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Coatings, Volume 12, Issue 12 (December 2022) – 201 articles

Cover Story (view full-size image):

Ice protection systems based on heating elements are common in structures exposed to icing weather, such as wind turbines or airplanes. Although the basis of their operation is well known, they are often neglected in the design stages of those devices, especially when integrated in a multilayered system with several other functions, causing huge efficiency losses or unsatisfactory performances.

The difficulty of assessing the amount of energy needed to homogeneously heat the surface of a structure, through multiple materials and under real operating conditions (especially in the case of an aircraft), shows the need for models and simulated environment tests as tools to develop and optimize those devices. View this paper

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13 pages, 4004 KiB  
Article
Effects of Copper Content on the Microstructural, Mechanical and Tribological Properties of TiAlSiN–Cu Superhard Nanocomposite Coatings
by Sung-Bo Heo, Wang Ryeol Kim, Jun-Ho Kim, Su-Hyeon Choe, Daeil Kim, Jae-Hun Lim and In-Wook Park
Coatings 2022, 12(12), 1995; https://doi.org/10.3390/coatings12121995 - 19 Dec 2022
Cited by 3 | Viewed by 1686
Abstract
The effects of the Cu content on the microstructural, mechanical and tribological properties of the TiAlSiN–Cu coatings were investigated in an effort to improve the wear resistance with a good fracture toughness for cutting tool applications. A functionally graded TiAlSiN–Cu coating with various [...] Read more.
The effects of the Cu content on the microstructural, mechanical and tribological properties of the TiAlSiN–Cu coatings were investigated in an effort to improve the wear resistance with a good fracture toughness for cutting tool applications. A functionally graded TiAlSiN–Cu coating with various copper (Cu) contents was fabricated by a filtered cathodic arc ion plating technique using four different (Ti, TiAl2, Ti4Si, and Ti4Cu) targets in an argon-nitrogen atmosphere. The results showed that the TiAlSiN–Cu coatings are a nanocomposite consisting of (Ti,Al)N nano-crystallites (~5 to 7 nm) embedded in an amorphous matrix, which is a mixture of TiOx, AlOx, SiOx, SiNx, and CuOx phase. The addition of Cu atoms into the TiAlSiN coatings led to the formation of an amorphous copper oxide (CuOx) phase in the coatings. The maximum nanohardness (H) of ~46 GPa, H/E ratio of ~0.102, and adhesion bonding strength between coating and substrate of ~60 N (LC2) were obtained at a Cu content ranging from 1.02 to 2.92 at.% in the TiAlSiN–Cu coatings. The coating with the lowest friction coefficient and best wear resistance was also obtained at a Cu content of 2.92 at.%. The formation of the amorphous CuOx phase during coating growth or sliding test played a key role as a smooth solid-lubricant layer, and reduced the average friction coefficient (~0.46) and wear rate (~10 × 10−6 mm3/N·m). Full article
(This article belongs to the Special Issue Multifunctional Coatings and Lubrication)
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1 pages, 140 KiB  
Editorial
Recent Progress in Surface and Interface Properties of Nanostructures
by Aleksandr S. Lenshin and Vladimir M. Kashkarov
Coatings 2022, 12(12), 1994; https://doi.org/10.3390/coatings12121994 - 19 Dec 2022
Viewed by 904
Abstract
The surface of any solid-state object is characterized by enhanced surface energy as compared with the volume of a part of the bulk object [...] Full article
(This article belongs to the Special Issue Recent Progress in Surface and Interface Properties of Nanostructures)
12 pages, 5196 KiB  
Article
Effect of Mo and C Additions on Eta Phase Evolution of WC-13Co Cemented Carbides
by Xun Li, Xianwei Zhang, Junfei Zhang, Qiang Zhang, Vincent Ji and Jinlong Liu
Coatings 2022, 12(12), 1993; https://doi.org/10.3390/coatings12121993 - 19 Dec 2022
Cited by 4 | Viewed by 1774
Abstract
The WC-13Co (wt.%) cemented carbide was prepared by simple pressureless sintering, and the influence of Mo and C additions on the eta evolution and mechanical properties was analyzed by XRD, SEM, EDS, XPS, and Vickers hardness tester. The results show that the addition [...] Read more.
The WC-13Co (wt.%) cemented carbide was prepared by simple pressureless sintering, and the influence of Mo and C additions on the eta evolution and mechanical properties was analyzed by XRD, SEM, EDS, XPS, and Vickers hardness tester. The results show that the addition of Mo has an important influence on the composition, size, and distribution of the eta phase and Mo2C phase. When the Mo content increases from 0 to 2.5%, the Mo-enriched eta phase grows abnormally and the area fraction of the eta phase significantly increases to 40%, leading to an obvious increase in hardness from 1232 HV30 to 1321 HV30, and a decrease in fracture toughness from 12.5 MPa·m1/2 to 9.8 MPa·m1/2. The addition of carbon black effectively inhibits the formation of the eta phase in the samples with 2.5% Mo. Moreover, adding Mo can suppress WC coarsening in a high-carbon content, which is different from the obvious growth of WC grains in a high-carbon environment in traditional research. Finally, the mechanism of eta phase evolution during the sintering process of WC-Co cemented carbides containing Mo is discussed systematically. Full article
(This article belongs to the Special Issue Ceramic Films and Coatings: Properties and Applications)
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9 pages, 2391 KiB  
Article
Influence of Annealing on the Microstructure and Mechanical Properties of Ni-W/Boron Composite Coatings
by Malay Kumar Das, Waralee Pinitpuwadol, Kohpong Wonlopsiri, Panyawat Wangyao and Jiaqian Qin
Coatings 2022, 12(12), 1992; https://doi.org/10.3390/coatings12121992 - 19 Dec 2022
Cited by 1 | Viewed by 1147
Abstract
Ni-W/boron composite coatings are deposited from an ammonia citrate bath with a boron particle suspension. The effect of the boron incorporation into the Ni-W alloy coating and subsequent heat treatment of the deposits on the microstructure and properties of the Ni-W/boron coatings have [...] Read more.
Ni-W/boron composite coatings are deposited from an ammonia citrate bath with a boron particle suspension. The effect of the boron incorporation into the Ni-W alloy coating and subsequent heat treatment of the deposits on the microstructure and properties of the Ni-W/boron coatings have been investigated. The boron particles can be uniformly dispersed in the Ni-W alloy, which can lead to an enhancement in the wear performance and hardness of the coatings. The XRD results show that a new Ni4W phase can be formed, especially at heat treatment temperatures beyond 400 °C. The grain size of the deposits is smaller than 10 nm with heat treatment temperatures lower than 600 °C and increases with the heat treatment temperature increasing. The higher temperature will significantly cause the grain coarsening (25.8 nm at 700 °C). Furthermore, the hardness and wear resistance increase with the formation of the Ni4W phase and the inverse Hall–Petch relationship at the lower heat treatment temperatures (<600 °C). While the grain coarsening causes the hardness of the deposits to decrease at the temperature of 700 °C. Full article
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16 pages, 4404 KiB  
Article
Numerical Modelling on the Effect of Temperature on MOCVD Growth of ZnO Using Diethylzinc and Tertiarybutanol
by Yiyi Wu, Rui Wu, Xiaosong Zhou, Hongli Wang, Yang Hu, Dengpan Nie and Dongmei Bao
Coatings 2022, 12(12), 1991; https://doi.org/10.3390/coatings12121991 - 19 Dec 2022
Cited by 3 | Viewed by 1233
Abstract
The dynamic growth of MOCVD-grown ZnO thin films under temperature effect was systematically investigated by a numerical approach using computational fluid dynamics (CFD) technique. A three-dimensional (3D) reactor-scale model was developed to determine the growth rate and uniformity of ZnO thin film in [...] Read more.
The dynamic growth of MOCVD-grown ZnO thin films under temperature effect was systematically investigated by a numerical approach using computational fluid dynamics (CFD) technique. A three-dimensional (3D) reactor-scale model was developed to determine the growth rate and uniformity of ZnO thin film in the temperature range of 593 K to 713 K. The mixed-convection flow and heat transfer inside the reactor chamber were assessed. The results showed that as the temperature increased, ZnO thickness increased initially before decreasing. At 673 K, the highest deposition rate with acceptable uniformity was achieved. The admixture of transverse and longitudinal rolls was observed for the flow conditions. Temperature variations were found to directly affect the axial and lateral uniformity of deposition, but had a minor impact on the size and position of transverse rolls. Experimental verification studies were conducted, and high-quality ZnO films were successfully fabricated by using diethylzinc (DEZn) and tertiarybutanol (t-BuOH) as precursors; it was found that the comprehensive thickness and structural properties of ZnO deposited at temperature of 673 K are preferred. Experimental results and numerical simulations exhibited good agreement. Full article
(This article belongs to the Section Thin Films)
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17 pages, 4157 KiB  
Article
Phase Field Modeling of Air Entrapment in Binary Droplet Impact with Solidification Microstructure Formation
by Mingguang Shen and Ben Q. Li
Coatings 2022, 12(12), 1990; https://doi.org/10.3390/coatings12121990 - 19 Dec 2022
Cited by 1 | Viewed by 1635
Abstract
A novel numerical model was developed to investigate air entrapment in binary droplet impact with solidification microstructure formation under practical plasma spraying conditions. The evolving liquid–gas interface was tracked by the explicit finite difference solution to the Cahn–Hilliard equation, coupled with the Navier–Stokes [...] Read more.
A novel numerical model was developed to investigate air entrapment in binary droplet impact with solidification microstructure formation under practical plasma spraying conditions. The evolving liquid–gas interface was tracked by the explicit finite difference solution to the Cahn–Hilliard equation, coupled with the Navier–Stokes equations. Another diffuse interface model was invoked to trace solid–liquid and grain–grain boundaries. The model was discretized using an explicit finite difference method on a half-staggered grid. The velocity pressure coupling was decoupled with the projection method. The in-house code was written in Fortran and was run with the aid of the shared memory parallelism, OpenMP. The time duration over which gas compressibility matters was estimated. Typical cases with air entrapment were studied with the model. The effect of droplet porosity on air entrapment was probed into as well: the larger the porosity of a droplet, the bigger the trapped air bubble. The grain growth near the air bubble is skewed. Moreover, a case without air entrapment was also shown herein to stress that air bubbles could be suppressed or even eliminated in plasma spraying by adjusting the landing positions of successive droplets. Full article
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25 pages, 9226 KiB  
Review
Nanomaterial-Based Sensors for Exhaled Breath Analysis: A Review
by Mohan Velumani, Asokan Prasanth, Subramaniyam Narasimman, Arunkumar Chandrasekhar, Abraham Sampson, Samir Ranjan Meher, Sivacoumar Rajalingam, Elizabeth Rufus and Zachariah C. Alex
Coatings 2022, 12(12), 1989; https://doi.org/10.3390/coatings12121989 - 19 Dec 2022
Cited by 11 | Viewed by 3001
Abstract
The quantification of gases in breath has gained significant attention as a modern diagnosis method due to its non-invasive nature, and as a painless and straightforward method for the early detection of physiological disorders. Several notable clinical applications have been established for disease [...] Read more.
The quantification of gases in breath has gained significant attention as a modern diagnosis method due to its non-invasive nature, and as a painless and straightforward method for the early detection of physiological disorders. Several notable clinical applications have been established for disease diagnosis by correlating exhaled breath samples and specific diseases. In addition, diverse breath molecules represent a biomarker of specific illnesses and are precisely identified by the standard analytical method. However, because of the bulky equipment size, expensive cost, and complexity in measurement when using analytical methods, many researchers are focusing on developing highly selective, sensitive, stable, robust, and economical sensors for breath analysis. It is essential to optimize approaches such as breath sampling, biomarker sensing, data analysis, etc. However, the detection of ppb-level biomarkers in exhaled breath is too challenging to solve due to the abundance of interfering gases. We present a brief and comprehensive review of a recent diagnostic technique that employs nanomaterial (NM)-based sensors to identify the volatile organic compounds (VOCs) associated to diseases. Because they are easily fabricated, chemically versatile, and can be integrated with existing sensing platforms, NMs are ideal for such sensors. Initially, this review provides crucial details about certain representative biomarkers found in diseased patients’ exhaled breath and the demand for breath sensors. Subsequently, the review highlights diverse sensor technologies such as electrical, optical, and mass-sensitive gas sensors and describes their sensing capability for detecting the biomarkers’ concentrations and their primary endeavor of diagnosing disease. Finally, the pitfalls and challenges of sensor characteristics are discussed. This article lays the basis for developing high-performance gas sensors based on novel NMs. Full article
(This article belongs to the Section Thin Films)
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12 pages, 2522 KiB  
Article
An In Vitro Study of the Antifungal Efficacy of Zinc Oxide Nanoparticles against Saccharomyces cerevisiae
by Eng Pei Tan, Sinouvassane Djearamane, Ling Shing Wong, Ranjithkumar Rajamani, Anto Cordelia Tanislaus Antony, Suresh Kumar Subbaih, Ashok Kumar Janakiraman, Mohammod Aminuzzaman, Vetriselvan Subramaniyan, Mahendran Sekar and Siddharthan Selvaraj
Coatings 2022, 12(12), 1988; https://doi.org/10.3390/coatings12121988 - 19 Dec 2022
Cited by 4 | Viewed by 2102
Abstract
Zinc oxide nanoparticles (ZnO NPs) are widely used in biomedical applications due to their antimicrobial and antioxidant properties. The objective of the present study was to determine the antifungal activity of ZnO NPs against the yeast Saccharomyces cerevisiae. The turbidity test results [...] Read more.
Zinc oxide nanoparticles (ZnO NPs) are widely used in biomedical applications due to their antimicrobial and antioxidant properties. The objective of the present study was to determine the antifungal activity of ZnO NPs against the yeast Saccharomyces cerevisiae. The turbidity test results showed a significant (p < 0.05) dose-dependent growth inhibitory effect of ZnO NPs on S. cerevisiae as the growth inhibition increased from 7.04 ± 0.64 to 70.30 ± 3.19% as the concentration of ZnO NPs increased from 5 to 150 μg/mL. The scanning microscopy images evidenced the morphological alterations such as regional invagination, pitting, cracks, wrinkles, and cell wall rupture in the yeast cells treated with ZnO NPs. In addition, the FTIR spectrum revealed the possible involvement of hydroxyl, alkene, amides, carbonyl, and phosphate groups from polysaccharides, polypeptides, phospholipids, and ergosterol of the yeast cells wall for binding of ZnO NPs on the cell surface. The present study has demonstrated the antifungal activity of ZnO NPs on S. cerevisiae through growth inhibition and the morphological damages resulting from the treatment of ZnO NPs. Full article
(This article belongs to the Special Issue Nanoparticles for Energy, Sensing and Biomedical Applications)
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3 pages, 183 KiB  
Editorial
Special Issue: Multi-Functional Nanostructured Sustainable Coatings
by Kamal Kumar, Arihan Jain and Arshad Noor Siddiquee
Coatings 2022, 12(12), 1987; https://doi.org/10.3390/coatings12121987 - 18 Dec 2022
Viewed by 1055
Abstract
The applications of surface coatings have been extensively explored in various technological fields, including the aeronautic and transport, tool and die, chemical and petroleum, nuclear, electronics, and biomedical industries [...] Full article
(This article belongs to the Special Issue Multi-Functional Nanostructured Sustainable Coatings)
4 pages, 189 KiB  
Editorial
Advanced Cold-Spraying Technology
by Wen Sun, Adrian Wei-Yee Tan, Xin Chu and Jian Huang
Coatings 2022, 12(12), 1986; https://doi.org/10.3390/coatings12121986 - 18 Dec 2022
Cited by 1 | Viewed by 1336
Abstract
Cold-spraying technology is a solid-state, powder-based coating deposition and additive manufacturing (AM) technology, which utilises a high-pressure gas stream to accelerate micron-sized particles through a de-Laval nozzle for supersonic speed and impact on substrates and to generate dense, high-quality deposits [...] Full article
(This article belongs to the Special Issue Advanced Cold Spraying Technology)
13 pages, 4799 KiB  
Article
Mechanical and Anticorrosive Properties of TiNbTa and TiNbTaZr Films on Ti-6Al-4V Alloy
by Yung-I Chen, Yi-Jyun Chen, Cheng-Yi Lai and Li-Chun Chang
Coatings 2022, 12(12), 1985; https://doi.org/10.3390/coatings12121985 - 18 Dec 2022
Cited by 3 | Viewed by 1454
Abstract
In this study, TiNbTa and TiNbTaZr films were utilized as protective coatings on a Ti-6Al-4V alloy to inhibit corrosive attacks from NaCl aqueous solution and simulated body fluid. The structural and mechanical properties of multicomponent TiNbTa(Zr) films were investigated. The corrosion resistance of [...] Read more.
In this study, TiNbTa and TiNbTaZr films were utilized as protective coatings on a Ti-6Al-4V alloy to inhibit corrosive attacks from NaCl aqueous solution and simulated body fluid. The structural and mechanical properties of multicomponent TiNbTa(Zr) films were investigated. The corrosion resistance of the TiNbTa(Zr)-film-modified Ti-6Al-4V alloy was evaluated using potentiodynamic polarization tests in a NaCl aqueous solution. The results indicate that the TiNbTa(Zr) films with high Ti and Zr contents exhibited inferior corrosive resistance related to the films with high Ta and Nb contents. Moreover, the TiNbTa(Zr)-coated Ti-6Al-4V plates were immersed in Ringer’s solution for eight weeks; this solution was widely used as a simulated body fluid. The formation of surficial oxide layers above the TiNbTa(Zr) films was examined using transmission electron microscopy and X-ray photoelectron spectroscopy, which prevented the elution of Al and V from the Ti-6Al-4V alloy. Ti33Nb19Ta21Zr27, Ti15Nb68Ta8Zr9, and Ti8Nb8Ta79Zr5 films are suggested as preferential candidates for TiNbTa(Zr)/Ti-6Al-4V assemblies applied as biocompatible materials. Full article
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12 pages, 2333 KiB  
Article
The Role of Biochar Nanoparticles Performing as Nanocarriers for Fertilizers on the Growth Promotion of Chinese Cabbage (Brassica rapa (Pekinensis Group))
by Ruiping Yang, Jiamin Shen, Yuhan Zhang, Lin Jiang, Xiaoping Sun, Zhengyang Wang, Boping Tang and Yu Shen
Coatings 2022, 12(12), 1984; https://doi.org/10.3390/coatings12121984 - 18 Dec 2022
Cited by 1 | Viewed by 1947
Abstract
Chinese cabbage (Brassica rapa) belongs to the Pekinensis Group and is grown annually as a salad crop. It is one of the most important food crops in Eastern Asia and the most widely grown vegetable in China, accounting for more one-quarter [...] Read more.
Chinese cabbage (Brassica rapa) belongs to the Pekinensis Group and is grown annually as a salad crop. It is one of the most important food crops in Eastern Asia and the most widely grown vegetable in China, accounting for more one-quarter of the total annual vegetable consumption in northern parts of the country. It is reported that nitrogen (N), phosphorus (P), and potassium (K) fertilizations play important roles in the physio-morphological traits and yields of Chinese cabbage. However, N, P, and K use in agriculture continues to increase. Excessive application of fertilizers has a harmful impact on the environment. Yet how to improve the irrigation effects on Chinese cabbage growth is still limited. In this study, we firstly selected biochar nanoparticles (BNPs) prepared from corn straw, which had been air-dried and heated in a muffle furnace at 350 °C for 120 min, with K (potassium sulfate), N (calcium nitrate tetrahydrate), and P (sodium dihydrogen phosphate dihydrate) fertilizers. Then, a screening experiment (Experiment I) was performed via the response model to find the best solution for Chinese cabbage growth. Treatment with 2 g/kg of N and 2 g/kg of K for 4 weeks was the optimum application to promote Chinese cabbage growth. Then, a comparison experiment (Experiment II) was carried out to test the best formula for Chinese cabbage growth with or without BNPs. After co-irrigation with N and K for 4 weeks, treatment with a combination of 2 g/kg of BNPs, 2 g/kg of N, and 2 g/kg of K was the optimum formula for Chinese cabbage growth. Plant biomass increased by more than 1796.86% and 32.80%, respectively, in two combined treatments of BNPs and fertilizers as compared to the control treatment. After the addition of BNPs, Chinese cabbage height (aboveground) and the dry weight of belowground biomass in the N + K treatment increased to 10.97% and 20.48%, respectively. These results suggest that BNPs have great potential as a nanocarrier for fertilization as they are highly efficient (over 50% increase), reducing fertilizer use while promoting plant growth. The use of BNPs as a nanocarrier for fertilizers represents a step toward more environmentally friendly agriculture. Full article
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7 pages, 2607 KiB  
Article
Buckling Behavior of Few-Layer Graphene on Soft Substrate
by Yancheng Meng, Baowen Li, Luxian Li and Jianqiang Zhang
Coatings 2022, 12(12), 1983; https://doi.org/10.3390/coatings12121983 - 17 Dec 2022
Cited by 1 | Viewed by 1338
Abstract
The buckling behavior of graphene on soft films has been extensively studied. However, to avoid graphene fracture, most studies focus only on the primary buckling behavior induced by tiny compression. Here, the buckling behavior of monolayer, three-layer, and four-layer graphene on soft films [...] Read more.
The buckling behavior of graphene on soft films has been extensively studied. However, to avoid graphene fracture, most studies focus only on the primary buckling behavior induced by tiny compression. Here, the buckling behavior of monolayer, three-layer, and four-layer graphene on soft films is systematically studied in the experiment under large compression. The cross-sections of buckling patterns in these few-layer graphenes are provided, which depend on focused ion beam (FIB) technology. More significantly, the moduli of few-layer graphene are calculated based on the buckling behavior. We demonstrate that the modulus, 1.12621 TPa, is independent of the number of graphene layers if the number is less than four. Our investigations are crucial for the application of two-dimensional (2D) materials into flexible hybrid electronics, bionics, and various other stiff/soft bilayer systems. Full article
(This article belongs to the Special Issue Dielectric and Pyroelectric Films for Electronic Device Applications)
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22 pages, 9513 KiB  
Article
Comparative Surface Quality of Maple (Acer pseudoplatanus) Cut through by CNC Routing and by CO2 Laser at Different Angles as Related to the Wood Grain
by Lidia Gurău, Camelia Coșereanu, Maria Cristina Timar, Antonela Lungu and Cristina Daria Condoroţeanu
Coatings 2022, 12(12), 1982; https://doi.org/10.3390/coatings12121982 - 17 Dec 2022
Cited by 4 | Viewed by 1345
Abstract
The evaluation of surface quality is an important criterion to understand the effect of the cutting angle in relation to the grain and of the processing tool on wood. This paper examines, in a comparison, the surface quality of maple cut through by [...] Read more.
The evaluation of surface quality is an important criterion to understand the effect of the cutting angle in relation to the grain and of the processing tool on wood. This paper examines, in a comparison, the surface quality of maple cut through by CNC and CO2 laser, for different angles with regard to the wood grain: 0°, 15°, 30°, 45°, 60°, 75°, and 90° and at different feed speeds of the CNC router: 2; 2.5; 3; 3.5 and 4 m/min. The direction of processing as related to the grain was a more significant factor in comparison with the feed speed when CNC was used, with best options for 0°, 90° and 75° and worst for 15°, where fuzzy grain was predominant, followed in order by 30°, 45°, and 60°, where pull-out material prevailed. The laser smoothed the core roughness, Rk, with no significant differences as related to the wood grain direction and enhanced an anatomical waviness earlywood-latewood, with the earlywood processed deeper. As the cutting advanced from along to across the grain, the laser uncovered more wood anatomical details and with less destruction. No significant differences in Rk between CNC cutting and laser processing were found for angles: 0°, 60°, and 75°, but surfaces processed at 15°, 30°, and 45° were significantly rougher in the case of CNC cutting. Comparative FTIR investigation of surfaces cut by laser and CNC (at 0° and 90°) clearly revealed temperature-induced chemical changes, such as hemicelluloses degradation, possibly demethylation and advanced condensation in the structure of lignin, in the case of laser processing. Full article
(This article belongs to the Special Issue Wood Coatings: Formulation, Testing and Performance)
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19 pages, 4132 KiB  
Review
Efficient Planar Perovskite Solar Cells with ZnO Electron Transport Layer
by Chufeng Qiu, Yan Wu, Jiaxing Song, Wentao Wang and Zaifang Li
Coatings 2022, 12(12), 1981; https://doi.org/10.3390/coatings12121981 - 17 Dec 2022
Cited by 10 | Viewed by 4845
Abstract
Perovskite solar cells (PSCs) have experienced rapid development in the past period of time, and a record efficiency of up to 25.7% has been yielded. At present, the PSCs with the planar structure are the most prevailing, which not only can significantly simplify [...] Read more.
Perovskite solar cells (PSCs) have experienced rapid development in the past period of time, and a record efficiency of up to 25.7% has been yielded. At present, the PSCs with the planar structure are the most prevailing, which not only can significantly simplify the device fabrication process but also reduce the processing temperature. Particularly, the electron transport layer (ETL) plays a critical role in boosting the device performance of planar PSCs. ZnO is a promising candidate as the ETL owing to its high transparency, suitable energy band structure, and high electron mobility. Moreover, ZnO is easy to be processed at a low cost and low energy. This review mainly summarized the recent advances in the application and strategic optimization of ZnO ETL for planar PSCs. The basic properties of ZnO, including energy levels, mobility, processability, trap defects, as well as chemical stability, are clearly clarified. The most available deposition means for preparing ZnO ETLs were also described briefly. Finally, we presented the challenges and guidelines for utilizing ZnO as ETL on efficient planar PSCs. Full article
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12 pages, 8484 KiB  
Article
Effect of Cr3C2 Content on the Microstructure and Wear Resistance of Fe3Al/Cr3C2 Composites
by Yingkai Feng, Jiguo Shan, Lin Zhao, Zhenbo Liu, Karin Gong and Changhai Li
Coatings 2022, 12(12), 1980; https://doi.org/10.3390/coatings12121980 - 17 Dec 2022
Cited by 3 | Viewed by 1349
Abstract
In this paper, an engine piston ring coating comprising composite material of Fe3Al and Cr3C2 mixed powder was prepared by laser cladding onto carbon structural steel. The microstructure and tribological properties of the cladding materials were investigated through [...] Read more.
In this paper, an engine piston ring coating comprising composite material of Fe3Al and Cr3C2 mixed powder was prepared by laser cladding onto carbon structural steel. The microstructure and tribological properties of the cladding materials were investigated through X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), and wear tests. The influence mechanism of the Cr3C2 content in cladding powder was studied. During the process of wear, the soft Fe3Al/Fe2AlCr matrix is first ground off, and the hard Cr7C3 phase initially supports the abrasive surface before being worn away into hard particles, resulting in abrasive wear. With the increase in Cr3C2 content, the hardness of the cladding layer increases, the proportion of the Cr7C3 phase increases, and the morphology changes from a sparse network to a dense floccule. Of the cladding layers with different Cr3C2 content, the 15 wt.% Cr3C2 cladding layer had the lowest friction coefficient, and the 25 wt.% Cr3C2 cladding layer had the lowest wear rate. The low wear rate of the 25 wt.% Cr3C2 cladding layer can be attributed to the fact that adhesive wear does not easily occur and the fine microstructure of the strengthening phase, which facilitates better separation in the grinding surfaces. Full article
(This article belongs to the Special Issue Laser Cladding Coatings: Microstructure, Properties, and Applications)
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38 pages, 9222 KiB  
Review
High-Temperature Solid Particle Erosion of Aerospace Components: Its Mitigation Using Advanced Nanostructured Coating Technologies
by Venkataramana Bonu and Harish C. Barshilia
Coatings 2022, 12(12), 1979; https://doi.org/10.3390/coatings12121979 - 16 Dec 2022
Cited by 8 | Viewed by 2589
Abstract
Solid particle erosion of gas turbine blades in the aerospace sector results in increased maintenance costs, high pollution, reduced engine efficiency, etc. Gas turbines in aircraft are usually operated at high temperatures. Based on the compressor stage, the temperature varies from 100–600°C, whereas [...] Read more.
Solid particle erosion of gas turbine blades in the aerospace sector results in increased maintenance costs, high pollution, reduced engine efficiency, etc. Gas turbines in aircraft are usually operated at high temperatures. Based on the compressor stage, the temperature varies from 100–600°C, whereas turbine blades, after combustion, experience a very high temperature between 1000–1400 °C. So, a better understanding of temperature-dependent solid particle erosion is required to develop suitable solid particle erosion-resistant coatings for gas turbine blades. In this review, a detailed overview of the effect of temperature on the solid particle erosion process and different types of erosion-resistant coatings developed over the last four decades for compressor blades are discussed in detail. In the initial sections of the paper, solid particle erosion mechanisms, erosion by different erodent media, and the influence of erosion on gas turbine engines are discussed. Then, the erosion rate trend with increasing temperature for ductile and brittle materials, high-temperature erosion tests in a corrosive environment, and the role of oxidation and bonding nature in high-temperature erosion are examined. In most cases, the erosion rate of materials decreased with increasing temperature. After this, the evolution of erosion-resistant coatings over the last four decades that are first-generation (single-phase coatings), second-generation (metal/ceramic multilayer coatings), and third-generation (nanocomposite and nano-multilayer coatings) erosion-resistant coatings are reviewed in detail. The third-generation nano coatings were found to be superior to the first- and second-generation erosion-resistant coatings. Finally, some of the commercial or notable erosion-resistant coatings developed in the last decade are discussed. The paper concluded with the research gaps that need to be addressed to develop efficient erosion-resistant coatings. Full article
(This article belongs to the Special Issue Physical Vapor Deposition II)
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18 pages, 9587 KiB  
Article
Study on Parameter Correlation of Thickness and Performance of Anodizing Film on 6061 Aluminum Alloy Frame in High Energy Laser System
by Kaijie Wang, Yongzhi Cao, Yaowen Cui, Aiying Ye, Shaofan Yi and Zhenjiang Hu
Coatings 2022, 12(12), 1978; https://doi.org/10.3390/coatings12121978 - 16 Dec 2022
Viewed by 1125
Abstract
As stray laser light is difficult to avoid in high-energy laser systems, it is of great significance to improve the laser damage resistance of the aluminum alloy frame anodizing film system. In this paper, the effects of anodic oxidation parameters on the thickness [...] Read more.
As stray laser light is difficult to avoid in high-energy laser systems, it is of great significance to improve the laser damage resistance of the aluminum alloy frame anodizing film system. In this paper, the effects of anodic oxidation parameters on the thickness and performance of 6061 aluminium alloy anodic oxide composite film systems are investigated combining experiments and simulations. The thickness of the oxide film is calculated theoretically, and the simulation model is established. Then the effects of anodizing parameters and the reasons are analyzed. After characterizing the surface quality and laser damage resistance of the oxide film, the influence of anodizing parameters is summarized. This paper enables advance calculations of film thickness within a certain range, combined with the film properties, to provide a reference for the laboratory preparation of 6061 anodizing films and the preparation of structure-specific composite film systems based on the film. Full article
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13 pages, 5841 KiB  
Article
Study of the Tribological Properties of HVOF-Sprayed Ni-Based Coatings on Ti6Al4V Titanium Alloys
by Pengcheng Du, Chang Liu, Hongyun Hu, Chunhui Zhang, Mingzhen Fan, Mingchuan Gao and Tongzhou Chen
Coatings 2022, 12(12), 1977; https://doi.org/10.3390/coatings12121977 - 16 Dec 2022
Cited by 3 | Viewed by 1364
Abstract
In aviation, the relative sliding between titanium alloy components causes varying degrees of wear. This work aimed at reducing abrasion between titanium alloy parts and improving their service life. Three different Ni-based coatings, WC-10Ni, Ni45, and NiCr coatings, are sprayed on the surface [...] Read more.
In aviation, the relative sliding between titanium alloy components causes varying degrees of wear. This work aimed at reducing abrasion between titanium alloy parts and improving their service life. Three different Ni-based coatings, WC-10Ni, Ni45, and NiCr coatings, are sprayed on the surface of Ti6Al4V alloy by HVOF. Test results of the mechanical and tribological properties of such coatings show that the hardness of the Ni45 and NiCr coatings are 673 HV0.1 and 438 HV0.1, respectively, which are lower than that of the WC-10Ni coating. When subjected to a high load, the Ni45 and NiCr coatings suffer a cracking of flat particle interfaces due to the low hardness, which lowers the fracture toughness more than that of the WC-10Ni coating. The specific wear rates of the coatings gradually decrease with the increase in the coating hardness and fracture toughness. However, the cutting of Ti6Al4V by the WC-10Ni coating and the adhesion of the NiCr coating to Ti6Al4V result in severe wear loss of the Ti6Al4V friction pair. The moderately hard Ni45 coating has a weaker cutting and adhesion effect on Ti6Al4V than the WC-10Ni and NiCr coatings, respectively, and the Ti6Al4V friction pair has the lowest wear loss. This study is a viable scheme for the design of wear-resistant coatings on titanium alloy surfaces and for improving the tribological properties between titanium alloy components. Full article
(This article belongs to the Section Corrosion, Wear and Erosion)
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14 pages, 8862 KiB  
Article
Viscoelastic Simulation of Stress and Warpage for Memory Chip 3D-Stacked Package
by Xiyou Wang, Sicheng Cao, Guangsheng Lu and Daoguo Yang
Coatings 2022, 12(12), 1976; https://doi.org/10.3390/coatings12121976 - 16 Dec 2022
Viewed by 1351
Abstract
Three-dimensional-stacked packaging technology is widely used in memory chip packaging, which can greatly increase the utilization ratio of the packaging area. However, problems with the reliability of 3D-stacked packaging are also becoming more and more serious. In this paper, first, a dynamic mechanical [...] Read more.
Three-dimensional-stacked packaging technology is widely used in memory chip packaging, which can greatly increase the utilization ratio of the packaging area. However, problems with the reliability of 3D-stacked packaging are also becoming more and more serious. In this paper, first, a dynamic mechanical analyzer is used to obtain the EMC viscoelasticity parameters. Then, the influence trend of different factors, such as EMC, die bond material and chip, on the performance of the memory chip 3D-stacked packaging under a fixed temperature cyclic loading condition is explored by the FE method. Full article
(This article belongs to the Special Issue Coatings for Advanced Devices)
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19 pages, 6634 KiB  
Article
Synthesis of a Hydroxyl-Containing Corrosion Inhibitor and Its Inhibitory Performance on N80 Steel in Hydrochloric Acid Solution
by Shoumin Sun, Yang Li, Kejing Gao, Li Cheng, Xue Yang and Ruiquan Liao
Coatings 2022, 12(12), 1975; https://doi.org/10.3390/coatings12121975 - 16 Dec 2022
Cited by 1 | Viewed by 1364
Abstract
In the process of petroleum exploitation, in order to effectively inhibit the corrosion damage of acid to metal equipment. Mannich base corrosion inhibitors are generally added to inhibit the corrosion damage of acid. In order to enhance the solubility of Mannich base corrosion [...] Read more.
In the process of petroleum exploitation, in order to effectively inhibit the corrosion damage of acid to metal equipment. Mannich base corrosion inhibitors are generally added to inhibit the corrosion damage of acid. In order to enhance the solubility of Mannich base corrosion inhibitor. This paper intends to introduce hydrophilic groups to enhance the solubility of the Mannich base corrosion inhibitor. In this paper, two efficient corrosion inhibitors 3-(2-hydroxyethylamino)-1-phenylpropan-1-one (MY1) and 3-(2-aminoethylamino)-1-phenylpropan-1-one (MY2), were synthesized based on the Mannich reaction, using formaldehyde, acetophenone and ethanolamine/ethylenediamine as reaction raw materials. The corrosion inhibition performance of the inhibitor on N80 steel in 15% (mass fraction) hydrochloric acid solution was studied by means of the static weight loss method, electrochemical test and optical contact angle analysis. It could be seen from the static weight loss method that the corrosion rate in the hydrochloric acid solution before and after adding 0.7% (mass fraction) corrosion inhibitor concentration decreased from 129.39 g·m−2·h−1 to 1.45 g·m−2·h−1 and 2.79 g·m−2·h−1, respectively. The corrosion inhibition rate could reach 98%, indicating that both inhibitors had good corrosion inhibition performance, and the corrosion inhibition effect of MY1 was better than that of MY2. It was found from the electrochemical tests that the two inhibitors were mixed corrosion inhibitors mainly inhibiting the anodic reaction, and both inhibitors belonged to spontaneous adsorption, and their adsorption behaviors followed the Langmuir adsorption isotherm. In addition, the surface of N80 steel was characterized by SEM, EDS elemental mapping and contact angle measurement. The results show that a dense hydrophobic film is formed on the surface of the steel sheet after the addition of a corrosion inhibitor, which prevents corrosion. Full article
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12 pages, 21232 KiB  
Article
On Variable Scale Evolution of Stress and Strain of TA2 Titanium Plate in Combined Hammering
by Xudong Xiao, Bolun Zhang, Dan Qiao, Yong Li, Renfeng Zhao and Pengkang Zhao
Coatings 2022, 12(12), 1974; https://doi.org/10.3390/coatings12121974 - 16 Dec 2022
Viewed by 889
Abstract
Combined peening composed of multiple peening processes or peening media is a surface treatment method for comprehensive control of the macro shape and performance of the part. Compared to combined peening, the impact kinetic energy of the combined hammering can be easier to [...] Read more.
Combined peening composed of multiple peening processes or peening media is a surface treatment method for comprehensive control of the macro shape and performance of the part. Compared to combined peening, the impact kinetic energy of the combined hammering can be easier to control over a wide range, and the hammer tool head size is larger than the shot. This paper focused on investigating the effect of combined hammering treatment, 6 mm and 14 mm tool heads with peening density 3.7 to 4.2/mm2, on the variable scale evolution of titanium TA2. Three types of contact relation between the tool head and existing dimple were proposed for impacting at the same position. The size of the dimple of combined hammering varies in width or depth direction, resulting in nest morphology composed of different size dimples. The cross-section microstructure of the test plate was observed, and the gradient changes of dislocation, slip, and grain size are smoothed by combined hammering. The change in hammer tool head size makes the target plastic deform at different depths. The hammering sequence has a significant influence on the evolution of stress and strain fields. When the tool head is first large and then small, a large compressive residual stress near the surface is introduced, about 1000 Mpa; on the contrary, the compressive residual stress distributes uniformly in the depth direction, with an affected layer depth of about 4.4 mm. The measured dimple size and residual stress verified the reliability of the simulation results. Full article
(This article belongs to the Special Issue Surface Treatment for Metals and Alloys)
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14 pages, 4935 KiB  
Article
Improvement of 3D Printing Cement-Based Material Process: Parameter Experiment and Analysis
by Zihan Li, Huanbao Liu, Xiang Cheng, Ping Nie, Xianhai Yang, Guangming Zheng, Hongxing Su and Wenyu Jin
Coatings 2022, 12(12), 1973; https://doi.org/10.3390/coatings12121973 - 16 Dec 2022
Viewed by 1504
Abstract
Three-dimensional printing concrete is a digital and automating construction technology, which is expected to solve a series of problems existing in the traditional construction industry, such as low automation, high labor intensity, low efficiency and high risk. However, there are still many technical [...] Read more.
Three-dimensional printing concrete is a digital and automating construction technology, which is expected to solve a series of problems existing in the traditional construction industry, such as low automation, high labor intensity, low efficiency and high risk. However, there are still many technical and operational challenges. The purpose of this paper is to provide insights into the effects of process parameters on the geometry and stability of the printed layer. Firstly, a theoretical model is established to analyze the structure of the printed layer under different nozzle speeds, material flow rates and nozzle offset. Secondly, a slump test is carried out to select the optimal ratio suitable for 3D cement printers, and the specimen is printed under various conditions. Finally, based on the obtained parameters, multiple nozzles are used for printing, and a pressure value suitable for each nozzle in the nonlinear path is calculated. The experimental results show that theoretical model can sufficiently verify printing structure in different parameter intervals, and the process parameters (nozzle speed, material flow rate and nozzle offset) can be changed to achieve the best effect of cement-based material forming structure. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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25 pages, 7115 KiB  
Article
Laser Ablation of Copper Alloy under Varying Environmental Conditions to Achieve Purpose-Built Surface Structures
by Asadullah Dawood, Naveed Ahmed, Shazia Bashir, Asma Hayat, Syed Muhammad Abouzar Sarfraz and Ambreen Ayub
Coatings 2022, 12(12), 1972; https://doi.org/10.3390/coatings12121972 - 15 Dec 2022
Cited by 3 | Viewed by 1784
Abstract
In the manufacturing industry, surface structures and surface topographies present at functional areas of the mechanical parts play a vital role in various performance characteristics, such as corrosion resistance, weldability, and wear behaviors, etc. Copper–zinc alloys are extensively used in the manufacturing industry. [...] Read more.
In the manufacturing industry, surface structures and surface topographies present at functional areas of the mechanical parts play a vital role in various performance characteristics, such as corrosion resistance, weldability, and wear behaviors, etc. Copper–zinc alloys are extensively used in the manufacturing industry. Laser ablation has the potential to create a variety of surface structures on the ablated substrate. The size and geometry of such structures largely depend on the selection of process parameters and the ablation environment. In the present study, a copper–zinc alloy (95% Cu and 5% Zn) has been laser ablated under different gaseous and magnetic environments to realize a variety of micro-structuring at the ablation surfaces. The effect of plasma plume pressure on the geometry of the structures is deeply investigated through optical emission spectroscopy (OES) and scanning electron microscopy (SEM). By analytically evaluating thermal beta (βt), directional beta (βd), and containment radii (Rs) for the plasma of the Cu–Zinc alloy, the validity of magnetic confinement has been proven. In general, five types of microstructures are produced: micro-sized spherical cones, mounted ablated networks, cavities, pores, ridges, and ablation channels with uplifted cones. Moreover, it has been found that, under a magnetic environment, the geometry of the structures is distinct and well-defined compared to those structures achieved when the ablation is carried out without applying a magnetic field. Full article
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16 pages, 5078 KiB  
Article
Experimental and Numerical Investigation of CMT Wire and Arc Additive Manufacturing of 2205 Duplex Stainless Steel
by Yuheng Yuan, Ruifeng Li, Xiaolin Bi, Jiayang Gu and Chen Jiao
Coatings 2022, 12(12), 1971; https://doi.org/10.3390/coatings12121971 - 15 Dec 2022
Cited by 2 | Viewed by 1677
Abstract
In this paper, the mechanical properties, microhardness and metallographic structure of 2205 duplex stainless steel by cold metal transfer (CMT) wire and arc additive manufacturing process are studied. The results show that the ultimate tensile strength, yield strength and elongation at break of [...] Read more.
In this paper, the mechanical properties, microhardness and metallographic structure of 2205 duplex stainless steel by cold metal transfer (CMT) wire and arc additive manufacturing process are studied. The results show that the ultimate tensile strength, yield strength and elongation at break of reciprocating additive along building direction (BD) are 856.73 MPa, 710.5 MPa and 42.35%, respectively. In addition, the same direction motion (SDM) and reciprocating motion (RM) is selected as parameter variables in the experiment, and the finite element model is established by ABAQUS software, and the temperature and residual stress field of the additive forming at different paths are tested and simulated. Firstly, the accuracy of the selected finite element model was verified by comparing the experimental results from the simulation results to the macroscopic morphology of the cross-section of the single-pass additive specimen. The numerical simulation results show that due to the difference of the additive scanning paths, the distribution of the temperature field has a large difference, and with the increase of the deposited layer, the heat accumulation of the SDM additive is larger than that of the RM, so that the end collapses of the SDM additive will occur in the actual additive specimen. By simulating and comparing the equivalent stress distribution of different paths, the equivalent stress distribution of SDM and RM is approximately the same in the vertical direction, and the minimum of equivalent stress appears at the bottom of the deposition layers, about 116.5 MPa, and the maximum of equivalent stress appears at 8 mm from the top, about 348 MPa. Full article
(This article belongs to the Topic Properties of the Corroding Interface)
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15 pages, 2838 KiB  
Article
Geometric Tuning for Enhanced Moisture-Driven Electricity Generation Enabled by Graphene-Oxide Flakes
by Katerina Anagnostou, George Veisakis, Ioannis Kalogerakis, George Viskadouros, Konstantinos Rogdakis and Emmanuel Kymakis
Coatings 2022, 12(12), 1970; https://doi.org/10.3390/coatings12121970 - 15 Dec 2022
Cited by 1 | Viewed by 1614
Abstract
In this work, we formulate water-based graphene oxide (GO) inks to fabricate moisture energy generators (MEGs) while a two-fold geometric tuning is proposed to encourage enhanced performance. Two GO-based structures with distinctly different thicknesses were prepared as the moisture absorbing layer: a GO-pellet [...] Read more.
In this work, we formulate water-based graphene oxide (GO) inks to fabricate moisture energy generators (MEGs) while a two-fold geometric tuning is proposed to encourage enhanced performance. Two GO-based structures with distinctly different thicknesses were prepared as the moisture absorbing layer: a GO-pellet (GOP) and a thinner GO-film (GOF). The effect of electrical contacts’ configuration on the MEG’s output voltage (Vo) was evaluated as a second geometric tunning approach by varying the surface area of the contacts and their orientation with respect to the GO plane, i.e., horizontal or vertical. GOF-based devices that employed a horizontal contacts’ configuration demonstrated champion Vo values (~350 mV) and the fastest response to humidity (3 min required to reach maximum Vo when the relative humidity, or RH, was increased). In GOP devices with horizontal point-like contacts, Vo is inversely related to the contacts’ distance, with a maximum Vo of ~205 mV achieved at a ~1 mm contacts’ distance. GOP-based MEGs with point-like contacts placed vertically to the GO-plane yielded a higher Vo value (~285 mV), while the humidity response time was 15 min. Replacing these contacts with large area electrodes in GOP devices resulted in devices with a slower response to humidity (~30 min) due to a smaller exposed GO surface area. These geometric tuning techniques allowed for the investigation of the optimum device configuration towards efficient moisture-based energy generation with a fast response. Full article
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7 pages, 2054 KiB  
Communication
Self-Standing Soft Carbon-Coated MoS2 Nanofiber Film Anode for Superior Potassium Storage
by Qinglin Deng and Lingmin Yao
Coatings 2022, 12(12), 1969; https://doi.org/10.3390/coatings12121969 - 15 Dec 2022
Cited by 1 | Viewed by 1190
Abstract
The poor electronic conductivity and large volume expansion effect of MoS2 limit its application in potassium-ion batteries (PIBs). In addition to exploring effective modification methods, it is also necessary to build a new self-standing electrode system to improve its energy density. In [...] Read more.
The poor electronic conductivity and large volume expansion effect of MoS2 limit its application in potassium-ion batteries (PIBs). In addition to exploring effective modification methods, it is also necessary to build a new self-standing electrode system to improve its energy density. In this work, based on the potassium storage advantages and disadvantages of MoS2 and carbon nanofibers, we have successfully prepared a self-standing soft carbon-coated MoS2 nanofiber film electrode without any additives or metal collectors. As for the application in PIBs, it exhibits excellent rate performances (about 93 mA h g−1 at the current density of 10 A g−1), and superior long-term cycling stability performances (a high-capacity retention of ~75% after 1800 cycles at the current density of 1 A g−1). The enhanced potassium storage performance can be attributed to the unique self-standing nanofiber film architectures. Full article
(This article belongs to the Special Issue Advanced Materials for Electrocatalysis and Energy Storage)
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13 pages, 2494 KiB  
Article
Does the Nano Character and Type of Nano Silver Coating Affect Its Influence on Calcareous Soil Enzymes Activity?
by Ahmad Bazoobandi, Amir Fotovat, Akram Halajnia and Allan Philippe
Coatings 2022, 12(12), 1968; https://doi.org/10.3390/coatings12121968 - 15 Dec 2022
Viewed by 1035
Abstract
Numerous applications of silver nanoparticles (AgNPs), as well as the toxic effects of these particles on soil organisms and microorganisms, raise the question of how reasonable the entry of these nanoparticles into the environment is. Studying the behavior of these nanoparticles with soil [...] Read more.
Numerous applications of silver nanoparticles (AgNPs), as well as the toxic effects of these particles on soil organisms and microorganisms, raise the question of how reasonable the entry of these nanoparticles into the environment is. Studying the behavior of these nanoparticles with soil organisms and also their effect on soil microorganisms may be the first step to finding out the answer. Structural and form differences in these nanoparticles for use in different conditions can change their behavior. The surface of these nanoparticles is covered with diverse coatings with differing surface charges affecting their fate in soil environments. Naturally, studying this aspect is essential to better understand how these particles impact the environment. In the present study, urease and dehydrogenase enzymes were used as soil health indicators to evaluate the effect of AgNPs and silver nitrate (AgNO3). In order to investigate the effect of surface charge, concentration, and exposure time, three concentration levels (5, 25, 125 mg/kg soil), three different types of charged coatings (citrate (Cit), polyvinylpyrrolidone (PVP) and polyethyleneimine (PEI)) were added to the soil as a treatment and the activities of dehydrogenase (as an indicator of overall microbial activity) and urease (indicator of nitrogen cycle) were measured at three times (1 h, 1 day and 90 days) after soil contamination. The results showed that with increasing the concentration of AgNO3 and AgNPs, the amount of dehydrogenase and urease activity decreased significantly. In the case of urease enzyme, nanoparticles with PEI coating (positive charge) had the greatest effect on reducing activity. In the case of dehydrogenase the opposite was true, and nanoparticles with Cit coating (negative charged) showed a greater inhibitory effect. With increasing incubation time, the amount of enzymatic activity of both types of enzymes showed less decrease, so that the greatest decrease in activity was in the first hour, then in the first day, and finally in 90 days. By comparing silver nitrate and nanoparticles it was found that the effect of AgNPs on enzymatic activity was greater than silver nitrate. Full article
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28 pages, 10443 KiB  
Article
Corrosion, Wear, and Antibacterial Behaviors of Hydroxyapatite/MgO Composite PEO Coatings on AZ31 Mg Alloy by Incorporation of TiO2 Nanoparticles
by Hanane Mozafarnia, Arash Fattah-Alhosseini, Razieh Chaharmahali, Meisam Nouri, Mohsen K. Keshavarz and Mosab Kaseem
Coatings 2022, 12(12), 1967; https://doi.org/10.3390/coatings12121967 - 15 Dec 2022
Cited by 24 | Viewed by 1849
Abstract
Plasma electrolytic oxidation (PEO) is a promising surface treatment for generating a thick, adherent coating on valve metals using an environmentally friendly alkaline electrolyte. In this study, the PEO method was used to modify the surface of AZ31 Mg alloy. The composite coatings [...] Read more.
Plasma electrolytic oxidation (PEO) is a promising surface treatment for generating a thick, adherent coating on valve metals using an environmentally friendly alkaline electrolyte. In this study, the PEO method was used to modify the surface of AZ31 Mg alloy. The composite coatings were formed in a phosphate-based electrolyte containing hydroxyapatite nanoparticles (NPs) and different concentrations (1, 2, 3, and 4 g/L) of TiO2 NPs. The results showed that the incorporation of TiO2 NPs in the composite coatings increased the porosity, coating thickness, surface roughness, and surface wettability of the coatings. The corrosion-resistance results of coatings in simulated body fluid (SBF) were tested for up to 72 h and all coatings showed superior corrosion resistance compared to the bare substrate. Among samples containing TiO2, the sample containing 1 g/L TiO2 had the highest inner layer resistance (0.51 kΩ·cm2) and outer resistance (285 kΩ·cm2) and the lowest average friction coefficient (395.5), so it had the best wear and corrosion resistance performance. The antibacterial tests showed that the higher the concentration of TiO2 NPs, the lower the adhesion of bacteria, resulting in enhanced antibacterial properties against S. aureus. The addition of 4 g/L of TiO2 NPs to the electrolyte provided an antibacterial rate of 97.65% for the coating. Full article
(This article belongs to the Special Issue Advances in Corrosion Resistant Coatings)
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11 pages, 5487 KiB  
Article
Plasma-Induced Graft Polymerization of Polyethylenimine onto Chitosan/Polycaprolactone Composite Membrane for Heavy Metal Pollutants Treatment in Industrial Wastewater
by Sung-Lin Tu, Chih-Kuang Chen, Shih-Chen Shi and Jason Hsiao Chun Yang
Coatings 2022, 12(12), 1966; https://doi.org/10.3390/coatings12121966 - 15 Dec 2022
Cited by 3 | Viewed by 1926
Abstract
The present study manifests an innovative and green approach to graft metal ion adsorbent, polyethylenimine (PEI), onto an electrospun chitosan (CS)/polycaprolactone (PCL) composite membrane via atmospheric pressure nitrogen plasma grafting polymerization. FTIR absorption peak at around 1690 cm−1 was attributed to the [...] Read more.
The present study manifests an innovative and green approach to graft metal ion adsorbent, polyethylenimine (PEI), onto an electrospun chitosan (CS)/polycaprolactone (PCL) composite membrane via atmospheric pressure nitrogen plasma grafting polymerization. FTIR absorption peak at around 1690 cm−1 was attributed to the bending vibration of N-H from PEI. Since the plasma exposure time is a dependent factor of –NH bond formation, an increased nitrogen content up to 3.3% was observed with an extensive reaction time under plasma treatment. In addition, N1s spectra showed a clear PEI dominating characteristic at 401.7 eV, which suggested a successful grafting of PEI onto the CS/PCL membrane. According to the EDX analysis, a significant amount of copper ions was detected in PEI-CS/PCL membranes. This study showed that a greener wastewater treatment can be realized with the developed plasma synthesis technology. Full article
(This article belongs to the Special Issue Plasma Surface Engineering II)
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