Materials

18 pages, 5362 KiB

Open AccessArticle

Effect of Air Velocity and Initial Conditioning on the Moisture Buffer Value of Four Different Building Materials

by Sana Khaled, Florence Collet, Sylvie Prétot and Marjorie Bart

Materials 2023, 16(8), 3284; https://doi.org/10.3390/ma16083284 - 21 Apr 2023

Cited by 4 | Viewed by 1783

Porous materials are able to exchange moisture with the surrounding air. The more hygroscopic they are, the more they contribute to regulate ambient humidity. This ability is characterized by the moisture buffer value (MBV) which is measured under dynamic solicitations according to different [...] Read more.

Porous materials are able to exchange moisture with the surrounding air. The more hygroscopic they are, the more they contribute to regulate ambient humidity. This ability is characterized by the moisture buffer value (MBV) which is measured under dynamic solicitations according to different protocols. The NORDTEST protocol is the most commonly-used. It gives recommendations regarding the air velocity and the ambient conditions for initial stabilization. The purpose of this article is to measure the MBV according to the NORDTEST protocol and to study the effect of air velocity and of initial conditioning on the MBV results for different materials. Two mineral and two bio-based materials are considered: gypsum (GY), cellular concrete (CC), thermo-hemp (TH) and fine-hemp (FH). Following the NORDTEST classification, GY is a moderate hygric regulator, CC is good, TH and FH are excellent. When the air velocity ranges from 0.1 to 2.6 m/s, the MBV of GY and CC materials remains constant, but the MBV of TH and FH materials is highly affected. The initial conditioning has no effect on the MBV, but has an effect on the water content of the material, whatever the material. Full article

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39 pages, 13120 KiB

Open AccessReview

Research Progress on Porous Carbon-Based Non-Precious Metal Electrocatalysts

by Hongda Yu, Luming Wu, Baoxia Ni and Tiehong Chen

Materials 2023, 16(8), 3283; https://doi.org/10.3390/ma16083283 - 21 Apr 2023

Cited by 11 | Viewed by 3047

Abstract

The development of efficient, stable, and economic electrocatalysts are key to the large-scale application of electrochemical energy conversion. Porous carbon-based non-precious metal electrocatalysts are considered to be the most promising materials to replace Pt-based catalysts, which are limited in large-scale applications due to [...] Read more.

The development of efficient, stable, and economic electrocatalysts are key to the large-scale application of electrochemical energy conversion. Porous carbon-based non-precious metal electrocatalysts are considered to be the most promising materials to replace Pt-based catalysts, which are limited in large-scale applications due to high costs. Because of its high specific surface area and easily regulated structure, a porous carbon matrix is conducive to the dispersion of active sites and mass transfer, showing great potential in electrocatalysis. This review will focus on porous carbon-based non-precious metal electrocatalysts and summarize their new progress, focusing on the synthesis and design of porous carbon matrix, metal-free carbon-based catalysts, non-previous metal monatomic carbon-based catalyst, and non-precious metal nanoparticle carbon-based catalysts. In addition, current challenges and future trends will be discussed for better development of porous carbon-based non-precious metal electrocatalysts. Full article

(This article belongs to the Special Issue Current and Future Trends in Carbon-Based Materials)

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Graphical abstract

11 pages, 2054 KiB

Open AccessArticle

Release Kinetics Model Fitting of Drugs with Different Structures from Viscose Fabric

by Weiwei Zhu, Jiajie Long and Meiwu Shi

Materials 2023, 16(8), 3282; https://doi.org/10.3390/ma16083282 - 21 Apr 2023

Cited by 33 | Viewed by 5337

Abstract

(1) Background: It is simpler and more environmentally friendly to use supercritical CO₂ fluid technology to process skincare viscose fabrics. Therefore, it is significant to study the release properties of drug-loaded viscose fabrics to choose suitable skincare drugs. In this work, the [...] Read more.

(1) Background: It is simpler and more environmentally friendly to use supercritical CO₂ fluid technology to process skincare viscose fabrics. Therefore, it is significant to study the release properties of drug-loaded viscose fabrics to choose suitable skincare drugs. In this work, the release kinetics model fittings were investigated in order to clarify the release mechanism and provide a theoretical basis for processing skincare viscose fabrics with supercritical CO₂ fluid. (2) Methods: Nine kinds of drugs with different substituent groups, different molecular weights, and different substitution positions were loaded onto viscose fabrics using supercritical CO₂ fluid. Then, the drug-loaded viscose fabrics were placed in an ethanol medium, and the release curves were drawn. Finally, the release kinetics were fitted using zero-order release kinetics, the first-order kinetics model, the Higuchi model, and the Korsmeyer–Peppas model. (3) Results: The Korsmeyer–Peppas model was the best-fitting model for all the drugs. Drugs with different substituent groups were released via a non-Fickian diffusion mechanism. On the contrary, other drugs were released via a Fickian diffusion mechanism. (4) Conclusions: In view of the release kinetics, it was found that the viscose fabric can swell when a drug with a higher solubility parameter is loaded onto it using supercritical CO₂ fluid, and the release rate is also slower. Full article

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31 pages, 16693 KiB

Open AccessArticle

Impact Fracture Surfaces as the Indicators of Structural Steel Post-Fire Susceptibility to Brittle Cracking

by Mariusz Maslak, Michal Pazdanowski, Marek Stankiewicz, Anna Wassilkowska, Paulina Zajdel and Michal Zielina

Materials 2023, 16(8), 3281; https://doi.org/10.3390/ma16083281 - 21 Apr 2023

Cited by 5 | Viewed by 1435

Abstract

The results of experimental research on forecasting post-fire resistance to brittle failure of selected steel grades used in construction are presented and discussed in this paper. The conclusions are based on detailed analysis of fracture surfaces obtained in instrumented Charpy tests. It has [...] Read more.

The results of experimental research on forecasting post-fire resistance to brittle failure of selected steel grades used in construction are presented and discussed in this paper. The conclusions are based on detailed analysis of fracture surfaces obtained in instrumented Charpy tests. It has been shown that the relationships formulated based on these tests agree well with conclusions drawn based on precise analysis of appropriate F–s curves. Furthermore, other relationships between lateral expansion LE and energy W_t required to break the sample constitute an additional verification in both qualitative and quantitative terms. These relationships are accompanied here by values of the SFA_(n) parameter, which are different, depending on the character of the fracture. Steel grades differing in microstructure have been selected for the detailed analysis, including: S355J2+N—representative for materials of ferritic-pearlitic structure, and also stainless steels such as X20Cr13—of martensitic structure, X6CrNiTi18-10—of austenitic structure and X2CrNiMoN22-5-3 duplex steel—of austenitic-ferritic structure. Full article

(This article belongs to the Special Issue Investigation of Microstructural and Corrosion Properties of Steels and Light Alloys)

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26 pages, 8334 KiB

Open AccessReview

Multicomponent Metal Oxide- and Metal Hydroxide-Based Electrocatalysts for Alkaline Water Splitting

by Goeun Lee, Sang Eon Jun, Yujin Kim, In-Hyeok Park, Ho Won Jang, Sun Hwa Park and Ki Chang Kwon

Materials 2023, 16(8), 3280; https://doi.org/10.3390/ma16083280 - 21 Apr 2023

Cited by 16 | Viewed by 4180

Abstract

Developing cost-effective, highly catalytic active, and stable electrocatalysts in alkaline electrolytes is important for the development of highly efficient anion-exchange membrane water electrolysis (AEMWE). To this end, metal oxides/hydroxides have attracted wide research interest for efficient electrocatalysts in water splitting owing to their [...] Read more.

Developing cost-effective, highly catalytic active, and stable electrocatalysts in alkaline electrolytes is important for the development of highly efficient anion-exchange membrane water electrolysis (AEMWE). To this end, metal oxides/hydroxides have attracted wide research interest for efficient electrocatalysts in water splitting owing to their abundance and tunable electronic properties. It is very challenging to achieve an efficient overall catalytic performance based on single metal oxide/hydroxide-based electrocatalysts due to low charge mobilities and limited stability. This review is mainly focused on the advanced strategies to synthesize the multicomponent metal oxide/hydroxide-based materials that include nanostructure engineering, heterointerface engineering, single-atom catalysts, and chemical modification. The state of the art of metal oxide/hydroxide-based heterostructures with various architectures is extensively discussed. Finally, this review provides the fundamental challenges and perspectives regarding the potential future direction of multicomponent metal oxide/hydroxide-based electrocatalysts. Full article

(This article belongs to the Special Issue Advanced Nanostructured Materials for Catalytic Applications)

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16 pages, 6752 KiB

Open AccessArticle

Steering Potential for Printing Highly Aligned Discontinuous Fibre Composite Filament

by Narongkorn Krajangsawasdi, Duc H. Nguyen, Ian Hamerton, Benjamin K. S. Woods, Dmitry S. Ivanov and Marco L. Longana

Materials 2023, 16(8), 3279; https://doi.org/10.3390/ma16083279 - 21 Apr 2023

Cited by 4 | Viewed by 1704

Abstract

DcAFF (discontinuous aligned fibre filament) is a novel material for fused filament fabrication (FFF) 3D printing made of highly aligned discontinuous fibres produced using high performance discontinuous fibre (HiPerDiF) technology. It reinforces a thermoplastic matrix to provide high mechanical performance and formability. Accurate [...] Read more.

DcAFF (discontinuous aligned fibre filament) is a novel material for fused filament fabrication (FFF) 3D printing made of highly aligned discontinuous fibres produced using high performance discontinuous fibre (HiPerDiF) technology. It reinforces a thermoplastic matrix to provide high mechanical performance and formability. Accurate printing of DcAFF poses a challenge, especially for complex geometries, because: (i) there is a discrepancy between the path where the filament experiences the adhering pressure from the filleted nozzle and the nozzle path; and (ii) the rasters display poor adhesion to the build platform immediately after deposition, which causes the filament to be dragged when the printing direction changes. This paper explains the implication of these phenomena on steering capabilities and examines the techniques for improving DcAFF printing accuracy. In the first approach, the machine parameters were adjusted to improve the quality of the sharp turning angle without changing the desired path, but this showed insignificant effects in terms of precision improvements. In the second approach, a printing path modification with a compensation algorithm was introduced. The nature of the inaccuracy of the printing at the turning point was studied with a first-order lag relationship. Then the equation to describe the deposition raster inaccuracy was determined. A proportional–integral (PI) controller was added to the equation to calculate the nozzle movement in order to bring the raster back to the desired path. The applied compensation path is shown to give an accuracy improvement in curvilinear printing paths. This is particularly beneficial when printing larger circular diameter curvilinear printed parts. The developed printing approach can be applied with other fibre reinforced filaments to achieve complex geometries. Full article

(This article belongs to the Special Issue Advances in Additively Manufactured Reinforced Polymers)

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11 pages, 4281 KiB

Open AccessArticle

Femtosecond Laser Fabrication of Curved Plasma Channels with Low Surface Roughness and High Circularity for Multistage Laser-Wakefield Accelerators

by Hongyang Deng, Ziyang Zhang, Min Chen, Jianlong Li, Qiang Cao and Xuejiao Hu

Materials 2023, 16(8), 3278; https://doi.org/10.3390/ma16083278 - 21 Apr 2023

Cited by 2 | Viewed by 1944

Abstract

A multistage laser-wakefield accelerator with curved plasma channels was proposed to accelerate electrons to TeV energy levels. In this condition, the capillary is discharged to produce plasma channels. The channels will be used as waveguides to guide intense lasers to drive wakefields inside [...] Read more.

A multistage laser-wakefield accelerator with curved plasma channels was proposed to accelerate electrons to TeV energy levels. In this condition, the capillary is discharged to produce plasma channels. The channels will be used as waveguides to guide intense lasers to drive wakefields inside the channel. In this work, a curved plasma channel with low surface roughness and high circularity was fabricated by a femtosecond laser ablation method based on response surface methodology. The details of the fabrication and performance of the channel are introduced here. Experiments show that such a channel can be successfully used to guide lasers, and electrons with an energy of 0.7 GeV were achieved. Full article

(This article belongs to the Special Issue Fundamentals and Applications of Laser Micro/Nanostructuring and Synthesis of Micro/Nanomaterials)

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9 pages, 876 KiB

Open AccessOpinion

The Boom in Nanomaterials for Built Heritage Conservation: Why Does Size Matter?

by Jorge Otero, Giovanni Borsoi and Luis Monasterio-Guillot

Materials 2023, 16(8), 3277; https://doi.org/10.3390/ma16083277 - 21 Apr 2023

Cited by 3 | Viewed by 2343

Abstract

There is no doubt that nanotechnology and nanoscience open new doors to new applications and products that can potentially revolutionize the practice field and how we conserve built heritage materials. However, we are living at the beginning of this era and the potential [...] Read more.

There is no doubt that nanotechnology and nanoscience open new doors to new applications and products that can potentially revolutionize the practice field and how we conserve built heritage materials. However, we are living at the beginning of this era and the potential benefits of nanotechnology to specific conservation practice needs are not always fully understood. This opinion/review paper aims to present reflections and answer a question that we are often asked when working directly with stone field conservators: why should we use a nanomaterial instead of a conventional product? Why does size matter? To answer this question, we revise the basic concepts of nanoscience with implications for the built heritage conservation field. Full article

(This article belongs to the Special Issue Advances in Nanolime and Other Nanomaterials for Built Heritage Conservation)

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18 pages, 10210 KiB

Open AccessArticle

Glass-Ceramic Coating on Silver Electrode Surface via 3D Printing

by Lilin Yang, Dongzhi Wang, Guoxiang Zhou, Zhidan Lan and Zhihua Yang

Materials 2023, 16(8), 3276; https://doi.org/10.3390/ma16083276 - 21 Apr 2023

Cited by 2 | Viewed by 1987

Abstract

Silver electrodes are commonly used as a conductive layer for electromagnetic devices. It has the advantages of good conductivity, easy processing, and good bonding with a ceramic matrix. However, the low melting point (961 °C) results in a decrease in electrical conductivity and [...] Read more.

Silver electrodes are commonly used as a conductive layer for electromagnetic devices. It has the advantages of good conductivity, easy processing, and good bonding with a ceramic matrix. However, the low melting point (961 °C) results in a decrease in electrical conductivity and migration of silver ions under an electric field when it works at high temperatures. Using a dense coating layer on the silver surface is a feasible way to effectively prevent the performance fluctuation or failure of the electrodes without sacrificing its wave-transmitting performance. Calcium-magnesium-silicon glass-ceramic (CaMgSi₂O₆) is a diopside material that has been widely used in electronic packaging materials. However, CaMgSi₂O₆ glass-ceramics (CMS) are facing tough challenges, such as high sintering temperature and insufficient density after sintering, which significantly confine its applications. In this study, CaO, MgO, B₂O₃, and SiO₂ were used as raw materials to manufacture a uniform glass coating on the silver and Al₂O₃ ceramics surface via 3D printing technology followed by high-temperature sintering. The dielectric and thermal properties of the glass/ceramic layer prepared with various CaO-MgO-B₂O₃-SiO₂ components were studied, and the protective effect of the glass-ceramic coating on the silver substrate at high temperatures were evaluated. It was found that the viscosity of the paste and the surface density of the coating increase with the increase of solid contents. The 3D-printed coating shows well-bonded interfaces between the Ag layer, the CMS coating, and the Al₂O₃ substrate. The diffusion depth was 2.5 μm, and no obvious pores and cracks can be detected. According to the high density and well-bonded glass coating, the silver was well protected from the corrosion environment. Increasing the sintering temperature and extending the sintering time is beneficial to form the crystallinity and the densification effect. This study provides an effective method to manufacture a corrosive-resistant coating on an electrically conductive substrate with outstanding dielectric performances. Full article

(This article belongs to the Special Issue Recent Trends in Functional Nanocomposites: Synthesis and Performance)

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9 pages, 2777 KiB

Open AccessArticle

pH-Effect in the Fabrication of ZnO Nanostructured Thin Films by Chemical Bath Deposition for Increasing the Efficiency of Solar Cells

by Abel Garcia-Barrientos, Roberto Carlos Ambrosio-Lazaro, Rafael Ramirez-Bone, Mario A. Garcia-Ramirez, Obed Perez-Cortes, Ruben Tapia-Olvera and Jairo Plaza-Castillo

Materials 2023, 16(8), 3275; https://doi.org/10.3390/ma16083275 - 21 Apr 2023

Cited by 4 | Viewed by 1975

Abstract

In this study, the impact of pH on the production of ZnO nanostructured thin films using chemical bath deposition was investigated for the purpose of enhancing the efficiency of solar cells. The ZnO films were directly deposited onto glass substrates at various pH [...] Read more.

In this study, the impact of pH on the production of ZnO nanostructured thin films using chemical bath deposition was investigated for the purpose of enhancing the efficiency of solar cells. The ZnO films were directly deposited onto glass substrates at various pH levels during the synthesis process. The results indicate that the crystallinity and overall quality of the material were not affected by the pH solution, as observed through X-ray diffraction patterns. However, scanning electron microscopy revealed that surface morphology improved with increasing pH values, leading to changes in the size of the nanoflowers between pH 9 and 11 values. Furthermore, the ZnO nanostructured thin films synthesized at pH levels of 9, 10, and 11 were utilized in the fabrication of dye-sensitized solar cells. The ZnO films synthesized at pH 11 exhibited superior characteristics in short-circuit current density and open-circuit photo-voltage compared with those produced at lower pH values. Full article

(This article belongs to the Special Issue Advanced Materials and Devices for Energy Harvesting)

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14 pages, 3042 KiB

Open AccessEditor’s ChoiceArticle

Detecting Single Microwave Photons with NV Centers in Diamond

by Olivia Woodman, Abdolreza Pasharavesh, Christopher Wilson and Michal Bajcsy

Materials 2023, 16(8), 3274; https://doi.org/10.3390/ma16083274 - 21 Apr 2023

Viewed by 3005

Abstract

We propose a scheme for detecting single microwave photons using dipole-induced transparency (DIT) in an optical cavity resonantly coupled to a spin-selective transition of a negatively charged nitrogen-vacancy (NV⁻) defect in diamond crystal lattices. In this scheme, the microwave photons control [...] Read more.

We propose a scheme for detecting single microwave photons using dipole-induced transparency (DIT) in an optical cavity resonantly coupled to a spin-selective transition of a negatively charged nitrogen-vacancy (NV⁻) defect in diamond crystal lattices. In this scheme, the microwave photons control the interaction of the optical cavity with the NV⁻ center by addressing the spin state of the defect. The spin, in turn, is measured with high fidelity by counting the number of reflected photons when the cavity is probed by resonant laser light. To evaluate the performance of the proposed scheme, we derive the governing master equation and solve it through both direct integration and the Monte Carlo approach. Using these numerical simulations, we then investigate the effects of different parameters on the detection performance and find their corresponding optimized values. Our results indicate that detection efficiencies approaching 90% and fidelities exceeding 90% could be achieved when using realistic optical and microwave cavity parameters. Full article

(This article belongs to the Special Issue Materials Opportunities and Challenges for Quantum Information Processors)

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9 pages, 888 KiB

Open AccessArticle

Efficacy of Shock Wave-Enhanced Emission Photoacoustic Streaming (SWEEPS) in the Removal of Different Combinations of Sealers Used with Two Obturation Techniques: A Micro-CT Study

by Anja Baraba, Marko Rajda, Gorana Baršić, Silvana Jukić Krmek, Damir Šnjarić and Ivana Miletić

Materials 2023, 16(8), 3273; https://doi.org/10.3390/ma16083273 - 21 Apr 2023

Cited by 5 | Viewed by 1551

Abstract

This study sought to evaluate the efficacy of SWEEPS in the removal of epoxy-resin-based and calcium-silicate-containing endodontic sealer combined with single-cone and carrier-based obturation techniques through a micro-CT analysis. Seventy-six single-rooted extracted human teeth with single root canal were instrumented with Reciproc instruments. [...] Read more.

This study sought to evaluate the efficacy of SWEEPS in the removal of epoxy-resin-based and calcium-silicate-containing endodontic sealer combined with single-cone and carrier-based obturation techniques through a micro-CT analysis. Seventy-six single-rooted extracted human teeth with single root canal were instrumented with Reciproc instruments. Specimens were randomly divided into four groups (n = 19) according to the root canal filling material and obturation technique: (1) AH Plus sealer + Reciproc gutta-percha, (2) TotalFill BC sealer + TotalFill BC Points, (3) AH Plus sealer + Guttafusion obturator, and (4) MTA Fillapex + Guttafusion obturator. All specimens were re-treated one week later using Reciproc instruments. Following re-treatment, root canals were additionally irrigated using the Auto SWEEPS modality. The differences in the root canal filling remnants were analyzed by micro-CT scanning of each tooth after root canal obturation, after re-treatment, and after additional SWEEPS treatment. Statistical analysis was performed using an analysis of variance (p < 0.05). The additional treatment with SWEEPS significantly reduced the volume of the root canal filling materials in all experimental groups compared to the removal of root canal filling using only reciprocating instruments (p < 0.05). However, the root canal filling was not removed completely from any of the samples. SWEEPS can be used to enhance the removal of both epoxy-resin-based and calcium-silicate-containing sealers, in combination with single-cone and carrier-based obturation techniques. Full article

(This article belongs to the Special Issue Biomaterials and Mechanics in Dentistry)

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13 pages, 4347 KiB

Open AccessArticle

Obtaining of Mg-Zn Co-Doped GaN Powders via Nitridation of the Ga-Mg-Zn Metallic Solution and Their Structural and Optical Properties

by Erick Gastellóu, Rafael García, Ana M. Herrera, Antonio Ramos, Godofredo García, Gustavo A. Hirata, José A. Luna, Roberto C. Carrillo, Jorge A. Rodríguez, Mario Robles, Yani D. Ramírez and Guillermo Martínez

Materials 2023, 16(8), 3272; https://doi.org/10.3390/ma16083272 - 21 Apr 2023

Cited by 2 | Viewed by 1611

Abstract

Mg-Zn co-dopedGaN powders via the nitridation of a Ga-Mg-Zn metallic solution at 1000 °C for 2 h in ammonia flow were obtained. XRD patterns for the Mg-Zn co-dopedGaN powders showed a crystal size average of 46.88 nm. Scanning electron microscopy micrographs had an [...] Read more.

Mg-Zn co-dopedGaN powders via the nitridation of a Ga-Mg-Zn metallic solution at 1000 °C for 2 h in ammonia flow were obtained. XRD patterns for the Mg-Zn co-dopedGaN powders showed a crystal size average of 46.88 nm. Scanning electron microscopy micrographs had an irregular shape, with a ribbon-like structure and a length of 8.63 µm. Energy-dispersive spectroscopy showed the incorporation of Zn (Lα 1.012 eV) and Mg (Kα 1.253 eV), while XPS measurements showed the elemental contributions of magnesium and zinc as co-dopant elements quantified in 49.31 eV and 1019.49 eV, respectively. The photoluminescence spectrum showed a fundamental emission located at 3.40 eV(364.70 nm), which was related to band-to-band transition, besides a second emission found in a range from 2.80 eV to 2.90 eV (442.85–427.58 nm), which was related to a characteristic of Mg-doped GaN and Zn-doped GaN powders. Furthermore, Raman scattering demonstrated a shoulder at 648.05 cm⁻¹, which could indicate the incorporation of the Mg and Zn co-dopants atoms into the GaN structure. It is expected that one of the main applications of Mg-Zn co-doped GaN powders is in obtaining thin films for SARS-CoV-2 biosensors. Full article

(This article belongs to the Special Issue Advances in Semiconductor and Dielectric Materials)

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15 pages, 1813 KiB

Open AccessEditor’s ChoiceArticle

Cumulative Fatigue Damage of Composite Laminates: Engineering Rule and Life Prediction Aspect

by Nikolaos D. Batsoulas and Georgios I. Giannopoulos

Materials 2023, 16(8), 3271; https://doi.org/10.3390/ma16083271 - 21 Apr 2023

Cited by 3 | Viewed by 2017

Abstract

The analysis of cumulative fatigue damage is an important factor in predicting the life of composite elements and structures that are exposed to field load histories. A method for predicting the fatigue life of composite laminates under varying loads is suggested in this [...] Read more.

The analysis of cumulative fatigue damage is an important factor in predicting the life of composite elements and structures that are exposed to field load histories. A method for predicting the fatigue life of composite laminates under varying loads is suggested in this paper. A new theory of cumulative fatigue damage is introduced grounded on the Continuum Damage Mechanics approach that links the damage rate to cyclic loading through the damage function. A new damage function is examined with respect to hyperbolic isodamage curves and remaining life characteristics. The nonlinear damage accumulation rule that is presented in this study utilizes only one material property and overcomes the limitations of other rules while maintaining implementation simplicity. The benefits of the proposed model and its correlation with other relevant techniques are demonstrated, and a broad range of independent fatigue data from the literature is used for comparison to investigate its performance and validate its reliability. Full article

(This article belongs to the Special Issue Analysis and Design of Structures and Materials)

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10 pages, 2698 KiB

Open AccessArticle

Two-Dimensional Films Based on Graphene/Li₄Ti₅O₁₂ and Carbon Nanotube/Li₄Ti₅O₁₂ Nanocomposites as a Prospective Material for Lithium-Ion Batteries: Insight from Ab Initio Modeling

by Vladislav V. Shunaev, Alexander A. Petrunin, Haifei Zhan and Olga E. Glukhova

Materials 2023, 16(8), 3270; https://doi.org/10.3390/ma16083270 - 21 Apr 2023

Cited by 1 | Viewed by 1977

Abstract

The combination of spinel Li₄Ti₅O₁₂ (LTO) with carbon nanostructures, such as graphene (G) and carbon nanotubes (CNTs), provides all of the required properties for modern chemical power sources such as Li-ion batteries (LIBs) and supercapacitors (SCs). G/LTO and [...] Read more.

The combination of spinel Li₄Ti₅O₁₂ (LTO) with carbon nanostructures, such as graphene (G) and carbon nanotubes (CNTs), provides all of the required properties for modern chemical power sources such as Li-ion batteries (LIBs) and supercapacitors (SCs). G/LTO and CNT/LTO composites demonstrate a superior reversible capacity, cycling stability, and good rate performances. In this paper, an ab initio attempt to estimate the electronic and capacitive properties of such composites was made for the first time. It was found that the interaction between LTO particles and CNTs was higher than that with graphene due to the larger amount of transfer charge. Increasing the graphene concentration raised the Fermi level and enhanced the conductive properties of G/LTO composites. For CNT/LTO samples, the radius of CNT did not affect the Fermi level. For both G/LTO and CNT/LTO composites, an increase in the carbon ratio resulted in a similar reduction in quantum capacitance (QC). It was observed that during the charge cycle in the real experiment, the non-Faradaic process prevailed during the charge cycle, while the Faradaic process prevailed during the discharge cycle. The obtained results confirm and explain the experimental data and improve the understanding of the processes occurring in G/LTO and CNT/LTO composites for their usages in LIBs and SCs. Full article

(This article belongs to the Special Issue New Advances in Low-Dimensional Materials and Nanostructures II)

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15 pages, 4109 KiB

Open AccessArticle

Modulating the Performance of the SAW Strain Sensor Based on Dual-Port Resonator Using FEM Simulation

by Chunlong Cheng, Zihan Lu, Jingwen Yang, Xiaoyue Gong and Qingqing Ke

Materials 2023, 16(8), 3269; https://doi.org/10.3390/ma16083269 - 21 Apr 2023

Cited by 1 | Viewed by 1887

Abstract

Surface acoustic wave (SAW) strain sensors fabricated on piezoelectric substrates have attracted considerable attention due to their attractive features such as passive wireless sensing ability, simple signal processing, high sensitivity, compact size and robustness. To meet the needs of various functioning situations, it [...] Read more.

Surface acoustic wave (SAW) strain sensors fabricated on piezoelectric substrates have attracted considerable attention due to their attractive features such as passive wireless sensing ability, simple signal processing, high sensitivity, compact size and robustness. To meet the needs of various functioning situations, it is desirable to identify the factors that affect the performance of the SAW devices. In this work, we perform a simulation study on Rayleigh surface acoustic wave (RSAW) based on a stacked Al/LiNbO₃ system. A SAW strain sensor with a dual-port resonator was modeled using multiphysics finite element model (FEM) method. While FEM has been widely used for numerical calculations of SAW devices, most of the simulation works mainly focus on SAW modes, SAW propagation characteristics and electromechanical coupling coefficients. Herein, we propose a systematic scheme via analyzing the structural parameters of SAW resonators. Evolution of RSAW eigenfrequency, insertion loss (IL), quality factor (Q) and strain transfer rate with different structural parameters are elaborated by FEM simulations. Compared with the reported experimental results, the relative errors of RSAW eigenfrequency and IL are about 3% and 16.3%, respectively, and the absolute errors are 5.8 MHz and 1.63 dB (the corresponding V_out/V_in is only 6.6%). After structural optimization, the obtained resonator Q increases by 15%, IL decreases by 34.6% and the strain transfer rate increases by 2.4%. This work provides a systematic and reliable solution for the structural optimization of dual-port SAW resonators. Full article

(This article belongs to the Special Issue Design, Performance and Application Research of Smart Piezoelectric Materials)

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19 pages, 10363 KiB

Open AccessArticle

Analysis of the Mechanical Properties of 3D-Printed Plastic Samples Subjected to Selected Degradation Effects

by Josef Sedlak, Zdenek Joska, Jiri Jansky, Jan Zouhar, Stepan Kolomy, Martin Slany, Adam Svasta and Jan Jirousek

Materials 2023, 16(8), 3268; https://doi.org/10.3390/ma16083268 - 21 Apr 2023

Cited by 17 | Viewed by 3796

Abstract

The Fused Filament Fabrication (FFF) method is an additive technology that is used for the creation of prototypes within Rapid Prototyping (RP) as well as for the creation of final components in piece or small-series production. The possibility of using FFF technology in [...] Read more.

The Fused Filament Fabrication (FFF) method is an additive technology that is used for the creation of prototypes within Rapid Prototyping (RP) as well as for the creation of final components in piece or small-series production. The possibility of using FFF technology in the creation of final products requires knowledge of the properties of the material and, at the same time, how these properties change due to degradation effects. In this study, the mechanical properties of the selected materials (PLA, PETG, ABS, and ASA) were tested in their non-degenerate state and after exposure of the samples to the selected degradation factors. For the analysis, which was carried out by the tensile test and the Shore D hardness test, samples of normalized shape were prepared. The effects of UV radiation, high temperature environments, high humidity environments, temperature cycles, and exposure to weather conditions were monitored. The parameters obtained from the tests (tensile strength and Shore D hardness) were statistically evaluated, and the influence of degradation factors on the properties of individual materials was assessed. The results showed that even between individual manufacturers of the same filament there are differences, both in the mechanical properties and in the behavior of the material after exposure to degradation effects. Full article

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13 pages, 16939 KiB

Open AccessArticle

Comparative Study of the Microstructure and Properties of Cast-Fabricated and 3D-Printed Laser-Sintered Co–Cr Alloys for Removable Partial Denture Frameworks

by Dejan Stamenković, Miljana Popović, Rebeka Rudolf, Milorad Zrilić, Karlo Raić, Kosovka Obradović Đuričić and Dragoslav Stamenković

Materials 2023, 16(8), 3267; https://doi.org/10.3390/ma16083267 - 21 Apr 2023

Cited by 4 | Viewed by 2312

Abstract

Since additive technologies in dentistry are gradually replacing metal casting technology, it is necessary to evaluate new dental constructions intended for the development of removable partial denture frameworks. The aim of this research was to evaluate the microstructure and mechanical properties of 3D-printed, [...] Read more.

Since additive technologies in dentistry are gradually replacing metal casting technology, it is necessary to evaluate new dental constructions intended for the development of removable partial denture frameworks. The aim of this research was to evaluate the microstructure and mechanical properties of 3D-printed, laser-melted and -sintered Co–Cr alloys, and perform a comparative study with Co–Cr castings for the same dental purposes. The experiments were divided into two groups. The first group consisted of samples produced by conventional casting of the Co–Cr alloy. The second group consisted of 3D-printed, laser-melted and -sintered specimens produced from a Co–Cr alloy powder divided into three subgroups, depending on the technological parameters chosen for manufacturing (angle, location and heat treatment). Examination of the microstructure was carried out by classical metallographic sample preparation, using optical microscopy and scanning electron microscopy with energy dispersive X-ray spectroscopy (EDX) analysis. A structural phase analysis was also performed by XRD. The mechanical properties were determined using a standard tensile test. The microstructure observation showed a dendritic character in the case of castings, while in the case of 3D-printed, laser-melted and -sintered Co–Cr alloys, the microstructure was typical for additive technologies. The XRD phase analysis confirmed the presence of Co–Cr phases (ε and γ). The results of the tensile test showed remarkably higher yield and tensile strength values and slightly lower elongation of the 3D-printed, laser-melted and -sintered samples than those produced by conventional casting. Full article

(This article belongs to the Section Materials Physics)

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12 pages, 2702 KiB

Open AccessArticle

Cyclic Voltammetry of Screen-Printed Carbon Electrode Coated with Ag-ZnO Nanoparticles in Chitosan Matrix

by Elena Emanuela Herbei, Petrică Alexandru and Mariana Busila

Materials 2023, 16(8), 3266; https://doi.org/10.3390/ma16083266 - 21 Apr 2023

Cited by 5 | Viewed by 2963

Abstract

In this paper, the authors describe the fabrication of nanocomposite chitosan-based systems of zinc oxide (ZnO), silver (Ag) and Ag-ZnO. Recently, the development of coated screen-printed electrodes using metal and metal oxide nanoparticles (NPs) for the specific detection and monitoring of different cancer [...] Read more.

In this paper, the authors describe the fabrication of nanocomposite chitosan-based systems of zinc oxide (ZnO), silver (Ag) and Ag-ZnO. Recently, the development of coated screen-printed electrodes using metal and metal oxide nanoparticles (NPs) for the specific detection and monitoring of different cancer tumors has been obtaining important results. Ag, ZnO NPs and Ag-ZnO prepared by the hydrolysis of zinc acetate blended with a chitosan (CS) matrix were used for the surface modification of screen-printed carbon electrodes (SPCEs) in order to analyze the electrochemical behavior of the typical redox system of a 10 mM potassium ferrocyanide—0.1 M buffer solution (BS). The solutions of CS, ZnO/CS, Ag/CS and Ag-ZnO/CS were prepared in order to modify the carbon electrode surface, and were measured at different scan rates from 0.02 V/s to 0.7 V/s by cyclic voltammetry. The cyclic voltammetry (CV) was performed on a house-built potentiostat (HBP). The cyclic voltammetry of the measured electrodes showed the influence of varying the scan rate. The variation of the scan rate has an influence on the intensity of the anodic and cathodic peak. Both values of currents (anodic and cathodic currents) have higher values for 0.1 V/s (Ia = 22 μA and Ic = −25 μA) compared to the values for 0.06 V/s (Ia = 10 μA and Ic = −14 μA). The CS, ZnO/CS, Ag/CS and Ag-ZnO/CS solutions were characterized using a field emission scanning electron microscopy (FE-SEM) with EDX elemental analysis. The modified coated surfaces of screen-printed electrodes were analyzed using optical microscopy (OM). The present coated carbon electrodes showed a different waveform compared to the voltage applied to the working electrode, depending on the scan rate and chemical composition of the modified electrodes. Full article

(This article belongs to the Special Issue Recent Advances and Perspectives in Welding and Joining Process and Technology)

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18 pages, 6920 KiB

Open AccessArticle

Modeling and Testing of a Composite Steel–Concrete Joint for Hybrid Girder Bridges

by Bing Shangguan, Qingtian Su, Joan R. Casas, Hang Su, Shengyun Wang and Rongxin Zhao

Materials 2023, 16(8), 3265; https://doi.org/10.3390/ma16083265 - 21 Apr 2023

Cited by 5 | Viewed by 2036

Abstract

A hybrid girder bridge adopts a steel segment at the mid-span of the main span of a continuous concrete girder bridge. The critical point of the hybrid solution is the transition zone, connecting the steel and concrete segments of the beam. Although many [...] Read more.

A hybrid girder bridge adopts a steel segment at the mid-span of the main span of a continuous concrete girder bridge. The critical point of the hybrid solution is the transition zone, connecting the steel and concrete segments of the beam. Although many girder tests revealing the structural behavior of hybrid girders have been conducted by previous studies, few specimens took the full section of a steel–concrete joint due to the large size of prototype hybrid bridges. In this study, a static load test on a composite segment to bridge the joint between the concrete and steel parts of a hybrid bridge with full section was conducted. A finite element model replicating the tested specimen results was established through Abaqus, while parametric studies were also conducted. The test and numerical results revealed that the concrete filling in the composite solution prevented the steel flange from extensive buckling, which significantly improved the load-carrying capacity of the steel–concrete joint. Meanwhile, strengthening the interaction between the steel and concrete helps to prevent the interlayer slip and simultaneously contributes to a higher flexural stiffness. These results are an important basis for establishing a rational design scheme for the steel–concrete joint of hybrid girder bridges. Full article

(This article belongs to the Special Issue Modeling and Testing of Reinforced Concrete or Composite Structures Using Advanced New Materials)

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11 pages, 4817 KiB

Open AccessArticle

Single-Shot Multi-Frame Imaging of Femtosecond Laser-Induced Plasma Propagation

by Tianyong Zhang, Baoshan Guo, Lan Jiang, Tong Zhu, Yanhong Hua, Ningwei Zhan and Huan Yao

Materials 2023, 16(8), 3264; https://doi.org/10.3390/ma16083264 - 21 Apr 2023

Cited by 3 | Viewed by 2199

Abstract

Single-shot ultrafast multi-frame imaging technology plays a crucial role in the observation of laser-induced plasma. However, there are many challenges in the application of laser processing, such as technology fusion and imaging stability. To provide a stable and reliable observation method, we propose [...] Read more.

Single-shot ultrafast multi-frame imaging technology plays a crucial role in the observation of laser-induced plasma. However, there are many challenges in the application of laser processing, such as technology fusion and imaging stability. To provide a stable and reliable observation method, we propose an ultrafast single-shot multi-frame imaging technology based on wavelength polarization multiplexing. Through the frequency doubling and birefringence effects of the BBO and the quartz crystal, the 800 nm femtosecond laser pulse was frequency doubled to 400 nm, and a sequence of probe sub-pulses with dual-wavelength and different polarization was generated. The coaxial propagation and framing imaging of multi-frequency pulses provided stable imaging quality and clarity, as well as high temporal/spatial resolution (200 fs and 228 lp/mm). In the experiments involving femtosecond laser-induced plasma propagation, the probe sub-pulses measured their time intervals by capturing the same results. Specifically, the measured time intervals were 200 fs between the same color pulses and 1 ps between the adjacent different. Finally, based on the obtained system time resolution, we observed and revealed the evolution mechanism of femtosecond laser-induced air plasma filaments, the multifilament propagation of femtosecond laser in fused silica, and the influence mechanism of air ionization on laser-induced shock waves. Full article

(This article belongs to the Special Issue Advances in Laser Technologies and Applications (Volume II))

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13 pages, 3973 KiB

Open AccessArticle

Effect of Temperature and Load on Tribological Behavior in Laser-Cladded FeCrSiNiCoC Coatings

by Haiyang Long, Wei Hao, Rucheng Ma, Yongliang Gui, Chunyan Song, Tieyu Qin and Xuefeng Zhang

Materials 2023, 16(8), 3263; https://doi.org/10.3390/ma16083263 - 21 Apr 2023

Viewed by 1439

Abstract

The FeCrSiNiCoC coatings with fine macroscopic morphology and uniform microstructure were made on 1Cr11Ni heat resistant steel substrate by a laser-based cladding technique. The coating consists of dendritic γ-Fe and eutectic Fe-Cr intermetallic with an average microhardness of 467 HV_0.5 ± 22.6 [...] Read more.

The FeCrSiNiCoC coatings with fine macroscopic morphology and uniform microstructure were made on 1Cr11Ni heat resistant steel substrate by a laser-based cladding technique. The coating consists of dendritic γ-Fe and eutectic Fe-Cr intermetallic with an average microhardness of 467 HV_0.5 ± 22.6 HV_0.5. At the load of 200 N, the average friction coefficient of the coating dropped as temperature increased, while the wear rate decreased and then increased. The wear mechanism of the coating changed from abrasive wear, adhesive wear and oxidative wear to oxidative wear and three-body wear. Apart from an elevation in wear rate with increasing load, the mean friction coefficient of the coating hardly changed at 500 °C. Due to the coating’s transition from adhesive wear and oxidative wear to three-body wear and abrasive wear, the underlying wear mechanism also shifted. Full article

(This article belongs to the Special Issue Advances in Metal Cutting, Casting, Forming and Heat Treatment)

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15 pages, 11369 KiB

Open AccessArticle

Study on Concave Direction Impact Performance of Similar Concave Hexagon Honeycomb Structure

by Guanxiao Zhao, Tao Fu and Jiaxing Li

Materials 2023, 16(8), 3262; https://doi.org/10.3390/ma16083262 - 21 Apr 2023

Cited by 6 | Viewed by 1785

Abstract

Based on the traditional concave hexagonal honeycomb structure, three kinds of concave hexagonal honeycomb structures were compared. The relative densities of traditional concave hexagonal honeycomb structures and three other classes of concave hexagonal honeycomb structures were derived using the geometric structure. The impact [...] Read more.

Based on the traditional concave hexagonal honeycomb structure, three kinds of concave hexagonal honeycomb structures were compared. The relative densities of traditional concave hexagonal honeycomb structures and three other classes of concave hexagonal honeycomb structures were derived using the geometric structure. The impact critical velocity of the structures was derived by using the 1-D impact theory. The in-plane impact characteristics and deformation modes of three kinds of similar concave hexagonal honeycomb structures in the concave direction at low, medium, and high velocity were analyzed using the finite element software ABAQUS. The results showed that the honeycomb structure of the cells of the three types undergoes two stages: concave hexagons and parallel quadrilaterals, at low velocity. For this reason, there are two stress platforms in the process of strain. With the increase in the velocity, the joints and middle of some cells form a glue-linked structure due to inertia. No excessive parallelogram structure appears, resulting in the blurring or even disappearance of the second stress platform. Finally, effects of different structural parameters on the plateau stress and energy absorption of structures similar to concave hexagons were obtained during low impact. The results provide a powerful reference for the negative Poisson’s ratio honeycomb structure under multi-directional impact. Full article

(This article belongs to the Special Issue Recent Advances in the Mechanical Properties and Microstructural Features of Porous Materials)

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13 pages, 8606 KiB

Open AccessArticle

Comparison of Implant Surgery Methods of Cortical Tapping and Cortical Widening in Bone of Various Density: A Three-Dimensional Finite Element Study

by Yeon-Wha Baek, Young-Jun Lim and Bongju Kim

Materials 2023, 16(8), 3261; https://doi.org/10.3390/ma16083261 - 21 Apr 2023

Cited by 2 | Viewed by 2212

Abstract

Purpose: The primary stability of a dental implant is critical for successful osseointegration during immediate loading. The cortical bone should be prepared to achieve enough primary stability, but not overcompressed. In this study, we investigated the stress and strain distribution in the bone [...] Read more.

Purpose: The primary stability of a dental implant is critical for successful osseointegration during immediate loading. The cortical bone should be prepared to achieve enough primary stability, but not overcompressed. In this study, we investigated the stress and strain distribution in the bone around the implant induced by the occlusal force applied during immediate loading at various bone densities by the FEA method to compare cortical tapping and widening surgical techniques. Materials and Methods: A three-dimensional geometrical model of a dental implant and bone system was created. Five types of bone density combination (D111, D144, D414, D441 and D444) were designed. Two surgical methods—cortical tapping and cortical widening—were simulated in the model of the implant and bone. An axial load of 100 N and an oblique load of 30 N were applied to the crown. The maximal principal stress and strain were measured for comparative analysis of the two surgical methods. Results: Cortical tapping showed lower maximal stress of bone and maximal strain of bone than cortical widening when dense bone was located around the platform, regardless of the direction of the applied load. Conclusions: Within the limitations of this FEA study, it can be concluded that cortical tapping is biomechanically more advantageous to the implants under occlusal force during immediate loading, especially when the bone density around the platform is high. Full article

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16 pages, 2829 KiB

Open AccessArticle

Multi-Physical Field Simulation of Cracking during Crystal Growth by Bridgman Method

by Xinke He, Linnong Li, Xinqi He and Chao Xie

Materials 2023, 16(8), 3260; https://doi.org/10.3390/ma16083260 - 20 Apr 2023

Cited by 4 | Viewed by 1886

Abstract

Crystal materials are prone to cracking during growth, which is a key problem leading to slow growth and difficulty in forming large-size crystals. In this study, based on the commercial finite element software COMSOL Multiphysics, the transient finite element simulation of the multi-physical [...] Read more.

Crystal materials are prone to cracking during growth, which is a key problem leading to slow growth and difficulty in forming large-size crystals. In this study, based on the commercial finite element software COMSOL Multiphysics, the transient finite element simulation of the multi-physical field, including fluid heat transfer—phase transition—solid equilibrium—damage coupling behaviors, is performed. The phase-transition material properties and maximum tensile strain damage variables are customized. Using the re-meshing technique, the crystal growth and damage are captured. The results show the following: The convection channel at the bottom of the Bridgman furnace greatly influences the temperature field inside the furnace, and the temperature gradient field significantly influences the solidification and cracking behaviors during crystal growth. The crystal solidifies faster when it enters the higher-temperature gradient region and is prone to cracking. The temperature field inside the furnace needs to be properly adjusted so that the crystal temperature decreases relatively uniformly and slowly during the growth process to avoid crack formation. In addition, the crystal growth orientation also significantly affects the nucleation and growth direction of cracks. Crystals grown along the a-axis tend to form long cracks starting from the bottom and growing vertically, while crystals grown along the c-axis induce the laminar cracks from the bottom in a horizontal direction. The numerical simulation framework of the damage during crystal growth, which can accurately simulate the process of crystal growth and crack evolution and can be used to optimize the temperature field and crystal growth orientation in the Bridgman furnace cavity, is a reliable method to solve the crystal cracking problem. Full article

(This article belongs to the Section Mechanics of Materials)

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21 pages, 5758 KiB

Open AccessArticle

Combined Effect of Ceramic Waste Powder Additives and PVA on the Structure and Properties of Geopolymer Concrete Used for Finishing Facades of Buildings

by Evgenii M. Shcherban’, Alexey N. Beskopylny, Sergey A. Stel’makh, Levon R. Mailyan, Besarion Meskhi, Alexandr A. Shilov, Elena Pimenova and Diana El’shaeva

Materials 2023, 16(8), 3259; https://doi.org/10.3390/ma16083259 - 20 Apr 2023

Cited by 8 | Viewed by 2173

Abstract

Currently, there is great interest in geopolymer composites as an alternative and environmentally friendly basis for compositions for restoring the facades of historical and modern buildings. Although the use of these compounds is much smaller than conventional concrete, replacing their main components with [...] Read more.

Currently, there is great interest in geopolymer composites as an alternative and environmentally friendly basis for compositions for restoring the facades of historical and modern buildings. Although the use of these compounds is much smaller than conventional concrete, replacing their main components with ecological geopolymer counterparts still has the potential to significantly reduce the carbon footprint and reduce the amount of greenhouse gas emitted into the atmosphere. The study aimed to obtain geopolymer concrete with improved physical, mechanical, and adhesive characteristics, designed to restore the finishing of building facades. Regulatory methods, chemical analysis, and scanning electron microscopy were applied. The most optimal dosages of additives of ceramic waste powder (PCW) and polyvinyl acetate (PVA) have been established, at which geopolymer concretes have the best characteristics: 20% PCW introduced into the geopolymer instead of a part of metakaolin, and 6% PVA. The combined use of PCW and PVA additives in optimal dosages provides the maximum increase in strength and physical characteristics. Compressive strength increased by up to 18%, bending strength increased by up to 17%, water absorption of geopolymer concretes decreased by up to 54%, and adhesion increased by up to 9%. The adhesion of the modified geopolymer composite is slightly better with a concrete base than with a ceramic one (up to 5%). Geopolymer concretes modified with PCW and PVA additives have a denser structure with fewer pores and microcracks. The developed compositions are applicable for the restoration of facades of buildings and structures. Full article

(This article belongs to the Special Issue Concretes and Cement-Based Composites: Additives/Admixtures, Hydration Process and Durability Research)

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50 pages, 6105 KiB

Open AccessReview

Modeling of Reactive Sputtering—History and Development

by Viktor I. Shapovalov

Materials 2023, 16(8), 3258; https://doi.org/10.3390/ma16083258 - 20 Apr 2023

Cited by 6 | Viewed by 2432

Abstract

This work critically reviews the evolution of reactive sputtering modeling that has taken place over the last 50 years. The review summarizes the main features of the deposition of simple metal compound films (nitrides, oxides, oxynitrides, carbides, etc.) that were experimentally found by [...] Read more.

This work critically reviews the evolution of reactive sputtering modeling that has taken place over the last 50 years. The review summarizes the main features of the deposition of simple metal compound films (nitrides, oxides, oxynitrides, carbides, etc.) that were experimentally found by different researchers. The above features include significant non-linearity and hysteresis. At the beginning of the 1970s, specific chemisorption models were proposed. These models were based on the assumption that a compound film was formed on the target due to chemisorption. Their development led to the appearance of the general isothermal chemisorption model, which was supplemented by the processes on the surfaces of the vacuum chamber wall and the substrate. The model has undergone numerous transformations for application to various problems of reactive sputtering. At the next step in the development of modeling, the reactive sputtering deposition (RSD) model was proposed, which was based on the implantation of reactive gas molecules into the target, bulk chemical reaction, chemisorption, and the “knock-on effect”. Another direction of the modeling development is represented by the nonisothermal physicochemical model, in which the Langmuir isotherm and the law of mass action are used. Various modifications of this model allowed describing reactive sputtering processes in more complex cases when the sputtering unit included a hot target or a sandwich one. Full article

(This article belongs to the Special Issue Sputter Deposition/Physical Vapor Deposition (PVD) Materials and Processes)

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14 pages, 3628 KiB

Open AccessArticle

Effect of Material Change on Stirnol Engine: A Combination of NiTiNOL (Shape Memory Alloy) and Gamma Stirling Engine

by Humayun Arif, Aqueel Shah, Tahir Abdul Hussain Ratlamwala, Khurram Kamal and Maqsood Ahmed Khan

Materials 2023, 16(8), 3257; https://doi.org/10.3390/ma16083257 - 20 Apr 2023

Cited by 2 | Viewed by 2039

Abstract

Population explosion, industrialization, and urbanization have accelerated energy requirements across the globe. This has led to the human quest to find simple and cost-effective energy solutions. A promising solution is the revival of the Stirling engine with the addition of Shape Memory Alloy [...] Read more.

Population explosion, industrialization, and urbanization have accelerated energy requirements across the globe. This has led to the human quest to find simple and cost-effective energy solutions. A promising solution is the revival of the Stirling engine with the addition of Shape Memory Alloy NiTiNOL in it. The experimental results reveal that the addition of a NiTiNOL spring at the base plate of the Stirling engine enhances the overall efficiency of the engine, demonstrating some impact of the shape memory alloy toward the performance output of the Stirling engine. The newly modified engine has been named the STIRNOL ENGINE. The comparative study of Stirling and Stirnol engines reveals a minuscule efficiency improvement, yet there is a furtherance that opens a window for future researchers to get a lead and venture into this new field. We are confident that with more complex designs and better Stirling and NiTiNOL combinations, more efficient engines can be invented in the future. This research focuses on changing the material of the base plate of the Stirnol engine and ascertaining its performance differential through the integration of the NiTiNOL spring. A minimum of four types of materials are utilized for experimentation. Full article

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24 pages, 12784 KiB

Open AccessArticle

Analysis of Asphalt Mixtures Modified with Steel Slag Surface Texture Using 3D Scanning Technology

by Shuai Zhang, Rongxin Guo, Feng Yan, Ruzhu Dong, Chuiyuan Kong and Junjie Li

Materials 2023, 16(8), 3256; https://doi.org/10.3390/ma16083256 - 20 Apr 2023

Cited by 2 | Viewed by 1602

Abstract

This paper investigates the use of steel slag in the place of basalt coarse aggregate in Stone Mastic Asphalt-13 (SMA-13) gradings in the early forming of an experimental pavement and evaluates the test performance of the mixes, combined with 3D scanning techniques to [...] Read more.

This paper investigates the use of steel slag in the place of basalt coarse aggregate in Stone Mastic Asphalt-13 (SMA-13) gradings in the early forming of an experimental pavement and evaluates the test performance of the mixes, combined with 3D scanning techniques to analyse the initial textural structure of the pavement. Laboratory tests were carried out to design the gradation of the two asphalt mixtures and to assess the strength, chipping and cracking resistance of the asphalt mixtures using water immersion Marshall tests, freeze–thaw splitting tests, rutting tests and for comparison with laboratory tests, while surface texture collection and analysis of the height parameters (i.e., Sp, Sv, Sz, Sq, Ssk) and morphological parameters (i.e., Spc) of the pavement were performed to assess the skid resistance of the two asphalt mixtures. Firstly, the results show that a substitution of steel slag for basalt in pavements is a good alternative for efficient resource utilization. Secondly, when steel slag was used in place of basalt coarse aggregate, the water immersion Marshall residual stability improved by approximately 28.8% and the dynamic stability by approximately 15.8%; the friction values decayed at a significantly lower rate, and the MTD did not change significantly. Thirdly, in the early stages of pavement formation, Sp, Sv, Sz, Sq and Spc showed a good linear relationship with BPN values, and these texture parameters can be used as parameters to describe steel slag asphalt pavements. Finally, this study also found that the standard deviation of peak height was higher for steel slag–asphalt mixes than for basalt–asphalt mixes, with little difference in texture depth, while the former formed more peak tips than the latter. Full article

(This article belongs to the Special Issue Industrial Solid Wastes for Construction and Building Materials)

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15 pages, 8143 KiB

Open AccessArticle

Mechanical, Morphological, Thermal and the Attenuation Properties of Heavy Mortars Doped with Nanoparticles for Gamma-Ray Shielding Applications

by Mohammed Thamer Alresheedi, Mohamed Elsafi, Yosef T. Aladadi, Ahmad Fauzi Abas, Abdullrahman Bin Ganam, M. I. Sayyed and Mohd Adzir Mahdi

Materials 2023, 16(8), 3255; https://doi.org/10.3390/ma16083255 - 20 Apr 2023

Cited by 6 | Viewed by 1662

Abstract

This study aimed to develop a mortar composite with improved gamma ray shielding properties using WO₃ and Bi₂O₃ nanoparticles, as well as granite residue as a partial replacement of sand. The physical properties and effects of sand substitution and [...] Read more.

This study aimed to develop a mortar composite with improved gamma ray shielding properties using WO₃ and Bi₂O₃ nanoparticles, as well as granite residue as a partial replacement of sand. The physical properties and effects of sand substitution and nanoparticle addition on the mortar composite were analyzed. TEM analysis confirmed the size of Bi₂O₃ and WO₃ NPs to be 40 ± 5 nm and 35 ± 2 nm, respectively. SEM images showed that increasing the percentage of granite residues and nanoparticles improved the homogeneity of the mixture and decreased the percentage of voids. TGA analysis indicated that the thermal properties of the material improved with the increase in nanoparticles, without decreasing the material weight at higher temperatures. The linear attenuation coefficients were reported and we found that the LAC value at 0.06 MeV increases by a factor of 2.47 when adding Bi₂O₃, while it is enhanced by a factor of 1.12 at 0.662 MeV. From the LAC data, the incorporation of Bi₂O₃ nanoparticles can greatly affect the LAC at low energies, and still have a small but noticeable effect at higher energies. The addition of Bi₂O₃ nanoparticles into the mortars led to a decrease in the half value layer, resulting in excellent shielding properties against gamma rays. The mean free path of the mortars was found to increase with increasing photon energy, but the addition of Bi₂O₃ led to a decrease in MFP and better attenuation, making the CGN-20 mortar the most ideal in terms of shielding ability among the prepared mortars. Our findings on the improved gamma ray shielding properties of the developed mortar composite have promising implications for radiation shielding applications and granite waste recycling. Full article

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