Coatings

19 pages, 6947 KiB

Open AccessArticle

Surface Functionalization of CaCO₃ Whiskers for Improved Asphalt Binder Compatibility: From Microscale Characterization to Molecular Dynamics

by Xiangyang Xing, Jiyang Wang, Qingyue Zhou, Jiupeng Zhang, Guoqing Sun, Shiru Guo and Yong Wen

Coatings 2024, 14(12), 1480; https://doi.org/10.3390/coatings14121480 - 22 Nov 2024

Abstract

CaCO₃ whiskers, as a micron-level inorganic fiber material, can enhance and toughen composite materials. In order to study the technical feasibility of CaCO₃ whisker-modified asphalt, two types of silane coupling agent (SCA), KH-550 and KH-570, were applied to treat the surface [...] Read more.

CaCO₃ whiskers, as a micron-level inorganic fiber material, can enhance and toughen composite materials. In order to study the technical feasibility of CaCO₃ whisker-modified asphalt, two types of silane coupling agent (SCA), KH-550 and KH-570, were applied to treat the surface of CaCO₃ whiskers, and the treatment effects of the original and treated whiskers were characterized by scanning electron microscopy (SEM), energy-dispersive spectrometer (EDS) and contact angle test. Meanwhile, models of CaCO₃ whiskers, SCA, and asphalt molecules were established by Material Studio (MS, 2020 version) software, and the adhesion mechanism between the CaCO₃ whiskers-and-asphalt interface was predicted. The results of microscopic characterization experiments indicate that the surface of the whiskers treated with SCA became rougher. Compared with the original whiskers, the contact angle between the treated whisker surface and water increased from 50° to 92.2° and 103.4°, and the surface of whiskers changed from hydrophilic to hydrophobic. The results of molecular dynamics simulation analysis show that the adhesion performance between the CaCO₃ whisker surface and asphalt increased from 100.1 mJ/m² to 112.5 mJ/m² and 126.6 mJ/m² after modification with SCA, and the increase in adhesion energy of KH550 is greater than that of KH570. The above research results indicate that the micro-characterization results were consistent with the molecular dynamics simulation results; that is, after treatment with SCA, the adhesion energy between the whiskers and asphalt was increased to varying degrees. The research method in this article combines micro-characterization with molecular dynamics simulation, which has a certain degree of innovation. Full article

(This article belongs to the Section Environmental Aspects in Colloid and Interface Science)

12 pages, 1994 KiB

Open AccessArticle

Performance and Thermal Properties of 3D Printed CF-Reinforced PLA Monofilaments

by Pen Jin, Tuo Pan, Yaxuan Li, Tianran Zhong, Jing Jiang, Chengcui Pu and Chunyang Ma

Coatings 2024, 14(12), 1479; https://doi.org/10.3390/coatings14121479 - 22 Nov 2024

Abstract

This study reports the fabrication of carbon fiber-reinforced poly(lactic acid) (CF-PLA) monofilaments using 3D printing technology. The effects of print head movement speed and retraction rate on the diameter of the CF-PLA monofilaments were investigated. The surface morphology and properties were analyzed using [...] Read more.

This study reports the fabrication of carbon fiber-reinforced poly(lactic acid) (CF-PLA) monofilaments using 3D printing technology. The effects of print head movement speed and retraction rate on the diameter of the CF-PLA monofilaments were investigated. The surface morphology and properties were analyzed using scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The CF-PLA monofilaments were also printed into boards with varying CF content, and the mechanical properties of these boards were assessed. The results showed that the optimal printing parameters were a nozzle diameter of ϕ0.4 mm, fiber feed rate (V_f) of 3 mm/s, print head movement speed (V_m) of 40 mm/s, and retraction speed (V_r) of 5 mm/s. At a CF-PLA monofilament diameter of ϕ135 µm, the tensile strength and Young’s modulus reached maximum values of 48.3 MPa and 2481.8 MPa, respectively. Numerous CF monofilaments (approximately 135 µm in diameter) were observed on the surface and within the CF-PLA boards, significantly enhancing their strength. When the CF content was 4 vol%, the thermal decomposition temperature of the CF-PLA monofilament was 312.53 °C. At 8 vol% CF content, the thermal decomposition temperature increased to 342.62 °C—approximately 30 °C higher than that of the monofilament with 4 vol% CF. The CF-PLA monofilaments fabricated at 8 vol% demonstrated high thermal stability. Full article

14 pages, 3577 KiB

Open AccessArticle

Nonlinear Oxidation Behavior at Interfaces in Coated Steam Dual-Pipe with Initial Waviness and Cooling Temperature

by Bo Yuan, Ke Wang, Xiaofeng Guo, Junxiang Gao and Pengfei Chen

Coatings 2024, 14(12), 1478; https://doi.org/10.3390/coatings14121478 - 22 Nov 2024

Abstract

A numerical simulation method is proposed to investigate the nonlinear growth of thermally grown oxide (TGO) on a novel coated steam dual-pipe system operating at 700

^{\circ}

C. Utilizing oxidation kinetics data from high-temperature water vapor experiments, the study examines interface stresses and [...] Read more.

A numerical simulation method is proposed to investigate the nonlinear growth of thermally grown oxide (TGO) on a novel coated steam dual-pipe system operating at 700

^{\circ}

C. Utilizing oxidation kinetics data from high-temperature water vapor experiments, the study examines interface stresses and morphology evolution, considering initial surface waviness and cooling temperature effects. The findings indicate that the parabolic law accurately describes the nonlinear growth of TGO during high-temperature water vapor oxidation, with the TGO growth oxidation rate constant being

4.5 \times 10^{- 4} μ m^{2} / h

. The growth rate of TGO thickness decreases with increasing oxidation duration. Stress concentrations are found to develop at TGO interfaces, particularly in regions with high curvature, and those with elevated wavy amplitudes. The primary factor influencing stress redistribution and morphology evolution is the wavy amplitude of the TGO. Additionally, variations in cooling temperature affect interface stresses along the axial direction of the pipe system during nonlinear oxidation, resulting in relatively minor changes in morphology. Full article

(This article belongs to the Section Ceramic Coatings and Engineering Technology)

1 pages, 129 KiB

Open AccessCorrection

Correction: Zhao et al. Plasma Spraying NiCoCrAlY-Cr₂O₃-AgMo Coatings: Fabrication and Tribological Mechanisms. Coatings 2024, 14, 1233

by Yafei Zhao, Yanping Gao, Zhaoyang Zhai, Yanchao Zhang and Dongya Zhang

Coatings 2024, 14(12), 1477; https://doi.org/10.3390/coatings14121477 - 22 Nov 2024

Abstract

In the published paper [...] Full article

13 pages, 6488 KiB

Open AccessArticle

Microstructure and Tribological Properties of FeCrCoMnSi_x High-Entropy Alloy Coatings

by Shuling Zhang, Di Jiang, Shengdi Sun and Bo Zhang

Coatings 2024, 14(12), 1476; https://doi.org/10.3390/coatings14121476 - 22 Nov 2024

Abstract

For shaft parts, 45 steel has been widely used due to its favorable mechanical properties and low cost. However, the relatively low wear resistance of 45 steel limits its application. In this work, high-entropy alloy of FeCrCoMnSi_x (x = 0, 0.3, 0.6, [...] Read more.

For shaft parts, 45 steel has been widely used due to its favorable mechanical properties and low cost. However, the relatively low wear resistance of 45 steel limits its application. In this work, high-entropy alloy of FeCrCoMnSi_x (x = 0, 0.3, 0.6, 0.9, 1) coatings were prepared on the surface of a 45 steel substrate using laser cladding technology to improve the wear performance of 45 steel. The effect of the Si element on the microstructure and tribological property of these coatings is investigated. The results show that the structure of FeCrCoMn coatings is mainly an FCC + HCP dual-phase solid solution, grown in equiaxial crystals. When a small amount of Si (x = 0.3) is added, the BCC phase is generated in the coating; meanwhile, the microstructure is transformed into the divorced eutectic character. When the content of Si is x = 0.6, the eutectic structure is promoted, and the microstructure is refined and becomes denser. When the content of Si increases to x = 0.9 and 1.0, the metal silicate phase containing Mn and Cr is formed due to the precipitation of supersaturated solid solution. At the same time, the microstructure is transformed into dendritic crystals due to the composition super-cooling effect by the excessive Si element, inducing serious element segregation. The hardness of FeCrCoMnSi_x high-entropy alloy coatings increases to 425.8 HV when the Si content is 0.6 under the synergistic effect of the solid-solution and dense eutectic structure. The friction and wear analysis shows that the friction and wear mechanisms of the coating are mainly abrasive wear and oxidative wear. The coefficient of friction and the wear rate of the FeCrCoMnSi_x high-entropy alloy coating decreases to 0.202 and 4.06 × 10⁻⁵ mm³/N·m, respectively, when the content of Si is 0.6 due to the dense microstructure and high hardness. The above studies prove that the presence of Si in the FeCrCoMnSi_0.6 high-entropy alloy coating induces a refined eutectic microstructure and improves the coating’s anti-wear properties by increasing hardness and decreasing the coefficient of friction. Full article

(This article belongs to the Section Laser Coatings)

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27 pages, 1946 KiB

Open AccessReview

Solid–Liquid Composite Lubrication (SLCL) Based on Diamond-Like Carbon (DLC) Coatings and Lubricating Oils: Properties and Challenges

by Wei Qi, Lei Chen, Hui Li, Lieming Tang and Zhiliang Xu

Coatings 2024, 14(12), 1475; https://doi.org/10.3390/coatings14121475 - 21 Nov 2024

Abstract

In the field of industrial lubrication, solid–liquid composite lubrication (SLCL) techniques based on diamond-like carbon (DLC) coatings and lubricating oils are emerging recently, which may be applied in many fields in the near future, especially automotive industries. The tribological behaviors of SLCL systems [...] Read more.

In the field of industrial lubrication, solid–liquid composite lubrication (SLCL) techniques based on diamond-like carbon (DLC) coatings and lubricating oils are emerging recently, which may be applied in many fields in the near future, especially automotive industries. The tribological behaviors of SLCL systems depend strongly on the compatibility between DLC coatings and oils. This review describes the advantages of SLCL techniques by pointing out the synergistic effects between DLC coatings and lubricating oils. Then the main factors determining the tribological performance of SLCL systems are discussed in detail. Finally, a conclusion about the characteristics of reported SLCL systems is made, and a prospect about the potential development of SLCL technology is proposed. On the basis of the relevant literature, it could be found that the tribological properties of SLCL systems were influenced by many more factors compared with individual DLC lubrication or individual oil lubrication due to the complicated tribo-chemical reactions involving DLC and oil during friction. And under some optimized working conditions, the tribological performances of SLCL systems (friction and wear reduction) are superior to individual DLC lubrication and individual oil lubrication. However, the tribological performance of SLCL systems needs to be further improved (for example, to achieve superlubricity and ultra-low wear simultaneously) by adjusting the structures of DLC coatings, regulating the compositions of oils, and most importantly, enhancing the physicochemical and tribological synergies between DLC coatings and oils. This review provides a comprehensive understanding of the SLCL technology, which may be very helpful for the researchers and engineers in the field of industrial lubrication and tribology. Full article

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19 pages, 12688 KiB

Open AccessArticle

Comprehensive Study on the Thrust Estimation and Anti-Freezing Lubricant of Pipe Jacking in Frozen Soil

by Kai Wen, Wei Zeng, Qing Ye, Hideki Shimada, Siliang Qin and Benhao Fu

Coatings 2024, 14(12), 1474; https://doi.org/10.3390/coatings14121474 - 21 Nov 2024

Abstract

Recent advancements in underground construction have led to the widespread utilization of pipe jacking. However, the engineering challenges posed by frozen ground in pipe jacking projects have not been extensively studied. This research aims to address the critical challenges linked to employing pipe [...] Read more.

Recent advancements in underground construction have led to the widespread utilization of pipe jacking. However, the engineering challenges posed by frozen ground in pipe jacking projects have not been extensively studied. This research aims to address the critical challenges linked to employing pipe jacking in frozen ground for underground construction. It is widely recognized that the accurate calculation of jacking thrust and mitigation of pipe–soil interaction plays a crucial role in determining the success or failure of pipe jacking operations. To explore these issues, this study conducted numerical simulations and comparative analyses, considering various factors such as soil properties, geometric dimensions, and burial depth, to assess their influence on jacking thrust. Additionally, the study also examines the freeze–thaw effect on concrete pipes and the injected lubricant. The results indicate that the numerical model, which considers the temperature effects and static friction instead of sliding friction, provides a more reliable estimation of jacking thrust in frozen ground compared to traditional theoretical models. Furthermore, the freezing point depression method was successfully employed in the development of an anti-freezing lubricant, which can effectively reduce pipe–soil interaction even at extremely low temperatures of up to −10 °C. Full article

(This article belongs to the Section Environmental Aspects in Colloid and Interface Science)

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10 pages, 2161 KiB

Open AccessArticle

TiO₂ Coated with Carbon via Chemical Vapor Deposition as Li-Ion Batteries Anode

by Bin Zhu, Wenjun Li, Wu Tang and Hui Tang

Coatings 2024, 14(11), 1473; https://doi.org/10.3390/coatings14111473 - 20 Nov 2024

Abstract

With the increasing demand for renewable energy and sustainable technologies, lithium-ion batteries (LIBs) have become crucial energy storage components. Despite the promising properties of the high capacity and stability of TiO₂, its large-scale application as an anode for LIBs is hindered [...] Read more.

With the increasing demand for renewable energy and sustainable technologies, lithium-ion batteries (LIBs) have become crucial energy storage components. Despite the promising properties of the high capacity and stability of TiO₂, its large-scale application as an anode for LIBs is hindered by challenges like poor conductivity and volumetric changes during cycling. Here, a rutile TiO₂ composite material with a thinned carbon coating (TiO₂@TC) was synthesized through chemical vapor deposition (CVD) and a subsequent annealing process, which significantly improved the reversibility, cycling stability, and rate performance of the TiO₂ anode materials. The thickness of the carbon layer on TiO₂ was precisely controlled and thinned from 4.2 nm to 1.9 nm after secondary annealing treatment, leading to a smaller steric hindrance and an improved conductivity while serving as protective coatings by preventing the electrochemical degradation of the TiO₂ surface and hindering volumetric changes during cycling. The resulting TiO₂@TC with the thin carbon layer demonstrated a high specific capacity of 167 mAh g⁻¹ at 0.5 C in Li-based half cells, which could stably run for 200 cycles with nearly 100% capacity retention. The thin carbon layer also contributes to an improved rate performance of 90 mAh g⁻¹ at even 20 C. This work provides an innovational strategy for improving the conductivity and volumetric changes during the cycling of TiO₂ anodes. Full article

(This article belongs to the Special Issue Recent Progress in Advanced Materials for Solid-State Lithium Batteries)

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14 pages, 3204 KiB

Open AccessArticle

The Influence of Nano-Silicon Carbide on the Properties of Aluminum Alloy Under Salt Dry–Wet Alternations

by Shengpeng Song, Chuanyuan Liu, Wentao Chen, Zhen Wang, Chuanyin Wang, Zihao Cao, Hui Wang and Feiting Shi

Coatings 2024, 14(11), 1472; https://doi.org/10.3390/coatings14111472 - 20 Nov 2024

Abstract

In this study, the influence of silicon carbide on an aluminum alloy’s yield tensile strength, ultimate tensile strength, compressive strength, tensile toughness and impact toughness were investigated. Meanwhile, the aluminum alloy specimens were exposed to the dry–wet alternations with a 3% NaCl solution [...] Read more.

In this study, the influence of silicon carbide on an aluminum alloy’s yield tensile strength, ultimate tensile strength, compressive strength, tensile toughness and impact toughness were investigated. Meanwhile, the aluminum alloy specimens were exposed to the dry–wet alternations with a 3% NaCl solution or 3% Na₂SO₄ solution. Scanning electron microscope (SEM) photos and scanning electron microscopy energy spectra (SEM-EDS) were obtained. The results indicate that the silicon carbide with a mass ratio of 0%~8% of the total mass of the aluminum alloy can increase the yield tensile strength, the ultimate tensile strength, and the compressive strength by rates of 0%~30.4%, 0%~14.1% and 0%~13.1%. However, when the mass ratio of the silicon carbide increased from 8% to 10%, the yield tensile strength, the ultimate tensile strength and the compressive strength decreased by rates of 0%~3.2%, 0%~2.6% and 0%~0.43%. The tensile toughness and the impact toughness decreased when silicon carbide was added, with reduction rates of 0%~15.3% and 0%~12.8%. The NaCl dry–wet alternations led to decreases in the yield tensile strength, the ultimate tensile strength, the compressive strength, the tensile toughness and the impact toughness by rates of 0%~7.3%, 0%~6.7%, 0%~13.9%, 0%~12.7% and 0%~11.2%, respectively. After the Na₂SO₄ dry–wet alternations, the corresponding decreasing rates were 0%~5.1%, 0%~5.4%, 0%~1.73%, 0%~11.4% and 0%~9.7%. The addition of silicon carbide resulted in a decrease in the effect on the mechanical strength by the NaCl and Na₂SO₄ dry–wet alternations. The elements carbon, oxygen, magnesium, aluminum and silicon were observed in the aluminum alloy. The structures of the aluminum alloy with 8% silicon carbide were the highest. Full article

(This article belongs to the Special Issue Mechanical Properties and Tribological Behavior of Alloy/Coatings, 2nd Edition)

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9 pages, 4300 KiB

Open AccessArticle

Preparation and Properties of Thick Tungsten Coating Electrodeposited from Na₂WO₄-WO₃-KCl-NaF Molten Salt System

by Yusha Li, Xiaoxu Dong, Qing Liu, Yajie You, Zeyu Gao and Yingchun Zhang

Coatings 2024, 14(11), 1471; https://doi.org/10.3390/coatings14111471 - 20 Nov 2024

Abstract

The pulsed current electrodeposition method was employed for the first time to achieve tungsten coating with a thickness of 433.72 μm on a CuCrZr alloy from Na₂WO₄-WO₃-KCl-NaF molten salt. The microstructure of the coating was observed and [...] Read more.

The pulsed current electrodeposition method was employed for the first time to achieve tungsten coating with a thickness of 433.72 μm on a CuCrZr alloy from Na₂WO₄-WO₃-KCl-NaF molten salt. The microstructure of the coating was observed and the coating density, porosity, hardness, bonding strength, residual stress and oxygen content were tested. The results revealed that the tungsten coating exhibited desirable characteristics such as high density, absence of impurities, excellent adhesion to the matrix (53.16 MPa), residual compressive stress as surface stress, and good stability and durability. Moreover, this thick tungsten coating possesses high density and hardness, low oxygen content and porosity. This offers a novel solution to solve the challenging issue of the connection between tungsten material and heat sink material. Full article

(This article belongs to the Special Issue New Functional Coatings and Thin Films for Sensor and Green Energy Technologies)

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12 pages, 4115 KiB

Open AccessArticle

Effect of Humidity on Interfacial Debonding Behavior Between Larger Graphene Sheet and Cement-Based Composites

by Yongliang Han, Yongzhe Zhao, Yijie Wang and Tong Chen

Coatings 2024, 14(11), 1470; https://doi.org/10.3390/coatings14111470 - 20 Nov 2024

Abstract

This paper investigates the interface debonding behavior of graphene (G) on a calcium silicate hydrate (C-S-H) substrate using molecular dynamics (MD) simulations. The effect of interfacial water content on the debonding behavior of graphene on cement-based composites was studied. Simulation results reveal that [...] Read more.

This paper investigates the interface debonding behavior of graphene (G) on a calcium silicate hydrate (C-S-H) substrate using molecular dynamics (MD) simulations. The effect of interfacial water content on the debonding behavior of graphene on cement-based composites was studied. Simulation results reveal that there is only a van der Waals force between G and C-S-H; the interface bonding strength is weak; and the debonding properties (maximum peeling force (F_max) and work (W)) are low. The debonding energy of graphene decreases with an increase in interfacial water content, indicating that water intrusion will weaken the binding effect of G and C-S-H, and reduce the difficulty of graphene’s debonding on a C-S-H substrate. Exploring the adhesion behavior of graphene on C-S-H under the influence of humidity at the nanoscale is of great significance for understanding the basic adhesion mechanism, optimizing composite material properties, and promoting the development of related disciplines. Full article

(This article belongs to the Special Issue Recent Progress in Surface and Interface Properties of Nanostructures)

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16 pages, 5245 KiB

Open AccessArticle

Ball-on-Disk Wear Maps for Bearing Steel–Hard Anodized EN AW-6082 Aluminum Alloy Tribocouple in Dry Sliding Conditions

by Enrico Baroni, Annalisa Fortini, Lorenzo Meo, Chiara Soffritti, Mattia Merlin and Gian Luca Garagnani

Coatings 2024, 14(11), 1469; https://doi.org/10.3390/coatings14111469 - 19 Nov 2024

Abstract

In recent years, Golden Hard Anodizing (G.H.A.^®) has been developed as a variant of the traditional hard anodizing process with the addition of Ag⁺ ions in the nanoporous structure. The tribological properties of this innovative surface treatment are still not [...] Read more.

In recent years, Golden Hard Anodizing (G.H.A.^®) has been developed as a variant of the traditional hard anodizing process with the addition of Ag⁺ ions in the nanoporous structure. The tribological properties of this innovative surface treatment are still not well understood. In this study, ball-on-disk tests were conducted in dry sliding conditions using 100Cr6 (AISI 52100) bearing steel balls as a counterbody and GHA^®-anodized EN AW-6082 aluminum alloy disks. The novelty of this work lies in the mapping of the wear properties of the tribocouple under different test conditions for a better comparison of the results. Three different normal loads (equal to 5, 10, and 15 N) and three different reciprocating frequencies (equal to 2, 3, and 4 Hz) were selected to investigate a spectrum of operating conditions for polished and unpolished G.H.A.^®-anodized EN AW-6082 aluminum alloy. Quantitative wear maps were built based on the resulting wear rate values to define the critical operating limits of the considered tribocouple. The results suggest that the coefficient of friction (COF) was independent of test conditions, while different wear maps were found for polished and non-polished surfaces. Polishing before anodizing permitted the acquisition of lower wear for the anodized disks and the steel balls. Full article

(This article belongs to the Special Issue Mechanical Properties and Tribological Behavior of Alloy/Coatings, 2nd Edition)

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16 pages, 4760 KiB

Open AccessArticle

Influence of Construction Process on Aggregate Spalling Behavior on Ultrathin Waterborne Epoxy Resin Layer

by Jiaquan Yuan, Yifan Zhang, Haoyang Huang, Gang Zhou, Chaoliang Fu, Wenhong Duan, Weihong Jiang, Li Xiong, Huimei Li, Xiaohua Yang and Chuanqiang Li

Coatings 2024, 14(11), 1468; https://doi.org/10.3390/coatings14111468 - 18 Nov 2024

Abstract

The waterborne epoxy resin (WER) colored antiskid thin layer has been widely used in asphalt pavement to improve driving safety. The tectonic depth determines the antiskid performance of aparticle antiskid type thin layer. The spalling of aggregate from a thin layer may reduce [...] Read more.

The waterborne epoxy resin (WER) colored antiskid thin layer has been widely used in asphalt pavement to improve driving safety. The tectonic depth determines the antiskid performance of aparticle antiskid type thin layer. The spalling of aggregate from a thin layer may reduce the tectonic depth, thus damaging antiskid performance. The spreading process of aggregate on the WER binder surface plays an important role in the spalling behavior of the thin layer. Herein, the influence of spreading processes on the ceramic aggregate spalling behavior on the WER thin layer was investigated based on laboratory experiments. The abrasion and British Pendulum Number (BPN) tests were employed to evaluate the antispalling and antiskid properties of the WER thin layers with different amounts of WER mortar, coverage rates of first-spread aggregate, and spreading orders of coarse/fine aggregates. Moreover, the tectonic depths of the layers before/after the spalling test were also investigated. The results indicated that the optimal dosage of WER mortar is 2.8 kg/m². The WER thin layer exhibited better anti-striping property when coarse ceramic aggregate was spread first. The first-spread coverage rate of the aggregate on the WER surface is 70%. The thin layer exhibited a superior antispalling performance according to the resulting scheme, with a spalling rate of 3.77%. The tectonic depth only decreased from 1.87 to 1.80 mm after the spalling test. Full article

(This article belongs to the Special Issue Green Asphalt Materials—Surface Engineering and Applications)

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18 pages, 2514 KiB

Open AccessArticle

Aloe Vera as a Printed Coating to Mitigate the Wear of Textiles

by Michail Karypidis, Amalia Stalika, Maria Zarkogianni, Apostolos Korlos and Eleftherios G. Andriotis

Coatings 2024, 14(11), 1467; https://doi.org/10.3390/coatings14111467 - 18 Nov 2024

Abstract

Aloe vera is well known for its biological properties as a bioflavonoid anti-inflammatory and antibacterial agent. It has been used frequently in the food sector as a food coating due to its hygroscopic properties and as an ingredient in the lucrative cosmetic industry. [...] Read more.

Aloe vera is well known for its biological properties as a bioflavonoid anti-inflammatory and antibacterial agent. It has been used frequently in the food sector as a food coating due to its hygroscopic properties and as an ingredient in the lucrative cosmetic industry. Studies have also included aloe vera as an eco-friendly green solution based on these properties. The current research focuses on the use of aloe vera gel in printing pastes as an alternative sustainable solution to synthetic thickeners, evaluating its wet performance and ease of fabric stitching, and has been inspired by studies that similarly used this substance and measured its effect on the fabric’s coefficient of friction and antimicrobial action. In the current study, printing pastes with natural colourants, such as saffron, curcumin, and annatto, and aloe vera gel thickener derived from natural leaves from Crete increased the fabric’s mechanical resistance to abrasion compared to the untreated pastes. The measured performance did not differ substantially from prints with traditional synthetic pastes, hence tolerating the substitution with the non-contaminant variant. The enhanced resistance to abrasion and wear extends the fabric’s serviceable life and resulting garments, decreasing the need for high industry processing volumes and, as a result, reducing pollution. The resistance to wear was evaluated using the dominant method in textile testing of the Martindale apparatus, which measured the cycles to failure, weight loss, and general appearance deterioration using the official photographic standards. Full article

(This article belongs to the Special Issue Coatings for Antimicrobial Textiles)

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50 pages, 64978 KiB

Open AccessArticle

Investigating the Surface Damage to Fuzhou’s Ancient Houses (Gu-Cuo) Using a Non-Destructive Testing Method Constructed via Machine Learning

by Lei Zhang, Yile Chen, Liang Zheng, Binwen Yan, Jiali Zhang, Ali Xie and Senyu Lou

Coatings 2024, 14(11), 1466; https://doi.org/10.3390/coatings14111466 - 18 Nov 2024

Abstract

As an important part of traditional Chinese architecture, Fuzhou’s ancient houses have unique cultural and historical value. However, over time, environmental factors such as efflorescence and plant growth have caused surface damage to their gray brick walls, leading to a decline in the [...] Read more.

As an important part of traditional Chinese architecture, Fuzhou’s ancient houses have unique cultural and historical value. However, over time, environmental factors such as efflorescence and plant growth have caused surface damage to their gray brick walls, leading to a decline in the quality of the buildings’ structure and even posing a threat to the buildings’ safety. Traditional damage detection methods mainly rely on manual labor, which is inefficient and consumes a lot of human resources. In addition, traditional non-destructive detection methods, such as infrared imaging and laser scanning, often face difficulty in accurately identifying specific types of damage, such as efflorescence and plant growth, on the surface of gray bricks and are easily hampered by diverse surface features. This study uses the YOLOv8 machine learning model for the automated detection of two common types of damage to the gray brick walls of Fuzhou’s ancient houses: efflorescence and plant growth. We establish an efficient gray brick surface damage detection model through dataset collection and annotation, experimental parameter optimization, model evaluation, and analysis. The research results reveal the following. (1) Reasonable hyperparameter settings and model-assisted annotation significantly improve the detection accuracy and stability. (2) The model’s average precision (AP) is improved from 0.30 to 0.90, demonstrating good robustness in detecting complex backgrounds and high-resolution real-life images. The F1 value of the model’s gray brick detection efficiency is improved (classification model performance index) from 0.22 to 0.77. (3) The model’s ability to recognize the damage details of gray bricks under high-resolution conditions is significantly enhanced, demonstrating its ability to cope with complex environments. (4) The simplified data enhancement strategy effectively reduces the feature extraction interference and enhances the model’s adaptability in different environments. Full article

(This article belongs to the Special Issue Advanced Technology in Surface Characterization and Conservation for Architectural and Archaeological Heritage)

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10 pages, 9967 KiB

Open AccessArticle

Embedment of Molybdenum Disulfide in Electrospun Fibers as an Integrated Cathode for Lithium-Ion Batteries

by Jiaqi Pan, Zhen Liu, Baoyan Zhang, Meili Qi and Yao Feng

Coatings 2024, 14(11), 1465; https://doi.org/10.3390/coatings14111465 - 18 Nov 2024

Abstract

As an important component of LIBs, the electrode material plays a crucial role in determining the lithium (Li) storage performance in LIBs. In this study, MoS₂ nano-flowers were synthesized using a one-pot hydrothermal method. The resulting MoS₂ nano-flower, along with PAN, [...] Read more.

As an important component of LIBs, the electrode material plays a crucial role in determining the lithium (Li) storage performance in LIBs. In this study, MoS₂ nano-flowers were synthesized using a one-pot hydrothermal method. The resulting MoS₂ nano-flower, along with PAN, were used as raw materials for electrospinning. After annealing treatment, MoS₂/(carbon nanofibers) CNFs nano-composites coated with carbon fibers were formed. The CNFs coating exhibited electrical conductivity and enhanced structural stability of the MoS₂ due to the stabilizing effect of the carbon fibers. Additionally, electrochemical tests, including CV and GCD, indicated that the optimal capacity and cycling stability were achieved when the MoS₂ content was 10%. The results indicated that the charge/discharge capacity of MoS₂/CNFs-10% at a current density of 100 mA/g was ~650 mAh/g. After the cycling current returned to 100 mA/g, the current recovery was ~600 mAh/g, thereby indicating outstanding cycling stability. Accordingly, our fabrication technique and new insight could both widen design strategy of multicomponent composite electrode materials and promote the practical applications of the latest emerging transition metal sulfides in next-generation high-performance lithium-ion batteries. Full article

(This article belongs to the Special Issue Surface Modification of Advanced Transition Metal-Based Materials for Electrochemical Energy Storage)

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17 pages, 10712 KiB

Open AccessArticle

Optical Properties of Yttrium Ferrite Films Prepared by Pulse Laser Deposition

by Dinara Sobola, Saleh H. Fawaeer, Pavla Kočková, Richard Schubert, Rashid Dallaev and Tomáš Trčka

Coatings 2024, 14(11), 1464; https://doi.org/10.3390/coatings14111464 - 18 Nov 2024

Abstract

This study investigates the optical properties of yttrium ferrite thin films fabricated via pulse laser deposition. Yttrium orthoferrite, a ferrimagnetic material known for its potential applications in spintronics and photonics, was deposited on single-crystal substrates under controlled conditions to analyze its optical characteristics. [...] Read more.

This study investigates the optical properties of yttrium ferrite thin films fabricated via pulse laser deposition. Yttrium orthoferrite, a ferrimagnetic material known for its potential applications in spintronics and photonics, was deposited on single-crystal substrates under controlled conditions to analyze its optical characteristics. The influence of deposition time on the film quality and optical properties was examined. Atomic force microscopy in contact mode revealed surface roughness variations up to 35 nm, indicating the films’ ability to cover substrate defects. Reflectance measurements determined the optical band gap, which decreased from 3.17 eV for thinner films (44 nm) to 2.91 eV for thicker films (93 nm). Forbidden electronic transitions were also observed, attributed to heteroepitaxial growth and phonon interactions. These results demonstrate the effect of film thickness on morphology and optical properties, making YFeO₃ films promising for a range of optoelectronic applications. Full article

(This article belongs to the Special Issue Advances in Deposition and Surface Modification of Oxide Thin Films and Nanocoatings)

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4 pages, 2370 KiB

Open AccessCorrection

Correction: Chen et al. High-Sensitivity and -Stability Thin-Film Heat Flux Sensor Based on Transverse Thermoelectric Effect. Coatings 2023, 13, 1610

by Hao Chen, Yong Wang, Zao Yi, Bo Dai, Bin Tang, Xibin Xu and Yougen Yi

Coatings 2024, 14(11), 1463; https://doi.org/10.3390/coatings14111463 - 18 Nov 2024

Abstract

In the original publication [...] Full article

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16 pages, 7346 KiB

Open AccessArticle

Study on Mechanism of Microstructure Refinement by Ultrasonic Cavitation Effect

by Chang Li, Shuchao Li, Jiabo Liu, Yichang Sun, Yuhao Wang and Fanhong Kong

Coatings 2024, 14(11), 1462; https://doi.org/10.3390/coatings14111462 - 17 Nov 2024

Abstract

During the solidification process of the alloy, the temperature lies in the range between the solid-phase line and the liquidus. Dendrite growth exhibits high sensitivity to even slight fluctuations in temperature, thereby significantly influencing the tip growth rate. The increase in temperature can [...] Read more.

During the solidification process of the alloy, the temperature lies in the range between the solid-phase line and the liquidus. Dendrite growth exhibits high sensitivity to even slight fluctuations in temperature, thereby significantly influencing the tip growth rate. The increase in temperature can result in a reduction in the rate of tip growth, whereas a decrease in temperature can lead to an augmentation of the tip growth rate. In cases where there is a significant rise in temperature, dendrites may undergo fracture and subsequent remelting. Within the phenomenon of ultrasonic cavitation, the release of internal energy caused by the rupture of cavitation bubbles induces a substantial elevation in temperature, thereby causing both dendrite remelting and fracture phenomena. This serves as the main mechanism behind microstructure refinement induced by ultrasonic cavitation. Although dendrite remelting and fracture exert significant influences on the solidification process of alloys, most studies primarily focus on microscopic characterization experiments, which fail to unveil the transient evolution law governing dendrite remelting and fracture processes. Numerical simulation offers an effective approach to address this gap. The existing numerical models primarily focus on predicting the dendrite growth process, while research on remelting and fracture phenomena remains relatively limited. Therefore, a dendrite remelting model was established by incorporating the phase field method (PFM) and finite element difference method (FDM) into the temperature-induced modeling, enabling a comprehensive investigation of the entire process evolution encompassing dendrite growth and subsequent remelting. Full article

(This article belongs to the Special Issue Effects of Laser Treatment on Surface Characterization and Mechanical Properties of Alloys, 2nd Edition)

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