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Materials, Volume 15, Issue 21 (November-1 2022) – 462 articles

Cover Story (view full-size image): Information coding via magnetic state is an idea dating back to the 1970s, when bubble domains in micrometric ferrite films were investigated. Half a century later, this idea has been revisited, backed by a breakthrough in ultra-thin film technologies, as well as progress in the solid-state physics of ferromagnetic chiral nanostructures such as skyrmions. Theoretically predicted in 2006 as topologically protected local whirls of the spin configuration, the skyrmions hosted in ultra-thin FM films (1–5 nm) in contact with a heavy metal are regarded as promising candidates for the role of information carriers in next-generation magnetic computing. View this paper
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15 pages, 4798 KiB  
Article
Study on Low-Temperature Index and Improvement Measures of Emulsified Asphalt Cold Recycled Mixture
by Xiaoqing Yu, Zhanchuang Han, Yu Cai, Liping Liu and Lijun Sun
Materials 2022, 15(21), 7867; https://doi.org/10.3390/ma15217867 - 7 Nov 2022
Cited by 1 | Viewed by 1442
Abstract
With the promotion of cold recycled mixture (CRM) in cold areas and the improvement of its application layer, the enhancement of the low-temperature performance of mixtures is particularly important. The applicability of the current low-temperature bending test method to CRM is controversial. Firstly, [...] Read more.
With the promotion of cold recycled mixture (CRM) in cold areas and the improvement of its application layer, the enhancement of the low-temperature performance of mixtures is particularly important. The applicability of the current low-temperature bending test method to CRM is controversial. Firstly, the low-temperature crack resistance of CRM with different gradations and emulsified asphalt contents was studied by the indirect tensile (IDT) test and the semi-circular bending (SCB) test. Thereafter, the low-temperature performance evaluation index suitable for CRM was put forward. Then, the low-temperature performance of CRM with different gradations, fiber types, and contents was evaluated by using the above low-temperature evaluation index. The results show that the low-temperature performance of CRM with different gradations and emulsified asphalt contents can be distinguished by fracture work (W) and fracture energy (Gf). Not only do the test results have little variability (about 12% and 15%, respectively), but also the correlation coefficient with the new asphalt film thickness is the highest (0.8595 and 0.8939, respectively). Compared with coarse gradation (AC-25) and fine gradation (AC-13), medium-gradation (AC-20) CRM has higher low-temperature performance, and polyester fiber can significantly improve the low-temperature performance of CRM. Compared with non-fiber, the W and Gf of CRM of polyester fiber (0.3% content) can be increased by at least 42% and 30%, respectively. Full article
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9 pages, 5552 KiB  
Article
Enhanced Mechanical Properties of Yellow ZrN Ceramic with Addition of Solid Solution of TiN
by Zongpeng Wu, Zhen Gao, Jun Zhao, Saisai Li, Qi Hao and Songlin Ran
Materials 2022, 15(21), 7866; https://doi.org/10.3390/ma15217866 - 7 Nov 2022
Cited by 1 | Viewed by 1343
Abstract
As a superhard ceramic with a yellow color and excellent electrical conductivity, ZrN has potential applications in the field of decoration, but it is limited by its poor mechanical properties. In this work, the mechanical properties of ZrN ceramic were improved by forming [...] Read more.
As a superhard ceramic with a yellow color and excellent electrical conductivity, ZrN has potential applications in the field of decoration, but it is limited by its poor mechanical properties. In this work, the mechanical properties of ZrN ceramic were improved by forming a (Zr, Ti)N solid solution via spark plasma sintering of a ZrN and TiN powder mixture. The influences of the amount of TiN additive on the sinterability, microstructure, color, and mechanical properties of ZrN ceramic were investigated. X-ray diffraction analysis, energy-dispersive spectroscopy, and microstructural images indicated that Ti atoms dissolved into a ZrN lattice, and a (Zr, Ti)N solid solution was formed during the sintering process. When the content of TiN was 10 vol%, the obtained (Zr, Ti)N composite exhibited the best comprehensive mechanical properties; the Vickers hardness, flexural strength, and fracture toughness were 15.17 GPa, 520 MPa, and 6.03 MPa·m1/2, respectively. The color coordinates and color temperature diagram revealed the addition of TiN hardly impacted the color performance of the ZrN ceramic. Full article
(This article belongs to the Special Issue Recent Studies in Advanced Structural Ceramics)
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15 pages, 4125 KiB  
Article
Synthesis of Superhydrophobic Barium Hexaferrite Coatings with Low Magnetic Hardness
by Arsen E. Muslimov, Makhach Kh Gadzhiev and Vladimir M. Kanevsky
Materials 2022, 15(21), 7865; https://doi.org/10.3390/ma15217865 - 7 Nov 2022
Cited by 3 | Viewed by 1575
Abstract
Using the multifunctional material barium hexaferrite as an example, the prospects for treatment at a quasi-equilibrium low temperature in an open atmosphere to form superhydrophobic magnetic coatings with pronounced crystalline and magnetic anisotropy have been demonstrated for the first time. The relationship between [...] Read more.
Using the multifunctional material barium hexaferrite as an example, the prospects for treatment at a quasi-equilibrium low temperature in an open atmosphere to form superhydrophobic magnetic coatings with pronounced crystalline and magnetic anisotropy have been demonstrated for the first time. The relationship between plasma treatment conditions, structural-phase composition, morphology, and superhydrophobic properties of (0001) films of barium hexaferrite BaFe12O19 on C-sapphire is studied. X-ray photoelectron spectroscopy (XPS), X-ray diffractometry (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), as well as magnetometry and moisture resistance analysis, were used as research methods. During plasma treatment with a mass-average temperature of 8–10 kK, intense evaporation and surface melting were observed, and texturing of the deposit along (0001) is found. When the treatment temperature was reduced to 4–5 kK, the evaporation of the material was minimized and magnetic and crystal anisotropy increased. However, the increase in the size of crystallites was accompanied by the transition of oxygen atoms from lattice nodes to interstitial positions. All samples exhibited low coercive fields below 500 Oe, associated with the frustration of the magnetic subsystem. Features of growth of materials with a wurtzite structure were used to form a superhydrophobic coating of barium hexaferrite. Plasma treatment regimes for obtaining self-cleaning coatings are proposed. The use of magnetically hard barium hexaferrite to radically change the properties of a coating is demonstrated herein as an example. Full article
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31 pages, 13008 KiB  
Article
The Influence of Graded Amount of Potassium Permanganate on Corrosion of Hot-Dip Galvanized Steel in Simulated Concrete Pore Solutions
by Petr Pokorný, Vítězslav Vacek, Nikola Prodanovic, Adam Zabloudil, Jaroslav Fojt and Viktor Johánek
Materials 2022, 15(21), 7864; https://doi.org/10.3390/ma15217864 - 7 Nov 2022
Cited by 5 | Viewed by 2148
Abstract
This paper evaluates the amount of KMnO4 in simulated concrete pore solution (pH 12.8) on the corrosion behaviour of hot-dip galvanized steel (HDG). In the range of used MnO4 (10−4, 10−3, 10−2 mol·L−1), [...] Read more.
This paper evaluates the amount of KMnO4 in simulated concrete pore solution (pH 12.8) on the corrosion behaviour of hot-dip galvanized steel (HDG). In the range of used MnO4 (10−4, 10−3, 10−2 mol·L−1), corrosion behaviour is examined with regard to hydrogen evolution and composition (protective barrier properties) of forming corrosion products. The corrosion behaviour of HDG samples is evaluated using Rp/Ecorr and EIS. The composition of corrosion products is evaluated using SEM, XRD, XPS and AAS. The effective MnO4 ion concentration to prevent the corrosion of coating with hydrogen evolution is 10−3 mol·L−1; lower concentrations only prolong the time to passivation (corrosion with hydrogen evolution). The highest used MnO4 concentration ensures corrosion behaviour without hydrogen evolution but also leads to the formation of less-protective amorphous corrosion products rich in MnII/MnIII phases. Full article
(This article belongs to the Special Issue Advanced Processing Methods for Metals and Their Alloys)
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14 pages, 1934 KiB  
Article
Kinetics of Catalyst-Free and Position-Controlled Low-Pressure Chemical Vapor Deposition Growth of VO2 Nanowire Arrays on Nanoimprinted Si Substrates
by Sergey V. Mutilin, Lyubov V. Yakovkina, Vladimir A. Seleznev and Victor Ya. Prinz
Materials 2022, 15(21), 7863; https://doi.org/10.3390/ma15217863 - 7 Nov 2022
Cited by 3 | Viewed by 1504
Abstract
In the present article, the position-controlled and catalytic-free synthesis of vanadium dioxide (VO2) nanowires (NWs) grown by the chemical vapor deposition (CVD) on nanoimprinted silicon substrates in the form of nanopillar arrays was analyzed. The NW growth on silicon nanopillars with [...] Read more.
In the present article, the position-controlled and catalytic-free synthesis of vanadium dioxide (VO2) nanowires (NWs) grown by the chemical vapor deposition (CVD) on nanoimprinted silicon substrates in the form of nanopillar arrays was analyzed. The NW growth on silicon nanopillars with different cross-sectional areas was studied, and it has been shown that the NWs’ height decreases with an increase in their cross-sectional area. The X-ray diffraction technique, scanning electron microscopy, and X-ray photoelectron spectroscopy showed the high quality of the grown VO2 NWs. A qualitative description of the growth rate of vertical NWs based on the material balance equation is given. The dependence of the growth rate of vertical and horizontal NWs on the precursor concentration in the gas phase and on the growth time was investigated. It was found that the height of vertical VO2 NWs along the [100] direction exhibited a linear dependence on time and increased with an increase in the precursor concentration. For horizontal VO2 NWs, the height along the direction [011] varied little with the growth time and precursor concentration. These results suggest that the high-aspect ratio vertical VO2 NWs formed due to different growth modes of their crystal faces forming the top of the growing VO2 crystals and their lateral crystal faces related to the difference between the free energies of these crystal faces and implemented experimental conditions. The results obtained permit a better insight into the growth of high-aspect ratio VO2 NWs and into the formation of large VO2 NW arrays with a controlled composition and properties. Full article
(This article belongs to the Section Advanced Nanomaterials and Nanotechnology)
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22 pages, 11885 KiB  
Article
Effect of Air Storage on Stress Corrosion Cracking of ZK60 Alloy Induced by Preliminary Immersion in NaCl-Based Corrosion Solution
by Evgeniy Merson, Vitaliy Poluyanov, Pavel Myagkikh, Dmitri Merson and Alexei Vinogradov
Materials 2022, 15(21), 7862; https://doi.org/10.3390/ma15217862 - 7 Nov 2022
Cited by 5 | Viewed by 1548
Abstract
The preliminary exposure of Mg alloys to corrosion solutions can cause their embrittlement. The phenomenon is referred to as pre-exposure stress corrosion cracking (PESCC). It has been reported that relatively long storage in air after pre-exposure to the corrosion solution is capable of [...] Read more.
The preliminary exposure of Mg alloys to corrosion solutions can cause their embrittlement. The phenomenon is referred to as pre-exposure stress corrosion cracking (PESCC). It has been reported that relatively long storage in air after pre-exposure to the corrosion solution is capable of eliminating PESCC. This effect was attributed to the egress of diffusible hydrogen that accumulated in the metal during pre-exposure. However, recent findings challenged this viewpoint and suggested that the corrosion solution retained within the side surface layer of corrosion products could be responsible for PESCC. The present study is aimed at the clarification of the role of hydrogen and the corrosion solution sealed within the corrosion products in the “healing” effect caused by post-exposure storage in air. Using the slow strain rate tensile (SSRT) testing in air and detailed fractographic analysis of the ZK60 specimens subjected to the liquid corrosion followed by storage in air, we found that PESCC was gradually reduced and finally suppressed with the increasing time and temperature of air storage. The complete elimination of PESCC accompanied by recovery of elongation to failure from 20% to 38% was achieved after 24 h of air storage at 150–200 °C. It is established that the characteristic PESCC zone on the fracture surface is composed of two regions, of which the first is always covered by the crust of corrosion products, whereas the second one is free of corrosion products and is characterised by quasi-brittle morphology. It is argued that the corrosion solution and hydrogen stored within the corrosion product layer are responsible for the formation of these two zones, respectively. Full article
(This article belongs to the Special Issue Corrosion and Mechanical Behavior of Metal Materials)
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12 pages, 4228 KiB  
Article
Basic Characteristics of Dose Distributions of Photons Beam for Radiotherapeutic Applications Using YAG:Ce Crystal Detectors
by Janusz Winiecki, Sandra Witkiewicz-Lukaszek, Paulina Michalska, Seweryn Jakubowski, Sergiy Nizhankovskiy and Yuriy Zorenko
Materials 2022, 15(21), 7861; https://doi.org/10.3390/ma15217861 - 7 Nov 2022
Cited by 3 | Viewed by 1717
Abstract
Thermostimulated luminescence (TSL) dosimetry is a versatile tool for the assessment of dose from ionizing radiation. In this work, the Ce3+ doped Y3Al5O12 garnet (YAG:Ce) with a density ρ = 4.56 g/cm3 and effective atomic number [...] Read more.
Thermostimulated luminescence (TSL) dosimetry is a versatile tool for the assessment of dose from ionizing radiation. In this work, the Ce3+ doped Y3Al5O12 garnet (YAG:Ce) with a density ρ = 4.56 g/cm3 and effective atomic number Zeff = 35 emerged as a prospective TSL material in radiotherapy applications due to its excellent radiation stability, uniformity of structural and optical properties, high yield of TSL, and good position of main glow peak around 290–300 °C. Namely, the set of TSL detectors produced from the YAG:Ce single crystal is used for identification of the uniformity of dose and energy spectra of X-ray radiation generated by the clinical accelerator with 6 MV and 15 MV beams located in Radiotherapy Department at the Oncology Center in Bydgoszcz, Poland. We have found that the YAG:Ce crystal detects shows very promising results for registration of X-ray radiation generated by the accelerator with 6 MV beam. The next step in the research is connected with application of TSL detectors based on the crystals of much heavier garnets than YAG. It is estimated that the LuAG:Ce garnet crystals with high density ρ = 6.0 g/cm3 and Zeff = 62 can be used to evaluate the X-rays produced by the accelerator with the 15 MV beam. Full article
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10 pages, 5023 KiB  
Article
Quasi-One-Dimensional Linarite-Type PbCu(SeO4)(OH)2 with Competing Nearest-Neighbor and Next-Nearest-Neighbor Intrachain Exchange Interactions
by Maria Markina, Konstantin Zakharov, Yevgeniy Ovchenkov, Grigoriy Pashkov, Konstantin Lyssenko, Petr Berdonosov, Zlata Pchelkina and Alexander Vasiliev
Materials 2022, 15(21), 7860; https://doi.org/10.3390/ma15217860 - 7 Nov 2022
Viewed by 1535
Abstract
PbCu(SeO4)(OH)2, the selenate sibling of the mineral linarite, was synthesized hydrothermally, investigated in measurements of magnetization M, specific heat Cp and dielectric permittivity ε, and analyzed within density functional theory formalism. This quasi-one-dimensional compound evidences formation [...] Read more.
PbCu(SeO4)(OH)2, the selenate sibling of the mineral linarite, was synthesized hydrothermally, investigated in measurements of magnetization M, specific heat Cp and dielectric permittivity ε, and analyzed within density functional theory formalism. This quasi-one-dimensional compound evidences formation of a short-range correlation regime at T* ~ 8 K and experiences a long-range magnetic order at TN = 4.3 K. A magnetization saturation of approximately 1 µB is reached at µ0Hflip ~ 16 T preceded by a jump at µ0Hflop = 2.4 T. Additionally, there are multiple indicators of the formation of an additional electrically active phase above the Neel temperature, which suggests that PbCu(SeO4)(OH)2 is a multiferroic system. Full article
(This article belongs to the Section Materials Physics)
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14 pages, 3858 KiB  
Article
Computational Probing of Tin-Based Lead-Free Perovskite Solar Cells: Effects of Absorber Parameters and Various Electron Transport Layer Materials on Device Performance
by Arunkumar Prabhakaran Shyma and Raja Sellappan
Materials 2022, 15(21), 7859; https://doi.org/10.3390/ma15217859 - 7 Nov 2022
Cited by 11 | Viewed by 2345
Abstract
Tin-based perovskite solar cells have gained global research attention due to the lead toxicity and health risk associated with its lead-based analog. The promising opto-electrical properties of the Tin-based perovskite have attracted researchers to work on developing Tin-based perovskite solar cells with higher [...] Read more.
Tin-based perovskite solar cells have gained global research attention due to the lead toxicity and health risk associated with its lead-based analog. The promising opto-electrical properties of the Tin-based perovskite have attracted researchers to work on developing Tin-based perovskite solar cells with higher efficiencies comparable to lead-based analogs. Tin-based perovskites outperform lead-based ones in areas such as optimal band gap and carrier mobility. A detailed understanding of the effects of each parameter and working conditions on Tin-based perovskite is crucial in order to improve efficiency. In the present work, we have carried out a numerical simulation of a planar heterojunction Tin-based (CH3NH3SnI3) perovskite solar cell employing a SCAPS 1D simulator. Device parameters, namely, the thickness of the absorber layer, the defect density of the absorber layer, working temperature, series resistance, and metalwork function, were exclusively investigated. ZnO was employed as the ETL (electron transport layer) material in the initial simulation to obtain optimized parameters and attained a maximum efficiency of 19.62% with 1.1089 V open circuit potential (Voc) at 700 nm thickness (absorber layer). Further, different ETL materials were introduced into the optimized device architecture, and the Zn2SnO4-based device delivered an efficiency of 24.3% with a Voc of 1.1857 V. The obtained results indicate a strong possibility to model and construct better-performing perovskite solar cells based on Tin (Sn) with Zn2SnO4 as the ETL layer. Full article
(This article belongs to the Topic Perovskites for Energy Applications)
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11 pages, 978 KiB  
Article
Comparative Evaluation of Two Different Fiber-Reinforced Composite Materials in Class 1 Post-Endodontic Restorations in Molars—A Randomized Clinical Study
by Suwidhi Ranka, Ajay Singh Rao, Unnati Shah, Dikshit Solanki, Ajinkya M. Pawar, Rodolfo Reda, Alessio Zanza and Luca Testarelli
Materials 2022, 15(21), 7858; https://doi.org/10.3390/ma15217858 - 7 Nov 2022
Cited by 7 | Viewed by 2586
Abstract
This study aimed to evaluate and compare two different fiber-reinforced composite materials in class I post-endodontic restoration in molars. A total of 50 patients were randomly assigned into two groups (n = 25 for each group); group A: everX Posterior (packable composite) [...] Read more.
This study aimed to evaluate and compare two different fiber-reinforced composite materials in class I post-endodontic restoration in molars. A total of 50 patients were randomly assigned into two groups (n = 25 for each group); group A: everX Posterior (packable composite) with a top layer of solareX (nano-hybrid composite) and group B: everX Flow (flowable composite) with a top layer of G-aenial universal injectable (flowable composite). Patients were evaluated immediately after the procedure (baseline), at 6 months, and at 1 year time intervals based on the modified USPHS criteria. The statistical analysis using a chi-square test showed no statistically significant difference in the clinical performance of group A and group B. Clinical performance of the combination of everX Flow with overlying G-aenial universal injectable composite proved to be comparable with everX Posterior with overlying solareX composite as post-endodontic restorations in class I lesions in permanent molars. Full article
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15 pages, 3395 KiB  
Article
Experimental Study on the Mechanical Properties of Diatomite-Modified Coastal Cement Soil
by Jiyuan Fang, Yunfeng Wang, Kefa Wang, Wenhao Dai, Yanfei Yu and Cuihong Li
Materials 2022, 15(21), 7857; https://doi.org/10.3390/ma15217857 - 7 Nov 2022
Cited by 5 | Viewed by 1558
Abstract
Diatomite is a non-metallic mineral resource rich in SiO2, which can be used to modify coastal cement soil. In order to explore the mechanical modification effect of diatomite on coastal cement soil at the age of 7 days, based on coastal [...] Read more.
Diatomite is a non-metallic mineral resource rich in SiO2, which can be used to modify coastal cement soil. In order to explore the mechanical modification effect of diatomite on coastal cement soil at the age of 7 days, based on coastal cement soil with cement content of 5% (mass fraction), diatomite of 0%, 5%, 10%, 15% and 20% (mass fraction) was mixed for modification. Through the unconfined compressive strength test, the triaxial unconsolidated undrained test, backscattered electron imaging (BSE), and energy-dispersive spectroscopy (EDS) technology, the influence of diatomite content and confining pressure on the peak strength of modified coastal cement soil was explored. The empirical formula between the peak strength of the DE specimen and the content of diatomite and confining pressure was established by curve fitting, and the fitting effect was ideal. When diatomite was mixed with coastal cement soil, the optimal dosage of diatomite was 5% from the perspective of mechanical properties and economic benefits of the maximum growth rate of compression and shear. The unconfined compressive strength test showed that the peak strength and elastic modulus of the modified coastal cement soil with 5% diatomite content were 37% and 57% higher than those of cement soil, respectively. The triaxial unconsolidated undrained test showed that the internal friction angle of the modified coastal cement soil was stable at about 30°, and cohesion of DE-5, DE-10, DE-15, and DE-20 increased by 28%, 48%, 78%, and 97%, respectively, compared to cement soil. The microscopic test found that the pore distribution of modified coastal cement soil is closely related to the strength change. The results show that the addition of diatomite can effectively improve the mechanical properties of soil-cement. Full article
(This article belongs to the Special Issue Mechanical Performance of Composite Geomaterials)
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17 pages, 3855 KiB  
Article
Supercapacitor Properties of rGO-TiO2 Nanocomposite in Two-component Acidic Electrolyte
by Yury M. Volfkovich, Alexey Y. Rychagov, Valentin E. Sosenkin, Sergey A. Baskakov, Eugene N. Kabachkov and Yury M. Shulga
Materials 2022, 15(21), 7856; https://doi.org/10.3390/ma15217856 - 7 Nov 2022
Cited by 6 | Viewed by 2265
Abstract
The electrochemical properties of the highly porous reduced graphene oxide/titanium dioxide (rGO/TiO2) nanocomposite were studied to estimate the possibility of using it as a supercapacitor electrode. Granular aerogel rGO/TiO2 was used as an initial material for the first time of [...] Read more.
The electrochemical properties of the highly porous reduced graphene oxide/titanium dioxide (rGO/TiO2) nanocomposite were studied to estimate the possibility of using it as a supercapacitor electrode. Granular aerogel rGO/TiO2 was used as an initial material for the first time of manufacturing the electrode. For the aerogel synthesis, industrial TiO2 Hombikat UV100 with a high specific surface area and anatase structure was used, and the aerogel was carried out with hydrazine vapor. Porous structure and hydrophilic–hydrophobic properties of the nanocomposite were studied with a method of standard contact porosimetry. This is important for a supercapacitor containing an aqueous electrolyte. It was found that the hydrophilic specific surface area of the nanocomposite was approximately half of the total surface area. As a result of electrochemical hydrogenation in the region of zero potential according to the scale of a standard hydrogen electrode, a reversible Faraday reaction with high recharge rate (exchange currents) was observed. The characteristic charging time of the indicated Faraday reaction does not exceed several tens of seconds, which makes it possible to consider the use of this pseudocapacitance in the systems of fast energy storage such as hybrid supercapacitors. Sufficiently high limiting pseudo-capacitance (about 1200 C/g TiO2) of the reaction was obtained. Full article
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18 pages, 9126 KiB  
Article
Tensile Behaviour of Double- and Triple-Adhesive Single Lap Joints Made with Spot Epoxy and Double-Sided Adhesive Tape
by Przemysław Golewski
Materials 2022, 15(21), 7855; https://doi.org/10.3390/ma15217855 - 7 Nov 2022
Cited by 3 | Viewed by 1785
Abstract
Dual adhesives are mainly used to increase the strength of single lap joints (SLJs) by reducing the stress concentration at its ends. However, they can also be used to design the characteristics of the joint so that its operation and failure occur in [...] Read more.
Dual adhesives are mainly used to increase the strength of single lap joints (SLJs) by reducing the stress concentration at its ends. However, they can also be used to design the characteristics of the joint so that its operation and failure occur in several stages. This paper presents the results of uniaxial tensile tests for dual-adhesive and triple-adhesive SLJs. The adherends were made of aluminum and glass fiber-reinforced polymer (GFRP) composite. For dual-adhesive SLJs, 10 epoxies and 1.6 mm thick double-sided adhesive tape were used. The stiffest (Epidian 53 (100 g) + “PAC” hardener (80 g)) and most elastic (Scotch-Weld 2216 B/A Translucent) joints were determined, which were then used in a triple-adhesive joint with the same double-sided adhesive tape. Circular holes of different diameters from 8 mm to 20 mm were made in the double-sided adhesive tape, which were filled with liquid epoxy adhesive by injection after the adherends were joined. By using the double-sided adhesive tape, the geometry of the epoxy joints was perfect, free of spews, and had a constant thickness. The effect of the spot epoxy joint diameters and the arrangement of stiff and elastic joints in the SLJs were analyzed using digital image correlation (DIC). Full article
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15 pages, 2270 KiB  
Article
Effect of Super-Absorbent Polymer (SAP) Incorporation Method on Mechanical and Shrinkage Properties of Internally Cured Concrete
by Xingliang Huang, Xiaoyu Liu, Hongliu Rong, Xiaolong Yang, Yunsheng Duan and Tingting Ren
Materials 2022, 15(21), 7854; https://doi.org/10.3390/ma15217854 - 7 Nov 2022
Cited by 4 | Viewed by 2220
Abstract
To study the effect of SAP incorporation on the early shrinkage of SAP internally cured concrete with the aim to solve the problems of early shrinkage and cracking of bridge leveling-layer concrete, using the SAP incorporation method as a parameter, the mechanical properties [...] Read more.
To study the effect of SAP incorporation on the early shrinkage of SAP internally cured concrete with the aim to solve the problems of early shrinkage and cracking of bridge leveling-layer concrete, using the SAP incorporation method as a parameter, the mechanical properties test of internally cured concrete, the shrinkage performance test of ring restraint and the scanning electron microscope observation test were carried out. The effects of the SAP content and incorporation method on the flowability, mechanical properties, shrinkage performance and microstructure of internally cured concrete were analyzed. The experimental results show that when the content of the SAP in concrete is 0.2% of the mass of cementitious materials, it has the least influence on the compressive strength of concrete. The addition of preabsorbed water to the SAP can delay early cement hydration, increase the later cement hydration rate and final hydration degree, and improve the concrete strength. Preabsorbed water mixed with an SAP can effectively improve the shrinkage of concrete, and the shrinkage reduction effect is more obvious than that from the dry addition of the SAP; the early cracking risk of concrete without an SAP is high, and it will crack before day 28. The addition of an SAP can strengthen the microstructure of concrete and improve its density and crack resistance, effectively avoiding concrete cracking. It is recommended that the water-absorbent resin be incorporated in a preabsorbent manner, and the SAP preabsorbent ratio is equal to the maximum water storage rate of the SAP. Full article
(This article belongs to the Collection Concrete and Building Materials)
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10 pages, 985 KiB  
Article
Possible Utilization of Distillery Waste in the Carbonization Process
by Jacek Kluska
Materials 2022, 15(21), 7853; https://doi.org/10.3390/ma15217853 - 7 Nov 2022
Viewed by 1358
Abstract
This paper characterizes the carbonization process in terms of the utilization of distillery waste in a laboratory-scale reactor. Due to the increase in market prices of wood and environmental protection laws, biomass waste, including distillery waste, is a potential source for biochar production. [...] Read more.
This paper characterizes the carbonization process in terms of the utilization of distillery waste in a laboratory-scale reactor. Due to the increase in market prices of wood and environmental protection laws, biomass waste, including distillery waste, is a potential source for biochar production. An experimental investigation of the carbonization process was carried out for different mixtures of distillery waste and oak sawdust. The obtained results showed that due to the European Standard, biochar from distillery waste could be used for the production of charcoal briquettes for barbecue applications. In addition, biochar from carbonization samples with 66, 50, and 33% distillery waste meet the standards defined by the International Biochar Initiative for HMs content. The analysis of the dynamics of the heating rate showed that adding wood to distillery waste significantly shortens the carbonization process, but this reduces the number of bio-oils produced and its calorific value. Full article
(This article belongs to the Special Issue Recent Progress of Biochar and Biomass Pyrolysis)
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35 pages, 496 KiB  
Review
Biomechanical Modelling for Tooth Survival Studies: Mechanical Properties, Loads and Boundary Conditions—A Narrative Review
by Saúl Dorado, Ana Arias and Jesus R. Jimenez-Octavio
Materials 2022, 15(21), 7852; https://doi.org/10.3390/ma15217852 - 7 Nov 2022
Cited by 10 | Viewed by 3041
Abstract
Recent biomechanical studies have focused on studying the response of teeth before and after different treatments under functional and parafunctional loads. These studies often involve experimental and/or finite element analysis (FEA). Current loading and boundary conditions may not entirely represent the real condition [...] Read more.
Recent biomechanical studies have focused on studying the response of teeth before and after different treatments under functional and parafunctional loads. These studies often involve experimental and/or finite element analysis (FEA). Current loading and boundary conditions may not entirely represent the real condition of the tooth in clinical situations. The importance of homogenizing both sample characterization and boundary conditions definition for future dental biomechanical studies is highlighted. The mechanical properties of dental structural tissues are presented, along with the effect of functional and parafunctional loads and other environmental and biological parameters that may influence tooth survival. A range of values for Young’s modulus, Poisson ratio, compressive strength, threshold stress intensity factor and fracture toughness are provided for enamel and dentin; as well as Young’s modulus and Poisson ratio for the PDL, trabecular and cortical bone. Angles, loading magnitude and frequency are provided for functional and parafunctional loads. The environmental and physiological conditions (age, gender, tooth, humidity, etc.), that may influence tooth survival are also discussed. Oversimplifications of biomechanical models could end up in results that divert from the natural behavior of teeth. Experimental validation models with close-to-reality boundary conditions should be developed to compare the validity of simplified models. Full article
(This article belongs to the Special Issue Advances in Dental Composite Materials and Biomaterials)
28 pages, 4335 KiB  
Review
A Review of Radio Frequency Identification Sensing Systems for Structural Health Monitoring
by Muchao Zhang, Zhaoting Liu, Chuan Shen, Jianbo Wu and Aobo Zhao
Materials 2022, 15(21), 7851; https://doi.org/10.3390/ma15217851 - 7 Nov 2022
Cited by 9 | Viewed by 3076
Abstract
Structural health monitoring (SHM) plays a critical role in ensuring the safety of large-scale structures during their operational lifespan, such as pipelines, railways and buildings. In the last few years, radio frequency identification (RFID) combined with sensors has attracted increasing interest in SHM [...] Read more.
Structural health monitoring (SHM) plays a critical role in ensuring the safety of large-scale structures during their operational lifespan, such as pipelines, railways and buildings. In the last few years, radio frequency identification (RFID) combined with sensors has attracted increasing interest in SHM for the advantages of being low cost, passive and maintenance-free. Numerous scientific papers have demonstrated the great potential of RFID sensing technology in SHM, e.g., RFID vibration and crack sensing systems. Although considerable progress has been made in RFID-based SHM, there are still numerous scientific challenges to be addressed, for example, multi-parameters detection and the low sampling rate of RFID sensing systems. This paper aims to promote the application of SHM based on RFID from laboratory testing or modelling to large-scale realistic structures. First, based on the analysis of the fundamentals of the RFID sensing system, various topologies that transform RFID into passive wireless sensors are analyzed with their working mechanism and novel applications in SHM. Then, the technical challenges and solutions are summarized based on the in-depth analysis. Lastly, future directions about printable flexible sensor tags and structural health prognostics are suggested. The detailed discussion will be instructive to promote the application of RFID in SHM. Full article
(This article belongs to the Special Issue Electromagnetic Nondestructive Testing)
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21 pages, 7819 KiB  
Article
An Investigation of the Contact Fatigue Characteristics of an RV Reducer Crankshaft, Considering the Hardness Gradients and Initial Residual Stress
by Xin Li, Wen Shao, Jinyuan Tang, Han Ding and Weihua Zhou
Materials 2022, 15(21), 7850; https://doi.org/10.3390/ma15217850 - 7 Nov 2022
Cited by 6 | Viewed by 2399
Abstract
The crankshaft is one of the core components of a Rotate Vector (RV) reducer. The fatigue life of the RV reducer is severely hindered by fatigue failure on the eccentric cylindrical surface of the crankshaft. The hardness gradients and residual stress in the [...] Read more.
The crankshaft is one of the core components of a Rotate Vector (RV) reducer. The fatigue life of the RV reducer is severely hindered by fatigue failure on the eccentric cylindrical surface of the crankshaft. The hardness gradients and residual stress in the crankshaft, associated with machining operations, exert an enormous impact on the rolling contact fatigue (RCF). In this work, a finite element method (FEM)-based three-dimensional elasto-plastic contact model is established to calculate the stress–strain field by taking hardness gradients and initial residual stress into account. The RCF characteristics of an RV reducer crankshaft is investigated by applying modified Fatemi–Socie (FS) multiaxial fatigue criterion. The results indicate that initial residual stress plays an influential role in the fatigue damage by altering the distribution of the maximum normal stress near the contact surface. The modified FS fatigue criterion could better consider the effect of initial residual stress and the shear stress, which significantly improves the prediction accuracy of the contact fatigue life model. The contact fatigue performance could be considerably improved by designing appropriate shot peening parameters to obtain optimized residual stress distribution. Therefore, the technique presented may serve as an important guideline for the anti-fatigue design of an RV reducer crankshaft. Full article
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19 pages, 6527 KiB  
Article
Effect of Substrate Temperature on the Structural, Optical and Electrical Properties of DC Magnetron Sputtered VO2 Thin Films
by Chunzi Zhang, Ozan Gunes, Shi-Jie Wen, Qiaoqin Yang and Safa Kasap
Materials 2022, 15(21), 7849; https://doi.org/10.3390/ma15217849 - 7 Nov 2022
Cited by 2 | Viewed by 1955
Abstract
This study focuses on the effect of the substrate temperature (TS) on the quality of VO2 thin films prepared by DC magnetron sputtering. TS was varied from 350 to 600 °C and the effects on the surface morphology, [...] Read more.
This study focuses on the effect of the substrate temperature (TS) on the quality of VO2 thin films prepared by DC magnetron sputtering. TS was varied from 350 to 600 °C and the effects on the surface morphology, microstructure, optical and electrical properties of the films were investigated. The results show that TS below 500 °C favors the growth of V2O5 phase, whereas higher TS (≥500 °C) facilitates the formation of the VO2 phase. Optical characterization of the as-prepared VO2 films displayed a reduced optical transmittance (T˜) across the near-infrared region (NIR), reduced phase transition temperature (Tt), and broadened hysteresis width (ΔH) through the phase transition region. In addition, a decline of the luminous modulation (ΔT˜lum) and solar modulation (ΔT˜sol) efficiencies of the as-prepared films have been determined. Furthermore, compared with the high-quality films reported previously, the electrical conductivity (σ) as a function of temperature (T) reveals reduced conductivity contrast (Δσ) between the insulating and metallic phases of the VO2 films, which was of the order of 2. These outcomes indicated the presence of defects and unrelaxed lattice strain in the films. Further, the comparison of present results with those in the literature from similar works show that the preparation of high-quality films at TS lower than 650 °C presents significant challenges. Full article
(This article belongs to the Section Thin Films and Interfaces)
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21 pages, 6576 KiB  
Article
Formation of Shaped Charge Projectile in Air and Water
by Zhifan Zhang, Hailong Li, Longkan Wang, Guiyong Zhang and Zhi Zong
Materials 2022, 15(21), 7848; https://doi.org/10.3390/ma15217848 - 7 Nov 2022
Cited by 3 | Viewed by 1984
Abstract
With the improvement of the antiknock performance of warships, shaped charge warheads have been focused on and widely used to design underwater weapons. In order to cause efficient damage to warships, it is of great significance to study the formation of shaped charge [...] Read more.
With the improvement of the antiknock performance of warships, shaped charge warheads have been focused on and widely used to design underwater weapons. In order to cause efficient damage to warships, it is of great significance to study the formation of shaped charge projectiles in air and water. This paper uses Euler governing equations to establish numerical models of shaped charges subjected to air and underwater explosions. The formation and the movement of Explosively Formed Projectiles (EFPs) in different media for three cases: air explosion and underwater explosions with and without air cavities are discussed. First, the velocity distributions of EFPs in the formation process are discussed. Then, the empirical coefficient of the maximum head velocity of EFPs in air is obtained by simulations of air explosions of shaped charges with different types of explosives. The obtained results agree well with the practical solution, which validates the numerical model. Further, this empirical coefficient in water is deduced. After that, the evolutions of the head velocity of EFPs in different media for the above three cases are further compared and analyzed. The fitting formulas of velocity attenuation of EFPs, which form and move in different media, are gained. The obtained results can provide a theoretical basis and numerical support for the design of underwater weapons. Full article
(This article belongs to the Special Issue Materials under High Pressure)
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18 pages, 4106 KiB  
Article
Strength and Permeability Properties of Pervious Concrete Containing Coal Bottom Ash Aggregates
by Ji-Hun Park, Seung-Tae Jeong, Quang-The Bui and In-Hwan Yang
Materials 2022, 15(21), 7847; https://doi.org/10.3390/ma15217847 - 7 Nov 2022
Cited by 8 | Viewed by 1441
Abstract
This study investigates the strength and permeability properties of pervious concrete-containing coal bottom ash (CBA) aggregates. Two pervious concrete mixtures were fabricated with different aggregate size distributions. One mixture contained CBA aggregates with a single-type distribution and the other mixture contained CBA aggregates [...] Read more.
This study investigates the strength and permeability properties of pervious concrete-containing coal bottom ash (CBA) aggregates. Two pervious concrete mixtures were fabricated with different aggregate size distributions. One mixture contained CBA aggregates with a single-type distribution and the other mixture contained CBA aggregates with a hybrid-type distribution. The test parameters of the CBA pervious concrete included the water/cement (W/C) ratio and compaction level to investigate their effects on the properties. W/C ratios of 0.25, 0.30, and 0.35 were considered for the mixture, and compaction levels of 0.5, 1.5, and 3.0 MPa were applied to fabricate the pervious specimen. The increase in the W/C ratio reduced the strength by approximately 20% to 30% of the CBA pervious concrete. The increase in the compaction level reduced the permeability by approximately four to five times but significantly increased the strength of the CBA pervious concrete. The test results indicate that the use of single-type CBA or hybrid CBA aggregates with different size distributions affected the properties of the pervious concrete. The strength of specimens, including hybrid CBA aggregates, was 30% to 45% greater than that of the specimens containing single-type CBA aggregates. Meanwhile, the use of hybrid CBA aggregates reduced the permeability of the CBA pervious concrete by approximately 20% to 35%. Finally, relationships between the strength properties, permeability characteristics and total void ratios of the CBA pervious concrete specimens are suggested based on the test results. Full article
(This article belongs to the Special Issue Convergence & Sustainable Technology in Building Materials)
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14 pages, 3172 KiB  
Article
Optimization of Wire Electric Discharge Machining (WEDM) Process Parameters for AISI 1045 Medium Carbon Steel Using Taguchi Design of Experiments
by Uzair Khaleeq uz Zaman, Usman Ahmed Khan, Shahid Aziz, Aamer Ahmed Baqai, Sajid Ullah Butt, Danish Hussain, Ali Siadat and Dong Won Jung
Materials 2022, 15(21), 7846; https://doi.org/10.3390/ma15217846 - 7 Nov 2022
Cited by 10 | Viewed by 2592
Abstract
With the growth of the manufacturing industry, the demand for alloy materials with high hardness, toughness, and impact strength has increased. Since products from such alloy materials are extremely difficult to manufacture with high accuracy and reduced surface roughness using traditional machining techniques, [...] Read more.
With the growth of the manufacturing industry, the demand for alloy materials with high hardness, toughness, and impact strength has increased. Since products from such alloy materials are extremely difficult to manufacture with high accuracy and reduced surface roughness using traditional machining techniques, wire electric discharge machining can be used to machine such complex parts with more precision. In this case-study-based research, machining factors such as current, pulse-on time, and voltage are studied to determine their effects on the material removal rate for AISI 1045 medium carbon steel. The Taguchi L9 orthogonal array is used in the design of experiments for optimization. Statistical techniques such as analysis of variance and signal-to-noise ratio are used to identify the control parameters that matter most in bringing about optimal results. Based on the results, the current is the most crucial control variable in this investigation. Moreover, the maximum material removal rate obtained was 0.7112 mm3/min with the obtained optimized values of current (I) = 16 A, voltage (V) = 50 V, and pulse-on time (Ton) = 100 µs. Full article
(This article belongs to the Special Issue Recent Advances in Metal Forming Technology (Second Volume))
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12 pages, 1900 KiB  
Article
Tooth Bleaching of Discolorations Caused by Hydraulic Cements in Regenerative Endodontic Treatment: A 3-Year In Vitro Study
by Carmen Llena, Manuel Iglesias-Diaz, Paula Ciscar-Muñoz, Ana Belén Bataller-Martínez, María Melo and José Luis Sanz
Materials 2022, 15(21), 7845; https://doi.org/10.3390/ma15217845 - 7 Nov 2022
Viewed by 1133
Abstract
This study aimed to evaluate the color change caused by hydraulic cements after 3 years in vitro by simulating their use in regenerative endodontic treatment (RET) and to quantify the color change after external bleaching with 40% hydrogen peroxide at 1, 6, and [...] Read more.
This study aimed to evaluate the color change caused by hydraulic cements after 3 years in vitro by simulating their use in regenerative endodontic treatment (RET) and to quantify the color change after external bleaching with 40% hydrogen peroxide at 1, 6, and 12 months of follow-up. Fifty teeth were treated simulating RET. Samples were distributed according to the hydraulic cement to be used (n = 10 per group): negative control (no cement), ProRoot-MTA, MM-MTA, TotalFill BC-RRM, or Biodentine. Three years after RET, two sessions of external bleaching with Opalescence Boost were performed. The color was measured in the cervical and incisal halves of the teeth at different time points: baseline, 3 years after performing RET, and after 1, 6, and 12 months after bleaching. The ΔL, Δa, and Δb were determined. A generalized linear model was used to compare color considering group and time. The ΔEab and the ΔE00 were calculated and the acceptability in color change was determined. Three years after RET, a reduction in lightness (negative ΔL values) was found in all groups. These values significantly increased 1 month after bleaching in all groups (p < 0.05) and reversed at 6 months. One month after bleaching, ΔE00 values (color difference tolerance (CIEDE2000)) ranged from very good (>3.6 ≤ 5.4) to excellent (>5.4). One year after bleaching, the color reverted to values similar to those found 3 years after RET. All groups became darker after RET. The color recovered and even improved compared with the baseline measurement after one month of bleaching but did not remain stable over time. Full article
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23 pages, 8265 KiB  
Article
New Platforms Based on Frontal Cellular Automata and Lattice Boltzmann Method for Modeling the Forming and Additive Manufacturing
by Łukasz Łach and Dmytro Svyetlichnyy
Materials 2022, 15(21), 7844; https://doi.org/10.3390/ma15217844 - 7 Nov 2022
Cited by 2 | Viewed by 1648
Abstract
Materials science gives theoretical and practical tools, while new modeling methods and platforms provide rapid and efficient development, improvement, and optimization of old and new technologies. Recently, impressive progress has been made in the development of computer software and systems. The frontal cellular [...] Read more.
Materials science gives theoretical and practical tools, while new modeling methods and platforms provide rapid and efficient development, improvement, and optimization of old and new technologies. Recently, impressive progress has been made in the development of computer software and systems. The frontal cellular automata (FCA), lattice Boltzmann method (LBM), and modeling platforms based on them are considered in the paper. The paper presents basic information on these methods and their application for modeling phenomena and processes in materials science. Recrystallization, crystallization, phase transformation, processes such as flat and shape rolling, additive manufacturing technologies (Selective Laser Sintering (SLS)/ Selective Laser Melting (SLM)), and others are examples of comprehensive and effective modeling by the developed systems. Selected modeling results are also presented. Full article
(This article belongs to the Special Issue Polish Achievements in Materials Science and Engineering)
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15 pages, 6270 KiB  
Article
Numerical Analysis of Zirconium and Titanium Implants under the Effect of Critical Masticatory Load
by Miguel Martinez-Mondragon, Guillermo Urriolagoitia-Sosa, Beatriz Romero-Ángeles, Daniel Maya-Anaya, Jacobo Martínez-Reyes, Francisco Javier Gallegos-Funes and Guillermo Manuel Urriolagoitia-Calderón
Materials 2022, 15(21), 7843; https://doi.org/10.3390/ma15217843 - 7 Nov 2022
Cited by 5 | Viewed by 1777
Abstract
Dental implants have become an alternative to replace the teeth of people suffering from edentulous and meet the physiological and morphological characteristics (recovering 95% of the chewing function). The evolution and innovation of biomaterials for dental implants have had a trajectory that dates [...] Read more.
Dental implants have become an alternative to replace the teeth of people suffering from edentulous and meet the physiological and morphological characteristics (recovering 95% of the chewing function). The evolution and innovation of biomaterials for dental implants have had a trajectory that dates back to prehistory, where dental pieces were replaced by ivory or seashells, to the present day, where they are replaced by metallic materials such as titanium or ceramics such as zirconium or fiberglass. The numerical evaluation focuses on comparing the stress distribution and general displacement between different dental implants and a healthy tooth when applying a force of 850 N. For the analysis, a model of the anatomical structure was developed of a healthy tooth considering three essential parts of the tooth (enamel, dentin, and pulp). The tooth biomodel was established through computed tomography. Three dental implant models were considered by changing the geometry of the abutment. A structural simulation was carried out by applying the finite element method (FEM). In addition, the material considered for the analyses was zirconium oxide (ZrO2), which was compared against titanium alloy (Ti6Al4V). The analyses were considered with linear, isotropic, and homogeneous properties. The variables included in the biomodeling were the modulus of elasticity, Poisson’s ratio, density, and elastic limit. The results obtained from the study indicated a significant difference in the biomechanical behavior of the von Mises forces and the displacement between the healthy tooth and the titanium and zirconium implant models. However, the difference between the titanium implant and the zirconium implant is minimal because one is more rigid, and the other is more tenacious. Full article
(This article belongs to the Special Issue Dental Implants and Materials (Second Volume))
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22 pages, 8483 KiB  
Article
Effect of Pro-Ecological Cooling and Lubrication Methods on the Sharpening Process of Planar Blades Used in Food Processing
by Bartosz Zieliński, Krzysztof Nadolny, Wojciech Zawadka, Tomasz Chaciński, Wojciech Stachurski and Gilmar Ferreira Batalha
Materials 2022, 15(21), 7842; https://doi.org/10.3390/ma15217842 - 7 Nov 2022
Cited by 3 | Viewed by 1448
Abstract
This work presents the results of an experimental study of the sharpening of planar technical blades used in the fish processing industry. Sharpening was carried out in the grinding process using several environmentally friendly methods of cooling and lubricating the machining zone (MQL [...] Read more.
This work presents the results of an experimental study of the sharpening of planar technical blades used in the fish processing industry. Sharpening was carried out in the grinding process using several environmentally friendly methods of cooling and lubricating the machining zone (MQL method, CAG nozzle, hybrid method that is a combination of MQL and CAG methods, as well as WET flooding method as reference). The purpose of the research was to determine the possibility of reducing the negative environmental impact of the sharpening process of technical blades by minimizing the expenditure of coolant. The application of the MQL method and the hybrid MQL + CAG method provided a very good realization of the lubricating function so that the share of friction of dulled cutting vertices against the workpiece surface is reduced, which manifests itself in the reduction of the grinding force and the correlated grinding power. In the case of grinding under cooled compressed air delivery conditions, the average cutting force was as much as 91.6% higher (F = 22.63 N) compared to the result obtained for the most favorable flooding method, demonstrating the insufficient quality of the blade shaped under such conditions. A comprehensive comparison of test results on grinding power gain, cutting force and surface texture suggests that the most favorable sharpening results were obtained using the environmentally friendly MQL method of cooling and lubricating the grinding zone. Full article
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16 pages, 8130 KiB  
Article
Welding Defect and Mechanical Properties of Nanosecond Laser Cleaning 6005A Aluminum Alloy
by Yuelai Zhang, Qi Yao, Weifeng Long, Chunming Wang, Ji Lin and Zehui Liu
Materials 2022, 15(21), 7841; https://doi.org/10.3390/ma15217841 - 7 Nov 2022
Cited by 2 | Viewed by 1710
Abstract
Nanosecond laser cleaning effectively removes oxide film and dirt from the surface of aluminum body parts for rail transit, as well as improving surface properties. The effect of laser cleaning on the quality of weld was studied in detail for different scanning frequencies [...] Read more.
Nanosecond laser cleaning effectively removes oxide film and dirt from the surface of aluminum body parts for rail transit, as well as improving surface properties. The effect of laser cleaning on the quality of weld was studied in detail for different scanning frequencies and cleaning speeds. The effect of post-weld laser cleaning on weld quality was investigated. After laser cleaning at different parameters, the surface oxygen content was decreased and the surface roughness and surface hardness were increased. Variation of surface oxygen content was related to energy density and spot density. The lowest oxygen content was obtained at 150 W, 100 Hz and 0.8 m/min. Laser-generated craters changed surface morphology and improved surface roughness. The mechanical properties of the welded joints were slightly improved, which relates to a decrease in porosity. The minimum porosity of the laser-cleaned weld was 0.021%. This work provides new ideas for the nanosecond laser cleaning of aluminum alloy and its welding properties. Full article
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14 pages, 3565 KiB  
Article
Effect of Two-Step Sintering on Properties of Alumina Ceramics Containing Waste Alumina Powder
by Milan Vukšić, Irena Žmak, Lidija Ćurković and Andraž Kocjan
Materials 2022, 15(21), 7840; https://doi.org/10.3390/ma15217840 - 7 Nov 2022
Cited by 1 | Viewed by 1835
Abstract
This study aims to evaluate the recycling potential of solid waste alumina powder (WAP) by utilization of the two-step sintering (TSS) process. For the study, WAP was collected as an industrial scrap after the machining process for the formation of green alumina compacts. [...] Read more.
This study aims to evaluate the recycling potential of solid waste alumina powder (WAP) by utilization of the two-step sintering (TSS) process. For the study, WAP was collected as an industrial scrap after the machining process for the formation of green alumina compacts. The alumina samples were prepared according to the slip casting method by preparing suspensions containing commercial alumina with 0.8 μm average particle size and by adding up to 20 dwb. % (i.e., expressed on a dry weight basis) of WAP with 3.4 μm average particle size. The samples were sintered at optimized TSS conditions and compared with conventional one-step sintering (OSS) by conducting morphological analyses. The average grain size (AGS) was determined from the obtained field emission scanning electron microscopy (FESEM) images, while the sample porosity was calculated based on apparent densities. The obtained micrographs after TSS implementation revealed a partially textured microstructure. Furthermore, a comparison of the mechanical properties of alumina samples lacking or containing 20 dwb. % of WAP obtained after sintering is presented. The indentation fracture toughness (~3.2 MPa m1/2) and Vickers hardness data (~14.5 GPa) showed a positive effect of adding WAP to alumina samples. The slightly improved mechanical properties of ceramic samples containing waste alumina are a consequence of lower porosity, which is due to the remaining sintering additives in WAP. The collected results demonstrate the possibility of using TSS for sintering ceramic materials that contain WAP. Full article
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11 pages, 3304 KiB  
Article
Enhanced Piezoelectric Properties in a Single-Phase Region of Sm-Modified Lead-Free (Ba,Ca)(Zr,Ti)O3 Ceramics
by Andong Xiao, Xuefan Xie, Liqiang He, Yang Yang and Yuanchao Ji
Materials 2022, 15(21), 7839; https://doi.org/10.3390/ma15217839 - 7 Nov 2022
Cited by 4 | Viewed by 1684
Abstract
In ferroelectric materials, phase boundaries such as the morphotropic phase boundary (MPB) and polymorphic phase boundary (PPB) have been widely utilized to enhance the piezoelectric properties. However, for a single-ferroelectric-phase system, there are few effective paradigms to achieve the enhancement of piezoelectric properties. [...] Read more.
In ferroelectric materials, phase boundaries such as the morphotropic phase boundary (MPB) and polymorphic phase boundary (PPB) have been widely utilized to enhance the piezoelectric properties. However, for a single-ferroelectric-phase system, there are few effective paradigms to achieve the enhancement of piezoelectric properties. Herein, we report an unexpected finding that largely enhanced piezoelectric properties occur in a single-tetragonal-ferroelectric-phase region in the Sm-modified (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 (BCZT-xSm) system. An electrostrain maximum (0.13%) appears in the single-phase region of the BZCT-0.5Sm composition with the maximum polarization (Pm = 18.37 µC/cm2) and piezoelectric coefficient (d33 = 396 pC/N) and the minimum coercive field (EC = 3.30 kV/cm) at room temperature. Such an enhanced piezoelectric effect is due to the synergistic effect of large lattice distortion and domain miniaturization on the basis of the transmission electron microscope (TEM) observation and X-ray diffraction (XRD) Rietveld refinement. Our work may provide new insights into the design of high-performance ferroelectrics in the single-phase region. Full article
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16 pages, 5756 KiB  
Article
Microextrusion Printing of Hierarchically Structured Thick V2O5 Film with Independent from Humidity Sensing Response to Benzene
by Philipp Yu. Gorobtsov, Artem S. Mokrushin, Tatiana L. Simonenko, Nikolay P. Simonenko, Elizaveta P. Simonenko and Nikolay T. Kuznetsov
Materials 2022, 15(21), 7837; https://doi.org/10.3390/ma15217837 - 7 Nov 2022
Cited by 5 | Viewed by 1910
Abstract
The process of V2O5 oxide by the combination of sol-gel technique and hydrothermal treatment using heteroligand [VO(C5H7O2)2–x(C4H9O)x] precursor was studied. Using thermal analysis, X-ray powder diffraction [...] Read more.
The process of V2O5 oxide by the combination of sol-gel technique and hydrothermal treatment using heteroligand [VO(C5H7O2)2–x(C4H9O)x] precursor was studied. Using thermal analysis, X-ray powder diffraction (XRD) and infra-red spectroscopy (IR), it was found that the resulting product was VO2(B), which after calcining at 300 °C (1 h), oxidized to orthorhombic V2O5. Scanning electron microscopy (SEM) results for V2O5 powder showed that it consisted of nanosheets (~50 nm long and ~10 nm thick) assembled in slightly spherical hierarchic structures (diameter ~200 nm). VO2 powder dispersion was used as functional ink for microextrusion printing of oxide film. After calcining the film at 300 °C (30 min), it was found that it oxidized to V2O5, with SEM and atomic force microscopy (AFM) results showing that the film structure retained the hierarchic structure of the powder. Using Kelvin probe force microscopy (KPFM), the work function value for V2O5 film in ambient conditions was calculated (4.81 eV), indicating a high amount of deficiencies in the sample. V2O5 film exhibited selective response upon sensing benzene, with response value invariable under changing humidity. Studies of the electrical conductivity of the film revealed increased resistance due to high film porosity, with conductivity activation energy being 0.26 eV. Full article
(This article belongs to the Section Materials Chemistry)
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