Coatings

12 pages, 7036 KiB

Open AccessArticle

Experimental Investigation of the Effect of NiCrTi Coating on the Ash Condensation Characteristics of High-Alkali Coals

by Quan Liang, Lina Hu and Qiheng Ding

Coatings 2024, 14(12), 1594; https://doi.org/10.3390/coatings14121594 - 19 Dec 2024

To investigate the effect of NiCrTi coating on the ash condensation characteristics of high-alkali coal in Xinjiang South Mine, we first built an experimental rig for high-alkali-coal flue gas condensation and carried out experimental research on high-alkali-coal flue gas condensation. Physicochemical characterization of [...] Read more.

To investigate the effect of NiCrTi coating on the ash condensation characteristics of high-alkali coal in Xinjiang South Mine, we first built an experimental rig for high-alkali-coal flue gas condensation and carried out experimental research on high-alkali-coal flue gas condensation. Physicochemical characterization of the initial layer of the ash deposit (initial deposit) condensation products was also carried out using XRD, SEM, and EDX. Finally, the priority of products generated on the surface of NiCrTi coating and the three-phase diagram of Na₂O-SiO₂-Al₂O₃ were analyzed by using FactSage 8.3 thermodynamic software. The results show that the condensation products in the initial deposits layer of 15CrMo alloy contain other sodium salts, such as sodium feldspar (NaAlSi₃O₈), NaCl, and Na₂SO₄, and that other protective oxides, such as Cr₂O₃, NiCr₂O₄, and TiO₂, are formed on the surface of the NiCrTi coating. At the same time, the condensation experiment allows the fouling phase to be divided into four parts. Secondly, it was found that the densely flaky particles on the surface of NiCrTi coatings not only have excellent anti-fouling properties but also can effectively inhibit the penetration of other elements such as S. Finally, the reaction priority of protective oxides on NiCrTi coatings was calculated by FactSage 8.3 and found to have the following order: NiCr₂O₄ > Cr₂O₃ > TiO₂. The results of this paper provide theoretical support for the development of anti-staining NiCrTi coatings. Full article

(This article belongs to the Section Corrosion, Wear and Erosion)

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22 pages, 4942 KiB

Open AccessArticle

Sustainable Urban Regeneration with Wind and Thermal Environment Optimization: Design Roadshow of a Historic Town in China

by Yijie Lin, Menglong Zhang, Chang Yi, Yin Zhang, Jianwu Xiong, Liangbiao Lv, Xiaoke Peng and Jinyu He

Coatings 2024, 14(12), 1593; https://doi.org/10.3390/coatings14121593 - 19 Dec 2024

Abstract

With the acceleration of urbanization, many traditional buildings have been dismantled and built indiscriminately, resulting in a uniform urban landscape. The problem of urban microclimate has been aggravated, and the renovation of historic districts, especially including the renewal of microclimate, has become an [...] Read more.

With the acceleration of urbanization, many traditional buildings have been dismantled and built indiscriminately, resulting in a uniform urban landscape. The problem of urban microclimate has been aggravated, and the renovation of historic districts, especially including the renewal of microclimate, has become an important component of sustainable urban renewal. The old commercial street in Huili Ancient City is used as an example in this paper. Through literature research, we note that previous studies have mainly examined the renewal of historic districts from the perspective of the old city environment, while most of the traditional neighborhood renewal designs have neglected the wind and heat environments. Combining the limitations of previous studies and field research, we summarized the current problems of the neighborhood and developed specific renovation strategies for the identified problems in terms of historical and cultural heritage, the relationship between the old and the new, and the layout of green building technologies. In addition, the green building strategy was used to optimize the microclimate environment of the neighborhood, and the wind and heat environment simulation was conducted to evaluate the modeling of the renovated neighborhood. The results show that the outdoor wind environment is better in winter than in summer, and the natural ventilation environment of the neighborhood could be optimized by optimizing the building layout to form an alleyway wind. The indoor wind–heat environment simulation was carried out with the Green Pottery Experience Hall as an example, and the indoor and outdoor air circulation and ventilation were good, and the comfort of the human thermal environment was high. This paper explores the updating strategy of the historic district in the transition zone between old and new and the wind–heat environment simulation and evaluation of green building renovation, which provides a new perspective for the related renovation research and the optimization strategy of the microclimate environment in the district. Full article

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

20 pages, 8699 KiB

Open AccessArticle

Detection and Identification of Coating Defects in Lithium Battery Electrodes Based on Improved BT-SVM

by Xianju Wang, Shanhui Liu, Xuyang Kou, Yu Jiao and Yinfeng Li

Coatings 2024, 14(12), 1592; https://doi.org/10.3390/coatings14121592 - 19 Dec 2024

Abstract

Aiming to address the problems of uneven brightness and small defects of low contrast on the surface of lithium battery electrode (LBE) coatings, this study proposes a method for detection and identification of coatings defects in LBEs based on an improved Binary Tree [...] Read more.

Aiming to address the problems of uneven brightness and small defects of low contrast on the surface of lithium battery electrode (LBE) coatings, this study proposes a method for detection and identification of coatings defects in LBEs based on an improved Binary Tree Support Vector Machine (BT-SVM). Firstly, adaptive Gamma correction is applied to enhance an image, and an improved Canny algorithm combined with morphological processing is used to accurately detect the defect regions. Secondly, the shape and grayscale features of the defects are extracted from the connected defect areas, and these features are then fused and normalized. Finally, a BT-SVM multi-class classification model is constructed, with the Whale Optimization Algorithm (WOA) employed to assist in hyperparameter tuning. The experimental results show that the proposed method can effectively detect and identify five common types of defects in the coating of LBEs, including scratches, bubbles, metal leakage, particles, and decarbonization, with an average detection accuracy of 94.4% and an average detection time of less than 0.2 s, meeting the real-time detection requirements for online defect inspection. After Whale Optimization, the BT-SVM defect recognition model achieves an average recognition accuracy of 98.7%, significantly enhancing the performance of current defect detection technologies for LBE coatings. Full article

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14 pages, 2422 KiB

Open AccessArticle

Effect of Welding Current on the Dilution and Mechanical Properties of Co–Cr Alloy Stellite-6 Coatings Applied to AISI 4130 Steel

by Elias Rocha Gonçalves Júnior, Bárbara Ferreira de Oliveira, Luis Augusto Hernandez Terrones, Noan Tonini Simonassi and Sérgio Neves Monteiro

Coatings 2024, 14(12), 1591; https://doi.org/10.3390/coatings14121591 - 19 Dec 2024

Abstract

Coating welding with cobalt alloys on pipelines is crucial for the offshore industry due to its exceptional resistance to corrosion and wear. In this paper, two welding conditions with different currents were proposed to observe the behavior of the dissimilar joint. The microstructure, [...] Read more.

Coating welding with cobalt alloys on pipelines is crucial for the offshore industry due to its exceptional resistance to corrosion and wear. In this paper, two welding conditions with different currents were proposed to observe the behavior of the dissimilar joint. The microstructure, mechanical properties, and dilution of a dissimilar material consisting of AISI 4130 steel substrate coated with Stellite 6 alloy were analyzed. Firstly, samples were metallographically prepared for the evaluation of the weld bead and the coating phases using SEM, EDS, and XRD analyses. Then, microstructural characterization was performed qualitatively using confocal microscopy and quantitatively to determine the phase fraction volumes in the dendritic and interdendritic regions, as well as the resulting dilution. Results revealed that varying welding conditions did not significantly affect the hardness of the coatings, which remained within the alloy standard of 36-45 HRC, with microhardness varying by 3%–5% from one condition to another and phase fraction volume showing a variation of 5.6% between welding conditions. On the other hand, experimental results indicated a clear effect of welding current variation on dilution values, with 4.6% for condition 1 and 16.7% for condition 2, allowing for direct proportional relationships to be established, i.e., higher deposition current results in greater dilution. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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14 pages, 4160 KiB

Open AccessArticle

Selective CO₂ Detection at Room Temperature with Polyaniline/SnO₂ Nanowire Composites

by Gen Li, Muhammad Hilal, Hyojung Kim, Jiyeon Lee, Zhiyong Chen, Bin Li, Yunhao Cui, Jian Hou and Zhicheng Cai

Coatings 2024, 14(12), 1590; https://doi.org/10.3390/coatings14121590 - 19 Dec 2024

Abstract

In this study, tin oxide (SnO₂)/polyaniline (PANI) composite nanowires (NWs) with varying amounts of PANI were synthesized for carbon dioxide (CO₂) gas sensing at room temperature (RT, 25 °C). SnO₂ NWs were fabricated via the vapor–liquid–solid (VLS) method, [...] Read more.

In this study, tin oxide (SnO₂)/polyaniline (PANI) composite nanowires (NWs) with varying amounts of PANI were synthesized for carbon dioxide (CO₂) gas sensing at room temperature (RT, 25 °C). SnO₂ NWs were fabricated via the vapor–liquid–solid (VLS) method, followed by coating with PANI. CO₂ sensing investigations revealed that the sensor with 186 μL PANI exhibited the highest response to CO₂ at RT. Additionally, the optimized sensor demonstrated excellent selectivity for CO₂, long-term stability, and reliable performance across different humidity levels. The enhanced sensing performance of the optimized sensor was attributed to the formation of SnO₂-PANI heterojunctions and the optimal PANI concentration. This study underscores the potential of SnO₂-PANI composites for CO₂ detection at RT. Full article

(This article belongs to the Special Issue Advanced Nanomaterials and Coating Technologies for High-Performance Electronic, Optoelectronic, Energy, and Sensing Devices)

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17 pages, 10949 KiB

Open AccessArticle

Rheological Performance and UV Aging Resistance of Buton Rock Asphalt and Styrene-Butadiene-Styrene Composite Modified Asphalt Under High Temperature

by Lian Li, Chunxiang Huang, Xu Zeng, Jinfeng Yang, Wei Gao, Yaping Chen and Haibo Yang

Coatings 2024, 14(12), 1589; https://doi.org/10.3390/coatings14121589 - 19 Dec 2024

Abstract

This study aims to investigate the high-temperature rheological properties and ultraviolet (UV) aging resistance of Buton rock asphalt (BRA) and styrene-butadiene-styrene (SBS) composite modified asphalt. Initially, the surface morphology of BRA and SBS was examined using scanning electron microscopy. The high-temperature rheological properties [...] Read more.

This study aims to investigate the high-temperature rheological properties and ultraviolet (UV) aging resistance of Buton rock asphalt (BRA) and styrene-butadiene-styrene (SBS) composite modified asphalt. Initially, the surface morphology of BRA and SBS was examined using scanning electron microscopy. The high-temperature rheological properties and chemical characteristics of BRA modified asphalt, SBS modified asphalt, and BRA/SBS composite modified asphalt before and after UV aging were investigated. The results reveal that numerous pores and folds on the surface of BRA form a distinctive honeycomb-like structure that offers a large surface area, enhancing asphalt adsorption and thereby improving the high-temperature properties of asphalt. The addition of SBS enhances the elastic response of Buton rock asphalt modified asphalt (BRAMA). The Fourier transform infrared (FTIR) spectra indicate that BRA effectively reduces the carbonyl and sulfoxide index of asphalt, and the complex modulus aging index (CMAI) and phase angle aging index (PAI) suggest that the BRA/SBS composite modified asphalt exhibits better resistance to ultraviolet aging. Full article

(This article belongs to the Special Issue Surface Engineering and Mechanical Properties of Building Materials)

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21 pages, 2329 KiB

Open AccessReview

Black Nickel Coatings: From Plating Techniques to Applications

by Ewa Rudnik

Coatings 2024, 14(12), 1588; https://doi.org/10.3390/coatings14121588 - 19 Dec 2024

Abstract

Black nickel coatings are pursued for both decorative purposes and advanced applications, including solar collectors, space technologies, and optical devices. The term “black nickel” typically refers not only to nickel but also to nickel alloys that can exhibit the characteristic black coloration, either [...] Read more.

Black nickel coatings are pursued for both decorative purposes and advanced applications, including solar collectors, space technologies, and optical devices. The term “black nickel” typically refers not only to nickel but also to nickel alloys that can exhibit the characteristic black coloration, either bright or matte. This review provides an in-depth look at various techniques for producing black nickel coatings, focusing on both electrodeposition and electroless deposition methods. The discussion covers the different bath compositions and deposition conditions used to achieve the distinctive black color. The origins of black coloration in electrodeposited nickel and its alloys are shown in detail, emphasizing the crucial role of bath components and the formation of black compounds such as oxides, sulfides, and/or the nickel–zinc intermetallic compound. This review also highlights the necessity of oxidizing acid etching to blacken Ni–P electroless deposits, leading to the formation of a thin layer of black nickel oxides on a porous surface. The key properties of black nickel coatings are discussed, along with their relevance for various practical applications. Full article

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18 pages, 9573 KiB

Open AccessArticle

A Degradation Model of Electrical Contact Performance for Copper Alloy Contacts with Tin Coatings Under Power Current-Carrying Fretting Conditions

by Yuan Meng, Wanbin Ren and Chao Zhang

Coatings 2024, 14(12), 1587; https://doi.org/10.3390/coatings14121587 - 18 Dec 2024

Abstract

The fretting degradation of coating materials is complicated when the Joule heating effect of the load current is non-negligible. In this work, the fretting degradation behavior of tin-coated copper alloy contacts was examined across the current range from 5 A to 30 A [...] Read more.

The fretting degradation of coating materials is complicated when the Joule heating effect of the load current is non-negligible. In this work, the fretting degradation behavior of tin-coated copper alloy contacts was examined across the current range from 5 A to 30 A and the fretting amplitude range from 200 μm to 400 μm. The uniform degradation process and associated mechanisms, including the wear-dominated stage, softening-dominated stage, and oxidation-dominated stage were recognized and interpreted explicitly. An innovative fusion model for the degradation of electrical contact performance, data-driven and based on physics mechanism, was proposed. The contact voltage was selected as the characterization variable and pre-processed by the threshold-crossing filter method and the Levenberg–Marquardt algorithm. The optimal degradation model, considering the coupled effects of current and fretting amplitude, was presented with the use of the support vector regression method. Finally, the prediction accuracy of the model was validated by experiment results. Full article

(This article belongs to the Special Issue Tribological Behavior and Mechanical Performance of Coatings and Materials)

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22 pages, 493 KiB

Open AccessArticle

Optimization of Weight Reduction in Power Transmission Systems Using Bio-Inspired Algorithms and Composite Materials

by Miguel Angel Rodriguez-Cabal, Vanessa Botero-Gómez and Daniel Sanin-Villa

Coatings 2024, 14(12), 1586; https://doi.org/10.3390/coatings14121586 - 18 Dec 2024

Abstract

Traditional optimization approaches for power transmission systems often optimize gear and shaft designs separately, rely on conventional materials, and face challenges handling mixed-variable problems involving discrete and continuous variables. These limitations hinder the potential for significant weight reduction and performance improvements in modern [...] Read more.

Traditional optimization approaches for power transmission systems often optimize gear and shaft designs separately, rely on conventional materials, and face challenges handling mixed-variable problems involving discrete and continuous variables. These limitations hinder the potential for significant weight reduction and performance improvements in modern mechanical systems. This research presents an innovative optimization approach for reducing the gear pitch in a power transmission system comprising a shaft with two gears. By employing bio-inspired metaheuristic algorithms and utilizing materials common in additive manufacturing and composite materials, the study aims to minimize system weight while ensuring mechanical integrity. The optimization integrates gear and shaft design variables, accurately models mechanical constraints through penalty functions, and leverages the unique properties of advanced materials to enhance performance. In this work, we developed an integrated optimization model that overcomes the limitations of previous studies by combining advanced materials with bio-inspired algorithms to achieve significant weight reduction in gear systems. This approach effectively addresses the complexities of mixed-variable optimization and mechanical constraints, providing a practical and innovative solution for modern engineering applications. Full article

(This article belongs to the Special Issue Mechanical Automation Design and Intelligent Manufacturing)

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12 pages, 3024 KiB

Open AccessArticle

The Effect of Bone Glue on the Performance of Traditional Painted Furniture Ground Layers

by Yushu Chen, Wangyu Xu, Tong Chen and Jianan Wang

Coatings 2024, 14(12), 1585; https://doi.org/10.3390/coatings14121585 - 18 Dec 2024

Abstract

This research investigates how the inclusion of bone glue affects the performance of traditional painted furniture ground layers, particularly under dry–wet cycling conditions. The ground layers, applied to wood substrates in seven different ratios of bone glue to gypsum powder (10%, 20%, 30%, [...] Read more.

This research investigates how the inclusion of bone glue affects the performance of traditional painted furniture ground layers, particularly under dry–wet cycling conditions. The ground layers, applied to wood substrates in seven different ratios of bone glue to gypsum powder (10%, 20%, 30%, 40%, 50%, and 60%), were tested for mass changes, dimensional stability, adhesion, and surface roughness. The results showed that higher bone glue content (especially 50% and 60%) led to improved stability, reduced mass fluctuations, and better dimensional stability. The 50% bone glue sample exhibited the best overall stability with minimal weight change (<1.6%) and reduced shrinkage. Adhesion strength increased with bone glue content, reaching 3.48 MPa at 60% bone glue. Lower bone glue content resulted in poor adhesion and visible defects such as cracking and blistering. SEM analysis confirmed that higher bone glue content enhanced bonding between the ground layer and the wood substrate. Full article

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15 pages, 6548 KiB

Open AccessArticle

Formation of Coatings Containing Cr₂AlC MAX Phase During Plasma Spraying of Mixture of Cr₃C₂+Al Powders

by Natalia Vigilianska, Carolina Iantsevitch, Tania Tsymbalista, Oleksii Burlachenko, Oleksandr Grishchenko, Oleksandr Gudymenko, Szymon Zawadzki and Cezary Senderowski

Coatings 2024, 14(12), 1584; https://doi.org/10.3390/coatings14121584 - 18 Dec 2024

Abstract

In this article, the structure formation and phase composition of coatings containing Cr₂AlC MAX phase under the conditions of plasma spraying were studied. Mechanical mixtures of commercially available Cr₃C₂ and Al powders were used as a material for [...] Read more.

In this article, the structure formation and phase composition of coatings containing Cr₂AlC MAX phase under the conditions of plasma spraying were studied. Mechanical mixtures of commercially available Cr₃C₂ and Al powders were used as a material for spraying. The amount of aluminium in the mixtures was 9 and 18 wt.%. As a result of studying physicochemical processes occurring during plasma spraying of mechanical mixtures of selected compositions, the formation of coatings containing Cr₂AlC MAX phase was established, the synthesis of which occurs both at the stage of the particles flight of initial components in the plasma jet as a result of the collision and coagulation, and at the stage of a coating layer formation as a result of layering particles deformed during the collision–splats. It is shown that for the formation of a denser coating with a higher MAX phase content for spraying, it is rational to use a mixture of chromium carbide powders with 9 wt.% of aluminium. A coating with the composition 91Cr₃C₂-9Al (wt.%) has high corrosion resistance in operation conditions in a chloride-acetate solution, and by its indicators of corrosion resistance, is not inferior to the Cr₃C₂-NiCr coating, which is widely used in industry to protect parts from corrosion and wear. The obtained results show the possibility and feasibility of using mechanical mixtures of commercially available powders for the formation of coatings containing Cr₂AlC MAX phase instead of expensive synthesized MAX-Cr₂AlC powders. Full article

(This article belongs to the Special Issue Advances in Experimental Testing of Thermal Barrier Coatings)

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12 pages, 7596 KiB

Open AccessArticle

Finite-Difference Time-Domain Simulation of Double-Ridge Superimposed Structures for Optimizing Light-Trapping Characteristics in Ternary Organic Solar Cells

by Xiaoxiang Sun, Jinglin Song, Weijun Tan, Jing Chen, Mingxin Chen, Fen Li, Chang Li and Zhuoliang Yu

Coatings 2024, 14(12), 1583; https://doi.org/10.3390/coatings14121583 - 18 Dec 2024

Abstract

The double-ridge superimposed structures (DRSSs), formed by the superposition of a nano-ridged textured ZnO layer and a ternary organic active layer (PTB7:PC₇₀BM:PC₆₀BM) with self-assembled nano-ridged (SANR) structures, have been preliminarily examined experimentally for its positive effects in light-trapping for [...] Read more.

The double-ridge superimposed structures (DRSSs), formed by the superposition of a nano-ridged textured ZnO layer and a ternary organic active layer (PTB7:PC₇₀BM:PC₆₀BM) with self-assembled nano-ridged (SANR) structures, have been preliminarily examined experimentally for its positive effects in light-trapping for organic solar cells (OSCs). To obtain DRSSs with higher-performance light-trapping effects and enhance the light absorption of OSCs, the present work carried out prior theoretical simulations of the light-trapping characteristics of the DRSS using the finite-difference time-domain (FDTD) algorithm. The results show that the DRSS exhibits a significant light-trapping effect, with an active layer absorption peak around 530 nm due to the light-trapping effect. This helps the active layer capture more high-energy photons, significantly enhancing the photon utilization of the DRSS. Interestingly, the intensity of the light-trapping absorption peak is solely dependent on the height or width of the active layer ridges in the DRSS, while the position of the peak is jointly determined by both the ZnO and active layer ridges. By controlling the aspect ratio (W/H) of the dual ridges, the light-trapping absorption peak position can be fine-tuned, enabling precise light-trapping management for specific wavelength bands. It is certain that the outcomes of this work will provide theoretical foundations and practical guidance for the fabrication of light-trapping OSCs. Full article

(This article belongs to the Special Issue The Preparation and Characterization of Carbon- and Silicon-Based Materials and Their Applications)

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13 pages, 4174 KiB

Open AccessArticle

Spearmint Extract as a Sustainable Corrosion Inhibitor Through Advanced Spray Coating Applications

by Manuela Salazar Iglesias, Maria Valentina Suárez León, Daniel Alejandro Pineda Hernandez, Pedro José Arango Arango, Francy Nelly Jiménez García and Elisabeth Restrepo Parra

Coatings 2024, 14(12), 1582; https://doi.org/10.3390/coatings14121582 - 18 Dec 2024

Abstract

In this research, the high efficacy of Mentha spicata L. extract, commonly known as spearmint, as a corrosion inhibitor with an efficacy rate of 86.98% is highlighted. Analytical techniques, such as scanning electron microscopy (SEM) to obtain a detailed morphological view, Fourier transform [...] Read more.

In this research, the high efficacy of Mentha spicata L. extract, commonly known as spearmint, as a corrosion inhibitor with an efficacy rate of 86.98% is highlighted. Analytical techniques, such as scanning electron microscopy (SEM) to obtain a detailed morphological view, Fourier transform infrared spectroscopy (FTIR) to identify the functional groups of flavonoids, and electrochemical impedance spectroscopy (EIS) and Tafel plots for a corrosion assessment, were employed. This study pioneers a greener alternative to traditional corrosion inhibition methods. The distinctive aspect of this research is the innovative spray coating application method used to deliver the spearmint extract onto structural steel. This method involves the strategic use of an airbrush for spray coating, ensuring the uniform and efficient deposition of the organic inhibitor, thus forming a protective barrier against corrosion. This spray coating technique is emerging as an innovative approach for the industrial application of natural corrosion inhibitors, demonstrating significant advances in the corrosion resistance of coated steel. The results not only corroborate the efficacy of natural inhibitors, but also highlight the critical role that sophisticated application techniques play in improving their industrial viability. This methodological innovation presents a pathway to sustainable practices in corrosion management, prioritizing environmental protection and ecological footprint reduction in the quest for corrosion mitigation. Full article

(This article belongs to the Collection Feature Paper Collection in Corrosion, Wear and Erosion)

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31 pages, 12897 KiB

Open AccessArticle

Poly (Lactic Acid) Fibrous Film with Betalains from Pitaya (Stenocereus thurberi) by Electrospinning for Potential Use as Smart Food Packaging

by Dalila Fernanda Canizales-Rodríguez, Francisco Rodríguez-Félix, José Agustín Tapia-Hernández, Carmen Lizette Del-Toro-Sánchez, Saúl Ruíz-Cruz, Santiago P. Abourg, Victor Manuel Ocaño-Higuera, María Irene Silvas-García, Cielo Estefanía Figueroa-Enríquez and Milagros Guadalupe Álvarez-Moreno

Coatings 2024, 14(12), 1581; https://doi.org/10.3390/coatings14121581 - 18 Dec 2024

Abstract

The incorporation of biopolymers and natural colorants in smart packaging has garnered significant attention in the food packaging industry. This study investigates the design and characterization of novel fibrous films incorporating betalain extract (BE) from Stenocereus thurberi in poly (lactic acid) (PLA). An [...] Read more.

The incorporation of biopolymers and natural colorants in smart packaging has garnered significant attention in the food packaging industry. This study investigates the design and characterization of novel fibrous films incorporating betalain extract (BE) from Stenocereus thurberi in poly (lactic acid) (PLA). An electrospinning technique was developed with varying PLA concentrations (2%–12% w/v) and BE concentrations (8%–12% w/v) to create a colorimetric freshness indicator. BE was characterized by quantifying its phytochemical content and assessing its antioxidant capacity. Morphological and structural analyses included scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), polydispersity index (PI), mechanical properties, and functional characteristics such as ammonia sensitivity and total antioxidant activity. The results indicated that the incorporation of BE significantly influenced the average diameter of the nanofibers, ranging from 313 ± 74 nm to 657 ± 99 nm. SEM micrographs showed that PLA12-BE12 films exhibited smooth surfaces without bead formation. The FTIR analysis confirmed effective BE incorporation, revealing intermolecular interactions between the betalain molecules and the PLA matrix, which contributed to enhanced structural and functional stability. The mechanical properties analysis revealed that moderate BE additions (8%–10% w/v) enhanced the Young’s modulus and tensile strength, while higher BE concentrations (12% w/v) disrupted the polymer network, reducing these properties. Additionally, the strain at break decreased significantly with BE incorporation, reflecting limited molecular chain mobility. Increasing BE concentration notably improved antioxidant activity, with the BE concentration of 12% (w/v), the ABTS•+, DPPH•, and FRAP radical scavenging activities at the highest values of 84.28 ± 1.59%, 29.95 ± 0.34%, and 710.57 ± 28.90 µM ET/g, respectively. Ammonia sensitivity tests demonstrated a significant halochromic transition from reddish-pink to yellow, indicating high sensitivity to low ammonia concentrations. The possible mechanism is alkaline pH induces aldimine bond hydrolysis and generates betalamic acid (yellow) and cyclo-DOPA-5-O-ß-glucoside (colorless) The fibrous films also exhibited reversible color changes and maintained good color stability over 30 days, emphasizing their potential for use in smart packaging applications for real-time freshness monitoring and food quality assessment. Full article

(This article belongs to the Special Issue Novel Advances in Food Contact Materials)

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17 pages, 824 KiB

Open AccessReview

Application Prospect of Multifunctional Hydrogel Coating in Household Field

by Zhangbei Chen and Zhihui Wu

Coatings 2024, 14(12), 1580; https://doi.org/10.3390/coatings14121580 - 17 Dec 2024

Abstract

Hydrogel coatings are regarded as an ideal material for enhancing the health, safety, and environmental friendliness of the home environment, owing to their outstanding antifouling, flame-retardant, anticorrosive, and antibacterial properties. To fully exploit the performance advantages of hydrogel coatings in the domestic realm, [...] Read more.

Hydrogel coatings are regarded as an ideal material for enhancing the health, safety, and environmental friendliness of the home environment, owing to their outstanding antifouling, flame-retardant, anticorrosive, and antibacterial properties. To fully exploit the performance advantages of hydrogel coatings in the domestic realm, this review comprehensively examines their preparation methods, the progress of modification research, and the application status in other fields. It is revealed that hydrogel coatings can not only offer benefits by dint of their inherent flame retardancy and oleophobicity but also encapsulate chemical substances within the porous structure of certain special hydrogel coatings, thereby augmenting their anticorrosive and antibacterial capabilities. Moreover, the favorable interface adhesion between hydrogel coatings and diverse substrates, along with extensive modification research, has furnished novel concepts for applications in the domestic domain, including but not limited to the multifunctional surface modification of soft furniture, kitchen and bathroom furniture, and children’s furniture. The research findings demonstrate that hydrogel coatings hold substantial potential for enhancing the functionality and environmental sustainability of household products. Full article

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15 pages, 7977 KiB

Open AccessArticle

Effect of PLA-Nanochitosan Films on the Shelf-Life Extension of Fresh Rainbow Trout Fillets

by Reza Teimourifard, Ali Khanjari, Afshin Akhondzadeh Basti, Ali Misaghi, Ioannis Konstantinos Karabagias, Fereshteh Ghadami, Fatemeh Gholami, Negin Noori and Ramin Khorrami

Coatings 2024, 14(12), 1579; https://doi.org/10.3390/coatings14121579 - 17 Dec 2024

Abstract

Fish-packaging technology is essential in maintaining the quality and shelf life of fish as a valuable and perishable food. This research was performed to evaluate the influence of polylactic acid-nanochitosan (PLA-NC) films containing Bunium persicum essential oil (BPEO) (0, 0.3, 0.6, and 0.9%) [...] Read more.

Fish-packaging technology is essential in maintaining the quality and shelf life of fish as a valuable and perishable food. This research was performed to evaluate the influence of polylactic acid-nanochitosan (PLA-NC) films containing Bunium persicum essential oil (BPEO) (0, 0.3, 0.6, and 0.9%) on microbial, chemical, and organoleptic characteristics of rainbow trout fillets during storage under refrigeration for 13 days. On the last day of the storage period, in the rainbow trout fillets wrapped with PLA-NC films containing BPEO, the microbial population declined by at least 1 log CFU/g in comparison with control samples. The initial value of the total volatile base nitrogen (TVB-N) of fillets was 10.28 mg/100 g and it reached 31.75 mg/100 g in the control group on day 4, while in rainbow trout fillets wrapped with PLA-NC films and complemented with BPEO, TVB-N contents were below 25 mg/100 g, until the 10th day of storage. Regarding the results of the current study, the peroxide value (PV) on day 0 was 1.7 meq/kg and reached 13.66 meq/kg in the control samples on the 13th day, while this parameter was lower than 10 meq/kg in samples wrapped with PLA-NC films complemented with BPEO on the final day of the study. The findings of this study illustrated that wrapping rainbow trout fillets in PLA-nanochitosan films complemented with BPEO prolonged the shelf life of rainbow trout fillets without any undesirable organoleptic attributes during storage under refrigeration for 10 days. The topography and surface composition of the prepared films was further confirmed using scanning electron microscope (SEM) and field scanning electron microscope (FESEM) analyses. Full article

(This article belongs to the Special Issue Bio-Based and Biodegradable Packaging Materials for Food Contact)

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32 pages, 15051 KiB

Open AccessArticle

Buckling Resistance and Its Effect on the Gas Barrier of Composite Coating Layers Based on Polyvinyl Alcohol and Montmorillonite

by Nur Hanani Zainal Abedin, Stefan Schiessl and Horst-Christian Langowski

Coatings 2024, 14(12), 1578; https://doi.org/10.3390/coatings14121578 - 17 Dec 2024

Abstract

In addition to the mechanical properties and barrier performance, one of the key properties of flexible films used in food packaging is the resistance of their gas barrier layer to buckling and bending. Testing the gas barrier before and after mechanical stress is [...] Read more.

In addition to the mechanical properties and barrier performance, one of the key properties of flexible films used in food packaging is the resistance of their gas barrier layer to buckling and bending. Testing the gas barrier before and after mechanical stress is time-consuming and resource-intensive, but important to assure a certain gas barrier during the whole life time of the package until food consumption. The aim of this study was, on the one hand, to identify the most significant influencing factors of a composite lacquer formulation and coating on its buckling resistance and, on the other hand, to show a fast and efficient method to identify defects occurring during buckling. The influence of mechanical stress was simulated via Gelbo-Flex treatment, and the samples were examined and evaluated before and after using light microscopy. The evaluation was verified with scanning electron microscopy (SEM) and helium barrier measurement. Polyethylene terephthalate (PET) and polyethylene (PE) films were coated with composite barrier lacquers made of polyvinyl alcohol (PVA) and montmorillonite (MMT) and the wet coating layer thickness (20, 40, 80, and 130 μm) and the composition of the coating were changed. It was found that thin coatings are more resistant to buckling than thick coatings. It was also shown that a higher proportion of MMT in the coating layer leads to a better gas barrier, but poorer buckling resistance. Additionally, it was found that soft PE films are already subjected to high stresses during the coating process, which means that barrier coatings do not build up ideally. However, the barrier-coated soft film withstood mechanical stress better and lost less barrier by a lower factor than the counterpart on the basis of PET. To conclude, the evaluation of the buckling resistance with microscopy offers an efficient method during lacquer development; however, the final decision on the right lacquer composition is dependent on many factors. Full article

(This article belongs to the Section Coatings for Food Technology and System)

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22 pages, 6409 KiB

Open AccessArticle

The Study on the Freeze–Thaw Deterioration of Soil Sites Modified with the ZDS-2 Organosilicon Reinforcement Agent

by Xiaowen Zheng, Qingwen Ma, Haitao Yan, Xiang Chang and Fang Guo

Coatings 2024, 14(12), 1577; https://doi.org/10.3390/coatings14121577 - 17 Dec 2024

Abstract

Due to the large temperature fluctuations between day and night during the transition from winter to spring, soil sites in seasonally frozen soil areas go through repeated freeze–thaw cycles. During these cycles, the water in the soil undergoes phase transformation and migration, which [...] Read more.

Due to the large temperature fluctuations between day and night during the transition from winter to spring, soil sites in seasonally frozen soil areas go through repeated freeze–thaw cycles. During these cycles, the water in the soil undergoes phase transformation and migration, which changes the physical and mechanical properties of the soil and directly affects the stability and durability of the soil site. In order to explore the feasibility of using the ZDS-2 organosilicon reinforcement agent for the anti-freeze-and-thaw protection of soil sites, Qingtai site soil and the ZDS-2 organosilicon reinforcement agent were used as raw materials. The optimal ratio of modified soil samples with different freeze–thaw cycles was obtained by laboratory tests. The strengthening mechanism of the ZDS-2 organosilicon reinforcement agent under freeze–thaw cycles was revealed by a microscopic test. The test results showed that the ZDS-2 organosilicon reinforcement agent can inhibit the volume expansion of soil samples caused by the freeze–thaw cycle. After nine freeze–thaw cycles, the shear strength of the soil samples, to which 15% ZDS-2 organosilicon reinforcement agent was added, increased by 53.4% on average compared with plain soil. The highly cross-linked organic–inorganic hybrid network structure formed between the siloxane group in the ZDS-2 organosilicon reinforcement agent and the soil particles can fill the pores and form a protective layer. The experimental results provided a basis and reference for the research of freeze–thaw-resistant materials for soil sites in seasonally frozen soil areas. Full article

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14 pages, 10037 KiB

Open AccessArticle

Exploring the Impact of Surface Thermal Treatments on WC-Co Blocks Subjected to Linear Scratching: A Molecular Dynamics Simulation Study

by Duck Hyun Wang, Sehan Lee and Taeil Yi

Coatings 2024, 14(12), 1576; https://doi.org/10.3390/coatings14121576 - 17 Dec 2024

Abstract

High-energy thermal treatments, such as electron beam irradiation, are crucial for enhancing the performance of tungsten carbide–cobalt (WC-Co) composites in cutting tools and wear-resistant coatings. This study utilizes molecular dynamics simulations to analyze the nanoscale effects of such treatments on WC-Co surfaces, focusing [...] Read more.

High-energy thermal treatments, such as electron beam irradiation, are crucial for enhancing the performance of tungsten carbide–cobalt (WC-Co) composites in cutting tools and wear-resistant coatings. This study utilizes molecular dynamics simulations to analyze the nanoscale effects of such treatments on WC-Co surfaces, focusing on cobalt evaporation and linear scratching phenomena. The results demonstrate that electron beam irradiation significantly accelerates cobalt evaporation, with rates depending on energy flux and local atomic environments. Embedded cobalt atoms within WC grains exhibit higher resistance to evaporation due to stronger bonding, while pure cobalt surfaces show greater susceptibility to material loss. Under high energy flux, WC-Co surfaces experience an interplay of thermal expansion, density reduction, and evaporation, resulting in accelerated degradation. Linear scratching simulations reveal that thermally treated WC-Co surfaces exhibit increased structural instability, as indicated by broader distributions of local entropy and von Mises stress, reflecting heightened susceptibility to deformation and failure. Stress concentrations from indentation and scratching are more pronounced in thermally treated samples, highlighting the influence of thermal history on mechanical behavior. Molecular dynamics simulations enable detailed insights into atomic-scale phenomena, allowing precise quantification of the effects of energy flux, material composition, and thermal treatment on structural and mechanical responses. These findings emphasize the need to optimize thermal treatment protocols to enhance the durability and performance of WC-Co composites, providing valuable guidance for the development of robust materials for industrial applications. Full article

(This article belongs to the Collection Feature Paper Collection in Surface Characterization, Deposition and Modification)

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