Materials

28 pages, 8727 KiB

Open AccessArticle

Microstructural and Electrochemical Study: Pitting Corrosion Mechanism on A390 Al–Si Alloy and Ce–Mo Treatment as a Better Corrosion Protection

by Héctor Herrera Hernández, Araceli Mandujano Ruiz, Carlos Omar González Morán, José Guadalupe Miranda Hernández, José de Jesús Agustín Flores Cuautle, Jorge Morales Hernández and Irma Hernández Casco

Materials 2024, 17(12), 3044; https://doi.org/10.3390/ma17123044 - 20 Jun 2024

Viewed by 1141

Abstract

Sulfuric acid anodizing assisted by a hydrothermal sealing with inhibitors [Ce³⁺-Mo⁶⁺] was used to prevent pitting corrosion on spray-deposited hypereutectic Al–Si alloy (A390). An investigation concerning the evaluation of pitting corrosion resistance on the anodic oxide thin film with [...] Read more.

Sulfuric acid anodizing assisted by a hydrothermal sealing with inhibitors [Ce³⁺-Mo⁶⁺] was used to prevent pitting corrosion on spray-deposited hypereutectic Al–Si alloy (A390). An investigation concerning the evaluation of pitting corrosion resistance on the anodic oxide thin film with ions incorporated was carried out in NaCl solution using electrochemical measurements (i.e., potentiodynamic polarization and electrochemical impedance spectroscopy, EIS). The influence of Si phase morphology and size on the growth mechanism of an anodic oxide film was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results were then compared with those for its equivalent IM390 alloy (Al-17Si-4.5Cu-0.6Mg) produced through a conventional process ingot metallurgy, IM. The electrochemical findings indicate that sulfuric acid anodizing followed by a simple hot water sealing treatment was ineffective. In this manner, an intense attack was localized by pitting corrosion that occurred on the anodic oxide film in less than three days, as denoted by characteristic changes in the EIS spectra at the lowest frequencies. Improved results were achieved for Ce–Mo surface modification, which can provide better corrosion resistance on the aluminum alloys because no signs of pits were observed during the corrosion testing. Full article

(This article belongs to the Special Issue Corrosion Resistance Enhancement of the Materials Surface—Second Edition)

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15 pages, 3864 KiB

Open AccessArticle

Effect of Single Particle High-Speed Impingement on the Electrochemical Step Characteristics of a Stainless-Steel Surface

by Meihong Liu, Long Chai, Min Yang and Jiarui Cheng

Materials 2024, 17(12), 3043; https://doi.org/10.3390/ma17123043 - 20 Jun 2024

Viewed by 694

Abstract

In the process of particle erosion and electrochemical corrosion interaction, the electrolyte flow state change, product film destruction, and matrix structure change caused by particle impact affect the electrochemical corrosion process. Such transient, complex physical and electrochemical changes are difficult to capture because [...] Read more.

In the process of particle erosion and electrochemical corrosion interaction, the electrolyte flow state change, product film destruction, and matrix structure change caused by particle impact affect the electrochemical corrosion process. Such transient, complex physical and electrochemical changes are difficult to capture because of the short duration of action and the small collision area. The peak, step time, and recovery time in this transient step cycle can indirectly reflect the smoothness and reaction rate of the electrochemical reaction system, and thus characterize the resistance to scouring corrosion coupling damage of metals in liquid–solid two-phase flow. In this study, in order to obtain the electrochemical response at the moment of particle impact, electrochemical monitoring experiments using a specially designed miniature three-electrode system were used to test step-critical values, including step potential, current, and resistance, among others. Meanwhile, an electrochemical step model under particle impact considering boundary layer perturbation was developed. The experimental results reflect the effect law of particle impact velocity and particle size on the peak step and recovery period. Meanwhile, the effect of particle impingement on the electrochemical step of stainless steel in different electrolyte solutions was obtained by comparing the step curves in distilled water and Cl-containing water. The connection between the parameters in the electrochemical step model and in the particle impact, as well as the effect of the variation of these parameters on the surface repassivation process are discussed in this paper. By fitting and modeling the test curves, a new mathematical model of electrochemical step-decay under single-particle impact was obtained, which can be used to characterize the change pattern of electrochemical parameters on the metal surface before and after the impingement. Full article

(This article belongs to the Special Issue Corrosion and Mechanical Behavior of Metal Materials (2nd Edition))

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Diagram of particle impact experiment. Full article ">Figure 2
Diagram of three-electrode setup for particle impact electrochemical experiment. Full article ">Figure 3
Single-particle impact experiment using plastic particles. Full article ">Figure 4
Experimental results of potential variation of 304 stainless steel under single particle impact in distilled water (flow rate comparison). (a) 4 mm, (b) 6 mm, (c) 8 mm, (d) 10 mm, (e) 12 mm. Full article ">Figure 5
Experimental results of potential variation of 304 stainless steel under single particle impact in distilled water (comparison by particle diameter). (a) 1 m/s, (b) 2 m/s, (c) 3 m/s, (d) 4 m/s, (e) 5 m/s. Full article ">Figure 6
Experimental results of surface current density variation of 304 stainless steel subjected to single particle impact in water (comparison of flow velocities). (a) 4 mm, (b) 6 mm, (c) 8 mm, (d) 10 mm, (e) 12 mm. Full article ">Figure 7
Experimental results of surface current density variation of 304 stainless steel subjected to single particle impact in water (comparison of particle diameters). (a) 1 m/s, (b) 2 m/s, (c) 3 m/s, (d) 4 m/s, (e) 5 m/s. Full article ">Figure 8
Experimental results of surface current density variation of 304 stainless steel under single particle impact in 3.5 wt% NaCl solution (comparison of flow rates). (a) 4 mm, (b) 6 mm, (c) 8 mm, (d) 10 mm, (e) 12 mm. Full article ">Figure 9
Experimental results of surface current density variation of 304 stainless steel under single particle impact in 3.5 wt% NaCl solution (comparison of particle diameters). (a) 1 m/s, (b) 2 m/s, (c) 3 m/s, (d) 4 m/s, (e) 5 m/s. Full article ">Figure 10
The schematic diagram illustrates the trend of current density variation caused by particle impact on the metal surface. Full article ">

21 pages, 9899 KiB

Open AccessArticle

Alternative Method for Determination of Vibroacoustic Material Parameters for Building Applications

by Krzysztof Nering and Konrad Nering

Materials 2024, 17(12), 3042; https://doi.org/10.3390/ma17123042 - 20 Jun 2024

Cited by 1 | Viewed by 931

Abstract

The development of urbanization and the resulting expansion of residential and transport infrastructures pose new challenges related to ensuring comfort for city dwellers. The emission of transport vibrations and household noise reduces the quality of life in the city. To counteract this unfavorable [...] Read more.

The development of urbanization and the resulting expansion of residential and transport infrastructures pose new challenges related to ensuring comfort for city dwellers. The emission of transport vibrations and household noise reduces the quality of life in the city. To counteract this unfavorable phenomenon, vibration isolation is widely used to reduce the propagation of vibrations and noise. A proper selection of vibration isolation is necessary to ensure comfort. This selection can be made based on a deep understanding of the material parameters of the vibration isolation used. This mainly includes dynamic stiffness and damping. This article presents a comparison of the method for testing dynamic stiffness and damping using a single degree of freedom (SDOF) system and the method using image processing, which involves tracking the movement of a free-falling steel ball onto a sample of the tested material. Rubber granules, rubber granules with rubber fibers, and rebound polyurethanes were selected for testing. Strong correlations were found between the relative indentation and dynamic stiffness (at 10–60 MN/m³) and the relative rebound and damping (for 6–12%). Additionally, a very strong relationship was determined between the density and fraction of the critical damping factor/dynamic stiffness. The relative indentation and relative rebound measurement methods can be used as an alternative method to measure the dynamic stiffness and critical damping factor, respectively. Full article

(This article belongs to the Special Issue Innovative Material Design and Nondestructive Testing Applications for Infrastructure Materials)

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15 pages, 3261 KiB

Open AccessArticle

Recovery of Plastics from WEEE through Green Sink–Float Treatment

by Annarita Fiorente, Germano D’Agostino, Andrea Petrella, Francesco Todaro and Michele Notarnicola

Materials 2024, 17(12), 3041; https://doi.org/10.3390/ma17123041 - 20 Jun 2024

Cited by 1 | Viewed by 973

Abstract

Increasing demand for electrical and electronic equipment results in the generation of a rapidly growing waste stream, known by the acronym WEEE (waste electrical and electronic equipment). The purpose of this study was to evaluate the effectiveness of green sink–float treatment in sorting [...] Read more.

Increasing demand for electrical and electronic equipment results in the generation of a rapidly growing waste stream, known by the acronym WEEE (waste electrical and electronic equipment). The purpose of this study was to evaluate the effectiveness of green sink–float treatment in sorting plastic polymers typically found in WEEE (PP, ABS, PA6, PS, and PVC). Molasses, a by-product of sugar bio-refining, was added in various concentrations to water to form solutions at different densities. The methodology was initially tested on virgin polymers; later, it was applied to plastics from a WEEE treatment plant. The polymers were characterised through near infrared spectroscopy (NIRS) and Fourier-transform infrared spectroscopy (FTIRS) analyses; the detection of any additives and flame retardants was conducted using the sliding spark technology (SSS2) and scanning electron microscope (SEM—EDX). The results showed that, for plastics from WEEE, the recovery efficiency was 55.85% for PP in a solution of tap water while the remaining part of PP (44.15%) was recovered in a solution of water to which 90% molasses was added. Furthermore, 100% recovery efficiency was obtained for PS and 93.73% for ABS in a solution of tap water with the addition of 10% w/v molasses. A recovery efficiency of 100% was obtained for PVC and 100% for PA6 in a solution consisting solely of molasses. Full article

(This article belongs to the Section Advanced Composites)

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18 pages, 5241 KiB

Open AccessArticle

Thermo-Chemo-Mechanical Modeling of Residual Stress in Unidirectional Carbon Fiber-Reinforced Polymers during Manufacture

by Rui Bao, Junpeng Liu, Zhongmin Xiao and Sunil C. Joshi

Materials 2024, 17(12), 3040; https://doi.org/10.3390/ma17123040 - 20 Jun 2024

Cited by 1 | Viewed by 954

Abstract

The application of carbon fiber-reinforced composite materials in marine engineering is growing steadily. The mechanical properties of unbonded flexible risers using composite tensile armor wire are highly valued. However, the curing process generates a certain amount of internal residual stress. We present a [...] Read more.

The application of carbon fiber-reinforced composite materials in marine engineering is growing steadily. The mechanical properties of unbonded flexible risers using composite tensile armor wire are highly valued. However, the curing process generates a certain amount of internal residual stress. We present a detailed analysis of epoxy resin laminates to assess the impact of thermal, chemical, and mechanical effects on the curing stress and strain. An empirical model that correlates temperature and degree of cure was developed to precisely fit the elastic modulus data of the curing resin. The chemical kinetics of the epoxy resin system was characterized using differential scanning calorimetry (DSC), while the tensile relaxation modulus was determined through a dynamic mechanical analysis. The viscoelastic model was calibrated using the elastic modulus data of the cured resin combining temperature and degree of the curing (thermochemical kinetics) responses. Based on the principle of time–temperature superposition, the displacement factor and relaxation behavior of the material were also accurately captured by employing the same principle of time–temperature superposition. Utilizing the empirical model for degree of cure and modulus, we predicted micro-curing-induced strains in cured composite materials, which were then validated with experimental observations. Full article

(This article belongs to the Special Issue Characterizations, Mechanical Properties and Constitutive Modeling of Advanced Materials)

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18 pages, 8081 KiB

Open AccessArticle

Study on Spline Stress of Separator Plates in a Wet Multi-Plate Clutch

by Biao Ma, Xiaobo Chen, Changsong Zheng, Liang Yu, Qin Zhao and Weichen Lu

Materials 2024, 17(12), 3039; https://doi.org/10.3390/ma17123039 - 20 Jun 2024

Viewed by 816

Abstract

The spline teeth fracture of separator plates in wet multi-plate clutches compromises driving safety and the vehicle’s lifespan. Tooth fracture is mainly caused by stress concentration at the tooth root and uneven circumferential load distribution. This paper considers parameters such as torque, teeth [...] Read more.

The spline teeth fracture of separator plates in wet multi-plate clutches compromises driving safety and the vehicle’s lifespan. Tooth fracture is mainly caused by stress concentration at the tooth root and uneven circumferential load distribution. This paper considers parameters such as torque, teeth count, tooth profile, and misalignment errors, establishing the corresponding finite element (FE) model to analyze the impact of the above-mentioned parameters on the strength of the separator plates. Analysis under even and biased load circumstances demonstrated that an optimum tooth count and profile can significantly increase the strength of the separator plates, offering advice for the optimized design of wet multi-plate clutch separator plates. Full article

(This article belongs to the Section Advanced Materials Characterization)

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13 pages, 2343 KiB

Open AccessEditor’s ChoiceArticle

Thermodynamic Model for Hydrogen Production from Rice Straw Supercritical Water Gasification

by Zhigang Liu, Zhiyong Peng, Lei Yi, Le Wang, Jingwei Chen, Bin Chen and Liejin Guo

Materials 2024, 17(12), 3038; https://doi.org/10.3390/ma17123038 - 20 Jun 2024

Viewed by 1018

Abstract

Supercritical water gasification (SCWG) technology is highly promising for its ability to cleanly and efficiently convert biomass to hydrogen. This paper developed a model for the gasification of rice straw in supercritical water (SCW) to predict the direction and limit of the reaction [...] Read more.

Supercritical water gasification (SCWG) technology is highly promising for its ability to cleanly and efficiently convert biomass to hydrogen. This paper developed a model for the gasification of rice straw in supercritical water (SCW) to predict the direction and limit of the reaction based on the Gibbs free energy minimization principle. The equilibrium distribution of rice straw gasification products was analyzed under a wide range of parameters including temperatures of 400–1200 °C, pressures of 20–50 MPa, and rice straw concentrations of 5–40 wt%. Coke may not be produced due to the excellent properties of supercritical water under thermodynamic constraints. Higher temperatures, lower pressures, and biomass concentrations facilitated the movement of the chemical equilibrium towards hydrogen production. The hydrogen yield was 47.17 mol/kg at a temperature of 650 °C, a pressure of 25 MPa, and a rice straw concentration of 5 wt%. Meanwhile, there is an absorptive process in the rice straw SCWG process for high-calorific value hydrogen production. Energy self-sufficiency of the SCWG process can be maintained by adding small amounts of oxygen (ER < 0.2). This work would be of great value in guiding rice straw SCWG experiments. Full article

(This article belongs to the Special Issue Application of Biomass Materials in the Fields of Electrochemistry and Thermochemistry)

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13 pages, 7695 KiB

Open AccessArticle

Texture-Differentiated Grain Growth in Silicon Steel: Experiments and Modeling

by Songtao Chang, Yuhui Sha, Gengsheng Cao, Fang Zhang and Liang Zuo

Materials 2024, 17(12), 3037; https://doi.org/10.3390/ma17123037 - 20 Jun 2024

Viewed by 776

Abstract

Grain growth for various texture components in silicon steel was investigated via experiments and modeling. It was found that the clustered spatial arrangement of grains with specific orientations significantly altered the local environment for grain growth and consequently resulted in texture-differentiated grain size [...] Read more.

Grain growth for various texture components in silicon steel was investigated via experiments and modeling. It was found that the clustered spatial arrangement of grains with specific orientations significantly altered the local environment for grain growth and consequently resulted in texture-differentiated grain size distribution (GSD) evolution. A novel local-field model was proposed to describe grain growth driven by continuous changing orientation and size distribution of adjacent grains. The modelling results show that the texture-differentiated grain growth in microstructure with grain clusters can produce a GSD with increased proportion in small-sized range and large-sized range by more than two-times, accompanied with an evident change in area fractions of various texture components. The effect of clustered spatial arrangement on grain growth can be precisely predicted, which is valuable to design and control the texture-differentiated GSD as well as the global GSD. Full article

(This article belongs to the Special Issue Phase Transformation, Functional Properties, and Crystallography of Advanced Materials (Second Volume))

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10 pages, 3245 KiB

Open AccessArticle

Ultrathin Titanium Dioxide Coating Enables High-Rate and Long-Life Lithium Cobalt Oxide

by Liu Gao, Xin Jin, Zijin Li, Fujie Li, Binghui Xu and Chao Wang

Materials 2024, 17(12), 3036; https://doi.org/10.3390/ma17123036 - 20 Jun 2024

Viewed by 1050

Abstract

Lithium cobalt oxide (LCO) has been widely used as a leading cathode material for lithium-ion batteries in consumer electronics. However, unstable cathode electrolyte interphase (CEI) and undesired phase transitions during fast Li⁺ diffusivity always incur an inferior stability of the high-voltage LCO [...] Read more.

Lithium cobalt oxide (LCO) has been widely used as a leading cathode material for lithium-ion batteries in consumer electronics. However, unstable cathode electrolyte interphase (CEI) and undesired phase transitions during fast Li⁺ diffusivity always incur an inferior stability of the high-voltage LCO (HV-LCO). Here, an ultra-thin amorphous titanium dioxide (TiO₂) coating layer engineered on LCO by an atomic layer deposition (ALD) strategy is demonstrated to improve the high-rate and long-cycling properties of the HV-LCO cathode. Benefitting from the uniform TiO₂ protective layer, the Li⁺ storage properties of the modified LCO obtained after 50 ALD cycles (LCO-ALD50) are significantly improved. The results show that the average Li⁺ diffusion coefficient is nearly tripled with a high-rate capability of 125 mAh g⁻¹ at 5C. An improved cycling stability with a high-capacity retention (86.7%) after 300 cycles at 1C is also achieved, far outperforming the bare LCO (37.9%). The in situ XRD and ex situ XPS results demonstrate that the dense and stable CEI induced by the surface TiO₂ coating layer buffers heterogenous lithium flux insertion during cycling and prevents electrolyte, which contributes to the excellent cycling stability of LCO-ALD50. This work reveals the mechanism of surface protection by transition metal oxides coating and facilitates the development of long-life HV-LCO electrodes. Full article

(This article belongs to the Special Issue Electrochemical Materials and Devices for Energy Conversion and Storage)

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Graphical abstract
Full article ">Figure 1
Schematic illustration of the preparation procedure of the TiO2 layer on LCO by ALD. Full article ">Figure 2
TEM images of (a) bare LCO and (b) LCO-ALD50 after TiO2 coating. (c) XRD patterns of LCO-ALD50 with Rietveld refinement. (d) FESEM image of LCO-ALD50 and the corresponding EDS images with elements (e) Co, (f) O and (g) Ti. High-resolution O1s XPS spectra of bare (h) LCO and (i) LCO-ALD50. (j) High-resolution Ti2p XPS spectra of LCO-ALD50. Full article ">Figure 3
Electrochemical properties. (a) Rate capability at different C-rates and (b) cycling stability at 1C (1C = 274 mAh g−1) of bare LCO, LCO-ALD25, LCO-ALD50, and LCO-ALD100. The 1st, 50th, 100th, 200th and 300th galvanostatic charge/discharge profiles of (c) bare LCO and (d) LCO-ALD50 at 1C. (e) The comparison of cycling performance between LCO-ALD50 and the reported TiO2-coated LCO electrodes. (f) Nyquist plots before and after 300 cycles of LCO-ALD50. The 1st, 2nd, 5th and 10th CV curves of (g) bare LCO and (h) LCO-ALD50 measured at 0.1 mV s−1. Full article ">Figure 4
Investigation of the excellent surface stability of bare LCO and LCO-ALD50 at 4.5 V. XPS depth spectra of (a) C1s, (b) O1s, and (c) F1s for bare LCO and of (d) C1s, (e) O1s, and (f) F1s for LCO-ALD50 after 100 cycles at 1C. Full article ">Figure 5
FESEM images of (a,b) bare LCO and (c,d) LCO-ALD50 after 300 cycles at 1C. Full article ">

13 pages, 9232 KiB

Open AccessArticle

Impact of Lime Saturation Factor on Alite-Ye’Elimite Cement Synthesis and Hydration

by Xiaodong Li, Bing Ma, Wenqian Ji, Shang Dou, Hao Zhou, Houhu Zhang, Jiaqing Wang, Yueyang Hu and Xiaodong Shen

Materials 2024, 17(12), 3035; https://doi.org/10.3390/ma17123035 - 20 Jun 2024

Viewed by 3647

Abstract

Alite(C₃S)-Ye’elimite(C₄A₃$) cement is a high cementitious material that incorporates a precise proportion of ye’elimite into the ordinary Portland cement. The synthesis and hydration behavior of Alite-Ye’elimite clinker with different lime saturation factors were investigated. The clinkers were [...] Read more.

Alite(C₃S)-Ye’elimite(C₄A₃$) cement is a high cementitious material that incorporates a precise proportion of ye’elimite into the ordinary Portland cement. The synthesis and hydration behavior of Alite-Ye’elimite clinker with different lime saturation factors were investigated. The clinkers were synthesized using a secondary thermal treatment process, and their compositions were characterized. The hydrated pastes were analyzed for their hydration products, pore structure, mechanical strength, and microstructure. The clinkers and hydration products were characterized using XRD, TG-DSC, SEM, and MIP analysis. The results showed that the Alite-Ye’elimite cement clinker with a lime saturation factor (KH) of 0.93, prepared through secondary heat treatment, contained 64.88% C₃S and 2.06% C₄A₃$. At this composition, the Alite-Ye’elimite cement clinker demonstrated the highest 28-day strength. The addition of SO₃ to the clinkers decreased the content of tricalcium aluminate (C₃A) and the ratio of Alite/Belite (C₃S/C₂S), resulting in a preference for belite formation. The pore structure of the hydrated pastes was also investigated, revealing a distribution of pore sizes ranging from 0.01 to 10 μm, with two peaks on each differential distribution curve corresponding to micron and sub-micron pores. The pore volume decreased from 0.22 ± 0.03 to 0.15 ± 0.18 cm³ g⁻¹, and the main peak of pore distribution shifted towards smaller sizes with increasing hydration time. Full article

(This article belongs to the Special Issue Green and Sustainable Infrastructure Construction Materials (2nd Edition))

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16 pages, 2705 KiB

Open AccessArticle

Oxidation Driven Damage on SiC/BN/SiC Ceramic Matrix Composite Aero-Engine Structures: An Iterative Computational Framework

by Giacomo Canale and Roberto Citarella

Materials 2024, 17(12), 3034; https://doi.org/10.3390/ma17123034 - 20 Jun 2024

Viewed by 566

Abstract

Ceramic matrix composites (CMCs) could be a game changer in the aero-engine industry. Their density is circa one-third of their metallic counterpart. CMCs, furthermore, offer increased strength and greater capability at very high temperatures. This would allow for a reduction in cooling and [...] Read more.

Ceramic matrix composites (CMCs) could be a game changer in the aero-engine industry. Their density is circa one-third of their metallic counterpart. CMCs, furthermore, offer increased strength and greater capability at very high temperatures. This would allow for a reduction in cooling and an increased engine performance. Some challenges, besides the complexity of the manufacturing process, however, remain for the structural integrity of this technology. CMCs are inherently brittle; furthermore, they tend to oxidise when attacked by water or oxygen, and their constituents become brittle and more prone to failure. There are two main points of novelty proposed by this work. The first one is to model and reproduce recent oxidation experimental data with a simple Fick’s law implemented in Abaqus. The parameters of this modelling are a powerful tool for the design of such material systems. The second aspect consists in the development of a new computational framework for iteratively calculating oxygen diffusion and stiffness degradation of the material. Oxidation and stiffness degradation are in fact coupled phenomena. The crack (or microcracking) opening, the function of applied stress, accelerates oxygen diffusion whilst the oxidation diffusion itself contributes to embrittlement and then damage introduction in the material system. Full article

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

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11 pages, 4161 KiB

Open AccessArticle

Research and Design of Energy-Harvesting System Based on Macro Fiber Composite Cantilever Beam Applied in Low-Frequency and Low-Speed Water Flow

by Rui Huang, Jingjing Zhou, Jie Shen, Jing Tian, Jing Zhou and Wen Chen

Materials 2024, 17(12), 3033; https://doi.org/10.3390/ma17123033 - 20 Jun 2024

Cited by 1 | Viewed by 686

Abstract

In nature, lakes and water channels offer abundant underwater energy sources. However, effectively harnessing these green and sustainable underwater energy sources is challenging due to their low flow velocities. Here, we propose an underwater energy-harvesting system based on a cylindrical bluff body and [...] Read more.

In nature, lakes and water channels offer abundant underwater energy sources. However, effectively harnessing these green and sustainable underwater energy sources is challenging due to their low flow velocities. Here, we propose an underwater energy-harvesting system based on a cylindrical bluff body and a cantilever beam composed of a macro fiber composite (MFC), taking advantage of the MFC’s low-frequency, lightweight, and high piezoelectric properties to achieve energy harvesting in low-frequency and low-speed water flows. When a water flow impacts the cylindrical bluff body, it generates vibration-enhanced and low-frequency vortices behind the bluff body. The optimized diameter of the bluff body and the distance between the bluff body and the MFC were determined using finite element analysis software, specifically COMSOL. According to the simulation results, an energy-harvesting system based on an MFC cantilever beam applied in a low-frequency and low-speed water flow was designed and prepared. When the diameter of the bluff body was 25 mm, and the distance between the bluff body and MFC was 10 mm and the maximum output voltage was 22.73 V; the power density could reach 0.55 mW/cm² after matching the appropriate load. The simulation results and experimental findings of this study provide valuable references for designing and investigating energy-harvesting systems applied in low-frequency and low-speed water flows. Full article

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Low-frequency and low-velocity underwater energy harvesting using MFCs: (a) system design, (b) d33 operating mode of MFC, (c) and mechanism of energy harvesting. Red arrow represents the vibration direction of the MFC. Full article ">Figure 2
Theoretical analysis and modeling of MFC. Full article ">Figure 3
Influence of different distances on MFC energy harvesting: (a) 5 mm, (b) 10 mm, (c) 15 mm, (d) 20 mm, (e) 25 mm, and (f) 30 mm. Full article ">Figure 4
Influence of different diameters on MFC energy harvesting: (a) 10 mm, (b) 15 mm, (c) 20 mm, (d) 25 mm, (e) 27 mm, and (f) 30 mm. Full article ">Figure 5
The electrical output performance of the MFC: (a) the output voltage of the MFC on different substrates, (b) the energy-harvesting performance of the MFC cantilever beam with an aluminum substrate, (c) the influence of MFC energy harvesting, (d) the influence of the parallel resistor on MFC energy harvesting, (e) a comparison of simulated and tested output voltages for different bluff body diameters, and (f) a comparison of simulated and tested output voltages for different distances between the bluff body and the MFC. Full article ">

22 pages, 6244 KiB

Open AccessArticle

Bond Strength Assessment of Normal Strength Concrete–Ultra-High-Performance Fiber Reinforced Concrete Using Repeated Drop-Weight Impact Test: Experimental and Machine Learning Technique

by Sadi I. Haruna, Yasser E. Ibrahim, Ibrahim Hayatu Hassan, Ali Al-shawafi and Han Zhu

Materials 2024, 17(12), 3032; https://doi.org/10.3390/ma17123032 - 20 Jun 2024

Cited by 1 | Viewed by 1172

Abstract

Ultra-high-performance concrete (UHPC) has been used in building joints due to its increased strength, crack resistance, and durability, serving as a repair material. However, efficient repair depends on whether the interfacial substrate can provide adequate bond strength under various loading scenarios. The objective [...] Read more.

Ultra-high-performance concrete (UHPC) has been used in building joints due to its increased strength, crack resistance, and durability, serving as a repair material. However, efficient repair depends on whether the interfacial substrate can provide adequate bond strength under various loading scenarios. The objective of this study is to investigate the bonding behavior of composite U-shaped normal strength concrete–ultra-high-performance fiber reinforced concrete (NSC-UHPFRC) specimens using multiple drop-weight impact testing techniques. The composite interface was treated using grooving (Gst), natural fracture (Nst), and smoothing (Sst) techniques. Ensemble machine learning (ML) algorithms comprising XGBoost and CatBoost, support vector machine (SVM), and generalized linear machine (GLM) were employed to train and test the simulation dataset to forecast the impact failure strength (N2) composite U-shaped NSC-UHPFRC specimen. The results indicate that the reference NSC samples had the highest impact strength and surface treatment played a substantial role in ensuring the adequate bond strength of NSC-UHPFRC. NSC-UHPFRC-Nst can provide sufficient bond strength at the interface, resulting in a monolithic structure that can resist repeated drop-weight impact loads. NSC-UHPFRC-Sst and NSC-UHPFRC-Gst exhibit significant reductions in impact strength properties. The ensemble ML correctly predicts the failure strength of the NSC-UHPFRC composite. The XGBoost ensemble model gave coefficient of determination (R²) values of approximately 0.99 and 0.9643 at the training and testing stages. The highest predictions were obtained using the GLM model, with an R² value of 0.9805 at the testing stage. Full article

(This article belongs to the Special Issue Innovative Material Design and Nondestructive Testing Applications for Infrastructure Materials)

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12 pages, 9391 KiB

Open AccessArticle

The Influence of Heat Treatment on the Microstructure and Properties of a Cu-Bearing Ultra-Low Carbon Steel

by Weina Zhang, Zhanjie Gao, Huimin Zhang, Hao Wei, Zejin Chen, Wenying Xue and Zhenyu Liu

Materials 2024, 17(12), 3031; https://doi.org/10.3390/ma17123031 - 20 Jun 2024

Cited by 1 | Viewed by 841

Abstract

This study reveals the relationship between the Cu precipitates and mechanical properties of a Cu-baring ultra-low carbon steel after two-phase zone quenching and tempering at 923 K for 0.5–2.5 h. The tensile and microstructural properties were investigated as a function of heat treatment [...] Read more.

This study reveals the relationship between the Cu precipitates and mechanical properties of a Cu-baring ultra-low carbon steel after two-phase zone quenching and tempering at 923 K for 0.5–2.5 h. The tensile and microstructural properties were investigated as a function of heat treatment time. The contribution of the precipitation-strengthening mechanism to yield strength was calculated. The size, morphology, and distribution of the precipitated particles were observed using TEM. As the heat treatment time increased, the strength gradually decreased and then remained stable, and the elongation gradually increased and then remained stable. Additionally, the contributions of each strengthening mechanism to the yield strength under different heat treatments were 117, 107, 102, and 89 MPa, respectively. The size and quantity of the precipitates increased with the increase in heat treatment time. After tempering for more than 2 h, the precipitates continued to coarsen, but their quantity decreased. The precipitated Cu had a 3R structure with a length of approximately 17.1 nm and a width of approximately 9.7 nm, with no twinning inside. The stacking order was ABC/ABC. The stable Cu precipitation structure was FCC, maintaining a K-S orientation relationship

(1 \bar{1} 1)

_{FCC Cu} //(0 1 1) _α,

[\bar{1} 10]

_{FCC Cu}//

[1 \bar{1} 1

] _α. Full article

(This article belongs to the Special Issue Advanced Steel Materials: Recrystallization, Phase Transformation and Microstructure Analysis)

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Heat treatment process of the experimental steel. Full article ">Figure 2
Tensile properties of the experimental steel under different heat treatment conditions: (a) typical stretch curve; (b) tensile properties change trend. Full article ">Figure 3
OM and SEM images of microstructure under different heat treatment conditions: (a,b) 0.5 h, (c,d) 1 h, (e,f) 2 h, and (g,h) 2.5 h. Full article ">Figure 4
TEM images of microstructure under different heat treatment conditions: (a) 0.5 h, (b) 1 h, (c) 2 h, and (d) 2.5 h. Full article ">Figure 5
Statistical analysis of precipitation particle size under different heat treatment conditions: (a,b) 0.5 h, (c,d) 1 h, (e,f) 2 h, and (g,h) 2.5 h. Full article ">Figure 6
High-resolution image analysis of 3R Cu at 650 °C for 2 h. (a) 3R Cu image, (b) the FFT pattern of (a), (c) IFFT image after filtrating of 3R Cu. Full article ">Figure 7
HRTEM analysis of ellipsoidal FCC Cu at 650 °C for 2 h. (a) FCC Cu image, (b) the FFT pattern of (a), (c) IFFT image after filtrating of matrix. Full article ">

15 pages, 4861 KiB

Open AccessArticle

Optimization of Vertical Fixed-Bed Pyrolysis for Enhanced Biochar Production from Diverse Agricultural Residues

by Tasi-Jung Jiang, Hervan Marion Morgan, Jr. and Wen-Tien Tsai

Materials 2024, 17(12), 3030; https://doi.org/10.3390/ma17123030 - 20 Jun 2024

Viewed by 1014

Abstract

This study examines the pyrolysis of agricultural residues, namely, coconut shells, rice husks, and cattle manure, in a vertical fixed-bed reactor at varying temperatures from 300 to 800 degrees Celsius for biochar production. The research aimed to evaluate the potential of biochar as [...] Read more.

This study examines the pyrolysis of agricultural residues, namely, coconut shells, rice husks, and cattle manure, in a vertical fixed-bed reactor at varying temperatures from 300 to 800 degrees Celsius for biochar production. The research aimed to evaluate the potential of biochar as biofuels, adsorbents, and soil amendments. Proximate, ultimate, and elemental analyses were conducted to determine their composition and caloric values. Several analytical techniques were used in the physical and chemical characterization of the biochar (SEM, FTIR, BET). The results indicated that the highest S_BET values were achieved under different conditions for each biochar: 89.58 m²/g for BC-CS-700, 202.39 m²/g for BC-RH-600, and 42.45 m²/g for BC-CD-800. Additionally, all three biochars exhibited the highest caloric values at 600 °C. The results showed that 600 °C is the general optimal temperature to produce biochar from an assortment of biomass materials, considering their use for a variety of purposes. BC-CS-800 had the highest elemental carbon content at 93%, accompanied by a relative decrease in oxygen content. The van Krevelen diagram of biochar products shows that biochars derived from coconut shells and rice husks are suitable for use as fuels. Furthermore, FTIR analysis revealed the presence of oxygen-containing functional groups on the biochar surface, enhancing their pollutant adsorption capabilities. This study provides valuable insights into the scalable and environmentally sustainable production of biochar, emphasizing its role in improving soil quality, increasing energy density, and supporting sustainable agricultural practices. Full article

(This article belongs to the Special Issue Green Materials and Manufacturing Processes (2nd Edition))

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13 pages, 1335 KiB

Open AccessArticle

New Methodology for Modifying Sodium Montmorillonite Using DMSO and Ethyl Alcohol

by Adriana Stoski, Bruno Rafael Machado, Bruno Henrique Vilsinski, Lee Marx Gomes de Carvalho, Edvani Curti Muniz and Carlos Alberto Policiano Almeida

Materials 2024, 17(12), 3029; https://doi.org/10.3390/ma17123029 - 20 Jun 2024

Viewed by 823

Abstract

Modified clays with organic molecules have many applications, such as the adsorption of pollutants, catalysts, and drug delivery systems. Different methodologies for intercalating these structures with organic moieties can be found in the literature with many purposes. In this paper, a new methodology [...] Read more.

Modified clays with organic molecules have many applications, such as the adsorption of pollutants, catalysts, and drug delivery systems. Different methodologies for intercalating these structures with organic moieties can be found in the literature with many purposes. In this paper, a new methodology of modifying Sodium Montmorillonite clays (Na-Mt) with a faster drying time was investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), BET, and thermogravimetric analysis (TG and DTG). In the modification process, a mixture of ethyl alcohol, DMSO, and Na-Mt were kept under magnetic stirring for one hour. Statistical analysis was applied to evaluate the effects of the amount of DMSO, temperature, and sonication time on the modified clay (DMSO-SMAT) using a 2³-factorial design. XRD and FTIR analyses showed the DMSO intercalation into sodium montmorillonite Argel-T (SMAT). An average increase of 0.57 nm for the interplanar distance was found after swelling with DMSO intercalation. BET analysis revealed a decrease in the surface area (from 41.8933 m²/g to 2.1572 m²/g) of Na-Mt when modified with DMSO. The porosity increased from 1.74 (SMAT) to 1.87 nm (DMSO-SMAT) after the application of the methodology. Thermal analysis showed a thermal stability for the DMSO-SMAT material, and this was used to calculate the DMSO-SMAT formula of Na[Al₅Mg]Si₁₂O₃₀(OH)₆ · 0.54 DMSO. Statistical analysis showed that only the effect of the amount of DMSO was significant for increasing the interlayer space of DMSO-SMAT. In addition, at room temperature, the drying time of the sample using this methodology was 30 min. Full article

(This article belongs to the Section Materials Chemistry)

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16 pages, 6145 KiB

Open AccessArticle

Electrochemical Impedance Spectroscopy Analysis of Organic Epoxy Coatings Reinforced with Nano Clay

by Davide Asperti, Marina Cabrini, Sergio Lorenzi, Giuseppe Rosace, Abdollah Omrani and Tommaso Pastore

Materials 2024, 17(12), 3028; https://doi.org/10.3390/ma17123028 - 20 Jun 2024

Viewed by 829

Abstract

Electrochemical impedance spectroscopy (EIS) is a modern and efficient method for the evaluation of the protective abilities of coatings. However, the interpretation of the experimental data is a difficult task. This paper aims to investigate the effect of the addition of a nano [...] Read more.

Electrochemical impedance spectroscopy (EIS) is a modern and efficient method for the evaluation of the protective abilities of coatings. However, the interpretation of the experimental data is a difficult task. This paper aims to investigate the effect of the addition of a nano clay, Cloesite 30B^®, on the barrier properties of an epoxy-based system through electrochemical impedance spectroscopy in an aerated sodium chloride solution. The EIS spectra of the samples analysed showed different evolutions over time. The subsequent processing of spectra using equivalent electrical circuits is an excellent analytical tool and allows the protective capacity of coatings to be assessed. By using this analysis, it was possible to define and comprehend the impact of adding nano clay in different concentrations to the epoxy resin coating. The work has shown the effectiveness of increasing the barrier effect of the coating with this type of nano clay. However, the improvement is linked to obtaining a correct dispersion of nanoparticles. Otherwise, there is the formation of macro-clusters of particles inside the coating. Their appearance can cause a deterioration in coating performance. Full article

(This article belongs to the Special Issue Corrosion and Protection of Metals and Alloys: Recent Advances and Future Prospects)

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15 pages, 12866 KiB

Open AccessArticle

Utilization Potential of Aerated Concrete Block Powder and Coffee Grounds Ash in Green-Growing Concrete

by Jinping Li, Rong Huang, Zheng Chen, Xuedi Sun and Deliang Yu

Materials 2024, 17(12), 3027; https://doi.org/10.3390/ma17123027 - 20 Jun 2024

Viewed by 817

Abstract

The purpose of this research is to investigate the utilization potential of recycled powder made from spent coffee grounds (SCGs) and aerated concrete blocks (ACBs) in green-growing concrete. The green-growing concrete is prepared using ACB powder and SCG ash as raw materials instead [...] Read more.

The purpose of this research is to investigate the utilization potential of recycled powder made from spent coffee grounds (SCGs) and aerated concrete blocks (ACBs) in green-growing concrete. The green-growing concrete is prepared using ACB powder and SCG ash as raw materials instead of 5%, 15%, and 25% and 5%, 10%, and 15% cement, respectively. Then, the two raw materials are compounded with the optimal content. The compressive strength and alkalinity of green-growing concrete at 7d and 28d and the frost resistance after 25 freeze–thaw cycles at 28d are studied. The results showed that the optimum content of ACB powder and SCG ash was 5%. Replacing 5% cement with recycled powder could improve the strength of concrete. The alkalinity of concrete containing ACB powder gradually increased, while the alkalinity of concrete containing SCG ash gradually decreased. The alkalinity of ACB-SCG powder was lower than that of ACB powder but slightly higher than that of SCG ash. The frost resistance of concrete containing ACB powder decreased gradually, and the frost resistance of concrete containing SCG ash increased first and then decreased greatly. The frost resistance of ACB-SCG powder could neutralize that of ACB powder and SCG ash. Full article

(This article belongs to the Section Construction and Building Materials)

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18 pages, 5495 KiB

Open AccessEditor’s ChoiceArticle

Accelerated Design for Perovskite-Oxide-Based Photocatalysts Using Machine Learning Techniques

by Xiuyun Zhai and Mingtong Chen

Materials 2024, 17(12), 3026; https://doi.org/10.3390/ma17123026 - 20 Jun 2024

Viewed by 952

Abstract

The rapid discovery of photocatalysts with desired performance among tens of thousands of potential perovskites represents a significant advancement. To expedite the design of perovskite-oxide-based photocatalysts, we developed a model of ABO₃-type perovskites using machine learning methods based on atomic and [...] Read more.

The rapid discovery of photocatalysts with desired performance among tens of thousands of potential perovskites represents a significant advancement. To expedite the design of perovskite-oxide-based photocatalysts, we developed a model of ABO₃-type perovskites using machine learning methods based on atomic and experimental parameters. This model can be used to predict specific surface area (SSA), a key parameter closely associated with photocatalytic activity. The model construction involved several steps, including data collection, feature selection, model construction, web-service development, virtual screening and mechanism elucidation. Statistical analysis revealed that the support vector regression model achieved a correlation coefficient of 0.9462 for the training set and 0.8786 for the leave-one-out cross-validation. The potential perovskites with higher SSA than the highest SSA observed in the existing dataset were identified using the model and our computation platform. We also developed a webserver of the model, freely accessible to users. The methodologies outlined in this study not only facilitate the discovery of new perovskites but also enable exploration of the correlations between the perovskite properties and the physicochemical features. These findings provide valuable insights for further research and applications of perovskites using machine learning techniques. Full article

(This article belongs to the Section Materials Simulation and Design)

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15 pages, 6410 KiB

Open AccessArticle

Effects of High Al Content on the Phase Constituents and Thermal Properties in NiCoCrAlY Alloys

by Jin Zhang, Zhihua Nie, Chengpeng Tan, Rende Mu, Shilei Li, Xianjin Ning and Chengwen Tan

Materials 2024, 17(12), 3025; https://doi.org/10.3390/ma17123025 - 20 Jun 2024

Viewed by 831

Abstract

MCrAlY (M = Ni and/or Co) metallic coatings are essential for the protection of hot-end components against thermal and corrosion damage. Increasing the Al content is considered a feasible solution to improve the high-temperature performance of MCrAlY coatings. In this paper, the effects [...] Read more.

MCrAlY (M = Ni and/or Co) metallic coatings are essential for the protection of hot-end components against thermal and corrosion damage. Increasing the Al content is considered a feasible solution to improve the high-temperature performance of MCrAlY coatings. In this paper, the effects of high Al contents (12–20 wt.%) on the phase constituents and cast microstructures in MCrAlY alloys were studied by high-energy X-ray diffraction and electron microscopy techniques combined with phase equilibria calculations. High Al content improved the stability of β, σ, and α phases. Meanwhile, an evolution of the cast microstructure morphology from a dendrite structure to an equiaxed grain structure was observed. The thermal properties were analyzed, which were closely related to the phase constituents and solid-to-solid phase transitions at evaluated temperatures. This work is instructive for developing high-Al-content MCrAlY coatings for next-generation thermal barrier applications. Full article

(This article belongs to the Special Issue Microstructure and Mechanical Properties of Materials Characterized by Neutron and Synchrotron X-ray Diffraction)

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17 pages, 9927 KiB

Open AccessArticle

Experimental Studies of the Machinability of SiCp/Al with Different Volume Fractions under Ultrasonic-Assisted Grinding

by Chen Hu, Yongwei Zhu and Ruoxun Fan

Materials 2024, 17(12), 3024; https://doi.org/10.3390/ma17123024 - 20 Jun 2024

Cited by 1 | Viewed by 577

Abstract

High-volume fraction silicon carbide particle-reinforced aluminum (SiCp/Al) has a promising application for its high specific strength, wear resistance, and thermal conductivity. However, SiCp/Al components with a high-volume fraction are prone to poor surface quality and defects such as fractures, cracks, and micro-pits. It [...] Read more.

High-volume fraction silicon carbide particle-reinforced aluminum (SiCp/Al) has a promising application for its high specific strength, wear resistance, and thermal conductivity. However, SiCp/Al components with a high-volume fraction are prone to poor surface quality and defects such as fractures, cracks, and micro-pits. It has been reported that ultrasonic-assisted grinding machining (UAG) helps to improve the quality of SiCp/Al machined surfaces. However, the differences between SiCp/Al with different volume fractions obtained by UAG machining are not clear. Therefore, a comparative study of surface roughness, morphology, and cutting force was carried out by UAG machining on SiCp/Al samples with volume fractions of 45% and 60%. Compared to the 45% volume fraction SiCp/Al, the 60% volume fraction SiCp/Al has a higher cutting force and roughness under the same machining parameters. In addition, experiments have shown that cutting forces and surface roughness can be reduced by increasing the tool speed or decreasing the feed rate. UAG machining with an ultrasonic amplitude within 4 μm can also reduce cutting forces and surface roughness. However, more than 6 μm ultrasonic amplitude may lead to an increase in roughness. This study contributes to reasonable parameter settings in ultrasonically-assisted grinding of SiCp/Al with different volume fractions. Full article

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

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16 pages, 18963 KiB

Open AccessArticle

Separation of Damage Mechanisms in Full Forward Rod Extruded Case-Hardening Steel 16MnCrS5 Using 3D Image Segmentation

by Lars A. Lingnau, Johannes Heermant, Johannes L. Otto, Kai Donnerbauer, Lukas M. Sauer, Lukas Lücker, Marina Macias Barrientos and Frank Walther

Materials 2024, 17(12), 3023; https://doi.org/10.3390/ma17123023 - 20 Jun 2024

Cited by 2 | Viewed by 741

Abstract

In general, formed components are lightweight as well as highly economic and resource efficient. However, forming-induced ductile damage, which particularly affects the formation and growth of pores, has not been considered in the design of components so far. Therefore, an evaluation of forming-induced [...] Read more.

In general, formed components are lightweight as well as highly economic and resource efficient. However, forming-induced ductile damage, which particularly affects the formation and growth of pores, has not been considered in the design of components so far. Therefore, an evaluation of forming-induced ductile damage would enable an improved design and take better advantage of the lightweight nature as it affects the static and dynamic mechanical material properties. To quantify the amount, morphology and distribution of the pores, advanced scanning electron microscopy (SEM) methods such as scanning transmission electron microscopy (STEM) and electron channeling contrast imaging (ECCI) were used. Image segmentation using a deep learning algorithm was applied to reproducibly separate the pores from inclusions such as manganese sulfide inclusions. This was achieved via layer-by-layer ablation of the case-hardened steel 16MnCrS5 (DIN 1.7139, AISI/SAE 5115) with a focused ion beam (FIB). The resulting images were reconstructed in a 3D model to gain a mechanism-based understanding beyond the previous 2D investigations. Full article

(This article belongs to the Section Advanced Materials Characterization)

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18 pages, 5764 KiB

Open AccessArticle

The Potential Risk of Nanoparticulate Release from Photocatalytic Pavement Concrete Surface Due to a Simulated Abrasion Load—An Experimental Study

by Hubert Witkowski, Janusz Jarosławski, Artur Szkop, Karol Chilmon, Maciej Kalinowski and Wioletta Jackiewicz-Rek

Materials 2024, 17(12), 3022; https://doi.org/10.3390/ma17123022 - 20 Jun 2024

Cited by 2 | Viewed by 1034

Abstract

The risk of the releasing of nanometric particles from construction materials with nanometric components might be one of the biggest threats to further development of them. One of the possible ingress routes to human organisms is the respiratory system. Therefore, it is crucial [...] Read more.

The risk of the releasing of nanometric particles from construction materials with nanometric components might be one of the biggest threats to further development of them. One of the possible ingress routes to human organisms is the respiratory system. Therefore, it is crucial to determine the risk of emission of nanometric particles during material usage. In the presented paper, abrasion of mortar samples with nanometric TiO₂ was investigated. A special abrasion test setup was developed to reflect everyday abrasion of the concrete surface of pavements. In the study, three TiO₂-modifed mortar series (and respective reference series) underwent the developed test protocol and the grains were mobilized from their surface due to the applied load analyzed (granulation, morphology, and chemical composition). For a comparative analysis, an abrasion parameter was developed. Based on the obtained results, the modification of cementitious composites with nanometric TiO₂ contributed to a reduction in the emission of aerosols and, therefore, confirmed the compatibility between TiO₂ and cement matrix. Full article

(This article belongs to the Special Issue Advances in Alternative Asphalt and Pavement Materials: Design, Structure and Properties)

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12 pages, 4726 KiB

Open AccessArticle

Experimental Investigation of Damping Properties of Selected Polymer Materials

by Lucjan Witek and Piotr Łabuński

Materials 2024, 17(12), 3021; https://doi.org/10.3390/ma17123021 - 20 Jun 2024

Cited by 1 | Viewed by 796

Abstract

This paper presents the results of an experimental modal analysis of a beam covered by polymer materials used as a passive vibration isolation. The main aim of this study was to determine the damping properties of selected viscoelastic materials. In order to check [...] Read more.

This paper presents the results of an experimental modal analysis of a beam covered by polymer materials used as a passive vibration isolation. The main aim of this study was to determine the damping properties of selected viscoelastic materials. In order to check the damping properties of tested materials, an experimental modal analysis, with the use of an electrodynamic vibration system, was performed. In this study, four kinds of specimens were considered. In the first step of the work, the beam made out of aluminum alloy was investigated. Afterwards, a cantilever beam was covered with a layer of bitumen-based material acting as a damper. This method is commonly known as a free layer damping treatment (FLD). In order to increase the damping capabilities, the previous configuration was improved by fixing a thin aluminum layer directly to the viscoelastic core. Such a treatment is called constrained layer damping (CLD). Subsequently, another polymer (butyl rubber) in the CLD configuration was tested for its damping properties. As a result of the performed experimental modal analysis, the frequencies of resonant vibrations and their corresponding amplitudes were obtained. The experimental results were used to quantitatively evaluate the damping properties of tested materials. Full article

(This article belongs to the Section Mechanics of Materials)

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20 pages, 13744 KiB

Open AccessArticle

Research on Alloying Elements’ Influence on CuETP-Grade Copper’s Mechanical and Electrical Properties

by Krystian Franczak, Michał Sadzikowski, Paweł Kwaśniewski, Grzegorz Kiesiewicz, Wojciech Ściężor and Szymon Kordaszewski

Materials 2024, 17(12), 3020; https://doi.org/10.3390/ma17123020 - 20 Jun 2024

Viewed by 990

Abstract

The continuous industrial development that occurs worldwide generates the need to develop new materials with increasingly higher functional properties. This need also applies to the basic material for electricity purposes, which is copper. In this article, we carry out studies on the influence [...] Read more.

The continuous industrial development that occurs worldwide generates the need to develop new materials with increasingly higher functional properties. This need also applies to the basic material for electricity purposes, which is copper. In this article, we carry out studies on the influence of various alloying elements such as Mg, In, Si, Nb, Hf, Sb, Ni, Al, Fe, Zr, Cr, Zn, P, Ag, Sc, Pb, Sn, Co, Ti, Mn, Te and Bi on the electrical and mechanical properties of ETP-grade copper. The research involves producing copper alloys using the gravity die casting method with alloy additions of 0.1 wt.%, 0.3 wt.% and 0.5 wt.%. All resulting materials are cold-worked to produce wires, which are subsequently homogenized and annealed. The materials produced in this manner undergo testing to determine their specific electrical conductivity, tensile strength, yield strength, elongation and Vickers hardness (HV10 scale). Full article

(This article belongs to the Special Issue Characterization, Properties, and Applications of New Metallic Alloys)

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11 pages, 6782 KiB

Open AccessArticle

Effect of the Height of a 3D-Printed Model on the Force Transmission and Thickness of Thermoformed Orthodontic Aligners

by Omar Ghoraba, Christoph Bourauel, Mostafa Aldesoki, Lamia Singer, Ahmed M. Ismail, Hanaa Elattar, Abdulaziz Alhotan and Tarek M. Elshazly

Materials 2024, 17(12), 3019; https://doi.org/10.3390/ma17123019 - 20 Jun 2024

Viewed by 1266

Abstract

This research aims to investigate the influence of model height employed in the deep drawing of orthodontic aligner sheets on force transmission and aligner thickness. Forty aligner sheets (Zendura FLX) were thermoformed over four models of varying heights (15, 20, 25, and 30 [...] Read more.

This research aims to investigate the influence of model height employed in the deep drawing of orthodontic aligner sheets on force transmission and aligner thickness. Forty aligner sheets (Zendura FLX) were thermoformed over four models of varying heights (15, 20, 25, and 30 mm). Normal contact force generated on the facial surface of the upper right central incisor (Tooth 11) was measured using pressure-sensitive films. Aligner thickness around Tooth 11 was measured at five points. A digital caliper and a micro-computed tomography (µ-CT) were employed for thickness measurements. The normal contact force exhibited an uneven distribution across the facial surface of Tooth 11. Model 15 displayed the highest force (88.9 ± 23.2 N), while Model 30 exhibited the lowest (45.7 ± 15.8 N). The force distribution was more favorable for bodily movement with Model 15. Thickness measurements revealed substantial thinning of the aligner after thermoforming. This thinning was most pronounced at the incisal edge (50% of the original thickness) and least at the gingivo-facial part (85%). Additionally, there was a progressive reduction in aligner thickness with increasing model height, which was most significant on the facial tooth surfaces. We conclude that the thermoplastic aligner sheets undergo substantial thinning during the thermoforming process, which becomes more pronounced as the height of the model increases. As a result, there is a decrease in both overall and localized force transmission, which could lead to increased tipping by the aligner and a diminished ability to achieve bodily movement. Full article

(This article belongs to the Special Issue Orthodontic Materials: Properties and Effectiveness of Use)

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Different 3D-printed aligned resin models used for thermoforming, exhibiting varying heights. A shallow groove was positioned 2 mm beyond the gingival line to facilitate the standardization of aligner trimming. Full article ">Figure 2
A visual representation of the procedure followed for measuring the local normal contact force, generated on the crown of a maxillary right central incisor (Tooth 11), using Fuji® pressure-sensitive film. The pressurized film underwent scanning with a scanner, and the 2D scan was superimposed over a 3D digital model of the tooth to enhance visualization. Full article ">Figure 3
A µ-CT processed 3D image for a part of the aligner over the upper right central incisor (Tooth 11) for measurement of aligner thickness by MIMICS 25.0 software, at various reference points (gingivo-facial (GF), mid-facial (MF), incisal (I), mid-lingual (ML), gingivo-lingual (GL)). Full article ">Figure 4
Normal contact force generated on Tooth 11 by aligners, made from Zendura FLX sheets thermoformed over models of different heights (15, 20, 25, 30 mm), and recorded using Fuji pressure-sensitive film. Different uppercase and lowercase superscript letters indicate a statistically significant difference within the same horizontal row and vertical column, respectively. Full article ">Figure 5
Thickness of aligners, made from Zendura FLX sheets thermoformed over models of different heights (15, 20, 25, 30 mm), recorded using a digital caliper at different points of the aligner splint covering the crown of Tooth 11. Different lowercase superscript letters indicate a statistically significant difference within the same vertical column. Full article ">Figure 6
Thickness of aligners, made from Zendura FLX sheets thermoformed over models of different heights (15, 20, 25, 30 mm), recorded using a µ-CT device at different points of the aligner splint covering the crown of Tooth 11. Different lowercase superscript letters indicate a statistically significant difference within the same vertical column. Full article ">

17 pages, 5067 KiB

Open AccessArticle

Unloading Model of Elastic–Plastic Half-Space Contacted by an Elastic Spherical Indenter

by Wenhao Xie, Yuanyuan Guo, Huaiping Ding, Xiaochun Yin and Panpan Weng

Materials 2024, 17(12), 3018; https://doi.org/10.3390/ma17123018 - 20 Jun 2024

Viewed by 1001

Abstract

A new unloading contact model of an elastic–perfectly plastic half-space indented by an elastic spherical indenter is presented analytically. The recovered deformation of the elastic indenter and the indented half-space has been found to be dependent on the elastic modulus ratio after fully [...] Read more.

A new unloading contact model of an elastic–perfectly plastic half-space indented by an elastic spherical indenter is presented analytically. The recovered deformation of the elastic indenter and the indented half-space has been found to be dependent on the elastic modulus ratio after fully unloading. The recovered deformation of the indented half-space can be calculated based on the deformation of the purely elastic indenter. The unloading process is assumed to be entirely elastic, and then the relationship of contact force and indentation can be determined based on the solved recovered deformation and conforms to Hertzian-type. The model can accurately predict the residual indentation and residual curvature radius after fully unloading. Numerical simulations are performed to demonstrate the assumptions and the unloading model. The proposed unloading model can cover a wide range of indentations and material properties and is compared with existing unloading models. The cyclic behavior including loading and unloading can be predicted by combining the proposed unloading law with the existing contact loading model. The combined model can be employed for low-velocity impact and nanoindentation tests and the comparison results are in good agreement. Full article

(This article belongs to the Special Issue Instrumented Indentation Test for Materials Science and Industry: 2nd Edition)

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13 pages, 9385 KiB

Open AccessArticle

Yttria-Stabilized Zirconia Composite Coating as Barrier to Reduce Hydrogen Permeation into Steel

by Jianmeng Wu, Jiaqi Xie, Mengyuan He, Jingyi Zhang and Songjie Li

Materials 2024, 17(12), 3017; https://doi.org/10.3390/ma17123017 - 20 Jun 2024

Viewed by 1062

Abstract

Hydrogen atoms can enter into metallic materials through penetration and diffusion, leading to the degradation of the mechanical properties of the materials, and the application of hydrogen barrier coatings is an effective means to alleviate this problem. Zirconia coatings (ZrO₂) have [...] Read more.

Hydrogen atoms can enter into metallic materials through penetration and diffusion, leading to the degradation of the mechanical properties of the materials, and the application of hydrogen barrier coatings is an effective means to alleviate this problem. Zirconia coatings (ZrO₂) have been widely studied as a common hydrogen barrier coating, but zirconia undergoes a crystalline transition with temperature change, which can lead to volumetric changes in the coating and thus cause problems such as cracking and peeling of the coating. In this work, ZrO₂ coating was prepared on a Q235 matrix using a sol-gel method, while yttria-stabilized zirconia (YSZ) coatings with different contents of rare earth elements were prepared in order to alleviate a series of problems caused by the crystal form transformation of ZrO₂. The coating performances were evaluated by the electrochemical hydrogen penetration test, pencil hardness test, scratch test, and high-temperature oxidation test. The results show that yttrium can improve the stability of the high-temperature phase of ZrO₂, alleviating the cracking problem of the coating due to the volume change triggered by the crystalline transition; improve the consistency of the coating; and refine the grain size of the oxide. The performance of YSZ coating was strongly influenced by the yttria doping mass, and the coating with 10 wt% yttria doping had the best hydrogen barrier performance, the best antioxidant performance, and the largest adhesion. Compared with the matrix, the steady-state hydrogen current density of the YSZ coating decreased by 72.3%, the antioxidant performance was improved by 65.8%, and the ZrO₂ coating hardness and adhesion levels were B and 4B, respectively, while YSZ coating hardness and adhesion were upgraded to 2H and 5B. With the further increase in yttrium doping mass, the hardness of the coating continued to improve, but the defects of the coating increased, resulting in a decrease in the hydrogen barrier performance, antioxidant performance, and adhesion. In this work, the various performances of ZrO₂ coating were significantly improved by doping with the rare earth element, which provides a reference for further development and application of oxide coatings. Full article

(This article belongs to the Special Issue Corrosion and Crack Behavior of Metallic Materials in High-Temperature Environment)

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17 pages, 5108 KiB

Open AccessArticle

Investigation on Anti-Fuel Erosion Performance of Sasobit/SBS-Modified Asphalt and Its Mixtures

by Yongkang Wu, Meizhu Chen, Qi Jiang, Jianwei Zhang, Yansong Fan and Jun He

Materials 2024, 17(12), 3016; https://doi.org/10.3390/ma17123016 - 19 Jun 2024

Viewed by 697

Abstract

The fuel leakage of fuel vehicles will exacerbate the occurrence of distresses on asphalt pavements, including peeling, chipping and potholes, especially under the synergistic effect of traffic load and environment. In this research, Sasobit, which is commonly used as a warm agent in [...] Read more.

The fuel leakage of fuel vehicles will exacerbate the occurrence of distresses on asphalt pavements, including peeling, chipping and potholes, especially under the synergistic effect of traffic load and environment. In this research, Sasobit, which is commonly used as a warm agent in asphalt, is selected as the anti-fuel erosion agent and incorporated into SBS-modified asphalt and its mixtures. Diesel and gasoline are selected as the fuel erosion media. Sasobit/SBS-modified asphalt binder and its mixtures are investigated for fuel erosion. The rheological properties of bitumen and the mechanical properties of asphalt mixtures are assessed. The experimental findings show that the dissolution velocity of SBS-modified asphalt with 3% Sasobit is 0.2%/min for diesel erosion, while it is 1.7%/min for gasoline erosion, lower than the control sample without Sasobit. Meanwhile, the rutting factor of Sasobit/SBS-modified asphalt decreases less than that of the control sample without Sasobit. Furthermore, the mass loss ratio after the Cantabro test of Sasobit/SBS-modified asphalt mixtures is 1.2% for diesel erosion, while it is 6.8% for gasoline erosion, lower than that of the control sample without Sasobit. The results of the mechanical properties for asphalt mixtures demonstrate that Sasobit can enhance the anti-fuel erosion performance. Moreover, the research results of the Sasobit modification mechanism show that Sasobit can form a microcrystalline structure in SBS-modified asphalt, which subsequently improves the anti-fuel of asphalt and its mixtures. This research provides a reference for anti-fuel erosion assessment methods and solutions to improve the anti-fuel erosion of asphalt pavement. Full article

(This article belongs to the Section Construction and Building Materials)

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Open AccessArticle

Synthesis and Characterization of Sol–Gelled Barium Zirconate as Novel MTA Radiopacifiers

by Hsiu-Na Lin, May-Show Chen, Pei-Jung Chang, Yao-Chi Lee, Chin-Yi Chen, Yuh-Jing Chiou and Chung-Kwei Lin

Materials 2024, 17(12), 3015; https://doi.org/10.3390/ma17123015 - 19 Jun 2024

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Abstract

Barium zirconate (BaZrO₃, BZO), which exhibits superior mechanical, thermal, and chemical stability, has been widely used in many applications. In dentistry, BZO is used as a radiopacifier in mineral trioxide aggregates (MTAs) for endodontic filling applications. In the present study, BZO [...] Read more.

Barium zirconate (BaZrO₃, BZO), which exhibits superior mechanical, thermal, and chemical stability, has been widely used in many applications. In dentistry, BZO is used as a radiopacifier in mineral trioxide aggregates (MTAs) for endodontic filling applications. In the present study, BZO was prepared using the sol–gel process, followed by calcination at 700–1000 °C. The calcined BZO powders were investigated using X-ray diffraction and scanning electron microscopy. Thereafter, MTA-like cements with the addition of calcined BZO powder were evaluated to determine the optimal composition based on radiopacity, diametral tensile strength (DTS), and setting times. The experimental results showed that calcined BZO exhibited a majority BZO phase with minor zirconia crystals. The crystallinity, the percentage, and the average crystalline size of BZO increased with the increasing calcination temperature. The optimal MTA-like cement was obtained by adding 20% of the 700 °C-calcined BZO powder. The initial and final setting times were 25 and 32 min, respectively. They were significantly shorter than those (70 and 56 min, respectively) prepared with commercial BZO powder. It exhibited a radiopacity of 3.60 ± 0.22 mmAl and a DTS of 3.02 ± 0.18 MPa. After 28 days of simulated oral environment storage, the radiopacity and DTS decreased to 3.36 ± 0.53 mmAl and 2.84 ± 0.27 MPa, respectively. This suggests that 700 °C-calcined BZO powder has potential as a novel radiopacifier for MTAs. Full article

(This article belongs to the Special Issue New Materials and Techniques for Root Canal Preparation and Filling)

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Materials, Volume 17, Issue 12 (June-2 2024) – 257 articles

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