Materials

24 pages, 4102 KiB

Open AccessArticle

Failure Mechanism and Control Mechanism of Intermittent Jointed Rock Bridge Based on Acoustic Emission (AE) and Digital Image Correlation (DIC)

by Hang Lin, Xing Zhang and Su Li

Materials 2024, 17(13), 3190; https://doi.org/10.3390/ma17133190 (registering DOI) - 29 Jun 2024

Abstract

Abstract: Deep foundation pit excavation is an important way to develop underground space in congested urban areas. Rock bridges prevent the interconnection of joints and control the deformation and failure of the rock mass caused by excavation for foundation pits. However, few studies [...] Read more.

Abstract: Deep foundation pit excavation is an important way to develop underground space in congested urban areas. Rock bridges prevent the interconnection of joints and control the deformation and failure of the rock mass caused by excavation for foundation pits. However, few studies have considered the acoustic properties and strain field evolution of rock bridges. To investigate the control mechanisms of rock bridges in intermittent joints, jointed specimens with varying rock bridge length and angle were prepared and subjected to laboratory uniaxial compression tests, employing acoustic emission (AE) and digital image correlation (DIC) techniques. The results indicated a linear and positive correlation between uniaxial compressive strength and length, and a non-linear and negative correlation with angle. Moreover, AE counts and cumulative AE counts increased with loading, suggesting surges due to the propagation and coalescence of wing and macroscopic cracks. Analysis of RA-AF values revealed that shear microcracks dominated the failure, with the ratio of shear microcracks increasing as length decreased and angle increased. Notably, angle exerted a more significant impact on the damage form. As length diminished, the failure plane’s transition across the rock bridge shifted from a complex coalescence of shear cracks to a direct merger of only coplanar shear cracks, reducing the number of tensile cracks required for failure initiation. The larger the angle, the higher the degree of coalescence of the rock bridge and, consequently, the fewer tensile cracks required for failure. The decrease of length and the increase of angle make rock mass more fragile. The more inclined the failure mode is to shear failure, the smaller the damage required for failure, and the more prone the areas is to rock mass disaster. These findings can provide theoretical guidance for the deformation and control of deep foundation pits. Full article

(This article belongs to the Special Issue Study on Cyclic Mechanical Behaviors of Materials – 2nd Edition)

14 pages, 9952 KiB

Open AccessArticle

Silver-Assisted Chemical Etching for the Fabrication of Porous Silicon N-Doped Nanohollow Carbon Spheres Composite Anodes to Enhance Electrochemical Performance

by Zimu Zhang, Yuqi Zhang, Weixuan Chen, Xiang Zhang, Le Yu and Zisheng Guan

Materials 2024, 17(13), 3189; https://doi.org/10.3390/ma17133189 (registering DOI) - 29 Jun 2024

Abstract

Silicon (Si) shows great potential as an anode material for lithium-ion batteries. However, it experiences significant expansion in volume as it undergoes the charging and discharging cycles, presenting challenges for practical implementation. Nanostructured Si has emerged as a viable solution to address these [...] Read more.

Silicon (Si) shows great potential as an anode material for lithium-ion batteries. However, it experiences significant expansion in volume as it undergoes the charging and discharging cycles, presenting challenges for practical implementation. Nanostructured Si has emerged as a viable solution to address these challenges. However, it requires a complex preparation process and high costs. In order to explore the above problems, this study devised an innovative approach to create Si/C composite anodes: micron-porous silicon (p-Si) was synthesized at low cost at a lower silver ion concentration, and then porous silicon-coated carbon (p-Si@C) composites were prepared by compositing nanohollow carbon spheres with porous silicon, which had good electrochemical properties. The initial coulombic efficiency of the composite was 76.51%. After undergoing 250 cycles at a current density of 0.2 A·g⁻¹, the composites exhibited a capacity of 1008.84 mAh·g⁻¹. Even when subjected to a current density of 1 A·g⁻¹, the composites sustained a discharge capacity of 485.93 mAh·g⁻¹ even after completing 1000 cycles. The employment of micron-structured p-Si improves cycling stability, which is primarily due to the porous space it provides. This porous structure helps alleviate the mechanical stress caused by volume expansion and prevents Si particles from detaching from the electrodes. The increased surface area facilitates a longer pathway for lithium-ion transport, thereby encouraging a more even distribution of lithium ions and mitigating the localized expansion of Si particles during cycling. Additionally, when Si particles expand, the hollow carbon nanospheres are capable of absorbing the resulting stress, thus preventing the electrode from cracking. The as-prepared p-Si utilizing metal-assisted chemical etching holds promising prospects as an anode material for lithium-ion batteries. Full article

(This article belongs to the Special Issue Advances in Lithium Battery Technologies)

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17 pages, 8221 KiB

Open AccessArticle

Synergistic Thermal and Electron Wind Force-Assisted Annealing for Extremely High-Density Defect Mitigation

by Md Hafijur Rahman, Sarah Todaro, Daudi Waryoba and Aman Haque

Materials 2024, 17(13), 3188; https://doi.org/10.3390/ma17133188 (registering DOI) - 29 Jun 2024

Abstract

This study investigates the effectiveness of combined thermal and athermal stimuli in mitigating the extremely high-density nature of dislocation networks in the form of low-angle grain boundaries in FeCrAl alloy. Electron wind force, generated from very low duty cycle and high current density [...] Read more.

This study investigates the effectiveness of combined thermal and athermal stimuli in mitigating the extremely high-density nature of dislocation networks in the form of low-angle grain boundaries in FeCrAl alloy. Electron wind force, generated from very low duty cycle and high current density pulses, was used as the athermal stimulus. The electron wind force stimulus alone was unable to remove the residual stress (80% low-angle grain boundaries) due to cold rolling to 25% thickness reduction. When the duty cycle was increased to allow average temperature of 100 °C, the specimen could be effectively annealed in 1 min at a current density of 3300 A/mm². In comparison, conventional thermal annealing requires at least 750 °C and 1.5 h. For specimens with 50% thickness reduction (85% low-angle grain boundaries), the electron wind force was again unable to anneal the defects even at 3300 A/mm² current density and average temperature of 100 °C. Intriguingly, allowing average concurrent temperature of 200 °C eliminated almost all the low-angle grain boundaries at a current density of 700 A/mm², even lower than that required for the 25% thickness reduced specimens. Comprehensive electron and X-ray diffraction evidence show that alloys with extremely high defect density can be effectively annealed in less than a minute at approximately 200 °C, offering a substantial improvement over conventional high-temperature annealing. Full article

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

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13 pages, 4101 KiB

Open AccessArticle

Phosphor Ceramic Composite for Tunable Warm White Light

by Ross A. Osborne, Nerine J. Cherepy, Peter S. Bleier, Romain M. Gaume and Stephen A. Payne

Materials 2024, 17(13), 3187; https://doi.org/10.3390/ma17133187 (registering DOI) - 29 Jun 2024

Abstract

Composite phosphor ceramics for warm white LED lighting were fabricated with K₂SiF₆:Mn⁴⁺ (KSF) as both a narrowband red phosphor and a translucent matrix in which yellow-emitting Y₃Al₅O₁₂:Ce³⁺ (YAG) particles were dispersed. [...] Read more.

Composite phosphor ceramics for warm white LED lighting were fabricated with K₂SiF₆:Mn⁴⁺ (KSF) as both a narrowband red phosphor and a translucent matrix in which yellow-emitting Y₃Al₅O₁₂:Ce³⁺ (YAG) particles were dispersed. The emission spectra of these composites under blue LED excitation were studied as a function of YAG loading and thickness. Warm white light with a color temperature of 2716 K, a high CRI of 92.6, and an R9 of 77.6 was achieved. A modest improvement in the thermal conductivity of the KSF ceramic of up to 9% was observed with the addition of YAG particles. In addition, a simple model was developed for predicting the emission spectra based on several parameters of the composite ceramics and validated with the experimental results. The emission spectrum can be tuned by varying the dopant concentrations, thickness, YAG loading, and YAG particle size. This work demonstrates the utility of KSF/YAG composite phosphor ceramics as a means of producing warm white light, which are potentially suitable for higher-drive applications due to their increased thermal conductivity and reduced droop compared with silicone-dispersed phosphor powders. Full article

(This article belongs to the Special Issue Study on Rare Earth Doped Luminescent Materials and Transparent Ceramics)

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15 pages, 4552 KiB

Open AccessArticle

Synthesis and Evaluation of Gelatin–Chitosan Biofilms Incorporating Zinc Oxide Nanoparticles and 5-Fluorouracil for Cancer Treatment

by Viswanathan Kaliyaperumal, Srilekha Rajasekaran, Rajkumar Kanniah, Dhinakaraj Gopal, Ganeshraja Ayyakannu Sundaram and Alagarsamy Santhana Krishna Kumar

Materials 2024, 17(13), 3186; https://doi.org/10.3390/ma17133186 (registering DOI) - 29 Jun 2024

Abstract

In this study, a novel multifunctional biofilm was fabricated using a straightforward casting process. The biofilm comprised gelatin, chitosan, 5-fluorouracil (5-FU)-conjugated zinc oxide nanoparticles, and polyvinyl alcohol plasticized with glycerol. The 5-FU-conjugated nanoparticles were synthesized via a single-step co-precipitation process, offering a unique [...] Read more.

In this study, a novel multifunctional biofilm was fabricated using a straightforward casting process. The biofilm comprised gelatin, chitosan, 5-fluorouracil (5-FU)-conjugated zinc oxide nanoparticles, and polyvinyl alcohol plasticized with glycerol. The 5-FU-conjugated nanoparticles were synthesized via a single-step co-precipitation process, offering a unique approach. Characterization confirmed successful drug conjugation, revealing bar-shaped nanoparticles with sizes ranging from 90 to 100 nm. Drug release kinetics followed the Korsmeyer–Peppas model, indicating controlled release behavior. Maximum swelling ratio studies of the gelatin–chitosan film showed pH-dependent characteristics, highlighting its versatility. Comprehensive analysis using SEM, FT-IR, Raman, and EDX spectra confirmed the presence of gelatin, chitosan, and 5-FU/ZnO nanoparticles within the biofilms. These biofilms exhibited non-cytotoxicity to human fibroblasts and significant anticancer activity against skin cancer cells, demonstrating their potential for biomedical applications. This versatility positions the 5-FU/ZnO-loaded sheets as promising candidates for localized topical patches in skin and oral cancer treatment, underscoring their practicality and adaptability for therapeutic applications. Full article

(This article belongs to the Section Biomaterials)

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16 pages, 438 KiB

Open AccessReview

Application of Engineered Nanomaterials as Nanocatalysts in Catalytic Ozonation: A Review

by Rita M. F. Cardoso, Joaquim C. G. Esteves da Silva and Luís Pinto da Silva

Materials 2024, 17(13), 3185; https://doi.org/10.3390/ma17133185 (registering DOI) - 28 Jun 2024

Abstract

Given the growing scarcity of water and the continuous increase in emerging pollutants detected in water bodies, there is an imperative need to develop new, more effective, and sustainable treatments for wastewater. Advanced oxidation processes (AOPs) are considered a competitive technology for water [...] Read more.

Given the growing scarcity of water and the continuous increase in emerging pollutants detected in water bodies, there is an imperative need to develop new, more effective, and sustainable treatments for wastewater. Advanced oxidation processes (AOPs) are considered a competitive technology for water treatment. Specifically, ozonation has received notable attention as a promising approach for degrading organic pollutants in wastewater. However, different groups of pollutants are hardly degradable via single ozonation. With continuous development, it has been shown that using engineered nanomaterials as nanocatalysts in catalytic ozonation can increase efficiency by turning this process into a low-selective AOP for pollutant degradation. Nanocatalysts promote ozone decomposition and form active free radicals responsible for increasing the degradation and mineralization of pollutants. This work reviews the performances of different nanomaterials as homogeneous and heterogeneous nanocatalysts in catalytic ozonation. This review focuses on applying metal- and carbon-based engineered nanomaterials as nanocatalysts in catalytic ozonation and on identifying the main future directions for using this type of AOP toward wastewater treatment. Full article

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

9 pages, 1917 KiB

Open AccessArticle

Microstructure and Mechanical Properties of Multilayered Ti-Based Bulk Metallic Glass Composites Containing Various Thicknesses of Ti-Rich Laminates

by Shifeng Lin, Lei Zhang, Rushan Lin, Zhengwang Zhu and Haifeng Zhang

Materials 2024, 17(13), 3184; https://doi.org/10.3390/ma17133184 (registering DOI) - 28 Jun 2024

Abstract

In order to optimize the balance between strength and toughness, a series of multilayered Ti-based bulk metallic glass composites (BMGCs) with varying thicknesses of Ti-rich layers were successfully fabricated. The findings reveal that with an increase in the thickness of the Ti-rich layers, [...] Read more.

In order to optimize the balance between strength and toughness, a series of multilayered Ti-based bulk metallic glass composites (BMGCs) with varying thicknesses of Ti-rich layers were successfully fabricated. The findings reveal that with an increase in the thickness of the Ti-rich layers, both the flexural yield strength and ultimate strength decreased from 2066 MPa and 2717 MPa to 668 MPa and 1163 MPa, respectively. Conversely, there was a noticeable increase in flexural strain. The fracture toughness of these multilayered Ti-based BMGCs decreased as the thickness of the Ti-rich layers increased; nevertheless, it stabilized at approximately 80 MPa·m^1/2 when the thickness reached 100 μm. It was observed that a shift in the dominant deformation mode may be accountable for this phenomenon. These noteworthy characteristics suggest that adjusting the thickness of Ti-rich layers in multilayered BMGCs can effectively optimize mechanical performance, shedding light on the manufacturing of novel BMGCs with high performance. Full article

(This article belongs to the Special Issue Physical Metallurgy of Metals and Alloys II)

24 pages, 2093 KiB

Open AccessReview

Research Progress on the Oxidation Behavior of Ignition-Proof Magnesium Alloy and Its Effect on Flame Retardancy with Multi-Element Rare Earth Additions: A Review

by Duquan Zuo, Haolin Ding, Maoyong Zhi, Yi Xu, Zhongbo Zhang and Minghao Zhang

Materials 2024, 17(13), 3183; https://doi.org/10.3390/ma17133183 (registering DOI) - 28 Jun 2024

Abstract

The phenomenon of high-temperature oxidation in magnesium alloys constitutes a significant obstacle to their application in the aerospace field. However, the incorporation of active elements such as alloys and rare earth elements into magnesium alloys alters the organization and properties of the oxide [...] Read more.

The phenomenon of high-temperature oxidation in magnesium alloys constitutes a significant obstacle to their application in the aerospace field. However, the incorporation of active elements such as alloys and rare earth elements into magnesium alloys alters the organization and properties of the oxide film, resulting in an enhancement of their antioxidation capabilities. This paper comprehensively reviews the impact of alloying elements, solubility, intermetallic compounds (second phase), and multiple rare earth elements on the antioxidation and flame-retardant effects of magnesium alloys. The research progress of flame-retardant magnesium alloys containing multiple rare earth elements is summarized from two aspects: the oxide film and the matrix structure. Additionally, the existing flame-retardancy models for magnesium alloys and the flame-retardant mechanisms of various flame-retardant elements are discussed. The results indicate that the oxidation of rare earth magnesium alloys is a complex process determined by internal properties such as the structure and properties of the oxide film, the type and amount of rare earth elements added, the proportion of multiple rare earth elements, synergistic element effects, as well as external properties like heat treatment, oxygen concentration, and partial pressure. Finally, some issues in the development of multi-rare earth magnesium alloys are raised and the potential directions for the future development of rare earth flame-retardant magnesium alloys are discussed. This paper aims to promote an understanding of the oxidation behavior of flame-retardant magnesium alloys and provide references for the development of rare earth flame-retardant magnesium alloys with excellent comprehensive performance. Full article

(This article belongs to the Section Metals and Alloys)

17 pages, 5535 KiB

Open AccessArticle

Hot Deformation Constitutive Analysis and Processing Maps of Ultrasonic Melt Treated A5052 Alloy

by Sun-Ki Kim, Seung-Hyun Koo, Hoon Cho and Seong-Ho Ha

Materials 2024, 17(13), 3182; https://doi.org/10.3390/ma17133182 (registering DOI) - 28 Jun 2024

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Abstract

Hot deformation constitutive analysis and processing maps of ultrasonic melt treated (UST) A5052 alloy were carried out based on a hot torsion test in this study. The addition of the Al–Ti master alloy as a grain refiner with no UST produced a finer [...] Read more.

Hot deformation constitutive analysis and processing maps of ultrasonic melt treated (UST) A5052 alloy were carried out based on a hot torsion test in this study. The addition of the Al–Ti master alloy as a grain refiner with no UST produced a finer grain size than the UST and pure Ti sonotrode. The Al3Ti phase particles in the case of the Al–10Ti master alloy acted as a nucleus for grain refinement, while the Ti atoms dissolved in the melt from the sonotrode were considered to have less of a grain refinement effect, even under UST conditions, than the Al3Ti phase particles in the Al–Ti master alloy. The constitutive equations for each experimental condition by torsion test were derived. In the processing maps examined in this study, the flow instability region was not present under UST in the as-cast condition, but it existed under the no UST condition. The effects of UST examined in this study are considered as (i) the uniform distribution of Ti solutes from the sonotrode and (ii) the reduction of pores by the degassing effect. After the homogenization heat treatment, most instability regions disappeared because the microstructures became uniform following the decomposition of intermetallic compounds and distribution of solute elements. Full article

(This article belongs to the Special Issue Characterization of Metallic Materials: Microstructure, Forming and Heat Treatment (Second Edition))

16 pages, 5682 KiB

Open AccessArticle

Synthesis of Low-Silicon X-Type Zeolite from Lithium Slag and Its Fast Exchange Performance of Calcium and Magnesium Ions

by Yu Wang, Longbin Deng, Lin Zhang, Qun Cui and Haiyan Wang

Materials 2024, 17(13), 3181; https://doi.org/10.3390/ma17133181 (registering DOI) - 28 Jun 2024

Abstract

Without the addition of silicon and aluminum sources, a pure-phase KNaLSX zeolite was successfully synthesized from the residue (lithium slag), which was produced from spodumene in the production process of lithium carbonate. The KNaLSX samples were characterized by an X-ray Diffractometer (XRD), Scanning [...] Read more.

Without the addition of silicon and aluminum sources, a pure-phase KNaLSX zeolite was successfully synthesized from the residue (lithium slag), which was produced from spodumene in the production process of lithium carbonate. The KNaLSX samples were characterized by an X-ray Diffractometer (XRD), Scanning Electron Microscope (SEM), X-ray Fluorescence Spectrometer (XRF), Thermogravimetric Differential Thermal Analysis (TG-DTA), Fourier Transform Infrared Spectrometer (FT-IR), and N₂ adsorption measurement. The ion exchange capacity and the ion exchange rate of calcium and magnesium ions were measured as used for a detergent builder, and the results were compared with the standard zeolites (KNaLSX and 4A). The experimental results show that the pure-phase KNaLSX synthSynthesis and characterization of co-crystalline zeolite composite of LSX/esized from lithium slag has a SiO₂/Al₂O₃ ratio of 2.01 with a grain size of 3~4 μm, which is close to the commercial KNaLSX sample of a SiO₂/Al₂O₃ ratio of 2.0. The BET-specific surface area of KNaLSX is 715 m²/g, which is larger than the low-silicon X-type zeolite (LSX) synthesized from waste residue reported in the literature. The ion exchange rate constant of calcium and magnesium ions in KNaLSX is 5 times and 3 times that of 4A zeolite, respectively. KNaLSX also has a high ion exchange capacity for magnesium ion of 191 mgMgCO₃/g, which is 2 times than that of 4A zeolite, and a high ion exchange capacity for calcium ion of 302 mgCaCO₃/g, which meets the first-grade standard of zeolite for detergent builders in China. The work provides the basis for high-value resource utilization of lithium slag and the development of a detergent builder for rapid washing. Full article

(This article belongs to the Special Issue Application and Modification of Clay Minerals)

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26 pages, 4794 KiB

Open AccessArticle

Impact of Pyrolysis Temperature on the Physical and Chemical Properties of Non-Modified Biochar Produced from Banana Leaves: A Case Study on Ammonium Ion Adsorption

by Fernanda Pantoja, Sándor Beszédes, Tamás Gyulavári, Erzsébet Illés, Gábor Kozma and Zsuzsanna László

Materials 2024, 17(13), 3180; https://doi.org/10.3390/ma17133180 (registering DOI) - 28 Jun 2024

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Abstract

Given the current importance of using biochar for water treatment, it is important to study the physical–chemical properties to predict the behavior of the biochar adsorbent in contact with adsorbates. In the present research, the physical and chemical characteristics of three types of [...] Read more.

Given the current importance of using biochar for water treatment, it is important to study the physical–chemical properties to predict the behavior of the biochar adsorbent in contact with adsorbates. In the present research, the physical and chemical characteristics of three types of biochar derived from banana leaves were investigated, which is a poorly studied raw material and is considered an agricultural waste in some Latin American, Asian, and African countries. The characterization of non-modified biochar samples pyrolyzed at 300, 400, and 500 °C was carried out through pH, scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and specific surface area measurements. The adsorption properties of banana leaf-derived biochar were evaluated by ammonium ion adsorption experiments. The results demonstrated that the pyrolysis temperature has a large impact on the yield, structure, elemental composition, and surface chemistry of the biochar. Biochar prepared at 300 °C is the most efficient for NH₄⁺ adsorption, achieving a capacity of 7.0 mg of adsorbed NH₄⁺ on each gram of biochar used, while biochar samples prepared at 400 and 500 °C show lower values of 6.1 and 5.6 mg/g, respectively. The Harkins–Jura isotherm model fits the experimental data best for all biochar samples, demonstrating that multilayer adsorption occurs on our biochar. Full article

(This article belongs to the Special Issue Emerging Trends in Biomass-Derived Functional Materials)

14 pages, 3417 KiB

Open AccessArticle

An Extensive Study of the Influence of Key Flow Variables on Printed Line Quality Outcomes during Aerosol Jet Printing Using Coupled Three-Dimensional Numerical Models

by Haining Zhang, Haifeng Xu, Lin Cui, Zhenggao Pan, Pil-Ho Lee, Min-Kyo Jung and Joon-Phil Choi

Materials 2024, 17(13), 3179; https://doi.org/10.3390/ma17133179 (registering DOI) - 28 Jun 2024

Viewed by 31

Abstract

A three-dimensional (3D) numerical model was developed to explore the intricate aerodynamic mechanisms associated with aerosol jet printing (AJP). The proposed approach integrates computational fluid dynamics and discrete phase modeling, offering a comprehensive understanding of the deposition mechanisms of the AJP process. Initially, [...] Read more.

A three-dimensional (3D) numerical model was developed to explore the intricate aerodynamic mechanisms associated with aerosol jet printing (AJP). The proposed approach integrates computational fluid dynamics and discrete phase modeling, offering a comprehensive understanding of the deposition mechanisms of the AJP process. Initially, numerical solutions of the governing equations were obtained under the assumptions of compressible and laminar flows, facilitating an analysis of certain key flow variables, in this case, the sheath gas flow rate and carrier gas flow rate across the fluid domain. Subsequently, incorporating a Lagrangian discrete phase model allowed a detailed examination of the droplet behavior after nozzle ejection, considering the influence of the Saffman lift force. Finally, experiments were performed to elucidate the influence of key flow variables on the printed width. Generally, the measured printed line morphology and corresponding line electrical performance exhibited close conformity with the numerical model, demonstrating that the proposed numerical model is important for making well-informed decisions during process optimization. Full article

(This article belongs to the Special Issue State of the Art in Materials for Additive Manufacturing)

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16 pages, 8063 KiB

Open AccessArticle

Research on the Welding Process and Weld Formation in Multiple Solid-Flux Cored Wires Arc Hybrid Welding Process for Q960E Ultrahigh-Strength Steel

by Ting Xiang, Mingrui Zhang, Qiang Ma, Zhenlong Fang, Huan Li and Hao Wang

Materials 2024, 17(13), 3178; https://doi.org/10.3390/ma17133178 (registering DOI) - 28 Jun 2024

Viewed by 30

Abstract

This paper proposes a novel welding process for ultrahigh-strength steel. The effects of welding parameters on the welding process and weld formation were studied to obtain the optimal parameter window. It was found that the metal transfer modes of solid wires were primarily [...] Read more.

This paper proposes a novel welding process for ultrahigh-strength steel. The effects of welding parameters on the welding process and weld formation were studied to obtain the optimal parameter window. It was found that the metal transfer modes of solid wires were primarily determined by electrical parameters, while flux-cored wires consistently exhibited multiple droplets per pulse. The one droplet per pulse possessed better welding stability and weld formation, whereas the short-circuiting transfer or one droplet multiple pulses easily caused abnormal arc ignition that decreased welding stability, which could easily lead to a “sawtooth-shaped” weld formation or weld offset towards one side with more spatters. Thus, the electrical parameters corresponding to one droplet per pulse were identified as the optimal parameter window. Furthermore, the weld zone (WZ) was predominantly composed of AF, and the heat-affected zone (HAZ) primarily consisted of TM and LM. Consequently, the welded joint still exhibited excellent mechanical properties, particularly toughness, despite higher welding heat input. The average tensile strength reached 928 MPa, and the impact absorbed energy at −40 °C for the WZ and HAZ were 54 J and 126 J, respectively. In addition, the application of triple-wire welding for ultrahigh-strength steel (UHSS) demonstrated a significant enhancement in post-weld deposition rate, with increases of 106% and 38% compared to single-wire and twin-wire welding techniques, respectively. This process not only utilized flux-cored wire to enhance the mechanical properties of joints but also achieved high deposition rate welding. Full article

21 pages, 2484 KiB

Open AccessArticle

Use of Cohesive Approaches for Modelling Critical States in Fibre-Reinforced Structural Materials

by Vladislav Kozák and Jiří Vala

Materials 2024, 17(13), 3177; https://doi.org/10.3390/ma17133177 (registering DOI) - 28 Jun 2024

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Abstract

During the operation of structures, stress and deformation fields occur inside the materials used, which often ends in fatal damage of the entire structure. Therefore, the modelling of this damage, including the possible formation and growth of cracks, is at the forefront of [...] Read more.

During the operation of structures, stress and deformation fields occur inside the materials used, which often ends in fatal damage of the entire structure. Therefore, the modelling of this damage, including the possible formation and growth of cracks, is at the forefront of numerical and applied mathematics. The finite element method (FEM) and its modification will allow us to predict the behaviour of these structural materials. Furthermore, some practical applications based on cohesive approach are tested. The main effort is devoted to composites with fibres and searching for procedures for their accurate modelling, mainly in the area where damage can be expected to occur. The use of the cohesive approach of elements that represent the physical nature of energy release in front of the crack front has proven to be promising not only in the direct use of cohesive elements, but also in combination with modified methods of standard finite elements. Full article

(This article belongs to the Special Issue Methodology of the Design and Testing of Composite Structures)

13 pages, 764 KiB

Open AccessArticle

Wire Arc Additive Manufacturing of Aluminum Foams Using TiH2-Laced Welding Wires

by Marcel Köhler, Alexander Nikitin, Peter Sonnenfeld, Ralf Ossenbrink and Sven Jüttner

Materials 2024, 17(13), 3176; https://doi.org/10.3390/ma17133176 (registering DOI) - 28 Jun 2024

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Abstract

Composite materials made from aluminum foam are increasingly used in aerospace and automotive industries due to their low density, high energy absorption capacity, and corrosion resistance. Additive manufacturing processes offer several advantages over conventional manufacturing methods, such as the ability to produce significantly [...] Read more.

Composite materials made from aluminum foam are increasingly used in aerospace and automotive industries due to their low density, high energy absorption capacity, and corrosion resistance. Additive manufacturing processes offer several advantages over conventional manufacturing methods, such as the ability to produce significantly more geometrically complex components without the need for expensive tooling. Direct Energy Deposition processes like Wire Arc Additive Manufacturing (WAAM) enable the additive production of near-net-shape components at high build rates. This paper presents a technology for producing aluminum foam structures using WAAM. This paper’s focus is on the development of welding wires that are mixed with a foaming agent (TiH₂) and produce a foamed weld metal as well as their processing using MIG welding technology. Full article

(This article belongs to the Special Issue Design and Application of Additive Manufacturing: Volume II)

24 pages, 14155 KiB

Open AccessArticle

The Influence of Hybridization of Epoxy–Glass Laminates Modified with Metal Oxides and Graphite Particles

by Cezary Drenda, Przemysław Nosal, Kamil Badura and Patrycja Bazan

Materials 2024, 17(13), 3175; https://doi.org/10.3390/ma17133175 (registering DOI) - 28 Jun 2024

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Abstract

This study examined the impact of hybridization on the mechanical properties of glass–epoxy laminates by incorporating metal oxides and graphite particles into the resin matrix. Basic mechanical tests were conducted, followed by accelerated thermal aging tests. Results showed an increase in bending strength [...] Read more.

This study examined the impact of hybridization on the mechanical properties of glass–epoxy laminates by incorporating metal oxides and graphite particles into the resin matrix. Basic mechanical tests were conducted, followed by accelerated thermal aging tests. Results showed an increase in bending strength ranging from 12% to almost 30% depending on the used additive. Static tensile tests indicated a 10% increase in strength for materials modified with flake graphite. Accelerated aging tests resulted in a 20% decrease in elastic modulus and 10% decrease in tensile strength. Additives did not improve tensile strength but increased stiffness by 30% for laminates with flake graphite. Fatigue and conductivity tests were also performed, revealing enhanced thermal conductivity and reduced impedance in materials modified with graphite flakes. The study suggests that additives can enhance the mechanical properties of glass–epoxy laminates, making them suitable for applications in automotive and aerospace industries. Full article

(This article belongs to the Section Advanced and Functional Ceramics and Glasses)

21 pages, 3070 KiB

Open AccessArticle

Antifungal Hybrid Graphene–Transition-Metal Dichalcogenides Aerogels with an Ionic Liquid Additive as Innovative Absorbers for Preventive Conservation of Cultural Heritage

by George Gorgolis, Maria Kotsidi, Elena Messina, Valentina Mazzurco Miritana, Gabriella Di Carlo, Elsa Lesaria Nhuch, Clarissa Martins Leal Schrekker, Jeniffer Alves Cuty, Henri Stephan Schrekker, George Paterakis, Charalampos Androulidakis, Nikos Koutroumanis and Costas Galiotis

Materials 2024, 17(13), 3174; https://doi.org/10.3390/ma17133174 (registering DOI) - 28 Jun 2024

Viewed by 90

Abstract

The use and integration of novel materials are increasingly becoming vital tools in the field of preventive conservation of cultural heritage. Chemical factors, such as volatile organic compounds (VOCs), but also environmental factors such as high relative humidity, can lead to degradation, oxidation, [...] Read more.

The use and integration of novel materials are increasingly becoming vital tools in the field of preventive conservation of cultural heritage. Chemical factors, such as volatile organic compounds (VOCs), but also environmental factors such as high relative humidity, can lead to degradation, oxidation, yellowing, and fading of the works of art. To prevent these phenomena, highly porous materials have been developed for the absorption of VOCs and for controlling the relative humidity. In this work, graphene and transition-metal dichalcogenides (TMDs) were combined to create three-dimensional aerogels that absorb certain harmful substances. More specifically, the addition of the TMDs molybdenum disulfide and tungsten disulfide in such macrostructures led to the selective absorption of ammonia. Moreover, the addition of the ionic liquid 1-hexadecyl-3-methylimidazolium chloride promoted higher rates of VOCs absorption and anti-fungal activity against the fungus Aspergillus niger. These two-dimensional materials outperform benchmark porous absorbers in the absorption of all the examined VOCs, such as ammonia, formic acid, acetic acid, formaldehyde, and acetaldehyde. Consequently, they can be used by museums, galleries, or even storage places for the perpetual protection of works of art. Full article

(This article belongs to the Special Issue Materials in Cultural Heritage: Analysis, Testing, and Preservation)

29 pages, 10789 KiB

Open AccessReview

Overview of Multi-Scale Simulation Techniques for Three Typical Steel Manufacturing Processes

by Cheng-Hui Xia, Kaiyang Wang, Xuexia Song, Weiming Pan, Wei Li, Hong-Hui Wu, Kun Dou, Yuantao Xu, Zelin Tong, Shaojie Lv, Jingzhou Lu, Shuize Wang, Wanlin Wang, Xuejun Jin and Xinping Mao

Materials 2024, 17(13), 3173; https://doi.org/10.3390/ma17133173 (registering DOI) - 28 Jun 2024

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Abstract

Steel products typically undergo intricate manufacturing processes, commencing from the liquid phase, with casting, hot rolling, and laminar cooling being among the most crucial processes. In the background of carbon neutrality, thin-slab casting and direct rolling (TSCR) technology has attracted significant attention, which [...] Read more.

Steel products typically undergo intricate manufacturing processes, commencing from the liquid phase, with casting, hot rolling, and laminar cooling being among the most crucial processes. In the background of carbon neutrality, thin-slab casting and direct rolling (TSCR) technology has attracted significant attention, which integrates the above three processes into a simpler and more energy-efficient sequence compared to conventional methods. Multi-scale computational modeling and simulation play a crucial role in steel design and optimization, enabling the prediction of properties and microstructure in final steel products. This approach significantly reduces the time and cost of production compared to traditional trial-and-error methodologies. This study provides a review of cross-scale simulations focusing on the casting, hot-rolling, and laminar cooling processes, aiming at presenting the key techniques for realizing cross-scale simulation of the TSCR process. Full article

(This article belongs to the Section Manufacturing Processes and Systems)

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19 pages, 3645 KiB

Open AccessArticle

Cu- and Fe-Doped Ni-Mn-Sn Shape Memory Alloys with Enhanced Mechanical and Magnetocaloric Properties

by Siyao Ma, Xuexi Zhang, Guangping Zheng, Mingfang Qian and Lin Geng

Materials 2024, 17(13), 3172; https://doi.org/10.3390/ma17133172 (registering DOI) - 28 Jun 2024

Viewed by 99

Abstract

Ni-Mn-Sn-based ferromagnetic shape memory alloys (FSMAs) are multifunctional materials that are promising for solid-state refrigeration applications based on the magnetocaloric effect (MCE) and elastocaloric effect (eCE). However, a combination of excellent multi-caloric properties, suitable operating temperatures, and mechanical properties cannot be well achieved [...] Read more.

Ni-Mn-Sn-based ferromagnetic shape memory alloys (FSMAs) are multifunctional materials that are promising for solid-state refrigeration applications based on the magnetocaloric effect (MCE) and elastocaloric effect (eCE). However, a combination of excellent multi-caloric properties, suitable operating temperatures, and mechanical properties cannot be well achieved in these materials, posing a challenge for their practical application. In this work, we systematically study the phase transformations and magnetic properties of Ni₅₀₋_xMn₃₈Sn₁₂Cu_x (x = 0, 2, 3, 4, 5, and 6) and Ni₅₀₋_yMn₃₈Sn₁₂Fe_y (y = 0, 1, 2, 3, 4, and 5) alloys, and the magnetic-structural phase diagrams of these alloy systems are reported. The influences of the fourth-element doping on the phase transitions and magnetic properties of the alloys are elucidated by first-principles calculations. This work demonstrates that the fourth-element doping of Ni-Mn-Sn-based FSMA is effective in developing multicaloric refrigerants for practical solid-state refrigeration. Full article

(This article belongs to the Special Issue Physical Metallurgy of Metals and Alloys (3rd Edition))

20 pages, 4531 KiB

Open AccessArticle

Experimental Study of Avalanche Damage Protection Methods for Main Steel Gas Pipelines

by Nurlan Zhangabay, Ulzhan Ibraimova, Timur Tursunkululy, Svetlana Buganova, Arman Moldagaliev and Bolat Duissenbekov

Materials 2024, 17(13), 3171; https://doi.org/10.3390/ma17133171 (registering DOI) - 28 Jun 2024

Viewed by 106

Abstract

This paper conducted an experimental study of reduced models of a main gas pipeline for avalanche damage considering operational conditions. Two options were considered as a method of avalanche damage prevention: single steel rings at the crack edges and steel winding with a [...] Read more.

This paper conducted an experimental study of reduced models of a main gas pipeline for avalanche damage considering operational conditions. Two options were considered as a method of avalanche damage prevention: single steel rings at the crack edges and steel winding with a winding pitch of 0.25 m. For the tension force, 5% of the steel wire breaking force was taken, which was equal to 1 mm. The ambient environment was simulated by a climatic chamber, where two options of temperature loads were considered: +20 °C and −10 °C. It was found that reinforcement with single rings of pipeline models under conditions of positive (+20 °C) and negative (−10 °C) temperatures showed that the crack opening width in the ring direction decreased 1.63 times and 1.9 times, accordingly. The crack length (longitudinal direction) decreased 2.18 times and 2.45 times, accordingly. The reinforcement of the pipeline models with prestressed wire winding on the crack propagation under conditions of positive (+20 °C) and negative (−10 °C) temperatures showed that the width of the crack opening in the ring direction decreased 1.5 times and 1.46 times, accordingly. The crack length (longitudinal direction) decreased 1.4 times and 1.44 times accordingly, which is a positive moment in addressing the issue of the localisation and stoppage of a crack fracture in main gas pipelines. Simultaneously, the analysis of the prestressed pipelines model test results on crack fracture propagation showed that single rings are more effective, which decreased the crack opening width by 1.1 times and the crack length up to 1.5. Therefore, the experimental results obtained positively complement the available methods of crack localisation in main gas pipelines, which can be used by engineers and research communities when designing or reinforcing existing operating main steel gas pipelines. Full article

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19 pages, 3307 KiB

Open AccessArticle

Optimization of Ultrasonic-Assisted Incremental Sheet Forming

by Ngoc-Tuan La, Quoc-Huy Ngo, Van-Dam Vu, Thu-Ha Mai and Ky-Thanh Ho

Materials 2024, 17(13), 3170; https://doi.org/10.3390/ma17133170 - 28 Jun 2024

Viewed by 110

Abstract

Implementing the ultrasonic vibration-assisted incremental sheet-forming (UISF) process has been proven to significantly reduce the forming force, improve the surface quality, and enhance the accuracy of the sheet-forming process. However, such effectiveness has primarily focused on easily deformable materials (such as AA1050 and [...] Read more.

Implementing the ultrasonic vibration-assisted incremental sheet-forming (UISF) process has been proven to significantly reduce the forming force, improve the surface quality, and enhance the accuracy of the sheet-forming process. However, such effectiveness has primarily focused on easily deformable materials (such as AA1050 and AA1060 aluminum alloys) and small step-down sizes (from 0.3 mm to 0.5 mm). To further enhance the process, it is crucial to study larger step-down sizes and harder materials. In this study, a series of UISF experiments were conducted, with step-down sizes ranging from 0.5 mm to 1.5 mm and feed rates ranging from 200 mm/min to 1200 mm/min. The influence of ultrasonic vibration on the effectiveness of force reduction and the optimal operation parameters was experimentally tested. Forming aluminum alloy AA5052, a difficult-to-deform material with two thicknesses of 0.5 mm and 1.0 mm, indicates that the axial force Fz and the tool movement resistance force Fy tend to decrease significantly with ultrasonic vibration assistance. Optimal equations for force reduction Fz and Fy have been developed for plate thickness based on the step-down size and feed rate. The optimal results show that for 1.0 mm thickness, reductions in Fz and Fy can reach 58.73% and 69.17%, respectively, and that of 64.17% and 71.98%, respectively, for 0.5 mm thickness. Full article

(This article belongs to the Section Metals and Alloys)

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14 pages, 4823 KiB

Open AccessArticle

Multiscale Progressive Failure Analysis for Composite Stringers Subjected to Compressive Load

by Jian Shi, Jianjiang Zeng, Jie Zheng, Furui Shi, Guang Yang and Mingbo Tong

Materials 2024, 17(13), 3169; https://doi.org/10.3390/ma17133169 - 28 Jun 2024

Viewed by 109

Abstract

The fiber-reinforced composite stringer is commonly used in large civil aircraft wing structures. Under compression loads, it exhibits complex failure modes, with matrix cracking being one of the most common. The quantitative analysis of matrix failure is important and difficult. To address this [...] Read more.

The fiber-reinforced composite stringer is commonly used in large civil aircraft wing structures. Under compression loads, it exhibits complex failure modes, with matrix cracking being one of the most common. The quantitative analysis of matrix failure is important and difficult. To address this issue, a multiscale method combining the generalized method of cells (GMC) and macroscopic FEM models is employed to quantitatively predict matrix damage and failure. The extent of matrix damage in the composite structure is represented by the number of failed matrix subcells within the repeating unit cells. The 3D Tsai–Hill failure criterion is established for the matrix phase, and the maximum stress failure criterion is applied to the fiber subcell. Upon meeting the criterion, the stiffnesses of the failed subcells are immediately reduced to a nominal value. In the current study, the ultimate loads, failure modes and load–displacement curves of composite stringers subjected to compressive load are obtained by the experiment approach and the proposed multiscale model. The experimental and simulation results show good agreement, and the multiscale analysis method successfully predicts the extent of matrix damage in the composite stringer under compressive load. The number of failed matrix subcells quantitatively evaluates the damage extent within a 2 × 2 GMC model. The findings reveal that matrix subcell failures primarily occur in the 45° and −45° plies of the middle part of the stringer composite. Full article

(This article belongs to the Special Issue Materials Modeling: Structure Analysis, Physical Properties and Mechanisms)

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24 pages, 28600 KiB

Open AccessArticle

An Investigation into Sheet-Inconel 718 Forming with Flexible and Metal Tools—Simulation and Experiment

by Maciej Balcerzak, Stanislav Rusz, Radek Čada, Martin Pastrňák, Ondřej Hilšer and Miroslav Greger

Materials 2024, 17(13), 3168; https://doi.org/10.3390/ma17133168 - 28 Jun 2024

Viewed by 128

Abstract

The article presents the results of numerical simulations and experimental tests of plastic forming sheets made from the difficult-to-deform nickel alloy Inconel 718 with a thickness of 1 mm, using punches made from elastomeric materials with hardness 50–90 Shore A and steel dies. [...] Read more.

The article presents the results of numerical simulations and experimental tests of plastic forming sheets made from the difficult-to-deform nickel alloy Inconel 718 with a thickness of 1 mm, using punches made from elastomeric materials with hardness 50–90 Shore A and steel dies. Elastomeric stamps were created in the form of five layers with a diameter of 160 mm. The influence of the hardness of the elastomeric punches on the geometry of the elements obtained was determined. The dies were made from 90MnCrV8 steel with a hardness of over 60 HRC. Their task was to obtain the expected shape of the element while generating various stress states in specific areas of the semi-finished product. The research was carried out using an original device whose operating principle was based on the Guerin method. The shape and dimensions of the elements made from Inconel 718 nickel alloy were determined by optical 3D scanning. The geometry of the drawpiece showed a significant impact of the hardness of the layered elastomer matrices on the degree of shape reproduction. The results obtained from numerical modeling were confirmed by the results of experimental tests. It has been shown that the hardness of the elastomeric material used for punches for plastic forming Inconel 718 nickel alloy sheets should be adapted to the shape of the drawpiece. It was also found that one of the important aspects of plastic forming sheets using the Guerin method is the tendency to obtain a diversified shape of the final elements. Full article

(This article belongs to the Special Issue Forming Technologies and Mechanical Properties of Advanced Materials - 2nd Volume)

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9 pages, 504 KiB

Open AccessArticle

Preparation and Properties of Lightweight Geopolymer by Bio-Based Foaming Agent

by Tianlei Wang, Yao Chen, Xiudang Jing, Xueping Wang, Lei Zhang and Peisen Yang

Materials 2024, 17(13), 3167; https://doi.org/10.3390/ma17133167 - 27 Jun 2024

Viewed by 215

Abstract

Lightweight geopolymers have the advantages of a wide source of raw materials, chemical corrosion resistance, high mechanical strength and excellent durability, and are expected to replace traditional building insulation materials. In this paper, a green bio-based foaming agent with a small 1 h [...] Read more.

Lightweight geopolymers have the advantages of a wide source of raw materials, chemical corrosion resistance, high mechanical strength and excellent durability, and are expected to replace traditional building insulation materials. In this paper, a green bio-based foaming agent with a small 1 h settlement distance, high average foaming multiple and low bleeding ratio was obtained by a Cetyltrimethylammonium Bromide/yeast solution. When the amount of Cetyltrimethylammonium Bromide is 0.50 wt%, the foam prepared by the yeast and Cetyltrimethylammonium Bromide solution exhibits the improved 1 h settlement distance, the large average foaming multiple, the small bleeding ratio and uniform foam size. Subsequently, a lightweight geopolymer based on metakaolin and fly ash (or silica fume) was successfully prepared by the bio-based foaming agent, and the effects of different foam content on the properties of the geopolymer, such as dry density, water absorption, thermal conductivity, compressive strength and morphology, were studied. With an increase in foam content, the dry density, thermal conductivity and compressive strength of the geopolymer gradually decrease, the water absorption increases, regardless of whether silica fume or fly ash are added. Herein, it is confirmed that the foaming agent based on yeast can be effectively used to prepare lightweight geopolymers, which can provide vast opportunities to turn into candidates for novel inorganic thermal insulation materials. Full article

13 pages, 2295 KiB

Open AccessArticle

Effect of Discharge Energy on Micro-Arc Oxidation Coating of Zirconium Alloy

by Wei Wang, Kai Lv, Zhaoxin Du, Weidong Chen and Zhi Pang

Materials 2024, 17(13), 3166; https://doi.org/10.3390/ma17133166 - 27 Jun 2024

Viewed by 148

Abstract

The micro-arc oxidation (MAO) technique was used to grow in situ oxidation coating on the surface of R60705 zirconium alloy in Na₂SiO₃, Na₂EDTA, and NaOH electrolytes. The thickness, surface morphology, cross-section morphology, wear resistance, composition, and structure [...] Read more.

The micro-arc oxidation (MAO) technique was used to grow in situ oxidation coating on the surface of R60705 zirconium alloy in Na₂SiO₃, Na₂EDTA, and NaOH electrolytes. The thickness, surface morphology, cross-section morphology, wear resistance, composition, and structure of the micro-arc oxidation coating were analyzed by an eddy current thickness measuring instrument, XPS, XRD, scanning electron microscopy, energy spectrometer, and wear testing machine. The corrosion resistance of the coating was characterized by a polarization curve and electrochemical impedance spectroscopy (EIS). The results show that, with the increase in frequency, the single-pulse discharge energy decreases continuously, and the coating thickness shows a decreasing trend, from the highest value of 152 μm at 400 Hz to the lowest value of 87.5 μm at 1000 Hz. The discharge pore size on the surface of the coating gradually decreases, and the wear resistance and corrosion resistance of the coating first increase and then decrease. The corrosion resistance is the best when the frequency is 400 Hz. At this time, the corrosion potential is −0.215 V, and the corrosion current density is 2.546 × 10⁻⁸ A·cm⁻². The micro-arc oxidation coating of zirconium alloy is mainly composed of monoclinic zirconia (m-ZrO₂) and tetragonal zirconia (t-ZrO₂), in which the content of monoclinic zirconia is significantly more than that of tetragonal zirconia. Full article

(This article belongs to the Special Issue Advances in Surface Corrosion Protection of Alloys)

13 pages, 3172 KiB

Open AccessArticle

Experimental Study on Macro and Meso Characteristics of Steel-Slag-Based Cemented Backfill due to Microbial Mineralization Action

by Fengwen Zhao, Jianhua Hu, Yinan Yang and Taoying Liu

Materials 2024, 17(13), 3165; https://doi.org/10.3390/ma17133165 - 27 Jun 2024

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Abstract

Steel slag is an industrial solid waste, which can provide a new calcium source for microbial mineralization as it contains abundant calcium elements. This study treated cemented backfill material with microorganisms and steel slag to enhance its performance. The influence of microbial treatment [...] Read more.

Steel slag is an industrial solid waste, which can provide a new calcium source for microbial mineralization as it contains abundant calcium elements. This study treated cemented backfill material with microorganisms and steel slag to enhance its performance. The influence of microbial treatment on the strength, microstructure, and pore characteristics of the backfill was assessed using a strength test, nuclear magnetic resonance, scanning electron microscopy, and X-ray diffraction. The results indicate that (1) the microbial mineralization and the hydration reaction take place at the same time; (2) when the proportion of bacterial solution exceeded 50%, microorganisms excessively consumed Ca²⁺, which hindered the following hydration reaction; (3) the additional amount of bacterial solution added into the steel-slag-based cemented backfill material should be less than 50%, which increases the strength by up to 22.10%; (4) the excessive bacterial solution sharply reduces the strength of the backfill even by 21.41%; and (5) the addition of bacterial solution affects the pore characteristics. A 50% bacterial solution can make backfill reach its lowest porosity. The strength has an inversely proportional relationship with porosity, diameter, and roundness (σ = ax + b, a < 0). Full article

(This article belongs to the Special Issue Recycling and Sustainability of Industrial Solid Waste)

26 pages, 9763 KiB

Open AccessArticle

Microstructural Characterization, Tribological and Corrosion Behavior of H111 Hot-Rolled AA5754 after Homogenization and Aging

by Otman Farj Mohammed Abukhdair, Ismail Esen, Hayrettin Ahlatci and Esma Keskin

Materials 2024, 17(13), 3164; https://doi.org/10.3390/ma17133164 - 27 Jun 2024

Viewed by 218

Abstract

In this study, the microstructural properties, wear resistance, and corrosion behavior of H111 hot-rolled AA5754 alloy before heat treatment, after homogenization, and after aging were examined. The microstructure was mainly composed of the scattered forms of black and gray contrast particles on the [...] Read more.

In this study, the microstructural properties, wear resistance, and corrosion behavior of H111 hot-rolled AA5754 alloy before heat treatment, after homogenization, and after aging were examined. The microstructure was mainly composed of the scattered forms of black and gray contrast particles on the matrix and precipitations were observed at the boundaries of the grain. The as-rolled material exhibited a dense pancake-shaped grain structure, which is typical of as-rolled material. Observation along the L-direction did not yield distinct demarcations among the grains and was not uniformly distributed, with precipitates at the grain boundary. When they aged, there was a parallel increase in fine and huge black and gray contrast particles in the zone. Therefore, it could be stated that the amount of fine grains increased due to the rise in the homogenization process. The rolled base metal with the grain orientation was found to be parallel to the rolling direction. On the other hand, the coarse grains were clearly observed in the aging heat-treatment condition. The grains had an elongated morphology consistent with the rolling process of the metal before the heat-treatment process. The aged alloy had the highest hardness with a value of 86.83 HB; the lowest hardness was seen in the alloy before heat treatment with a value of 68.67 HB. The weight loss and wear rate of this material at the end of 10,000 m were, respectively, 1.01 × 10⁻³ g and 5.07 × 10⁻⁹ g/Nm. It was observed that the alloy had the highest weight loss and worst wear resistance before heat treatment. Weight loss and wear rates at the end of 10,000 m were, respectively, 3.42 × 10⁻³ g and 17.08 × 10⁻⁹ g/Nm. According to these results, the friction coefficients during wear were parallel and the material with the lowest friction coefficient after aging was 0.045. While the alloys corroded after aging showed more weight loss, the alloys corroded before heat treatment exhibited better corrosion behavior. Among the alloys, the least weight loss after 24 h was observed in the alloy that was corroded before heat treatment and this value was 0.69 × 10⁻³ mg/dm². The highest weight loss was observed in the aged alloy with a value of 1.37 × 10⁻³ mg/dm². The alloy before heat treatment, which corroded after casting, showed the lowest corrosion rate with a value of 0.39 × 10⁻³ mg/(dm²·day) after 72 h. The alloy that was corroded before heat treatment showed the best corrosion behavior by creating a corrosion potential of 1.04 ± 1.5 V at a current density of −586 ± 0.04 μA/cm². However, after aging, the corroded alloy showed the worst corrosion behavior with a corrosion potential of 5.16 ± 3.3 V at a current density of −880 ± 0.01 μA/cm². Full article

(This article belongs to the Section Metals and Alloys)

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18 pages, 1134 KiB

Open AccessArticle

The Multifaceted Comparison of Effects of Immobilisation of Waste Imperial Smelting Furnace (ISF) Slag in Calcium Sulfoaluminates (CSA) and a Geopolymer Binder

by Beata Łaźniewska-Piekarczyk, Monika Czop and Jan Antoni Rubin

Materials 2024, 17(13), 3163; https://doi.org/10.3390/ma17133163 - 27 Jun 2024

Viewed by 154

Abstract

Using waste materials as replacements for sand in building materials helps reduce waste and improve the properties and sustainability of the construction materials. Authors proved the possibility of using imperial smelting furnace (ISF) slag granules as a 100% substitute for natural sand in [...] Read more.

Using waste materials as replacements for sand in building materials helps reduce waste and improve the properties and sustainability of the construction materials. Authors proved the possibility of using imperial smelting furnace (ISF) slag granules as a 100% substitute for natural sand in self-compacting (SCC) cement-based mortars of calcium sulfoaluminates (CSA). The study proved that ISF slag’s radioactive properties meet this area’s requirements. CSA cement eliminates the noted problem in the case of concrete with Portland cement, which is the extended setting of the cement binder. The research findings indicate that using slag to replace sand up to 100% in mortars without grains smaller than 0.125 mm allows high flowability, compaction, low porosity and mechanical parameters. The compressive strength of the CSA cement mortars was about 110 MPa, and more than 140 MPa for geopolymer mortar. Unfortunately, the alkaline pH of a geopolymer causes high leachability of barium and sodium. Thus, the CSA cement is in a more favourable binder to achieve high strength, is environmentally friendly, and is a self-compacting mortar or concrete. Full article

(This article belongs to the Special Issue Environmentally Friendly Adsorption Materials)

14 pages, 2208 KiB

Open AccessArticle

Performance Research of Cement Concrete Pavements with a Lower Carbon Footprint

by Tomasz Rudnicki and Przemysław Stałowski

Materials 2024, 17(13), 3162; https://doi.org/10.3390/ma17133162 - 27 Jun 2024

Viewed by 143

Abstract

The growing interest in the use of building materials with a reduced carbon footprint was the aim of this research assessing the impact of four different types of low-emission cements on the properties of cement concretes used for the construction of local roads. [...] Read more.

The growing interest in the use of building materials with a reduced carbon footprint was the aim of this research assessing the impact of four different types of low-emission cements on the properties of cement concretes used for the construction of local roads. This research work attempted to verify the strength characteristics and assess the durability of such solutions, which used the commonly used CEM I 42.5 R pure clinker cement and three multi-component cements: CEM II/A-V 42.5 R, CEM III/A 42.5 N-LH/HSR/NA, and CEM V/A S-V 42.5 N-LH/HSR/NA. Cement was used in a constant amount of 360 kg/m³, sand of 0/2 mm, and granite aggregate fractions of 2/8 and 8/16 mm. This research was carried out in two areas: the first concerned strength tests and the second focused on the area of assessing the durability of concrete in terms of frost resistance F150, resistance to de-icing agents, water penetration under pressure, and an analysis of the air entrainment structure in concrete according to the PN EN 480-11 standard. Analyzing the obtained test results, it can be concluded that the highest compressive strength of more than 70 MPa was obtained for CEM III concrete, 68 MPa for CEM V concrete, and the lowest for CEM I cement after 90 days. After the durability tests, it was found that the smallest decrease in compressive strength after 150 freezing and thawing cycles was obtained for CEM III (−0.9%) and CEM V (−1.4%) concretes. The high durability of concrete is confirmed by water penetration tests under pressure, because for newly designed recipes using CEM II, CEM III, and CEM V, water penetration from 17 mm to 18 mm was achieved, which proves the very high tightness of the concrete. The assessment of the durability of low-emission cements was confirmed by tests of resistance to de-icing agents and the aeration structure performed under a microscope in accordance with the requirements of the PN-EN 480-11 standard. The obtained analysis results indicate the correct structure and minimal spacing of air bubbles in the concrete, which confirms and guarantees the durability of concrete intended for road construction. Concretes designed using CEM V cement are characterized by a carbon footprint reduction of 36%, and for the mixture based on CEM III, we even observed a decrease of 39% compared to traditional concrete. Concrete using CEM II, CEM III, and CEM V cements can be successfully used for the construction of local roads. Therefore, it is necessary to consider changing the requirements of the technical specifications recommended for roads in Poland. Full article

(This article belongs to the Special Issue Functional Cement-Based Composites for Civil Engineering (Volume II))

15 pages, 1181 KiB

Open AccessArticle

Advanced 3D Printing of Polyetherketoneketone Hydroxyapatite Composites via Fused Filament Fabrication with Increased Interlayer Connection

by Krzysztof Rodzeń, Eiméar O’Donnell, Frances Hasson, Alistair McIlhagger, Brian J. Meenan, Jawad Ullah, Beata Strachota, Adam Strachota, Sean Duffy and Adrian Boyd

Materials 2024, 17(13), 3161; https://doi.org/10.3390/ma17133161 - 27 Jun 2024

Viewed by 219

Abstract

Additively manufactured implants, surgical guides, and medical devices that would have direct contact with the human body require predictable behaviour when stress is applied during their standard operation. Products built with Fused Filament Fabrication (FFF) possess orthotropic characteristics, thus, it is necessary to [...] Read more.

Additively manufactured implants, surgical guides, and medical devices that would have direct contact with the human body require predictable behaviour when stress is applied during their standard operation. Products built with Fused Filament Fabrication (FFF) possess orthotropic characteristics, thus, it is necessary to determine the properties that can be achieved in the XY- and Z-directions of printing. A concentration of 10 wt% of hydroxyapatite (HA) in polyetherketoneketone (PEKK) matrix was selected as the most promising biomaterial supporting cell attachment for medical applications and was characterized with an Ultimate Tensile Strength (UTS) of 78.3 MPa and 43.9 MPa in the XY- and Z-directions of 3D printing, respectively. The effect of the filler on the crystallization kinetics, which is a key parameter for the selection of semicrystalline materials suitable for 3D printing, was explained. This work clearly shows that only in situ crystallization provides the ability to build parts with a more thermodynamically stable primary form of crystallites. Full article

(This article belongs to the Special Issue Advanced Biomaterials for Medical Applications (2nd Edition))

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