Przemysław Zamojski

Materials 2023, 16(2), 881; https://doi.org/10.3390/ma16020881 - 16 Jan 2023

Cited by 2 | Viewed by 1166

Abstract

The object of study is the temperature of a braking system, operating in repetitive short-term (RST) mode. One element of the considered friction pair is made of a functionally gradient material (FGM), and the other of a homogeneous material. To determine the temperature [...] Read more.

The object of study is the temperature of a braking system, operating in repetitive short-term (RST) mode. One element of the considered friction pair is made of a functionally gradient material (FGM), and the other of a homogeneous material. To determine the temperature on the friction surfaces of both elements, the previously obtained, exact solution of the boundary value problem of heat conduction was adopted, with account of the heat generation due to the friction. A calculation scheme was proposed that takes into consideration thermal sensitivity of materials and variations of the friction coefficient under the influence of temperature. Calculations were performed for two-component FGM (ZrO₂–Ti-6Al-4V) in combination with gray cast iron (ChNMKh). It was found that for selected friction pair materials, consideration of their thermal sensitivity reduces the time of braking and the value of temperature achieved on the friction surfaces. At the same time, the whole process was characterized by a good stability of braking with a slight decrease in efficiency in each subsequent cycle. Full article

(This article belongs to the Special Issue Use of Modern Materials in Technological Processes Accompanied by Frictional Heating)

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24 pages, 2863 KiB

Open AccessReview

Additive Manufacturing of 3D Anatomical Models—Review of Processes, Materials and Applications

by Magdalena Żukowska, Maryam Alsadat Rad and Filip Górski

Materials 2023, 16(2), 880; https://doi.org/10.3390/ma16020880 - 16 Jan 2023

Cited by 9 | Viewed by 2539

Abstract

The methods of additive manufacturing of anatomical models are widely used in medical practice, including physician support, education and planning of treatment procedures. The aim of the review was to identify the area of additive manufacturing and the application of anatomical models, imitating [...] Read more.

The methods of additive manufacturing of anatomical models are widely used in medical practice, including physician support, education and planning of treatment procedures. The aim of the review was to identify the area of additive manufacturing and the application of anatomical models, imitating both soft and hard tissue. The paper outlines the most commonly used methodologies, from medical imaging to obtaining a functional physical model. The materials used to imitate specific organs and tissues, and the related technologies used to produce, them are included. The study covers publications in English, published by the end of 2022 and included in the Scopus. The obtained results emphasise the growing popularity of the issue, especially in the areas related to the attempt to imitate soft tissues with the use of low-cost 3D printing and plastic casting techniques. Full article

(This article belongs to the Collection 3D Printing in Medicine and Biomedical Engineering)

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17 pages, 6694 KiB

Open AccessArticle

Theoretical and Experimental Investigation on the Flexural Behaviour of Prestressed NC-UHPC Composite Beams

by Pengzhen Lin, Weiyi Yan, Hongwei Zhao and Junjun Ma

Materials 2023, 16(2), 879; https://doi.org/10.3390/ma16020879 - 16 Jan 2023

Cited by 2 | Viewed by 1493

Abstract

To investigate the normal section strength and cracking bending moment of normal concrete–ultra-high-performance concrete (NC-UHPC) composite beams, calculation formulas were established considering the tensile strength of UHPC based on the current railway bridge design code. Using the railway T-beam as a template, prestressed [...] Read more.

To investigate the normal section strength and cracking bending moment of normal concrete–ultra-high-performance concrete (NC-UHPC) composite beams, calculation formulas were established considering the tensile strength of UHPC based on the current railway bridge design code. Using the railway T-beam as a template, prestressed NC-UHPC composite beams with different NC layer heights were built. A static bending test was performed, the pressure of the steel strand and the deflection and strain of the beam were measured, and the evolution of cracks in each beam was observed. The calculation formulas of the normal section strength and cracking bending moment of NC-UHPC composite beam were verified by the test. The results showed that the type of strain was similar to load-deflection curves with increasing load; the bending failure process of the NC-UHPC composite beam showed four obvious stages: elasticity, uniform cracking, crack development, and yield. Cracks in the beam started to appear at stage II, developed rapidly at stage III, and stopped emerging at stage IV. The calculation formulas for the normal section strength and the cracking bending moment of the NC-UHPC composite beam were in good agreement with the test values. Normal concrete with a compressive strength of 80 MPa can replace UHPC for the design of NC-UHPC composite beams. Full article

(This article belongs to the Special Issue Advances in Ultra-High Performance Concrete and Engineered Cementitious Composites)

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13 pages, 21819 KiB

Open AccessEditor’s ChoiceArticle

The Effect of Fe/Al Ratio and Substrate Hardness on Microstructure and Deposition Behavior of Cold-Sprayed Fe/Al Coatings

by You Wang, Nan Deng, Zhenfeng Tong and Zhangjian Zhou

Materials 2023, 16(2), 878; https://doi.org/10.3390/ma16020878 - 16 Jan 2023

Cited by 2 | Viewed by 1201

Abstract

Fe/Al composite coatings with compositions of Fe-25 wt.% Al, Fe-50 wt.% Al and Fe-75 wt.% Al were deposited on pure Al and P91 steel plates by a cold spray, respectively. The microstructure of the cross-section of the fabricated coatings was characterized by SEM [...] Read more.

Fe/Al composite coatings with compositions of Fe-25 wt.% Al, Fe-50 wt.% Al and Fe-75 wt.% Al were deposited on pure Al and P91 steel plates by a cold spray, respectively. The microstructure of the cross-section of the fabricated coatings was characterized by SEM and EDX. The bonding strength between the coatings and substrates was measured and analyzed. The effects of the Fe/Al ratios and substrate hardness on the deposition behavior were investigated. It was interesting to find fragmented zones in all fabricated coatings, which were composed of large integrated Al particles and small fragmented Al particles. Meanwhile, the fraction of fragmented zones varied with the fraction of the actual Fe/Al ratio. An Fe/Al ratio of 50/50 appeared to be an optimized ratio for the higher bonding strength of coatings. The in situ hammer effect caused by larger and harder Fe particles played an important role in the cold spray process. The substrate with the higher hardness strengthened the in situ hammer effect and further improved the bonding strength. Full article

(This article belongs to the Special Issue Synthesis, Properties and Applications of Intermetallics, Ceramic and Cermet Coatings)

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15 pages, 3640 KiB

Open AccessArticle

The Effect of PEGylated Graphene Oxide Nanoparticles on the Th17-Polarization of Activated T Helpers

by Svetlana Zamorina, Valeria Timganova, Maria Bochkova, Kseniya Shardina, Sofya Uzhviyuk, Pavel Khramtsov, Darya Usanina and Mikhail Rayev

Materials 2023, 16(2), 877; https://doi.org/10.3390/ma16020877 - 16 Jan 2023

Cited by 2 | Viewed by 1468

Abstract

We investigated the direct effect of PEGylated graphene oxide (P-GO) nanoparticles on the differentiation, viability, and cytokine profile of activated T helper type 17 (Th17) in vitro. The subject of the study were cultures of “naive” T-helpers (CD4+) isolated by immunomagnetic separation and [...] Read more.

We investigated the direct effect of PEGylated graphene oxide (P-GO) nanoparticles on the differentiation, viability, and cytokine profile of activated T helper type 17 (Th17) in vitro. The subject of the study were cultures of “naive” T-helpers (CD4+) isolated by immunomagnetic separation and polarized into the Th17 phenotype with a TCR activator and cytokines. It was found that P-GO at low concentrations (5 µg/mL) had no effect on the parameters studied. The presence of high concentrations of P-GO in T-helper cultures (25 μg/mL) did not affect the number and viability of these cells. However, the percentage of proliferating T-helpers in these cultures was reduced. GO nanoparticles modified with linear polyethylene glycol (PEG) significantly increased the percentage of Th17/22 cells in cultures of Th17-polarized T helpers and the production of IFN-γ, whereas those modified with branched PEG suppressed the synthesis of IL-17. Thus, a low concentration of PEGylated GO nanoparticles (5 μg/mL), in contrast to a concentration of 25 μg/mL, has no effect on the Th17-polarization of T helpers, allowing their further use for in-depth studies of the functions of T lymphocytes and other immune cells. Overall, we have studied for the first time the direct effect of P-GO nanoparticles on the conversion of T helper cells to the Th17 phenotype. Full article

(This article belongs to the Special Issue Advances in Biohybrid Micro/Nanostructures)

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20 pages, 4065 KiB

Open AccessArticle

Local Corrosion Behaviors in the Coarse-Grained Heat-Affected Zone in a Newly Developed Zr–Ti–Al–RE Deoxidized High-Strength Low-Alloy Steel

by Chao-Chao Yin, Lin Cheng, Zhi-Hui Wang, Tian-Liang Zhao, Shi Cheng, Shu-E Hu, Zi-Cheng Liu, Deng Luo, Da-Heng Xiao, Xing Jin, Han-Kun Liu and Kai-Ming Wu

Materials 2023, 16(2), 876; https://doi.org/10.3390/ma16020876 - 16 Jan 2023

Cited by 1 | Viewed by 1356

Abstract

Oxide metallurgy technology can improve the microstructure of a coarse-grained heat-affected zone (CGHAZ) but introduces extra inclusions. Local corrosion behavior of the CGHAZ of a Zr–Ti–Al–RE deoxidized steel was investigated in this work using theoretical calculations and experimental verification. The modified inclusions have [...] Read more.

Oxide metallurgy technology can improve the microstructure of a coarse-grained heat-affected zone (CGHAZ) but introduces extra inclusions. Local corrosion behavior of the CGHAZ of a Zr–Ti–Al–RE deoxidized steel was investigated in this work using theoretical calculations and experimental verification. The modified inclusions have a (Zr–Mg–Al–Ca–RE)O_x core claded by a CaS and TiN shell. CaS dissolves first, followed by the oxide core, leaving TiN parts. This confirms that the addition of rare earth can reduce lattice distortion and prevent a galvanic couple between the inclusions and the matrix, while the chemical dissolution of CaS causes localized acidification, resulting in the pitting corrosion initiation. Full article

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19 pages, 5358 KiB

Open AccessArticle

Hydro- and Icephobic Properties and Durability of Epoxy Gelcoat Modified with Double-Functionalized Polysiloxanes

by Katarzyna Ziętkowska, Rafał Kozera, Bartłomiej Przybyszewski, Anna Boczkowska, Bogna Sztorch, Daria Pakuła, Bogdan Marciniec and Robert Edward Przekop

Materials 2023, 16(2), 875; https://doi.org/10.3390/ma16020875 - 16 Jan 2023

Cited by 5 | Viewed by 1720

Abstract

Anti-icing coatings have provided a very good alternative to current, uneconomic, active deicing methods, and their use would bring a number of significant benefits to many industries, such as aviation and energy. Some of the most promising icephobic surfaces are those with hydrophobic [...] Read more.

Anti-icing coatings have provided a very good alternative to current, uneconomic, active deicing methods, and their use would bring a number of significant benefits to many industries, such as aviation and energy. Some of the most promising icephobic surfaces are those with hydrophobic properties. However, the relationship between hydrophobicity and low ice adhesion is not yet clearly defined. In this work, chemical modification of an epoxy gelcoat with chemical modifiers from the group of double organofunctionalized polysiloxanes (generally called multifunctionalized organosilicon compounds (MFSCs)) was applied. The anti-icing properties of manufactured coatings were determined by means of measurements of shear strength between the ice layer and the modified surface, conducted using a tensile machine. In the work, tests were also performed on the roughness, wettability, and durability of the properties in an aging chamber. It was found that the performed modifications of the coating’s chemical composition by the addition of polysiloxanes enabled us to reduce ice adhesion by 51% and to increase the water contact angle by 14% in comparison to the neat gelcoat. A reduction in ice adhesion was also observed with the increasing water contact angle and with decreasing surface roughness. In addition, only one modification recorded an increase in ice adhesion after exposure in the aging chamber. Full article

(This article belongs to the Special Issue New Polymeric Materials Modified with Silicones, Functional Silanes, Silica and Silicates)

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23 pages, 8301 KiB

Open AccessArticle

Behaviour and Microstructural Characteristics of Lime-GGBS-Treated Kaolin Clay Contaminated with Gypsum

by Jeremiah J. Jeremiah, Samuel J. Abbey, Colin A. Booth and Anil Kashyap

Materials 2023, 16(2), 874; https://doi.org/10.3390/ma16020874 - 16 Jan 2023

Cited by 3 | Viewed by 1588

Abstract

In this experimental study, the physico-mechanical and microstructural properties of sulphate-bearing clays have been investigated. Sulphate bearing soils constituted by mixing kaolin and gypsum at 0%, 15%, 25%, and 35% gypsum contents were treated with 12% ordinary Portland cement (OPC) and 4%Lime (L) [...] Read more.

In this experimental study, the physico-mechanical and microstructural properties of sulphate-bearing clays have been investigated. Sulphate bearing soils constituted by mixing kaolin and gypsum at 0%, 15%, 25%, and 35% gypsum contents were treated with 12% ordinary Portland cement (OPC) and 4%Lime (L) and 8% ground granulated blast furnace slag (GGBS) and subjected to compaction, swell, unconfined compressive strength (UCS), California bearing ratio (CBR), and scanning electron microscopy (SEM) and energy dispersive spectrometry (EDX) analyses. The results of the study showed that the use of L-GGBS improved the soaked CBRs of the treated samples by over 43% when compared to OPC-treated samples after 7-days curing. A reduction in water absorption by 82% was also observed with L-GGBS treatment after 28-days curing. The UCS results also showed better performance with L-GGBS treatment exceeding 856% at 28 days. The effect of increased cementitious product with increasing gypsum content was negated by simultaneous and rapid growth of ettringite minerals which reduced the strength and increased swelling of OPC treated samples up to 18.92%, exceeding allowable limits of 2.5% as specified in Highway Agency Advice Note HA 74/07. The L-GGBS treated gypseous soil samples meet the strength requirement for stabilised sub-base (CS) and stabilised road-bases (CB1 and CB2) as described in TRL ORN31. Hence, the use of L-GGBS combination was found to be effective in ameliorating sulphate-induced expansion and therefore encouraged in the stabilisation of subgrade and road-base materials with high sulphate contents. Full article

(This article belongs to the Special Issue Cement, Gypsum, and Lime Composites: Methods, Models, Kinetics, and Recent Advances)

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14 pages, 10062 KiB

Open AccessArticle

Effect of Process Parameters on Weld Quality in Vortex- Friction Stir Welding of 6061-T6 Aluminum Alloy

by Xiaochao Liu, Wentao Li, Yunqian Zhen, Luanluan Jia, Yongzhe Li and Xianjun Pei

Materials 2023, 16(2), 873; https://doi.org/10.3390/ma16020873 - 16 Jan 2023

Cited by 3 | Viewed by 1561

Abstract

Vortex- friction stir welding (VFSW) utilizes a stir bar made of an identical material to the workpiece to rub the workpiece’s top surface, which avoids the keyhole defect in conventional friction stir welding. It presents great potential in the repair field of aluminum [...] Read more.

Vortex- friction stir welding (VFSW) utilizes a stir bar made of an identical material to the workpiece to rub the workpiece’s top surface, which avoids the keyhole defect in conventional friction stir welding. It presents great potential in the repair field of aluminum alloys. In this study, the effect of stir bar diameter, rotation speed, and welding speed on the weld formation was investigated in the VFSW of 6061-T6 aluminum alloy. The weld macrostructure, penetration, and mechanical properties were characterized. The results show that a large diameter of the stir bar can enhance the vortex material flow, increase the heat input, and eliminate the incomplete-penetration defect. The increase in rotation speed within limits can enhance the weld penetration and the mechanical properties of the weld nugget zone (WNZ). However, too high a rotation speed reduces the weld penetration and weakens the mechanical properties of the WNZ. The increase in welding speed reduces the weld penetration but enhances the mechanical properties of the heat affected zone. The incomplete-penetration defect significantly weakens the ductility of the VFSW joint. It can be eliminated by enlarging the stir bar diameter and choosing a moderate rotation speed and a lower welding speed. Full article

(This article belongs to the Special Issue Advances in Materials Joining and Additive Manufacturing)

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17 pages, 3818 KiB

Open AccessArticle

Characterization and under Water Action Behaviour of a New Plaster-Based Lightened Composites for Precast

by Manuel Álvarez, Daniel Ferrández, Patricia Guijarro-Miragaya and Carlos Morón

Materials 2023, 16(2), 872; https://doi.org/10.3390/ma16020872 - 16 Jan 2023

Cited by 6 | Viewed by 1360

Abstract

Plaster is a construction material widely used for the production of prefabricated parts in building construction due to its high capacity for hygrothermal regulation, its good mechanical performance, and its fireproof nature, among other factors. Its historical use has been linked to ornamental [...] Read more.

Plaster is a construction material widely used for the production of prefabricated parts in building construction due to its high capacity for hygrothermal regulation, its good mechanical performance, and its fireproof nature, among other factors. Its historical use has been linked to ornamental elements, although more recent research is oriented towards the industrialisation of plaster composites and the design of prefabricated parts for false ceilings and interior partitions. In this work, the behaviour against water of four new plaster-based composite materials is studied, using additions of two types of super absorbent polymers (sodium polyacrylate and potassium polyacrylate) and a lightening material (vermiculite) in their manufacturing process. In addition, the transmission of water vapour through the samples was studied together with the water absorption capacity of the samples in order to check the suitability of the use of plaster-based materials exposed to these environments. The results of this study show that composites with the addition of super absorbent polymers as well as vermiculite significantly improve their water performance compared to traditional materials up to 7.3% water absorption with a minimal (13%) reduction in mechanical strength compared to current materials with similar additions. In this sense, a plaster material is obtained with wide possibilities of application in the construction sector that favours the development of sustainable and quality buildings, in line with Goal 9 for Sustainable Development included in the 2030 Agenda. Full article

(This article belongs to the Special Issue Advances in Thermal and Mechanical Properties of Polymeric Materials)

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16 pages, 597 KiB

Open AccessArticle

On the Need for Deconvolution Analysis of Experimental and Simulated Thermoluminescence Glow Curves

by George Kitis and Vasilis Pagonis

Materials 2023, 16(2), 871; https://doi.org/10.3390/ma16020871 - 16 Jan 2023

Cited by 2 | Viewed by 1104

Abstract

Simulation studies of thermoluminescence (TL) and other stimulated luminescence phenomena are a rapidly growing area of research. The presence of competition effects between luminescence pathways leads to the complex nature of luminescence signals, and therefore, it is necessary to investigate and validate the [...] Read more.

Simulation studies of thermoluminescence (TL) and other stimulated luminescence phenomena are a rapidly growing area of research. The presence of competition effects between luminescence pathways leads to the complex nature of luminescence signals, and therefore, it is necessary to investigate and validate the various methods of signal analysis by using simulations. The present study shows that in simulations of luminescence signals originating from multilevel phenomenological models, it is not possible to extract mathematically the individual information for each peak in the signal. It is further shown that computerized curve deconvolution analysis is the only reliable tool for extracting the various kinetic parameters. Simulation studies aim to explain experimental results, and therefore, it is necessary to validate simulation results by comparing with experiments. In this paper, testing of simulation results is performed using two methods. In the first method, the influence of competition effects is tested by comparing the input model parameters with the output values from the deconvolution analysis. In the second method, the agreement with experimental results is tested using the properties of well-known glow peaks with very high repeatability among TL laboratories, such as the 110 °C glow peak of quartz. Full article

(This article belongs to the Special Issue Advanced Luminescent Materials and Devices)

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23 pages, 8288 KiB

Open AccessArticle

Influence of Waste Basalt Powder Addition on the Microstructure and Mechanical Properties of Autoclave Brick

by Paulina Kostrzewa-Demczuk, Anna Stepien, Ryszard Dachowski and Rogério Barbosa da Silva

Materials 2023, 16(2), 870; https://doi.org/10.3390/ma16020870 - 16 Jan 2023

Cited by 1 | Viewed by 1710

Abstract

In the production of building materials, there has been an increased interest in the use of by-products and industrial waste in recent years. Such modifications make it possible to solve not only technical and economic problems, but also environmental problems. This article describes [...] Read more.

In the production of building materials, there has been an increased interest in the use of by-products and industrial waste in recent years. Such modifications make it possible to solve not only technical and economic problems, but also environmental problems. This article describes the use of basalt powder waste in sand-lime products (silicates). The aim of the study was to manage basalt powder waste and to investigate the changes it causes in sand-lime products. The article describes the planning of the experiment, which directly determines the number of samples and their composition, which was necessary to conducting a full analysis and correctly illustrating the relationships occurring in the samples. Basic tests were carried out: compressive strength, density and water absorption, as well as optical tests and scanning microscopy. Based on the research conducted, it was concluded that the use of basalt powder as a component of sand-lime products has positive effects. Studies show that the best results are achieved with a proportion of powder in the raw material mass of about 10%—the compressive strength reaches almost 30 MPa, which is almost twice that of traditional silicate. Full article

(This article belongs to the Special Issue Recycled Materials in Civil Engineering Application)

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20 pages, 5891 KiB

Open AccessArticle

Study of Chloride Ion Diffusion in Coral Aggregate Seawater Concrete with Different Water–Cement Ratios under Load

by Guangmin Dai, Qing Wu, Kailong Lu, Shiliang Ma, Wei Wang, Hao Zhou, Chenggong Cai, Zuocheng Han and Jiaming Chen

Materials 2023, 16(2), 869; https://doi.org/10.3390/ma16020869 - 16 Jan 2023

Cited by 1 | Viewed by 1267

Abstract

This study was conducted to investigate the chloride ion transport in coral aggregate seawater concrete (CASC) with varying water–cement ratios under different loads. The ultimate compressive strength was obtained by conducting compression testing of three groups of CASC with different water–cement ratios. Steady [...] Read more.

This study was conducted to investigate the chloride ion transport in coral aggregate seawater concrete (CASC) with varying water–cement ratios under different loads. The ultimate compressive strength was obtained by conducting compression testing of three groups of CASC with different water–cement ratios. Steady loads of 0%, 10%, and 20% of their respective ultimate compressive strengths were applied to the concrete specimens with different water–cement ratios. After being subjected to a seawater erosion test for 30, 60, 90, 120, and 180 days, the chloride ion concentration at different depths was measured to determine the chloride ion diffusion coefficient. Meanwhile, the chloride ion diffusion coefficients of CASC were verified by comparing them with results obtained from numerical simulations performed using COMSOL software. The test results show that the internal pore space of CASC expands, leading to acceleration of the chloride ion transport rate when applied loads are increased. The initial chloride ion concentration of CASC rises as the water–cement ratio rises, and the concentration gradient formed with artificial seawater lowers, decreasing the chloride ion transport rate. When the water cement ratio decreases and the load increases, the diffusion coefficient increases. Using the numerical simulation method of COMSOL software, it was proved that the model has good applicability and accuracy in predicting chloride ion transport in CASC. Full article

(This article belongs to the Special Issue Mechanical Performance of Composite Geomaterials)

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11 pages, 4262 KiB

Open AccessEditor’s ChoiceArticle

Construction of Z-Scheme TiO₂/Au/BDD Electrodes for an Enhanced Electrocatalytic Performance

by Kai Zhang, Kehao Zhang, Yuxiang Ma, Hailong Wang, Junyong Shao, Mingliang Li, Gang Shao, Bingbing Fan, Hongxia Lu, Hongliang Xu, Rui Zhang and Huanhuan Shi

Materials 2023, 16(2), 868; https://doi.org/10.3390/ma16020868 - 16 Jan 2023

Cited by 1 | Viewed by 1550

Abstract

TiO₂/Au/BDD composites with a Z-scheme structure was prepared by orderly depositing gold (Au) and titanium dioxide (TiO₂) on the surface of a boron-doped diamond (BDD) film using sputtering and electrophoretic deposition methods. It was found that the introduction of [...] Read more.

TiO₂/Au/BDD composites with a Z-scheme structure was prepared by orderly depositing gold (Au) and titanium dioxide (TiO₂) on the surface of a boron-doped diamond (BDD) film using sputtering and electrophoretic deposition methods. It was found that the introduction of Au between TiO₂ and the BDD, not only could reduce their contact resistance, to increase the carrier transport efficiency, but also could improve the surface Hall mobility of the BDD electrode. Meanwhile, the designed Z-scheme structure provided a fast channel for the electrons and holes combination, to promote the effective separation of the electrons and holes produced in TiO₂ and the BDD under photoirradiation. The electrochemical characterization elucidated that these modifications of the structure obviously enhanced the electrocatalytic performance of the electrode, which was further verified by the simulated wastewater degradation experiments with reactive brilliant red X-3B. In addition, it was also found that the photoirradiation effectively enhanced the pollution degradation efficiency of the modified electrode, especially for the TiO₂/Au/BDD-30 electrode. Full article

(This article belongs to the Section Carbon Materials)

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16 pages, 4890 KiB

Open AccessArticle

Nanosizing Approach—A Case Study on the Thermal Decomposition of Hydrazine Borane

by Nur Ain Abu Osman, Nor Izzati Nordin, Khai Chen Tan, Nur Aida Hanisa An Hosri, Qijun Pei, Eng Poh Ng, Muhammad Bisyrul Hafi Othman, Mohammad Ismail, Teng He and Yong Shen Chua

Materials 2023, 16(2), 867; https://doi.org/10.3390/ma16020867 - 16 Jan 2023

Cited by 2 | Viewed by 1489

Abstract

Hydrazine borane (HB) is a chemical hydrogen storage material with high gravimetric hydrogen density of 15.4 wt%, containing both protic and hydridic hydrogen. However, its limitation is the formation of unfavorable gaseous by-products, such as hydrazine (N₂H₄) and ammonia [...] Read more.

Hydrazine borane (HB) is a chemical hydrogen storage material with high gravimetric hydrogen density of 15.4 wt%, containing both protic and hydridic hydrogen. However, its limitation is the formation of unfavorable gaseous by-products, such as hydrazine (N₂H₄) and ammonia (NH₃), which are poisons to fuel cell catalyst, upon pyrolysis. Previous studies proved that confinement of ammonia borane (AB) greatly improved the dehydrogenation kinetics and thermodynamics. They function by reducing the particle size of AB and establishing bonds between silica functional groups and AB molecules. In current study, we employed the same strategy using MCM-41 and silica aerogel to investigate the effect of nanosizing towards the hydrogen storage properties of HB. Different loading of HB to the porous supports were investigated and optimized. The optimized loading of HB in MCM-41 and silica aerogel was 1:1 and 0.25:1, respectively. Both confined samples demonstrated great suppression of melting induced sample foaming. However, by-products formation was enhanced over dehydrogenation in an open system decomposition owing to the presence of extensive Si-O···BH₃(HB) coordination that further promote the B-N bond cleavage to release N₂H₄. The Si-OH···N(N₂H₄) hydrogen bonding may further promote N-N bond cleavage in the resulting N₂H₄, facilitating the formation of NH₃. As temperature increases, the remaining N-N-B oligomeric chains in the porous silica, which are lacking the long-range structure may further undergo intramolecular B-N or N-N cleavage to release substantial amount of N₂H₄ or NH₃. Besides open system decomposition, we also reported a closed system decomposition where complete utilization of the N-H from the released N₂H₄ and NH₃ in the secondary reaction can be achieved, releasing mainly hydrogen upon being heated up to high temperatures. Nanosizing of HB particles via PMMA encapsulation was also attempted. Despite the ester functional group that may favor multiple coordination with HB molecules, these interactions did not impart significant change towards the decomposition of HB selectively towards dehydrogenation. Full article

(This article belongs to the Special Issue Technology and Applications of Green Energy-Based Materials)

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11 pages, 2937 KiB

Open AccessArticle

Improvement in Processability for Injection Molding of Bisphenol-A Polycarbonate by Addition of Low-Density Polyethylene

by Yuki Kuroda, Ken-Ichi Suzuki, Genzo Kikuchi, Nantina Moonprasith, Takumitsu Kida and Masayuki Yamaguchi

Materials 2023, 16(2), 866; https://doi.org/10.3390/ma16020866 - 16 Jan 2023

Cited by 2 | Viewed by 1569

Abstract

The rheological properties and processability at injection molding were studied for bisphenol-A polycarbonate (PC) that was modified by low-density polyethylene (LDPE) having a low shear viscosity. The LDPE addition significantly decreased the steady-state shear viscosity, especially in the high shear rate region. The [...] Read more.

The rheological properties and processability at injection molding were studied for bisphenol-A polycarbonate (PC) that was modified by low-density polyethylene (LDPE) having a low shear viscosity. The LDPE addition significantly decreased the steady-state shear viscosity, especially in the high shear rate region. The decrease did not originate from slippage on the die wall but due to interfacial slippage between the PC and dispersed LDPE droplets that deformed to the flow direction to a great extent. As a result of the viscosity decrease, injection pressure largely decreased from 150 to 110 MPa with the addition only 5 wt.% of LDPE. The enhanced flowability also reduced the warpage of the molded product significantly, demonstrating that the processability at injection molding was improved by the addition of LDPE. Full article

(This article belongs to the Special Issue Multiphase Systems with Polymeric Matrices: Polymer Blends and Composites II)

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13 pages, 3353 KiB

Open AccessArticle

Tailored Synthesis of Catalytically Active Cerium Oxide for N, N-Dimethylformamide Oxidation

by Cedric Karel Fonzeu Monguen, En-Jie Ding, Samuel Daniel, Jing-Yang Jia, Xiao-Hong Gui and Zhen-Yu Tian

Materials 2023, 16(2), 865; https://doi.org/10.3390/ma16020865 - 16 Jan 2023

Cited by 2 | Viewed by 1667

Abstract

Cerium oxide nanopowder (CeO_x) was prepared using the sol–gel method for the catalytic oxidation of N, N-dimethylformamide (DMF). The phase, specific surface area, morphology, ionic states, and redox properties of the obtained nanocatalyst were systematically characterized using XRD, BET, TEM, EDS, [...] Read more.

Cerium oxide nanopowder (CeO_x) was prepared using the sol–gel method for the catalytic oxidation of N, N-dimethylformamide (DMF). The phase, specific surface area, morphology, ionic states, and redox properties of the obtained nanocatalyst were systematically characterized using XRD, BET, TEM, EDS, XPS, H₂-TPR, and O₂-TPO techniques. The results showed that the catalyst had a good crystal structure and spherelike morphology with the aggregation of uniform small grain size. The catalyst showed the presence of more adsorbed oxygen on the catalyst surface. XPS and H₂-TPR have confirmed the reduction of Ce⁴⁺ species to Ce³⁺ species. O₂-TPR proved the reoxidability of CeO_x, playing a key role during DMF oxidation. The catalyst had a reaction rate of 1.44 mol g⁻¹_cat s⁻¹ and apparent activation energy of 33.30 ± 3 kJ mol⁻¹. The catalytic performance showed ~82 ± 2% DMF oxidation at 400 °C. This work’s overall results demonstrated that reducing Ce⁴⁺ to Ce³⁺ and increasing the amount of adsorbed oxygen provided more suitable active sites for DMF oxidation. Additionally, the catalyst was thermally stable (~86%) after 100 h time-on-stream DMF conversion, which could be a potential catalyst for industrial applications. Full article

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24 pages, 28257 KiB

Open AccessArticle

Experimental Study of Steel–Aluminum Joints Made by RSW with Insert Element and Adhesive Bonding

by Anna Guzanová, Janette Brezinová, Ján Varga, Miroslav Džupon, Marek Vojtko, Erik Janoško, Ján Viňáš, Dagmar Draganovská and Ján Hašuľ

Materials 2023, 16(2), 864; https://doi.org/10.3390/ma16020864 - 16 Jan 2023

Cited by 4 | Viewed by 2003

Abstract

This work focuses on joining steel to aluminum alloy using a novel method of joining by resistance spot welding with an insert element based on anticorrosive steel in combination with adhesive bonding. The method aims to reduce the formation of brittle intermetallic compounds [...] Read more.

This work focuses on joining steel to aluminum alloy using a novel method of joining by resistance spot welding with an insert element based on anticorrosive steel in combination with adhesive bonding. The method aims to reduce the formation of brittle intermetallic compounds by using short welding times and a different chemical composition of the insert element. In the experiment, deep-drawing low-carbon steel, HSLA zinc-coated steel and precipitation-hardened aluminum alloy 6082 T6 were used. Two types of adhesives—one based on rubber and the other based on epoxy resin—were used for adhesive bonding, while the surfaces of the materials joined were treated with a unique adhesion-improving agent based on organosilanes. The surface treatment improved the chemical bonding between the substrate and adhesive. It was proved, that the use of an insert element in combination with adhesive bonding is only relevant for those adhesives that have a load capacity just below the yield strength of the substrates. For bonded joints with higher load capacities, plastic deformation of the substrates occurs, which is unacceptable, and thus, the overall contribution of the insert element to the load capacity of the joint becomes negligible. The results also show that the combination of the resistance spot welding of the insert element and adhesive bonding facilitates the joining process of galvanized and nongalvanized steels with aluminum alloys and suppresses the effect of brittle intermetallic phases by minimizing the joining area and welding time. It is possible to use the synergistic effect of insert element welding and adhesive bonding to achieve increased energy absorption of the joint under stress. Full article

(This article belongs to the Special Issue Advances in the Experimentation and Numerical Modeling of Material Joining Processes)

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20 pages, 2710 KiB

Open AccessEditor’s ChoiceArticle

Modeling Cyclic Crack Propagation in Concrete Using the Scaled Boundary Finite Element Method Coupled with the Cumulative Damage-Plasticity Constitutive Law

by Omar Alrayes, Carsten Könke, Ean Tat Ooi and Khader M. Hamdia

Materials 2023, 16(2), 863; https://doi.org/10.3390/ma16020863 - 16 Jan 2023

Cited by 13 | Viewed by 2441

Abstract

Many concrete structures, such as bridges and wind turbine towers, fail mostly due to the fatigue rapture and bending, where the cracks are initiated and propagate under cyclic loading. Modeling the fracture process zone (FPZ) is essential to understanding the cracking behavior of [...] Read more.

Many concrete structures, such as bridges and wind turbine towers, fail mostly due to the fatigue rapture and bending, where the cracks are initiated and propagate under cyclic loading. Modeling the fracture process zone (FPZ) is essential to understanding the cracking behavior of heterogeneous, quasi-brittle materials such as concrete under monotonic and cyclic actions. The paper aims to present a numerical modeling approach for simulating crack growth using a scaled boundary finite element model (SBFEM). The cohesive traction law is explored to model the stress field under monotonic and cyclic loading conditions. In doing so, a new constitutive law is applied within the cohesive response. The cyclic damage accumulation during loading and unloading is formulated within the thermodynamic framework of the constitutive concrete model. We consider two common problems of three-point bending of a single-edge-notched concrete beam subjected to different loading conditions to validate the developed method. The simulation results show good agreement with experimental test measurements from the literature. The presented analysis can provide a further understanding of crack growth and damage accumulation within the cohesive response, and the SBFEM makes it possible to identify the fracture behavior of cyclic crack propagation in concrete members. Full article

(This article belongs to the Special Issue Computational Mechanics of Structures and Materials)

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15 pages, 3516 KiB

Open AccessArticle

Osteogenic Potential of a Polyethylene Glycol Hydrogel Functionalized with Poly-Lysine Dendrigrafts (DGL) for Bone Regeneration

by Sandra Roumani, Charlotte Jeanneau, Thomas Giraud, Aurélie Cotten, Marc Laucournet, Jérôme Sohier, Martine Pithioux and Imad About

Materials 2023, 16(2), 862; https://doi.org/10.3390/ma16020862 - 16 Jan 2023

Cited by 3 | Viewed by 1506

Abstract

Resorbable hydrogels are widely used as scaffolds for tissue engineering. These hydrogels can be modified by grafting dendrimer-linked functionalized molecules (dendrigrafts). Our aim was to develop a tunable poly(L-lysine) dendrigrafts (DGL)/PEG-based hydrogel with an inverse porosity and to investigate its osteogenic potential. DGL/PEG [...] Read more.

Resorbable hydrogels are widely used as scaffolds for tissue engineering. These hydrogels can be modified by grafting dendrimer-linked functionalized molecules (dendrigrafts). Our aim was to develop a tunable poly(L-lysine) dendrigrafts (DGL)/PEG-based hydrogel with an inverse porosity and to investigate its osteogenic potential. DGL/PEG hydrogels were emulsified in a surfactant-containing oil solution to form microspheres. The toxicity was evaluated on Human Vascular Endothelial Cells (HUVECs) and Bone Marrow Mesenchymal Stem Cells (hMSCs) with Live/Dead and MTT assays. The effects on HUVECs were investigated through C5 Complement expression by RT-PCR and C5a/TGF-β1 secretion by ELISA. Recruitment of hMSCs was investigated using Boyden chambers and their osteogenic differentiation was studied by measuring Alkaline Phosphatase activity (ALP) and BMP-2 secretion by ELISA. Adjusting the stirring speed during the emulsification allowed to obtain spherical microspheres with tunable diameters (10–1600 µm). The cell viability rate with the hydrogel was 95 and 100% with HUVECs and hMSCs, respectively. Incubating HUVECs with the biomaterial induced a 5-fold increase in TGF-β1 and a 3-fold increase in Complement C5a release. Furthermore, HUVEC supernatants obtained after incubation with the hydrogel induced a 2.5-fold increase in hMSC recruitment. The hydrogel induced a 3-fold increase both in hMSC ALP activity and BMP-2 secretion. Overall, the functionalized hydrogel enhanced the osteogenic potential by interacting with endothelial cells and hMSCs and represents a promising tool for bone tissue engineering. Full article

(This article belongs to the Section Biomaterials)

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14 pages, 8414 KiB

Open AccessArticle

Boron Carbide as an Electrode Material: Tailoring Particle Morphology to Control Capacitive Behaviour

by Suna Avcıoğlu, Merve Buldu-Akturk, Emre Erdem, Figen Kaya and Cengiz Kaya

Materials 2023, 16(2), 861; https://doi.org/10.3390/ma16020861 - 16 Jan 2023

Cited by 3 | Viewed by 2081

Abstract

In this study, boron carbide powders consisting mainly of nano/micro fibers or polyhedral-equiaxed particles were synthesized via the sol–gel technique, and the influence of particle morphology on electrochemical performance of boron carbide electrodes was investigated. Thermal decomposition duration of the precursors played a [...] Read more.

In this study, boron carbide powders consisting mainly of nano/micro fibers or polyhedral-equiaxed particles were synthesized via the sol–gel technique, and the influence of particle morphology on electrochemical performance of boron carbide electrodes was investigated. Thermal decomposition duration of the precursors played a determinant role in the final morphology of the synthesized boron carbide powders. The morphology of boron carbide powders successfully tuned from polyhedral-equiaxed (with ~3 µm average particle size) to nano/micro fibers by adjusting the thermal decomposition duration of precursors. The length and thickness of fibers were in the range of 30 to 200 µm and sub-micron to 5 µm, respectively. The electrochemical performance analysis of boron carbide powders has shown that the particle morphology has a considerable impact on the boron carbide electrodes electrochemical performance. It was found that the synergetic effects of polyhedral-equiaxed and nano/micro fiber morphologies exhibited the best electrochemical performance in supercapacitor devices, resulting in the power and energy density of 34.9 W/kg and 0.016 Wh/kg, respectively. Full article

(This article belongs to the Special Issue MXenes and Their Composites for Emerging Applications)

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12 pages, 8535 KiB

Open AccessArticle

Through-Silicon via Device Non-Destructive Defect Evaluation Using Ultra-High-Resolution Acoustic Microscopy System

by Tae Hyeong Kim, Dongchan Kang, Jeong Nyeon Kim and Ik Keun Park

Materials 2023, 16(2), 860; https://doi.org/10.3390/ma16020860 - 16 Jan 2023

Viewed by 1429

Abstract

In this study, an ultra-high-resolution acoustic microscopy system capable of non-destructively evaluating defects that may occur in thin film structures was fabricated. It is an integrated system of the control module, activation module, and data acquisition system, in which an integrated control software [...] Read more.

In this study, an ultra-high-resolution acoustic microscopy system capable of non-destructively evaluating defects that may occur in thin film structures was fabricated. It is an integrated system of the control module, activation module, and data acquisition system, in which an integrated control software for controlling each module was developed. The control module includes the mechanical, control, and ultrasonic parts. The activation module was composed of the pulser/receiver, and the data acquisition system included an A/D board. In addition, the integrated control software performs system operation and material measurement and includes an analysis program to analyze the obtained A-Scan signals in various ways. A through-silicon via (TSV) device, which is a semiconductor structure, was prepared to verify the performance of the developed system. The TSV device was analyzed using an ultra-high-resolution acoustic microscope. When the C-Scan images were analyzed, void defects with a size of 20 μm were detected at a depth of approximately 32.5 μm. A similar result could be confirmed when the cross section was measured using focused ion beam (FIB) microscopy. Full article

(This article belongs to the Special Issue Future Trends in Non-destructive Testing of Materials Using Ultrasound Technology)

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18 pages, 6365 KiB

Open AccessArticle

Characterization of Biodegradable Food Contact Materials under Gamma-Radiation Treatment

by Karolina Wiszumirska, Dorota Czarnecka-Komorowska, Wojciech Kozak, Marta Biegańska, Patrycja Wojciechowska, Maciej Jarzębski and Katarzyna Pawlak-Lemańska

Materials 2023, 16(2), 859; https://doi.org/10.3390/ma16020859 - 16 Jan 2023

Cited by 3 | Viewed by 1944

Abstract

Radiation is an example of one of the techniques used for pasteurization and sterilization in various packaging systems. There is a high demand for the evaluation of the possible degradation of new composites, especially based on natural raw materials. The results of experimental [...] Read more.

Radiation is an example of one of the techniques used for pasteurization and sterilization in various packaging systems. There is a high demand for the evaluation of the possible degradation of new composites, especially based on natural raw materials. The results of experimental research that evaluated the impact of radiation technology on biodegradable and compostable packaging materials up to 40 kGy have been presented. Two commercially available flexible composite films based on aliphatic–aromatic copolyesters (AA) were selected for the study, including one film with chitosan and starch (AA-CH-S) and the other with thermoplastic starch (AA-S). The materials were subjected to the influence of ionizing radiation from 10 to 40 kGy and then tests were carried out to check their usability as packaging material for the food industry. The results showed that the mechanical properties of AA-S films improved due to the radiation-induced cross-linking processes, while in the case of AA-CH-S films, a considerable decrease in the elongation at break was observed. The results also showed a decrease in the WVTR in the case of AA-S and no changes in barrier properties in the case of AA-CH-S. Both materials revealed no changes in the odor analyzed by sensory analysis. In the case of the AA-S films, the higher the radiation dose, the faster the biodegradation rate. In the case of the AA-CH-S film, the radiation did not affect biodegradation. The performed research enables the evaluation of the materials intended for direct contact with food. AA-CH-S was associated with unsatisfactory parameters (exceeding the overall migration limit and revealing color change during storage) while AA-S showed compliance at the level of tests carried out. The study showed that the AA-CH-S composite did not show a synergistic effect due to the presence of chitosan. Full article

(This article belongs to the Special Issue Modification and Processing of Biodegradable Polymers)

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13 pages, 3845 KiB

Open AccessArticle

Effect of Zr and Er Addition on the Microstructural Evolution of a Novel Al−Mg−Zn−Er−Zr Alloy during Hot Compression

by Minbao Wu, Wu Wei, Rui Zuo, Shengping Wen, Wei Shi, Xiaorong Zhou, Xiaolan Wu, Kunyuan Gao, Hui Huang and Zuoren Nie

Materials 2023, 16(2), 858; https://doi.org/10.3390/ma16020858 - 16 Jan 2023

Cited by 3 | Viewed by 1224

Abstract

The hot compression experiment of homogenized Al−5.2Mg−0.6Mn−0.29Zn−0.16Er–0.12Zr alloy was carried out by the Gleeble-3500 thermal simulation testing system. The deformation behavior in temperatures of 350~500 ℃ and deformation rates of 0.01~10 s⁻¹ was studied. The relationship between stress and strain rate and [...] Read more.

The hot compression experiment of homogenized Al−5.2Mg−0.6Mn−0.29Zn−0.16Er–0.12Zr alloy was carried out by the Gleeble-3500 thermal simulation testing system. The deformation behavior in temperatures of 350~500 ℃ and deformation rates of 0.01~10 s⁻¹ was studied. The relationship between stress and strain rate and deformation temperature was analyzed. The constitutive equation of alloy high-temperature deformation was constructed by the Zener–Hollomon method, and the hot working diagram with the true strain of 0.2 and 0.5 was constructed according to the dynamic material model. The research results show that flow stress has a positive correlation with strain rate and a negative correlation with temperature. The steady flow stress during deformation can be described by a hyperbolic sinusoidal constitutive equation. Adding Er and Zr into Al−Mg alloy can not only refine grains and strengthen precipitation but also form a core–shell Al₃(Er, Zr) phase. In the deformation process, Al₃(Er, Zr) precipitates can pin dislocations and inhibit dynamic recrystallization (DRX). Dynamic recovery (DRV) is dominant during hot deformation. The mechanism of dynamic recovery is dislocation motion. At high temperatures, Al₃(Er, Zr) can also inhibit grain coarsening. The average hot deformation activation energy of the alloy is 203.7 kJ/mol. This high activation energy can be due to the pinning effect of Er and Zr precipitates. The processing map of the alloy was analyzed and combined with the observation of microstructure, the hot deformation instability zone of the alloy was determined, and the suitable process parameters for hot deformation were obtained, which were 450~480 °C, and the strain rate is 0.01~0.09 s⁻¹. Full article

(This article belongs to the Special Issue Structure and Mechanical Properties of Alloys, Volume II)

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