Coatings

15 pages, 3415 KiB

Open AccessEditor’s ChoiceArticle

Abrasive and Erosive Wear of TI6Al4V Alloy with Electrospark Deposited Coatings of Multicomponent Hard Alloys Materials Based of WC and TiB₂

by Todor Penyashki, Georgi Kostadinov, Mara Kandeva, Valentin Kamburov, Antonio Nikolov and Rayna Dimitrova

Coatings 2023, 13(1), 215; https://doi.org/10.3390/coatings13010215 - 16 Jan 2023

Cited by 9 | Viewed by 2058

Abstract

In the present work, abrasive and erosive wear of wear-resistant composite coatings with a complex structure and different phase compositions deposited on titanium surfaces was studied. The coatings were obtained by electrospark deposition (ESD) using two types of hard-alloy compositions: WC–TiB₂–B [...] Read more.

In the present work, abrasive and erosive wear of wear-resistant composite coatings with a complex structure and different phase compositions deposited on titanium surfaces was studied. The coatings were obtained by electrospark deposition (ESD) using two types of hard-alloy compositions: WC–TiB₂–B₄C–Co–Ni–Cr–Si–B and TiB₂–TiAl reinforced with dispersed nanoparticles of ZrO₂ and NbC. The influence of the ESD process parameters on the roughness, thickness, composition, structure and coefficient of friction of the coated surfaces was investigated, and their role in protecting the titanium surfaces from wear was clarified. Dense coatings with the presence of newly formed wear-resistant phases and crystalline-amorphous structures were obtained, with roughness, thickness and microhardness that can be varied by the ESD modes in the range Ra = 2.5 ÷ 4.5 µm, δ = 8 ÷ 30 µm and HV 8.5 ÷ 14.0 GPa. The new coatings were found to reduce the abrasive and erosive wear of the coated surfaces by up to four times. The influence of the geometric characteristics, composition and structure of coatings on the wear intensity and wear resistance of coatings was studied. Full article

(This article belongs to the Special Issue Coatings and Surface Modification for Tribological Applications)

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12 pages, 6916 KiB

Open AccessArticle

Multi-Criteria Optimization of Automatic Electro-Spark Deposition TiCrNiVSi_0.1 Multi-Principal Element Alloy Coating on TC4 Alloy

by Yong Lian, Menghui Cui, Aihua Han, Zhao Liu and Jin Zhang

Coatings 2023, 13(1), 214; https://doi.org/10.3390/coatings13010214 - 16 Jan 2023

Cited by 4 | Viewed by 1822

Abstract

In this work, TiCrNiVSi_0.1 coatings were prepared on TC4 alloy by CNC-controlled automatic electro-spark deposition (ESD). The TOPSIS-based Taguchi method was applied for multi-criteria optimization of ESD coating quality. Frequency (f), capacitance (c), and electrode moving speed (v) were considered process parameters [...] Read more.

In this work, TiCrNiVSi_0.1 coatings were prepared on TC4 alloy by CNC-controlled automatic electro-spark deposition (ESD). The TOPSIS-based Taguchi method was applied for multi-criteria optimization of ESD coating quality. Frequency (f), capacitance (c), and electrode moving speed (v) were considered process parameters for optimizing the coating quality criteria, which included coating thickness, coating coverage, and porosity in the coating. The optimized parametric setting of the ESD process (f = 700 Hz, c = 270 μF, v = 150 mm/min) was obtained. MPEA coatings with a thickness of about 70 um, a coverage rate almost reaching 100%, and porosity as low as about 1% were prepared. The wear- and burn-resistance functions of the TiCrNiVSi_0.1 ESD coatings were investigated. The wear rates of the coating at room temperature and 400 °C are one-sixth and one-fourth of the TC4 alloy, respectively. A TiCrNiVSi_0.1 alloy coating was deposited and significantly improved the burn resistance of the TC4 alloy. Full article

(This article belongs to the Section Surface Characterization, Deposition and Modification)

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11 pages, 2297 KiB

Open AccessArticle

Statistical Study of the Effectiveness of Surface Application of Graphene Oxide as a Coating for Concrete Protection

by Andrea Antolín-Rodríguez, Daniel Merino-Maldonado, Álvaro Rodríguez-González, María Fernández-Raga, José Miguel González-Domínguez, Andrés Juan-Valdés and Julia García-González

Coatings 2023, 13(1), 213; https://doi.org/10.3390/coatings13010213 - 16 Jan 2023

Cited by 7 | Viewed by 2179

Abstract

Improving the protection of concrete by applying graphene oxide (GO) as a surface treatment has become the objective of the present study. This study focuses on performing a statistical analysis to study different levels of GO application as an exterior coating, thus observing [...] Read more.

Improving the protection of concrete by applying graphene oxide (GO) as a surface treatment has become the objective of the present study. This study focuses on performing a statistical analysis to study different levels of GO application as an exterior coating, thus observing the effectiveness of the coating and the optimization of the treatment material for concrete protection. Four tests were performed to define concrete durability, such as pressurized water penetration, capillary absorption, freeze-thaw resistance and carbonation resistance. The results showed an increase in concrete durability with any level of GO application on the surface, considering that the optimum amount of application for water impermeability and freeze-thaw resistance is 26.2 µg/cm², since it was possible to reduce pressurized water penetration by 45%, capillary water absorption by 57% and freeze-thaw detachment by 25%. However, the optimum application rate for carbonation resistance is 52.4 µg/cm², reducing carbonation by almost 60%. In conclusion, if the concrete is going to be exposed to less aggressive environments, the application of a mild surface coating of GO is sufficient for its protection, and if the concrete is going to be exposed to more aggressive environments, it is necessary to increase the amount of GO. The performance of GO as a coating significantly increased the degree of protection of the concrete, increasing its service life and proving to be a promising treatment for concrete surface protection. Full article

(This article belongs to the Special Issue Surface Biotreatment of Building Materials)

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25 pages, 2464 KiB

Open AccessReview

Current Progress and Open Challenges for Combined Toxic Effects of Manufactured Nano-Sized Objects (MNO’s) on Soil Biota and Microbial Community

by Bismillah Mubeen, Ammarah Hasnain, Jie Wang, Hanxian Zheng, Syed Atif Hasan Naqvi, Ram Prasad, Ateeq ur Rehman, Muhammad Amir Sohail, Muhammad Zeeshan Hassan, Muhammad Farhan, Muhammad Altaf Khan and Mahmoud Moustafa

Coatings 2023, 13(1), 212; https://doi.org/10.3390/coatings13010212 - 16 Jan 2023

Cited by 7 | Viewed by 3437

Abstract

Soil is a porous matrix containing organic matter and minerals as well as living organisms that vary physically, geographically, and temporally. Plants choose a particular microbiome from a pool of soil microorganisms which helps them grow and stay healthy. Many ecosystem functions in [...] Read more.

Soil is a porous matrix containing organic matter and minerals as well as living organisms that vary physically, geographically, and temporally. Plants choose a particular microbiome from a pool of soil microorganisms which helps them grow and stay healthy. Many ecosystem functions in agrosystems are provided by soil microbes just like the ecosystem of soil, the completion of cyclic activity of vital nutrients like C, N, S, and P is carried out by soil microorganisms. Soil microorganisms affect carbon nanotubes (CNTs), nanoparticles (NPs), and a nanopesticide; these are called manufactured nano-objects (MNOs), that are added to the environment intentionally or reach the soil in the form of contaminants of nanomaterials. It is critical to assess the influence of MNOs on important plant-microbe symbiosis including mycorrhiza, which are critical for the health, function, and sustainability of both natural and agricultural ecosystems. Toxic compounds are released into rural and urban ecosystems as a result of anthropogenic contamination from industrial processes, agricultural practices, and consumer products. Once discharged, these pollutants travel through the atmosphere and water, settling in matrices like sediments and groundwater, potentially rendering broad areas uninhabitable. With the rapid growth of nanotechnology, the application of manufactured nano-objects in the form of nano-agrochemicals has expanded for their greater potential or their appearance in products of users, raising worries about possible eco-toxicological impacts. MNOs are added throughout the life cycle and are accumulated not only in the soils but also in other components of the environment causing mostly negative impacts on soil biota and processes. MNOs interfere with soil physicochemical qualities as well as microbial metabolic activity in rhizospheric soils. This review examines the harmful effect of MNOs on soil, as well as the pathways used by microbes to deal with MNOs and the fate and behavior of NPs inside the soils. Full article

(This article belongs to the Special Issue Functional Nanoparticles for Environmental Contaminants Removal and Agricultural Application)

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17 pages, 4889 KiB

Open AccessReview

X-ray Detectors Based on Halide Perovskite Materials

by Yimei Tan, Ge Mu, Menglu Chen and Xin Tang

Coatings 2023, 13(1), 211; https://doi.org/10.3390/coatings13010211 - 16 Jan 2023

Cited by 7 | Viewed by 3971

Abstract

Halide perovskite has remarkable optoelectronic properties, such as high atomic number, large carrier mobility-lifetime product, high X-ray attenuation coefficient, and simple and low-cost synthesis process, and has gradually developed into the next-generation X-ray detection materials. Halide perovskite-based X-ray detectors can improve the sensitivity [...] Read more.

Halide perovskite has remarkable optoelectronic properties, such as high atomic number, large carrier mobility-lifetime product, high X-ray attenuation coefficient, and simple and low-cost synthesis process, and has gradually developed into the next-generation X-ray detection materials. Halide perovskite-based X-ray detectors can improve the sensitivity and reduce the detectable X-ray dose, which is applied in imaging, nondestructive industrial inspection, security screening, and scientific research. In this article, we introduce the fabrication methods of halide perovskite film and the classification and progress of halide perovskite-based X-ray detectors. Finally, the existing challenges are discussed, and the possible directions for future applications are explored. We hope this review can stimulate the further improvement of perovskite-based X-ray detectors. Full article

(This article belongs to the Special Issue Application of Advanced Quantum Dots Films in Optoelectronics)

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21 pages, 7218 KiB

Open AccessArticle

Novel Thermal Barrier Coatings with Phase Composite Structures for Extreme Environment Applications: Concept, Process, Evaluation and Performance

by Xinqing Ma, Kristina Rivellini, Peter Ruggiero and George Wildridge

Coatings 2023, 13(1), 210; https://doi.org/10.3390/coatings13010210 - 16 Jan 2023

Cited by 6 | Viewed by 3225

Abstract

In this paper, a novel concept in the field of phase composite ceramics has been proposed and applied for creating the topcoats of durable thermal barrier coatings (TBCs), which is one of the most critical technologies for advanced high-efficiency gas turbine engines in [...] Read more.

In this paper, a novel concept in the field of phase composite ceramics has been proposed and applied for creating the topcoats of durable thermal barrier coatings (TBCs), which is one of the most critical technologies for advanced high-efficiency gas turbine engines in extreme environments. The phase composite ceramic TBCs were designed to demonstrate superior and comprehensive performance-related merits, benefits, and advantages over conventional single-phase TBCs with a topcoat of 8YSZ or Gd₂Zr₂O₇, including thermal phase stability, thermal shock durability, low thermal conductivity, and solid particle erosion resistance. In this paper, we review and summarize the development work conducted so far related to the phase composite ceramic concept, coatings processing, and experimental investigation into TBC behaviors at elevated temperatures (typically, ≥1250 °C) using different evaluation and characterization methods, including isothermal sintering, a burner rig test, a solid particle-impinging erosion test, and a CMAS corrosion test. Two-phase (t’+c) zirconia-based TBCs demonstrated improved thermal shock and erosion resistance in comparison to conventional single-phase (t’), 8YSZ TBC, and Gd₂Zr₂O₇ TBC, when used separately. Additionally, a triple-phase (t’+c+YAG) TBC sample demonstrated superior CMAS resistance. The TBC’s damage modes and failure mechanisms for thermal phase stability, thermal cycling resistance, solid particle erosion behavior, and CMAS infiltration are also characterized and discussed in detail, in terms of microstructural characterization and performance evaluation. Full article

(This article belongs to the Special Issue Coatings for Extreme Environments)

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9 pages, 2250 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Dual-Type Flexible-Film Thermoelectric Generators Using All-Carbon Nanotube Films

by Ryota Konagaya and Masayuki Takashiri

Coatings 2023, 13(1), 209; https://doi.org/10.3390/coatings13010209 - 16 Jan 2023

Cited by 6 | Viewed by 2913

Abstract

The long-term stability of n-type single-walled carbon nanotubes (SWCNTs) in air makes all-carbon thermoelectric generators (TEGs) viable. To increase the performance of TEGs, we developed a dual-type flexible-film thermoelectric generator (DFTEG). The vacuum filtering was used to form p- and n-type SWCNT films [...] Read more.

The long-term stability of n-type single-walled carbon nanotubes (SWCNTs) in air makes all-carbon thermoelectric generators (TEGs) viable. To increase the performance of TEGs, we developed a dual-type flexible-film thermoelectric generator (DFTEG). The vacuum filtering was used to form p- and n-type SWCNT films from ethanol-based dispersion and water-based solutions with cationic surfactant, respectively. DFTEGs were fabricated as follows: strip-shaped p- and n-type SWCNT films were attached on the top and back sides of a polyimide substrate, respectively, and were connected alternately in series by bending copper tapes on the edge of the polyimide substrate. The thermoelectric performance was measured after attaching the DFTEG outside a beaker full of water, where the water surface reached the center of the DFTEG. For a 10 mm long film and 15 p-n pairs, the DFTEG had an output voltage of 40 mV and a maximum power of 891 nW at a temperature difference of 25 K. The measured thermoelectric performance was significantly higher than that of the single-type TEG for almost the same SWCNT films. This result demonstrates that thermoelectric performance can be improved by using DFTEGs that are fabricated with optimum structural designs. Full article

(This article belongs to the Collection Feature Paper Collection in Thin Films)

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12 pages, 2921 KiB

Open AccessArticle

Study of Optical and Electrical Properties of RF-Sputtered ZnSe/ZnTe Heterojunctions for Sensing Applications

by Ana-Maria Panaitescu and Vlad-Andrei Antohe

Coatings 2023, 13(1), 208; https://doi.org/10.3390/coatings13010208 - 16 Jan 2023

Cited by 3 | Viewed by 2390

Abstract

Cadmium (Cd)-free photodiodes based on n-type Zinc Selenide/p-type Zinc Telluride (n-ZnSe/p-ZnTe) heterojunctions were prepared by Radio Frequency-Magnetron Sputtering (RF-MS) technique, and their detailed optical and electrical characterization was performed. Onto an optical glass substrate, 100 nm gold (Au) thin film was deposited by [...] Read more.

Cadmium (Cd)-free photodiodes based on n-type Zinc Selenide/p-type Zinc Telluride (n-ZnSe/p-ZnTe) heterojunctions were prepared by Radio Frequency-Magnetron Sputtering (RF-MS) technique, and their detailed optical and electrical characterization was performed. Onto an optical glass substrate, 100 nm gold (Au) thin film was deposited by Thermal Vacuum Evaporation (TVE) representing the back-contact, followed by the successive RF-MS deposition of ZnTe, ZnSe, Zinc Oxide (ZnO) and Indium Tin Oxide (ITO) thin films, finally resulting in the Au/ZnTe/ZnSe/ZnO/ITO sub-micrometric “substrate”-type configuration. Next, the optical characterization by Ultraviolet-Visible (UV-VIS) spectroscopy was performed on the component thin films, and their optical band gap values were determined. The electrical measurements in the dark and under illumination at different light intensities were subsequently performed. The Current–Voltage (I–V) characteristics in the dark are nonlinear with a relatively high asymmetry, following the modified Shockley–Read equation. From their analysis, the series resistance, shunt resistance, the ideality factor and saturation current were determined with high accuracy. It is worth noting that the action spectrum of the structure is shifted to short wavelengths. A sensibility test for the 420–500 nm range was performed while changing the intensity of the incident light from 100 mW/cm

^{2}

down to 10 mW/cm

^{2}

and measuring the photocurrent. The obtained results provided sufficient information to consider the present sub-micrometric photodiodes based on n-ZnSe/p-ZnTe heterojunctions to be more suitable for the UV domain, demonstrating their potential for integration within UV photodetectors relying on environmentally-friendly materials. Full article

(This article belongs to the Special Issue New Trends in Functional Materials and Devices)

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14 pages, 2710 KiB

Open AccessArticle

Research on Tool Wear and Surface Integrity of CFRPs with Mild Milling Parameters

by Jun Qiu, Shunqi Zhang, Bo Li, Yi Li and Libiao Wang

Coatings 2023, 13(1), 207; https://doi.org/10.3390/coatings13010207 - 16 Jan 2023

Cited by 4 | Viewed by 2372

Abstract

Carbon fiber-reinforced polymer composites are widely used in aviation and aerospace applications due to their excellent mechanical properties. Numerous studies have focused on tool wear at extreme machining parameters (f ≥ 540 mm/min) to accelerate tool wear experiments. However, using mild machining parameters [...] Read more.

Carbon fiber-reinforced polymer composites are widely used in aviation and aerospace applications due to their excellent mechanical properties. Numerous studies have focused on tool wear at extreme machining parameters (f ≥ 540 mm/min) to accelerate tool wear experiments. However, using mild machining parameters is also instructive for current process production. To investigate the effect of wear on the surface integrity of CFRPs under mild parameters, a tool wear experiment on CFRPs was carried out at a conventional feed rate (f = 60 mm/min). The results show a cutting temperature increase of 47%, a cutting force increase of 53% and a flank wear width increase of 282% for PCD tools (with mild milling parameters) from 0 to 100 m of cutting length. As the cutting temperature reaches the glass transition temperature,

T_{g}

, during the stable wear stage, severe burrs and a large number of cavities appeared on the groove, and the subsurface with granular wear on flank wear land due to the transform of the matrix. Furthermore, Ra and Rz exhibit good indicators of cutting length and subsurface damage. Full article

(This article belongs to the Special Issue Recent Advances in the Machining of Metals and Composites)

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13 pages, 5336 KiB

Open AccessArticle

Annealing Treatment on Homogenous n-TiO₂/ZnO Bilayer Thin Film Deposition as Window Layer for p-Cu₂O-Based Heterostructure Thin Film

by Nurliyana Mohamad Arifin, Fariza Mohamad, Rosniza Hussin, Anis Zafirah Mohd Ismail, Shazleen Ahmad Ramli, Norazlina Ahmad, Nik Hisyamudin Muhd Nor, Mohd Zainizan Sahdan, Mohd Zamzuri Mohammad Zain and Masanobu Izaki

Coatings 2023, 13(1), 206; https://doi.org/10.3390/coatings13010206 - 16 Jan 2023

Cited by 6 | Viewed by 2031

Abstract

Metal oxide semiconductor material has great potential to act as window layer in p–n heterojunction solar cell thin film owing to low production cost and significant properties in photovoltaic mechanism. In this work, n-TiO₂/ZnO bilayer thin film was effectively constructed by [...] Read more.

Metal oxide semiconductor material has great potential to act as window layer in p–n heterojunction solar cell thin film owing to low production cost and significant properties in photovoltaic mechanism. In this work, n-TiO₂/ZnO bilayer thin film was effectively constructed by means of sol-gel spin coating technique in an effort to diminish the electron-hole recombination rate from single-layered thin film. Annealing time is one of the important parameters in the fabrication process and was varied to study the impact of annealing treatment towards the thin film characteristics as window layer. It was found that the optimum parameter for the n-TiO₂/ZnO bilayer was 500 °C with an annealing time of 2 h. High crystallinity of the n-(101)-TiO₂/(002)-ZnO bilayer thin film was obtained, which consists of anatase and a hexagonal wurtzite structure, respectively. Orientation of (002)-ZnO is essential for deposition with the (111) Cu₂O-absorbing layer due to a low different lattice mismatch between these two interfaces. The homogenous morphology of n-TiO₂/ZnO bilayer was observed with a compact and dense layer. The improvement of transmittance has also been achieved in a range of 60%–80%, which indicated that the incident light can penetrate throughout the thin film directly. In addition, a p-Cu₂O absorbing layer was successfully fabricated on top of n-TiO₂/ZnO bilayer thin film to form a p-n junction in order to visualize significant electrical rectification properties. The existence of p-Cu₂O was confirmed by a (111)-peak orientation and triangular shape in structural and morphological properties, respectively. Full article

(This article belongs to the Section Surface Coatings for Biomedicine and Bioengineering)

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31 pages, 8579 KiB

Open AccessReview

Research Status of Stability in Dynamic Process of Laser-Arc Hybrid Welding Based on Droplet Transfer Behavior: A Review

by Qingyong Liu, Di Wu, Qingzhao Wang, Peilei Zhang, Hua Yan, Tianzhu Sun, Jie Zeng, Mingliang Yan, Zhenyu Liu and Ruifeng Li

Coatings 2023, 13(1), 205; https://doi.org/10.3390/coatings13010205 - 16 Jan 2023

Cited by 13 | Viewed by 3369

Abstract

With the synergistic effect of laser and arc heat sources, laser-arc hybrid welding (LAHW) technology can improve welding speed and penetration depth, and enhance gap-bridging ability. This review describes the fundamental concepts and characteristics of droplet transfer behavior in LAHW. Emphasis was placed [...] Read more.

With the synergistic effect of laser and arc heat sources, laser-arc hybrid welding (LAHW) technology can improve welding speed and penetration depth, and enhance gap-bridging ability. This review describes the fundamental concepts and characteristics of droplet transfer behavior in LAHW. Emphasis was placed on the physical interaction between the laser and arc and the effect of the combined laser/arc heat sources on the welding process. However, the physical understanding of these multivariable and complex interactions is still evolving. Through numerous research findings and summary, it is found that there are several critical factors, including the laser-to-arc distance, heat source leading mode, shielding gas composition, and laser power, affecting the droplet transfer characteristics. This review critically interprets the latest development in the basic understanding of LAHW. It lays great stress on the coupling effect of laser and arc in droplet transfer dynamic process of LAHW, and offers a direction for the future study and progress of LAHW. Significant fields for future research are also confirmed. Full article

(This article belongs to the Special Issue Recent Developments in Advanced Manufacturing Technology)

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17 pages, 5284 KiB

Open AccessArticle

High-Velocity Oxy-Fuel (HVOF) Spray Coating of Inconel, Colmonoy, and Aluminum on AISI 316L Stainless Steel: A Comparative Investigation of the Microstructure and Corrosion Resistance of Coatings

by M. Taghian, M. Heydarian, S. Torkian, M. Parham Dabir, A. Bahrami, S. H. Mousavi Anijdan and N. Park

Coatings 2023, 13(1), 204; https://doi.org/10.3390/coatings13010204 - 16 Jan 2023

Cited by 1 | Viewed by 2670

Abstract

This study examines the effect of high-velocity oxy-fuel (HVOF) coatings of Inconel, aluminum, and Colmonoy on the corrosion resistance of stainless steel substrates. The coated samples were characterized using SEM, XRD, and EDS techniques. Impedance and Tafel tests were used to investigate the [...] Read more.

This study examines the effect of high-velocity oxy-fuel (HVOF) coatings of Inconel, aluminum, and Colmonoy on the corrosion resistance of stainless steel substrates. The coated samples were characterized using SEM, XRD, and EDS techniques. Impedance and Tafel tests were used to investigate the coatings corrosion responses at 40, 50, and 60 °C. Inconel-coated specimens showed superior corrosion behavior thanks to the Cr₂O₃ layers formed between the lamella structures of the coating, preventing chloride ions from diffusing across the coating. Although the Nyquist curve indicated oxide layer formation for the Al-coated sample, the Tafel test results showed severe corrosion. Full article

(This article belongs to the Special Issue Corrosion Resistance, Mechanical Properties and Characterization of Metallic Materials and Coatings)

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13 pages, 5207 KiB

Open AccessArticle

Effect of Resin Content on the Surface Wettability of Engineering Bamboo Scrimbers

by Jinguang Wei, Yang Xu, Minzhen Bao, Yanglun Yu and Wenji Yu

Coatings 2023, 13(1), 203; https://doi.org/10.3390/coatings13010203 - 16 Jan 2023

Cited by 8 | Viewed by 2029

Abstract

Bamboo scrimber refers to a lignocellulosic structural material, which is usually attacked by water, ultraviolet radiation and fungus. Surface coating is an effective way to protect it, and its coating properties depend on surface wettability. In this study, the surface wettability of bamboo [...] Read more.

Bamboo scrimber refers to a lignocellulosic structural material, which is usually attacked by water, ultraviolet radiation and fungus. Surface coating is an effective way to protect it, and its coating properties depend on surface wettability. In this study, the surface wettability of bamboo scrimbers with varying resin content was investigated via the comprehensive analysis of surface roughness, surface contact angle, surface free energy, surface chemical composition and coating properties. The resultant scrimbers had a similar profile with low roughness. Their surface was hydrophilic, but the hydrophilicity decreased with the increase in resin content. High resin content gave rise to low total free energy, in which the Lifshitz–van der Waals component was dominant and it decreased with the increasing resin content. Meanwhile, the ratio of the electron-accepting component to the electron-donating component becomes higher. This was due to the decreasing hydrophilic groups (e.g., -OH and -COOH groups) and the increasing oxygen-free groups (e.g., C-H and -CH₂ groups) on the scrimber surface. The resin content affected the adhesion by decreasing the surface wettability, but the coating adhesion still reached the level of 2 for all bamboo scrimbers. The results will provide a theoretical reference for the surface coating of bamboo scrimbers in the structural application for good coating durability. Full article

(This article belongs to the Special Issue Surface Modification and Protection of Bio-Based Materials)

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16 pages, 6769 KiB

Open AccessArticle

Influence of Medium–High Temperature Annealing on Microstructure and Properties of High-Power Laser Melting Deposited Ti-6Al-4V Alloy

by Yarong Chen, Hang Lv, Zhenlin Zhang, Shimei Tao, Shao Xie, Junjie Li, Yan Liu and Hui Chen

Coatings 2023, 13(1), 202; https://doi.org/10.3390/coatings13010202 - 16 Jan 2023

Cited by 1 | Viewed by 2104

Abstract

A high-power laser melting deposition (HP-LMD) device with a maximum output of 5 kW was developed to enhance the production efficiency of fabricating large-scale titanium components. In this study, the medium–high temperature annealing strategy was proposed, wherein the effects of holding temperature and [...] Read more.

A high-power laser melting deposition (HP-LMD) device with a maximum output of 5 kW was developed to enhance the production efficiency of fabricating large-scale titanium components. In this study, the medium–high temperature annealing strategy was proposed, wherein the effects of holding temperature and holding time on the residual stress, microstructure evolution, and mechanical properties of the fabricated block were evaluated. The results showed that the residual stress on the surface of the fabricated blocks reduced significantly after annealing treatment. The microstructure of as-deposited Ti-6Al-4V alloy mainly consisted of α’ martensite and basket-weave microstructure, and the aspect ratio of the martensite decreased from 22 to 6 with the increases in annealing temperature and holding time. In addition, the annealing treatments had a favorable benefit on the microhardness and tensile performance of the HP-LMD fabricated Ti-6Al-4V alloy. The optimum annealing treatment was 650 °C/2 h followed by furnace cooling. The tensile samples processed by the optimum annealing treatment exhibited excellent properties with a yield strength of 912 MPa and an elongation of 11.48%, which far exceeded the Chinese aviation standard. In addition, the results of the statistical analysis revealed that the tensile properties of heat-treated samples were superior to as-deposited samples when the aspect ratio of martensite was in the range of 9–14. The fracture mode of both the as-deposited samples and annealed samples was ductile fracture. Full article

(This article belongs to the Section Laser Coatings)

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10 pages, 824 KiB

Open AccessArticle

Mechanical Stability of Self-Adhesive/Ion-Releasing Resin Composites

by Abdulrahman Alshabib, Abdullah Alshehri, Carlos A. Jurado, Ali Alrahlah, Abdulrahman Almazrou, Mansour Albuhayri, Abdullah Alnujaym, Abdullah Almuhanna, Nicholas G. Fischer and Hamad Algamaiah

Coatings 2023, 13(1), 201; https://doi.org/10.3390/coatings13010201 - 16 Jan 2023

Cited by 3 | Viewed by 2580

Abstract

The purpose of this study was to assess the effects of water storage on the surface microhardness (VHN) and fracture toughness (K_1C) of two self-adhesive restorative materials compared to traditional resin composite and resin-modified glass ionomer cement (RMGIC) restorative materials. Methods: [...] Read more.

The purpose of this study was to assess the effects of water storage on the surface microhardness (VHN) and fracture toughness (K_1C) of two self-adhesive restorative materials compared to traditional resin composite and resin-modified glass ionomer cement (RMGIC) restorative materials. Methods: Two self-adhesive materials (Activa and Vertise Flow), a nonflowable composite (Filtek Z250), and an RMGIC (Fuji II) were evaluated. Hardness measurements (n = 12) were recorded at three time intervals: (i) one-hour post-irradiation; (ii) after one day of storage in water at 37 °C; and (iii) after 90 days of storage in water at 37 °C. Fracture toughness (K_1C) measurements (n = 12) were conducted after one day of storage in water at 37 °C and 90 days of storage in water at 37 °C. ANOVA and Tukey post hoc tests were used for statistical analysis. Results: Baseline VHN data were 38.2–58.3, decreasing significantly to 28.8–55.6 following 90 days of water storage. The Filtek Z250 had the highest VHN before and after storage, while the Activa had the lowest. K_IC values varied between 0.98–1.32 MPa·m^0.5. The highest value was for the Filtek Z250 while the Fuji II showed the lowest value (after both 1 and 90 days of storage in water). However, K_IC values decreased significantly after storage, except for the Fuji II. Conclusion: Self-adhesive/ion-releasing resin composites were negatively affected by water storage. Material reinforcements are possible future areas to explore. Full article

(This article belongs to the Collection Feature Paper Collection in Bioactive Coatings and Biointerfaces)

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17 pages, 7257 KiB

Open AccessArticle

Effects of Reaction Parameters on the Geometry and Crystallinity of Hydrothermally Synthesized ZnO Nanorods for Bio-Fouling Applications

by Abderrahmane Hamdi, Chin Sing Lim, Mohamed Aymen Ben Achour, Ali Alshehri, Mervat Alamri, Dominique Deresmes, Serena Lay-Ming Teo, Denis Remiens and El Hadj Dogheche

Coatings 2023, 13(1), 200; https://doi.org/10.3390/coatings13010200 - 16 Jan 2023

Cited by 1 | Viewed by 1794

Abstract

In this present work, we have successfully synthesized vertical aligned ZnO nanorod arrays (ZnO NRs) on conductive stainless-steel substrate. These ZnO NRs were obtained by using a low temperature, low cost, and eco-friendly hydrothermal approach. The effect of the sol-gel deposited ZnO seed [...] Read more.

In this present work, we have successfully synthesized vertical aligned ZnO nanorod arrays (ZnO NRs) on conductive stainless-steel substrate. These ZnO NRs were obtained by using a low temperature, low cost, and eco-friendly hydrothermal approach. The effect of the sol-gel deposited ZnO seed layer on the vertical alignment ZnO NRs has been thoroughly studied. Characterizations of the seed layer and the as-obtained nanorods were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM), high-resolution transmission electron microscopy (HR-TEM), and water contact angles (WCA) measurement. SEM analysis shows that these nanorods were grown with a high uniformity and density over the entire substrate. TEM and XRD studies confirmed the hexagonal wurtzite structure of ZnO nanorods. Finally, field immersion tests using the optimized samples were conducted in a coastal sea environment to study biofouling settlement. To the best of our knowledge, there are few articles that investigate the influence of the seed layer deposited on stainless steel on the formation of vertically aligned nanorods for antifouling applications. The novelty of this work is manifested by optimizing the ZnO seed layer to obtain either thick or fine ZnO nanorods (NRs). Moreover, another novelty of this study is the use of the hydrothermal deposition of ZnO NRs on stainless steel for biofouling to replace paints in marine applications. Full article

(This article belongs to the Special Issue Deposition and Applications of Protective Films and Coatings)

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23 pages, 6175 KiB

Open AccessFeature PaperArticle

Biomechanical Properties and Corrosion Resistance of Plasma-Sprayed Fish Scale Hydroxyapatite (FsHA) and FsHA-Doped Yttria-Stabilized Zirconia Coatings on Ti–6Al–4V Alloy for Biomedical Applications

by Franklin A. Anene, Che Nor Aiza Jaafar, Azmah Hanim Mohamed Ariff, Ismail Zainol, Suraya Mohd Tahir, Bushroa Abdul Razak, Mohd Sapuan Salit and Joy Anene-Amaechi

Coatings 2023, 13(1), 199; https://doi.org/10.3390/coatings13010199 - 16 Jan 2023

Cited by 4 | Viewed by 2036

Abstract

Hydroxyapatite (HA) coatings on metallic implants have been extensively used in orthopedic applications to improve tissue-implant interactions, enhance their biocompatibility, and enhance their functionality. However, the expensive synthetic HA is the most widely used bioceramic for implant coatings, leading to high implants costs. [...] Read more.

Hydroxyapatite (HA) coatings on metallic implants have been extensively used in orthopedic applications to improve tissue-implant interactions, enhance their biocompatibility, and enhance their functionality. However, the expensive synthetic HA is the most widely used bioceramic for implant coatings, leading to high implants costs. Hence, this research explored the potential of an inexpensive biogenic HA derived from fish scales and FsHA/yttria-stabilized zirconia (YSZ) bioceramic coatings on a Ti–6Al–4V alloy as an alternative to synthetic HA coatings. The FsHA/YSZ powders and the coatings were examined with X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive X-ray (SEM/EDX), and the surface roughness, microhardness, corrosion resistance, bioactivity, and in vitro cytotoxicity of the coatings were also determined. The morphological powder analysis revealed particles with a slightly irregular morphology and a fine spherical morphology, while the coating microstructure analysis revealed a fine lamellar morphology, with partially melted and unmelted FsHA particles, and fine microcracks along with evenly dispersed ZrO₂ particles. The surface roughness of the FsHA coating increased by 87.5% compared with the uncoated substrate, and the addition of YSZ significantly reduced this value. A 35.5% increase in hardness was obtained in the FsHA + 20 wt.% YSZ coating, and the FsHA coating showed a 43.2% reduction in the corrosion rate compared with the uncoated substrate; a further 73% reduction was observed with the addition of YSZ. The microstructure of the coatings after 14 days of immersion in simulated body fluid (SBF) revealed enlarged cracks and delaminated segments with well-grown apatite spherulite layers on the whole surface of the coatings, while in vitro cytotoxicity analysis showed a good cell viability of 95% at the highest concentration of the specimen. Full article

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

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16 pages, 4463 KiB

Open AccessArticle

MXenes as Alternative Plasmonic Coatings on 1D Photonic Crystals Platforms for Tamm Plasmon Polaritons

by Marko Obradov, Zoran Jakšić, Ivana Mladenović, Anja Bartula and Olga Jakšić

Coatings 2023, 13(1), 198; https://doi.org/10.3390/coatings13010198 - 16 Jan 2023

Cited by 1 | Viewed by 2088

Abstract

New materials are of essential importance for the advancement of nanophotonics and nanoplasmonics. Numerous electromagnetic modes, especially various evanescent surface waves, prove themselves useful in multitudinous practical applications. Here we investigate the use of MXenes as alternative plasmonic materials in freestanding (substrateless) planar [...] Read more.

New materials are of essential importance for the advancement of nanophotonics and nanoplasmonics. Numerous electromagnetic modes, especially various evanescent surface waves, prove themselves useful in multitudinous practical applications. Here we investigate the use of MXenes as alternative plasmonic materials in freestanding (substrateless) planar nanocomposites that support the existence of Tamm plasmon polaritons (TPP). We use finite element simulations to consider the influence of using MXenes on the propagation and distribution of TPP and the difference in their electromagnetic behavior compared to that of commonly used noble metals. While MXenes allow for somewhat weaker coupling between incident light and TPP, even the thinnest MXene layers practically completely screen the structure behind them. Our diffraction grating-enhanced stacks achieved incident light direction-dependent improvement of the coupling strength and polarization-dependent hybridization of electromagnetic states. MXene ensures improvements in functionality, especially spectral, directional, and polarization selectivity, by imparting rich modal behavior. Importantly, we observed high optical asymmetry of reflectance when illuminating the structures from opposite directions and obtained large high-to-low reflection ratios with a very small number of dielectric layers in the capping 1D photonic crystal. We conclude that MXenes represent a viable alternative for TPP-supporting structures, offering many advantages. Full article

(This article belongs to the Special Issue Application of Graphene and Two-Dimensional Materials in Thin Films)

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16 pages, 7654 KiB

Open AccessArticle

Effects of Process Parameters on Microstructure and High-Temperature Oxidation Resistance of Laser-Clad IN718 Coating on Cr5Mo Steel

by Zelin Xu, Fengtao Wang, Shitong Peng, Weiwei Liu and Jianan Guo

Coatings 2023, 13(1), 197; https://doi.org/10.3390/coatings13010197 - 15 Jan 2023

Cited by 5 | Viewed by 2172

Abstract

Cr5Mo steel with high thermal strength is frequently applied as the material for hydrocracking furnace tubes. Nonetheless, Cr5Mo tubes are prone to material failure in a high-temperature environment, threatening production safety. Considering that the IN718 nickel-base superalloy has favorable high-temperature oxidation resistance, the [...] Read more.

Cr5Mo steel with high thermal strength is frequently applied as the material for hydrocracking furnace tubes. Nonetheless, Cr5Mo tubes are prone to material failure in a high-temperature environment, threatening production safety. Considering that the IN718 nickel-base superalloy has favorable high-temperature oxidation resistance, the IN718 coating was fabricated on Cr5Mo substrate through laser cladding. The effect of process parameters on the high-temperature oxidation resistance of laser cladding IN718 coating was investigated. The results confirm that laser power and scanning speed affected the eutectic quantity precipitation of this layer, and the eutectic quantity precipitation was positively correlated with the mass gain of the coating. The high-temperature behavior of the coating could be divided into surface oxidation, intergranular corrosion, and material shedding. The scanning speed has a more significant impact on the high-temperature oxidation resistance. When the scanning speed is 15 mm/s, cracks originating in the heat-affected zone could exert a negative impact on the high-temperature oxidation resistance. Full article

(This article belongs to the Special Issue Laser Cladding Coatings: Microstructure, Properties, and Applications)

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11 pages, 7665 KiB

Open AccessArticle

Influence of Heat Treatment on Corrosion Resistance of Sn/Mg Films Formed by PVD Method on Hot-Dip Galvanized Steel

by Sung-Hwa Hwang, Seung-Hyo Lee and Myeong-Hoon Lee

Coatings 2023, 13(1), 196; https://doi.org/10.3390/coatings13010196 - 15 Jan 2023

Cited by 2 | Viewed by 2224

Abstract

Double layers composed of Sn and Mg, each 0.8 μm thick, were fabricated on a hot-dip galvanized steel (8.4 μm) sheet using DC magnetron sputtering and post-annealing processes. With an increase in temperature, the surface morphologies were agglomerated with each other. Additionally, Sn/Mg [...] Read more.

Double layers composed of Sn and Mg, each 0.8 μm thick, were fabricated on a hot-dip galvanized steel (8.4 μm) sheet using DC magnetron sputtering and post-annealing processes. With an increase in temperature, the surface morphologies were agglomerated with each other. Additionally, Sn/Mg mixture sites, including an intermetallic compound of Mg₂Sn, were formed at 190 °C and locally clustered at 220 °C. In the salt-spray test, the corrosion resistance of the Sn/Mg film prepared at 190 °C was 960 h, which is longer than that at non-heat for 528 h or 220 °C for 480 h. In the polarization test, the Sn/Mg film formed at 190 °C displayed a lower corrosion current density of 1.07 μA/cm² and potential of 1.62 V/SSCE than those at non-heat or 220 °C. Full article

(This article belongs to the Special Issue Material Surface Treatment Technology for a New Era)

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16 pages, 14023 KiB

Open AccessFeature PaperArticle

Kaolin-Filled Styrene-Butadiene-Based Dispersion Coatings for Paper-Based Packaging: Effect on Water, Moisture, and Grease Barrier Properties

by Andrea Marinelli, Maria Vittoria Diamanti, MariaPia Pedeferri and Barbara Del Curto

Coatings 2023, 13(1), 195; https://doi.org/10.3390/coatings13010195 - 15 Jan 2023

Cited by 8 | Viewed by 3530

Abstract

Dispersion coating may represent an alternative technology to extrusion coating, currently dominating the market of coated paper-based packaging. Being processed as inks, dispersion coatings can be applied with conventional equipment, achieving lower dry coat grammages. In this work, two styrene-butadiene-based (T_g1 ≅ [...] Read more.

Dispersion coating may represent an alternative technology to extrusion coating, currently dominating the market of coated paper-based packaging. Being processed as inks, dispersion coatings can be applied with conventional equipment, achieving lower dry coat grammages. In this work, two styrene-butadiene-based (T_g1 ≅ 0 °C; T_g2 ≅ 15 °C) dispersion coatings filled with different amounts of kaolin were developed and rod-coated on two different paper substrates. The samples were tested for water, moisture, and grease barrier properties. Kaolin-containing formulations showed moisture barrier as low as 15 g/(m²∙day), as well as grease barrier higher than 24 h. The best formulation involved 20% by weight of kaolin, whereas higher amounts were detrimental for water barrier, beneficial for moisture barrier, and slightly detrimental for grease barrier properties. Benchmarked to two commercial grades, kaolin-filled coatings strongly improved grease barrier, yet achieving similar moisture barrier. Full article

(This article belongs to the Section Functional Polymer Coatings and Films)

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19 pages, 2632 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Laser Obtained Superhydrophobic State for Stainless Steel Corrosion Protection, a Review

by Kirill A. Emelyanenko, Alexandre M. Emelyanenko and Ludmila B. Boinovich

Coatings 2023, 13(1), 194; https://doi.org/10.3390/coatings13010194 - 15 Jan 2023

Cited by 33 | Viewed by 4575

Abstract

Stainless steel has become an integral part of modern engineering materials and daily life due to its mechanical efficiency, strength, recyclability, high resistance to oxidation and corrosive attack, which make it the ideal material for many kinds of applications. At the same time, [...] Read more.

Stainless steel has become an integral part of modern engineering materials and daily life due to its mechanical efficiency, strength, recyclability, high resistance to oxidation and corrosive attack, which make it the ideal material for many kinds of applications. At the same time, steel suffers from certain types of corrosion, such as intergranular corrosion, or contact corrosion that develops when stainless steel comes into contact with carbon steel or another metal with a different electrochemical potential. Finally, pitting corrosion is a serious problem often occurring when stainless steel parts work in sea water. This paper provides a brief overview of methods for protecting stainless steel from corrosion using a new approach based on superhydrophobization of the surface of stainless steel using laser processing followed by the deposition of a layer of a substance with a low surface energy. The review discusses the mechanisms of corrosion protection by such coatings and the properties of superhydrophobic coatings presented in the literature. Superhydrophobic protective coatings on stainless steel have been shown to significantly reduce corrosion, with some demonstrating a decrease in corrosion current of up to 156 times. However, a more comprehensive analysis of the mechanisms contributing to this effect, as well as a comparison with anti-corrosion coatings on other metals, suggests that the combination of these mechanisms has the potential to create even more durable and effective surfaces for corrosion protection of stainless steel. Full article

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

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11 pages, 4844 KiB

Open AccessFeature PaperArticle

The Microstructure of Zr/Nb Nanoscale Multilayer Coatings Irradiated with Helium Ions

by Roman Laptev, Ekaterina Stepanova, Natalia Pushilina, Egor Kashkarov, Dmitriy Krotkevich, Anton Lomygin, Alexey Sidorin, Oleg Orlov and Vladimir Uglov

Coatings 2023, 13(1), 193; https://doi.org/10.3390/coatings13010193 - 15 Jan 2023

Cited by 3 | Viewed by 2005

Abstract

The effect of helium ion irradiation on the microstructure and properties of composites based on Zr/Nb nanoscale multilayer coatings (NMCs) was studied. X-ray diffraction (XRD), transmission electron microscopy (TEM), and variable-energy Doppler broadening spectroscopy (DBS) were used for the in-depth analysis of defects [...] Read more.

The effect of helium ion irradiation on the microstructure and properties of composites based on Zr/Nb nanoscale multilayer coatings (NMCs) was studied. X-ray diffraction (XRD), transmission electron microscopy (TEM), and variable-energy Doppler broadening spectroscopy (DBS) were used for the in-depth analysis of defects in the irradiated NMCs. After irradiation of the Zr/Nb NMCs with helium ions at a 10¹⁷ ion/cm² dose, the layered structure was generally retained, but the internal stresses in the layers were increased, which caused wave-like distortion in the ion deposition zone. The Zr/Nb NMCs with an individual layer thickness of 25 nm were characterized by the smallest microstress changes, but single blisters were formed in the near-surface region. The microstructure of the Zr/Nb NMCs with a layer thickness of 100 nm exhibited relatively smaller changes upon helium ion irradiation. The prevailing positron-trapping center was the reduced-electron-density area at the interfaces before and after irradiation of the Zr/Nb NMCs regardless of the layer thickness. However, the layer thickness affected the DBS parameter profiles depending on the positron energy, which was probably due to the different localization of implanted ions within the layers or at the interfaces. Full article

(This article belongs to the Special Issue Advanced Coatings for Accident Tolerant Fuel Claddings)

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18 pages, 6619 KiB

Open AccessArticle

Revealing the Enhanced Passivation and Anti-Corrosion Performance of Surface-Nanocrystallization-Modified Cr-Alloyed Rebar via Electrochemical Testing and XPS Depth Analysis

by Weilin Liu, Qiuyue Wang, Gongnian Zou, Edwin Eyram Klu, Zhiyong Ai, Falin Yang, Ningning Liang, Lei Gu, Bo Gao, Beibei Lian, Yifeng Chen and Dan Song

Coatings 2023, 13(1), 192; https://doi.org/10.3390/coatings13010192 - 15 Jan 2023

Cited by 1 | Viewed by 2390

Abstract

Surface nanocrystallization (SNC) modification can be used to realize the high-efficiency derusting of rusted Cr-alloyed rebar and obtain nanostructured grains on the surface of the rebar. The corrosion resistance performance of SNC rebar in a simulated Cl^--containing concrete pore solution was [...] Read more.

Surface nanocrystallization (SNC) modification can be used to realize the high-efficiency derusting of rusted Cr-alloyed rebar and obtain nanostructured grains on the surface of the rebar. The corrosion resistance performance of SNC rebar in a simulated Cl^--containing concrete pore solution was evaluated on the basis of electrochemical experiments. Potentiodynamic polarization testing showed that the passivation current density of the SNC rebar was about 18% of that of the rusted rebar. The structural composition of the passivation film of the SNC rebar in a concrete environment was studied using a novel characterization method, namely XPS deep sputtering, which confirmed that it had higher concentrations of Cr/Fe oxide and hydroxide, and therefore exhibited an enhanced degree of oxidation. Moreover, scanning electron microscopy and transmission electron microscopy were employed to investigate the microstructural characteristics of the SNC rebar, which was characterized by nanostructured grains with grain sizes ranging from 250 nm to 300 nm and which contained massive high-energy crystal defects, thereby promoting the film-forming reaction of Cr/Fe elements. The results of XPS depth analysis and microstructure characterization demonstrated that the SNC rebar exhibited excellent passivation performance in the concrete environment. These findings offer a new perspective on enhancing the passivation performance and chloride resistance of alloyed rebar, and provide guidance on the implementation of SNC rebar in actual engineering applications. Full article

(This article belongs to the Topic Properties of the Corroding Interface)

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15 pages, 11523 KiB

Open AccessArticle

High-Temperature Steam Oxidation of Accident-Tolerant Cr/Mo-Coated Zr Alloy at 1200–1400 °C

by Maxim Syrtanov, Egor Kashkarov, Anastasia Abdulmenova, Kirill Gusev and Dmitrii Sidelev

Coatings 2023, 13(1), 191; https://doi.org/10.3390/coatings13010191 - 15 Jan 2023

Cited by 14 | Viewed by 2347

Abstract

The oxidation resistance under LOCA conditions of bilayer Cr/Mo coating deposited on Zr-1Nb zirconium alloy was investigated in this paper. The bilayer Cr (8 μm)/Mo (3 μm) coatings were deposited by magnetron sputtering. Then, oxidation resistance under high-temperature oxidation at 1200–1400 °C in [...] Read more.

The oxidation resistance under LOCA conditions of bilayer Cr/Mo coating deposited on Zr-1Nb zirconium alloy was investigated in this paper. The bilayer Cr (8 μm)/Mo (3 μm) coatings were deposited by magnetron sputtering. Then, oxidation resistance under high-temperature oxidation at 1200–1400 °C in a water steam was studied. The use of a Mo sublayer resulted in limiting Cr-Zr interdiffusion under high-temperature oxidation. It was shown that the Mo barrier sublayer (~3 μm) can provide the protective behavior of the Cr/Mo-coated Zr at 1330 °C in a water steam for at least 720 s. The weight gain of the bilayer Cr/Mo samples was comparable with the monolayer Cr samples after oxidation at 1400 °C. In addition, the analysis of the Cr/Mo-coated Zr alloy oxidation behavior at 1400 °C was carried out. Full article

(This article belongs to the Special Issue Advanced Coatings for Accident Tolerant Fuel Claddings)

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8 pages, 2516 KiB

Open AccessArticle

The Improved Non-Polar Gas Sensing Performance of Surface-Modified Porous Silicon-Based Gas Sensors

by Bakyt Khaniyev, Margulan Ibraimov, Yerulan Sagidolda, Yerbolat Tezekbay, Tolagay Duisebayev, Ayan Tileu and Ainur Khaniyeva

Coatings 2023, 13(1), 190; https://doi.org/10.3390/coatings13010190 - 15 Jan 2023

Cited by 3 | Viewed by 2102

Abstract

The present article studied gas sensor sensing characteristics based on surface-modified porous silicon (PS) by depositing the metal oxide semiconductor layer. The PS layer was prepared through the electrochemical etching of crystalline silicon in an HF-based solution. DC magnetron sputtering technology was used [...] Read more.

The present article studied gas sensor sensing characteristics based on surface-modified porous silicon (PS) by depositing the metal oxide semiconductor layer. The PS layer was prepared through the electrochemical etching of crystalline silicon in an HF-based solution. DC magnetron sputtering technology was used to obtain the p-CuO layer on the surface of the p-PS. The obtained material’s structural, morphological, and sensing behavior were investigated using SEM, XRD, Raman spectra, and the current–voltage characteristics. For the detection of toluene and chloroform vapors, a planar structure was used. The sensing response value revealed that the CuO/PS-based gas sensors have good sensitivity for toluene and chloroform vapors. The sensing mechanism is explained using schematic energy band diagrams. Therefore, this approach is helpful for the development of a simple, cost-effective sensor for detecting non-polar chemical analytes. Full article

(This article belongs to the Special Issue Advanced Functional Films and Materials for Sensors Application)

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12 pages, 8174 KiB

Open AccessFeature PaperArticle

Effects of Process Parameters and Heat Treatment on Microstructure and Mechanical Characteristics of Laser Powder Bed Fusion Alloy Inconel 718

by Hongbing Liu, Wenhao Cheng, Yiming Sun, Rui Ma, Yajun Wang, Jie Bai, Linan Xue, Xiaoguo Song and Caiwang Tan

Coatings 2023, 13(1), 189; https://doi.org/10.3390/coatings13010189 - 15 Jan 2023

Cited by 5 | Viewed by 2689

Abstract

A laser powder bed fusion (LPBF) Inconel 718 (IN718) alloy was fabricated under different process parameters, and the samples with optimal process parameters were treated by subsequent heat treatment. The outcomes demonstrated that the pores’ size and shape were influenced by the process [...] Read more.

A laser powder bed fusion (LPBF) Inconel 718 (IN718) alloy was fabricated under different process parameters, and the samples with optimal process parameters were treated by subsequent heat treatment. The outcomes demonstrated that the pores’ size and shape were influenced by the process parameters. The porosity of the samples first grew and subsequently reduced as the volume energy density increased, and the types of pores changed from lack-of-fusion pores to gas holes and keyhole pores. The porosity of the samples with three process parameters were 3.46%, 0.15% and 1.26%, respectively. The sample of 60.0 J/mm³ was chosen for a single solution (heat treatment at 980 °C for 1 h, SS) and direct aging (heat treatment at 720 °C for 8 h and then 620 °C for 8 h, DA), and the microstructure evolution of the samples was examined. Because of the segregation of the elements Nb and Mo, the Laves phase was distributed among the dendrites in the as-built (AB) sample. The solution heat treatment dissolved the Laves phase and precipitated the δ phase, while aging heat treatment precipitated the γ′/γ” phases. Additionally, the impact of the second phase on the tensile characteristics was looked into. The DA sample had the highest strength, with a tensile strength of 1458 MPa and a yield strength of 1271 MPa. With tensile and yield strengths of 980 MPa and 620 MPa, respectively, the AB sample had the lowest strength due to the Laves phase’s role as the crack initiator. The Laves phase dissolved and the γ′/γ”-strengthened phase precipitated, leading to an increase in the strength of the heat-treated specimens. Full article

(This article belongs to the Special Issue Recent Developments in Advanced Manufacturing Technology)

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16 pages, 2505 KiB

Open AccessReview

A Review on Sustainable Manufacturing of Ceramic-Based Thin Films by Chemical Vapor Deposition (CVD): Reactions Kinetics and the Deposition Mechanisms

by M. Sabzi, S. H. Mousavi Anijdan, M. Shamsodin, M. Farzam, A. Hojjati-Najafabadi, P. Feng, N. Park and U. Lee

Coatings 2023, 13(1), 188; https://doi.org/10.3390/coatings13010188 - 14 Jan 2023

Cited by 37 | Viewed by 7794

Abstract

Chemical vapor deposition (CVD) is a process that a solid is formed on a substrate by the chemical reaction in the vapor phase. Employing this technology, a wide range of materials, including ceramic nanocomposite coatings, dielectrics, and single crystalline silicon materials, can be [...] Read more.

Chemical vapor deposition (CVD) is a process that a solid is formed on a substrate by the chemical reaction in the vapor phase. Employing this technology, a wide range of materials, including ceramic nanocomposite coatings, dielectrics, and single crystalline silicon materials, can be coated on a variety of substrates. Among the factors influencing the design of a CVD system are the dimensions or geometry of the substrate, substrate temperature, chemical composition of the substrate, type of the deposition process, the temperature within the chamber, purity of the target material, and the economics of the production. Three major phenomena of surface reaction (kinetic), diffusion or mass transfer reaction, and desorption reaction are involved during the CVD process. Thermodynamically, CVD technology requires high temperatures and low pressures in most systems. Under such conditions, the Gibbs free energy of the chemical system quickly reaches its lowest value, resulting in the production of solids. The kinetic control of the CVD technology should always be used at low temperatures, and the diffusion control should be done at high temperatures. The coating in the CVD technology is deposited in the temperature range of 900–1400 °C. Overall, it is shown here that by controlling the temperature of the chamber and the purity of the precursors, together with the control of the flow rate of the precursors into the chamber, it is possible to partially control the deposition rate and the microstructure of the ceramic coatings during the CVD process. Full article

(This article belongs to the Special Issue Electrochemical Deposition: Properties and Applications)

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27 pages, 7027 KiB

Open AccessReview

Review of Research Progress in Nontraditional Machining of Ultrahigh-Temperature Ceramic Matrix Composites

by Ya Lu, Peiyan Sun, Xiaohong Yang, Xudong Guo, Xiaoke Li and Wuyi Ming

Coatings 2023, 13(1), 187; https://doi.org/10.3390/coatings13010187 - 14 Jan 2023

Cited by 9 | Viewed by 3627

Abstract

Ultrahigh-temperature ceramic matrix composites are currently among the most promising high-temperature-resistant materials, owing to their high-temperature strength, high-toughness and excellent corrosion resistance; they are widely used in national defense and aerospace fields. However, it is a difficult material to machine, and high precision [...] Read more.

Ultrahigh-temperature ceramic matrix composites are currently among the most promising high-temperature-resistant materials, owing to their high-temperature strength, high-toughness and excellent corrosion resistance; they are widely used in national defense and aerospace fields. However, it is a difficult material to machine, and high precision is difficult to achieve using traditional machining methods. Nontraditional machining methods are not constrained by material physical and mechanical properties, and good surface quality is easily obtained, which is an important direction in the field of ultrahigh-temperature ceramic matrix composites. This paper summarizes the recent nontraditional machining methods utilized in the fabrication of ultrahigh-temperature ceramic matrix composites. Firstly, various nontraditional machining methods for ultrahigh-temperature ceramic matrix composites based on borides, carbides and nitrides are reviewed, and the machining performances under different machining conditions are compared. Subsequently, the problems and challenges of ultrahigh-temperature ceramic matrix composite nontraditional machining are summarized and discussed. Lastly, the future development path of nontraditional machining methods for ultrahigh-temperature ceramic matrix composites is summarized and predicted. Full article

(This article belongs to the Special Issue Preparation and Applications of Functional Inorganic Coatings, Glass, Ceramics)

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12 pages, 2492 KiB

Open AccessArticle

Electrochemical and Optical Analysis of Various Compositions of Au and Ag Layers for Blood Cancer Prognosis

by Ulya Farahdina, Amastasia Salsabila Muliawati, Vinda Zakiyatuz Zulfa, Miftakhul Firdhaus, Ihwanul Aziz, Hari Suprihatin, Darsono Darsono, Nasori Nasori and Agus Rubiyanto

Coatings 2023, 13(1), 186; https://doi.org/10.3390/coatings13010186 - 14 Jan 2023

Cited by 1 | Viewed by 1986

Abstract

The fabrication of silver (Ag) and gold (Au) thin film electrodes was successfully carried out using the DC sputtering deposition method. These thin film electrodes were able to detect the increase in serum albumin concentration that was used as a prognostic factor for [...] Read more.

The fabrication of silver (Ag) and gold (Au) thin film electrodes was successfully carried out using the DC sputtering deposition method. These thin film electrodes were able to detect the increase in serum albumin concentration that was used as a prognostic factor for leukemia. The simulation and the optical experimental analysis show that an increase in BSA concentration can increase the absorbance peak observed at a wavelength of 435 nm on hypoalbumin medium and 470 nm on normal concentration of serum albumin medium. The performance of the electrodes was electrochemically tested, in which it was shown that a decrease in oxidation and reduction peaks occurred with respect to an increase in BSA concentration. An oxidation peak was observed at a voltage of 0.5 V for the Ag thin film. For the Au, Au/Ag, and Ag/Au thin films, an oxidation peak was observed at a voltage of 1.0 V. The limits of detection (LODs) of the Ag, Ag/Au, Au, and Au/Ag thin films were 0.56, 0.24, 0.64, and 0.36 g/dL, respectively. Therefore, based on both the electrochemical and optical analysis, the Ag/Au thin film possessed the highest potential for prognosis monitoring of leukemia compared with the other Ag and Au thin films. Full article

(This article belongs to the Special Issue Advances in Nanostructured Thin Films and Coatings)

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