Coatings

12 pages, 2556 KiB

Open AccessArticle

Comparison of Cobalt Integration with Various Dielectric Materials under Thermal and Electrical Stress

by Yi-Lung Cheng, Hong-Chang Huang, Wei-Fan Peng, Giin-Shan Chen and Jau-Shiung Fang

Coatings 2023, 13(10), 1818; https://doi.org/10.3390/coatings13101818 - 23 Oct 2023

Viewed by 707

Cobalt (Co) is proposed to replace copper (Cu) as a conductor in the back-end-of-line (BEOL) interconnects of integrated circuits. In this study, the electric characteristics and reliability of the integration of Co with various dielectric films (SiO₂, dense, and porous low- [...] Read more.

Cobalt (Co) is proposed to replace copper (Cu) as a conductor in the back-end-of-line (BEOL) interconnects of integrated circuits. In this study, the electric characteristics and reliability of the integration of Co with various dielectric films (SiO₂, dense, and porous low-k SiOCH films) under thermal and electrical stress were compared. Thermal annealing repaired sputtering-Co-deposition-induced damage to the dielectric film but reduced the breakdown field and time-dependence-dielectric-breakdown (TDDB) times due to the diffusion of Co atoms. After annealing, the SiO₂ film had the largest reductions in the breakdown field, TDDB failure time, and electric field acceleration factor, indicating that the diffusion of Co atoms dominates in the oxygen-rich surface. Under electrical stress, the drift of Co atoms favors the porous low-k film with the assistance of porosity. As a result, a barrier is required for Co metallization. To achieve barrier-free or barrier-less processing in Co metallization, the dense low-k film is the best option to integrate with Co. Full article

► Show Figures

Figure 1

13 pages, 4200 KiB

Open AccessArticle

Designing Gallium-Containing Hydroxyapatite Coatings on Low Modulus Beta Ti-45Nb Alloy

by Jithin Vishnu, Andrea Voss, Volker Hoffmann, Ludovico Andrea Alberta, Adnan Akman, Balakrishnan Shankar, Annett Gebert and Mariana Calin

Coatings 2023, 13(10), 1817; https://doi.org/10.3390/coatings13101817 - 23 Oct 2023

Viewed by 1053

Abstract

Low-modulus β-type Ti-45Nb alloy is a promising implant material due to its good mechanical biocompatibility, non-toxicity, and outstanding corrosion resistance. Its excellent chemical stability brings new challenges to chemical surface modification treatments, which are indispensable for both osteogenesis and antibacterial performance. Coatings containing [...] Read more.

Low-modulus β-type Ti-45Nb alloy is a promising implant material due to its good mechanical biocompatibility, non-toxicity, and outstanding corrosion resistance. Its excellent chemical stability brings new challenges to chemical surface modification treatments, which are indispensable for both osteogenesis and antibacterial performance. Coatings containing metal ions as anti-microbial agents can be an effective way to reduce implant-associated infections caused by bacterial biofilm. Gallium ion (Ga³⁺) has the potential to reduce bacterial viability and biofilm formation on implant surfaces. In this study, a novel two-step process has been proposed for Ga³⁺ incorporation in hydroxyapatite (HAP) to develop bioactive and antibacterial surfaces on Ti-45Nb alloy. For the generation of bioactive surface states, HAP electrodeposition was conducted, followed by wet chemical immersion treatments in gallium nitrate (1 mM). Different buffers such as phosphate, sodium bicarbonate, ammonium acetate, and citrate were added to the solution to maintain a pH value in the range of 6.5–6.9. Coating morphology and HAP phases were retained after treatment with gallium nitrate, and Ga³⁺ ion presence on the surface up to 1 wt.% was confirmed. Combining Ga and HAP shows great promise to enable the local delivery of Ga³⁺ ions and consequent antibacterial protection during bone regeneration, without using growth factors or antibiotics. Full article

(This article belongs to the Special Issue Advances in Surface Engineering and Biocompatible Coatings for Biomedical Applications)

► Show Figures

Graphical abstract

25 pages, 6461 KiB

Open AccessEditor’s ChoiceArticle

The Influence of the Magnetic Field on Ni Thin Film Preparation by Electrodeposition Method and Its Electrocatalytic Activity towards Hydrogen Evolution Reaction

by Safya Elsharkawy, Dawid Kutyła and Piotr Zabinski

Coatings 2023, 13(10), 1816; https://doi.org/10.3390/coatings13101816 - 23 Oct 2023

Cited by 4 | Viewed by 1599

Abstract

Ni thin films were synthesized through the electrodeposition method from three different electrolytes (acetate, borate, and citrate). Furthermore, they were assessed as electrocatalysts for hydrogen evolution reaction (HER) in 1 M NaOH. Herein, various electrodeposition parameters, such as the pH of the electrolytes, [...] Read more.

Ni thin films were synthesized through the electrodeposition method from three different electrolytes (acetate, borate, and citrate). Furthermore, they were assessed as electrocatalysts for hydrogen evolution reaction (HER) in 1 M NaOH. Herein, various electrodeposition parameters, such as the pH of the electrolytes, the deposition potential, and the influence of the magnetic field, were measured. We compared the different morphologies and characteristics depending on the thin film electrodeposition process parameters. Moreover, we studied the material’s wettability changes based on the electrolyte’s composition and the applied external magnetic field. It was found that the deposited Ni thin film from the citrate electrolyte under the influence of the magnetic field in the perpendicular direction to the electrode surface had the best catalytic performance to HER. It possessed an overpotential value of 231 mV and a Tafel slope of 118 mV dec⁻¹. The deposition process was accomplished by using the chronoamperometry technique. Measuring scanning electron microscope and X-ray diffraction were used to characterize the fabricated films’ surface morphologies and crystalline structures. Full article

(This article belongs to the Special Issue Recent Achievements in Coatings Electroplating from Non-aqueous Electrolytes)

► Show Figures

Figure 1

34 pages, 10055 KiB

Open AccessReview

Excitation Threshold Reduction Techniques for Organic Semiconductor Lasers: A Review

by Yao Wang, Xu Han, Linze Jin, Yuhui Meng, Chengming Jiang, Kyeiwaa Asare-Yeboah, Zhengran He and Sheng Bi

Coatings 2023, 13(10), 1815; https://doi.org/10.3390/coatings13101815 - 23 Oct 2023

Viewed by 1401

Abstract

Organic semiconductor lasers have shown great application potential in various fields, such as low-cost sensing, high-performance lighting and display, and lab-on-a-chip devices. Since the introduction of organic lasers in the 1960s, research on semiconductor laser devices has expanded to include various materials and [...] Read more.

Organic semiconductor lasers have shown great application potential in various fields, such as low-cost sensing, high-performance lighting and display, and lab-on-a-chip devices. Since the introduction of organic lasers in the 1960s, research on semiconductor laser devices has expanded to include various materials and structures. The organic laser has attracted much attention due to its wide range of emission spectrum and simple synthesis and processing. Researchers constantly pursue the goal of using organic semiconductors to fabricate low-threshold thin-film organic laser devices while retaining the characteristics of a wide luminescence spectrum of organic materials, simple and portable structure, and low cost. However, organic semiconductor lasers face challenges due to material stability under optical pumping and large optical losses under electrical pumping, making commercialization difficult. Many scholars have put great efforts into enhancing the performance of materials and optimizing the structure to minimize the threshold of organic semiconductor lasers. Herein, based on the basic principles of organic lasers, the main factors affecting the excitation threshold are summarized. A comprehensive analysis of the relevant factors and threshold conditions is performed, considering both positive and negative aspects of modal gain and modal loss that need to be addressed. We expect to provide a wide range of ideas for reducing the threshold of organic lasers and offer theoretical guidance for the practical industrial production of organic lasers. Full article

(This article belongs to the Special Issue Optical and Electrical Properties and Applications of Semiconductors)

► Show Figures

Figure 1

9 pages, 2280 KiB

Open AccessArticle

The Flame Retardancy and Smoke Suppression Performance of Polyvinyl Chloride Composites with an Efficient Flame Retardant System

by Yunan Chen, Qingshan Wu, Na Li, Tao Tang, Xin Xie, Cece Zhang and Yuxin Zuo

Coatings 2023, 13(10), 1814; https://doi.org/10.3390/coatings13101814 - 23 Oct 2023

Viewed by 1043

Abstract

Polyvinyl chloride (PVC) is the most widely used general flame-retardant plastic worldwide; however, the large number of plasticizers added during processing significantly reduces its flame-retardant property. To prepare a new type of PVC material with highly efficient flame retardancy and smoke suppression, antimony [...] Read more.

Polyvinyl chloride (PVC) is the most widely used general flame-retardant plastic worldwide; however, the large number of plasticizers added during processing significantly reduces its flame-retardant property. To prepare a new type of PVC material with highly efficient flame retardancy and smoke suppression, antimony trioxide (Sb₂O₃), talc powder, hydromagnesite, and zinc borate were added in different proportions to PVC to explore the flame-retardant properties, thermal weight, smoke density (Ds), and mechanical properties of the composite materials. Results showed that the limiting oxygen index value of each group was higher than 27% after adding talc powder, magnesite, and zinc borate to replace part of the Sb₂O₃. This value was within the refractory-grade level and indicated a good flame retardancy performance. The replacement effect was in line with the experimental expectation. The lowest Ds peak value was 656.4 when the flame retardants were added with 10 wt% Sb₂O₃, 50 wt% hydromagnesite, 20 wt% talc, and 20 wt% Zn₃BO₆. Compared with pure Sb₂O₃ as a flame retardant, the Ds peak value decreased by 46.7%. The thermogravimetric decomposition temperature of the composites in each group was generally higher than that of the group with pure Sb₂O₃ as a flame retardant, increasing by 45.3 °C. The thermal stability of the composites was improved, and the elongation at the break and tensile strength were 234.9% and 25.8 MPa, respectively, indicating good mechanical properties. The results showed that using compound flame retardants to replace most of the Sb₂O₃ is an effective technique for obtaining good flame retardancy and mechanical properties of PVC. This study, not only reduced the manufacturing cost of flame-retardant PVC, but also effectively reduced its smoke density and the time to reach the highest smoke density, which provided a research reference for the application and promotion of flame-retardant PVC. Full article

► Show Figures

Figure 1

15 pages, 6768 KiB

Open AccessArticle

Hybrid Polymer–Inorganic Coatings Enriched with Carbon Nanotubes on Ti-6Al-4V Alloy for Biomedical Applications

by Dominika Träger, Dagmara Słota, Karina Niziołek, Wioletta Florkiewicz and Agnieszka Sobczak-Kupiec

Coatings 2023, 13(10), 1813; https://doi.org/10.3390/coatings13101813 - 23 Oct 2023

Cited by 3 | Viewed by 1000

Abstract

Bone tissue degeneration, caused by disease as well as trauma, is a problem affecting many social groups in the 21st century. It involves pain and reduced patient comfort. Developments in materials engineering allow for the design of novel, innovative materials that can be [...] Read more.

Bone tissue degeneration, caused by disease as well as trauma, is a problem affecting many social groups in the 21st century. It involves pain and reduced patient comfort. Developments in materials engineering allow for the design of novel, innovative materials that can be used in therapies to promote bone regeneration. This work presents the preparation of a ceramic–polymer coating modified with carbon nanotubes on a titanium alloy for biomedical applications. The ceramic part is hydroxyapatite synthesized by the wet precipitation method using orthophosphate and calcium hydroxide. The polymer of choice was polyethylene glycol. A UV light synthesis method was successfully applied to obtain coatings characterized by continuity and full crosslinking. Extensive physicochemical analysis and incubation studies were carried out. Interactions between coatings and fluids mimicking artificial biological environments were analyzed for 9 days, i.e., in fluids such as SBF solution, artificial saliva, and distilled water. During the in vitro incubation, changes in pH values were measured by potentiometric tests, and ionic conductivity was measured by analyzing conductometry. After incubation, the surface morphology was studied by scanning electron microscopy (SEM) together with energy-dispersive (EDS) microanalysis, which made it possible to determine the presence of individual elements on the surface, as well as to observe the appearance of new apatite layers. Fourier-transform infrared (FT-IR) spectrometry was also performed before and at the end of the incubation period. On the basis of the presented studies, it was concluded that coatings that contain nanotubes are bioactive and do not negatively affect the properties of the coatings. Bioactivity was confirmed microscopically by observing new apatite layers after incubation in SBF, which were identified as phosphorus and calcium deposits. Degradation of the polymer phase was observed in the artificial saliva. These materials require further study, including safety analysis, but they demonstrate potential for further work. Full article

(This article belongs to the Special Issue Ceramic and Metallic Biomaterials. Application in Medical Sciences)

► Show Figures

Figure 1

12 pages, 4618 KiB

Open AccessArticle

Corrosion Performance Analysis of Tubing Materials with Different Cr Contents in the CO₂ Flooding Injection–Production Environment

by Xuehui Zhao, Guoping Li, Junlin Liu, Mingxing Li, Quanqing Du and Yan Han

Coatings 2023, 13(10), 1812; https://doi.org/10.3390/coatings13101812 - 23 Oct 2023

Cited by 1 | Viewed by 991

Abstract

In order to clarify the difference in corrosion performance between low Cr-containing (3Cr, 5Cr, and 9Cr) tubing material and carbon steel N80 in the Carbon dioxide (CO₂) flooding injection and production environment and the range of adaptation, corrosion tests and analysis [...] Read more.

In order to clarify the difference in corrosion performance between low Cr-containing (3Cr, 5Cr, and 9Cr) tubing material and carbon steel N80 in the Carbon dioxide (CO₂) flooding injection and production environment and the range of adaptation, corrosion tests and analysis were carried out in simulated working conditions. In this paper, the electrochemical potentiodynamic testing technology and the weight loss method were used to comparatively analyze the corrosion performance and variation law of three types of tubing materials with different Cr contents in a simulated CO₂ flooding-produced water environment under different partial pressure conditions. Additionally, scanning electron microscopy and Energy Dispersive Spectrometer (EDS) analysis were conducted to examine the surface corrosion morphology characteristics and elemental composition of material films under various conditions. The results indicate that the open circuit potentials of 3Cr, 5Cr, and carbon steel N80 were similar under the same experimental conditions. However, the open circuit potentials of 9Cr were relatively high and there was an obvious passivation zone in anodic polarization. Nevertheless, compared to that of 13Cr, the passivation state was unstable, and pitting corrosion continued to expand once it formed. This demonstrates that the corrosion resistance of the material can be effectively enhanced and a stable passivation state can be achieved in the anodic polarization region when the Cr content of the material reaches at least 13%. The service life of materials can be predicted based on their corrosion rate under high temperature and pressure simulation environments. We found that 9Cr materials exhibited good adaptability while 3Cr and 5Cr materials showed poor adaptability. Therefore, it was not recommended to use 3Cr and 5Cr materials. Therefore, 3Cr, 5Cr, and N80 materials will be used at lower partial pressure levels of CO₂ (<0.2 MPa). Full article

(This article belongs to the Special Issue Corrosion and Protection of Oil and Gas Field Materials)

► Show Figures

Figure 1

14 pages, 4021 KiB

Open AccessArticle

Deformation Behavior and Processing Map of AlCoCrFeNiTi_0.5 High-Entropy Alloy at High Temperature

by Xinbin Liu, Tiansheng Li, Yong Wang, Xianghua Kong and Chenyang Zhao

Coatings 2023, 13(10), 1811; https://doi.org/10.3390/coatings13101811 - 22 Oct 2023

Viewed by 891

Abstract

AlCoCrFeNiTi_0.5 high-entropy alloy (HEA) shows excellent properties in hardness and corrosion resistance. AlCoCrFeNiTi_0.5 HEA was prepared using a non-consumable vacuum arc furnace. Hot-deformation behavior of AlCoCrFeNiTi_0.5 HEA was explored under 1073–1373 K with a strain rate between 0.001 and 1 [...] Read more.

AlCoCrFeNiTi_0.5 high-entropy alloy (HEA) shows excellent properties in hardness and corrosion resistance. AlCoCrFeNiTi_0.5 HEA was prepared using a non-consumable vacuum arc furnace. Hot-deformation behavior of AlCoCrFeNiTi_0.5 HEA was explored under 1073–1373 K with a strain rate between 0.001 and 1 s⁻¹ using a Gleeble-3800 thermomechanical simulator. The constitutive equation was established using the Arrhenius model, and the deformation activation energy and material constant were obtained. The processing map of HEA within 0.3–0.6 deformation was drawn according to dynamic material model (DMM). The results show that the hot-deformation process of HEA is dominated by work hardening combined with dynamic recovery, and dynamic recrystallization. The flow stress of HEA is significantly affected by deformation temperature and strain rate. The constitutive equation was constructed and verified, and the correlation coefficient of R² = 0.9873 indicated that the constitutive equation can be used to accurately predict the flow stress of HEA. The processing map of HEA shows that the optimal hot-working process parameters are in the range of temperature 1150–1300 K and strain rate 0.002–0.05 s⁻¹. This work will provide theoretical guidance for the hot-processing of HEA, which effectively promotes the application of the HEA in industry. Full article

(This article belongs to the Special Issue New Insights of High Entropy Alloys and Its Applications)

► Show Figures

Figure 1

12 pages, 10971 KiB

Open AccessArticle

Effect of Atomic-Layer-Deposited Hydroxyapatite Coating on Surface Thrombogenicity of Titanium

by Faleh Abushahba, Nagat Areid, Elina Kylmäoja, Jani Holopainen, Mikko Ritala, Leena Hupa, Juha Tuukkanen and Timo Närhi

Coatings 2023, 13(10), 1810; https://doi.org/10.3390/coatings13101810 - 22 Oct 2023

Viewed by 1041

Abstract

This study aimed to evaluate the surface characteristics of a nanocrystalline hydroxyapatite coating made through atomic layer deposition (ALD-HA) on titanium surfaces and to investigate its effect on blood coagulation and platelet adhesion. Grade 2 square titanium discs (0.7 cm, 1 mm thick) [...] Read more.

This study aimed to evaluate the surface characteristics of a nanocrystalline hydroxyapatite coating made through atomic layer deposition (ALD-HA) on titanium surfaces and to investigate its effect on blood coagulation and platelet adhesion. Grade 2 square titanium discs (0.7 cm, 1 mm thick) were used (n = 108). Half of the substrates (n = 54) were coated with ALD-HA, and the other half were used as the non-coated control. Surface free energy (SFE), contact angle (CA), surface roughness (Ra), and chemical composition were evaluated. Blood thrombogenic properties were assessed on ALD-HA and non-coated surfaces using the kinetic clotting time method. The platelets’ adhesion and morphology were also evaluated. The ALD-HA-coated surfaces demonstrated significantly higher polar SFE (p < 0.001) and lower CA (p < 0.001) values compared to the non-coated surfaces. In addition, the surface roughness was significantly lower for the ALD-HA (p < 0.001) than for the non-coated surfaces. Platelets adhered to both surfaces; however, there was variability in platelet morphologies in different areas with higher platelet density on the ALD-HA surfaces. There was no significant difference in the overall absorbance values of the hemolyzed hemoglobin for both substrates, and the total clotting time was achieved at 60 min. It can be concluded that the ALD-HA coating of titanium can enhance surface wettability, increase surface free energy, and support blood coagulation and platelet adhesion. Full article

► Show Figures

Figure 1

16 pages, 9946 KiB

Open AccessArticle

Modification of Electrochemical Exfoliation of Graphene Oxide with Dopamine and Tannic to Enhance Anticorrosion Performance of Epoxy Coatings

by Suyun Liu, Hu Liu, Ningning Shao and Zhijun Dong

Coatings 2023, 13(10), 1809; https://doi.org/10.3390/coatings13101809 - 22 Oct 2023

Viewed by 1033

Abstract

Graphene oxide (EGO) was prepared via an electrochemical exfoliation method and modified with dopamine and tannic acid, and it was then incorporated into epoxy resins to enhance their barrier, self-healing and anticorrosion performances. The morphologies, structures and compositions of the HGO (GO prepared [...] Read more.

Graphene oxide (EGO) was prepared via an electrochemical exfoliation method and modified with dopamine and tannic acid, and it was then incorporated into epoxy resins to enhance their barrier, self-healing and anticorrosion performances. The morphologies, structures and compositions of the HGO (GO prepared via Hummers’ method), EGO and MGO (modified EGO) were characterized via SEM, TEM, AFM, Raman spectroscopy and XPS. The protective performances of the epoxy varnish coatings, EGO/epoxy coatings and MGO/epoxy coatings with different contents of MGO were evaluated via EIS measurements, and the role played by MGO on the coating defects was determined via LEIS and salt spray tests on the scratched coatings in a 3.5% NaCl solution. The results show that the dopamine and tannic were successfully grafted onto the EGO surface via π–π interactions and chemical bonding, and that the dispersibility of the MGO in the epoxy resins was facilitated. The epoxy coatings with a 0.1% addition of MGO possessed the best anticorrosion properties (|Z|_0.01Hz > 10¹⁰ Ω cm² after 70 days immersion in 3.5% NaCl solution) in comparison to the other coatings due to the “labyrinth effect” formed by the uniformly dispersed MGO. Meanwhile, the grafted tannic acid was released at the coating defects and provided inhibition functionalities for the substrate. As a result, the corrosion of the carbon steel was significantly decreased. This work provides a new perspective on the efficient modification of electrochemically exfoliated GO epoxy coatings for metals by combining the advantages of dopamine and corrosion inhibitors. Full article

(This article belongs to the Topic Materials for Corrosion Protection)

► Show Figures

Figure 1

12 pages, 9517 KiB

Open AccessArticle

Paint Film Formation Characteristics on Conical Surfaces for Electrostatic Air Spray Painting

by Shuzhen Zhang, Jiongde Jin, Shijie Wu, Lun Jia and Xujie Ma

Coatings 2023, 13(10), 1808; https://doi.org/10.3390/coatings13101808 - 21 Oct 2023

Viewed by 943

Abstract

When a curved target surface is coated in an electrostatic spray-painting process, the paint film pattern on curved targets will deform, and the thickness will change compared with the planar target due to the curvature characteristics of the target, the inhomogeneous electric field, [...] Read more.

When a curved target surface is coated in an electrostatic spray-painting process, the paint film pattern on curved targets will deform, and the thickness will change compared with the planar target due to the curvature characteristics of the target, the inhomogeneous electric field, and the flow field. Therefore, directly using the planar deposition distribution for painting the trajectory planning of curved surfaces causes large errors and low paint transfer efficiency. A study investigating the curved surface paint film thickness distribution characteristics is presented in this research to understand the relations among the target surface curvature, the electrostatic field, and the flow field distribution. Spray-painting process simulations were performed for conical surfaces of different curvatures. Moreover, the paint particle’ trajectories, electric potential, and film deposition distribution were computed using ANSYS Fluent. The paint transfer efficiencies of these targets were computed. The results show that when the generatrix curvature of the conical surface increases gradually, the electric field intensity near the wall increases, which enhances the deposition of charged droplets on the wall. Moreover, the airflow field velocity increases as the curvature increases, which leads to a large diffusions of the spray flow field, so the paint thickness decreases, and the transfer efficiency is low. Full article

► Show Figures

Figure 1

16 pages, 6260 KiB

Open AccessArticle

Effect of Microstructure on Electroless Ni Plating Behavior on Super Duplex Stainless Steel SAF2507 in Li-Ion Batteries

by Byung-Hyun Shin, Dohyung Kim, Doo-In Kim, Wookjin Lee and Se-Hun Kwon

Coatings 2023, 13(10), 1807; https://doi.org/10.3390/coatings13101807 - 20 Oct 2023

Cited by 2 | Viewed by 980

Abstract

The demand for Li-ion batteries has significantly increased in recent years, driven by the growing need for electric vehicles and electronic devices like smartphones. Among various materials, super duplex stainless steel (SDSS) is considered a suitable material for Li-ion batteries due to its [...] Read more.

The demand for Li-ion batteries has significantly increased in recent years, driven by the growing need for electric vehicles and electronic devices like smartphones. Among various materials, super duplex stainless steel (SDSS) is considered a suitable material for Li-ion batteries due to its excellent strength and corrosion resistance. However, SDSS is sensitive to heat-treatment conditions, necessitating research on heat treatment and Ni plating for battery case usage. While extensive research has been conducted on SDSS and its heat-treatment conditions, there is a research gap concerning the Ni plating of SDSS. This study addresses this gap by performing Ni plating on heat-treated SDSS. Ni plating can be executed via two methods: electroless and electro-Ni plating. To achieve a uniform plating layer, Ni plating was conducted after heat treatment at temperatures ranging from 1000 °C to 1300 °C, followed by an analysis of the behavior of electroless Ni plating. The heat-treated SDSS displayed three primary characteristics: secondary phase precipitation, solution annealing, and ferritization (ferrite fractions of 61% and 73%). The presence of secondary phases led to a slower Ni plating rate due to its lower reactivity with Ni. Post-solution annealing, the texture of SDSS exhibited the thickest Ni plating layer at the same plating time. As the volume fraction of ferrite increased from 50% to 73% on electrochemical impedance spectroscopy, the resistance of the Ni plating layer decreased from 45 kOhms to 13 kOhms. The lowest resistance was observed when the ferrite fraction reached 73%, attributed to the lower reactivity of ferrite compared to austenite. Both secondary phases and ferrite contributed to reducing the thickness of the electroless Ni plating layer. Therefore, optimizing the volume fraction of SDSS using solution annealing proves beneficial for optimizing Ni plating and enhancing corrosion resistance. Full article

(This article belongs to the Special Issue Recent Advances in Surface Functionalisation)

► Show Figures

Figure 1

20 pages, 47008 KiB

Open AccessArticle

Engineering Process Optimization and Quality Stability Control of High-Speed Laser Cladding Coatings Based on AHP-FCE

by Yifei Xv, Yaoning Sun, Wangjun Cheng and Yuhang Zhang

Coatings 2023, 13(10), 1806; https://doi.org/10.3390/coatings13101806 - 20 Oct 2023

Cited by 1 | Viewed by 832

Abstract

Due to the rapid advancement in processing efficiency, high-speed laser cladding has demonstrated significant potential in the repair and protection of various substrates. In this study, we established a comprehensive evaluation model for the coating quality of Fe-Cr-Ni-based alloy with high-speed laser cladding [...] Read more.

Due to the rapid advancement in processing efficiency, high-speed laser cladding has demonstrated significant potential in the repair and protection of various substrates. In this study, we established a comprehensive evaluation model for the coating quality of Fe-Cr-Ni-based alloy with high-speed laser cladding using the analytic hierarchy process and fuzzy comprehensive evaluation method (AHP-FCE). The weights obtained through the analytic hierarchy process for forming quality, microstructure, and surface performance are as follows: W_B1 = 0.1365, W_B2 = 0.2385, and W_B3 = 0.625, respectively. During the fuzzy comprehensive evaluation step, an evaluation level was graded while quantifying the level range through membership function judgment. By combining subjective and objective evaluations, qualitative issues were transformed into quantitative assessment methods. Through comprehensive evaluation analysis, it was concluded that the scanning speed of high-speed laser cladding had a greater impact on coating thickness compared to powder feeding speed while significantly enhancing microstructure densification. The overlap rate exerted the most influence on dilution rate homogenization of near-surface dendrites. Simultaneously, the optimal preparation technology was determined: laser power 660 W, scanning speed 14,400 mm/min, overlap rate/min. This study transforms multi-objective quality evaluation of high-speed laser cladding coatings into a single objective problem by realizing comprehensive quality quantification and providing a new method for quantitative evaluation and visualization of coating quality. Full article

► Show Figures

Figure 1

0 pages, 3449 KiB

Open AccessArticle

Suppression of Secondary Electron Emissions on the Graphene-Coated Polyimide Materials Prepared by Chemical Vapor Deposition

by Xin Qi, Yanzhao Ma, Sisheng Liu, Xiangyu Nie, Tao Zhang, Yong Wu, Weiping Peng and Guoming Hu

Coatings 2023, 13(10), 1805; https://doi.org/10.3390/coatings13101805 - 20 Oct 2023

Cited by 3 | Viewed by 1142

Abstract

Polyimide thin-film materials are widely used in aerospace and particle gas pedals, etc., but the phenomenon of secondary electron emission occurred under vacuum conditions. The graphene-coated polyimide materials were prepared for this phenomenon to suppress secondary electron emissions. The graphene coating was prepared [...] Read more.

Polyimide thin-film materials are widely used in aerospace and particle gas pedals, etc., but the phenomenon of secondary electron emission occurred under vacuum conditions. The graphene-coated polyimide materials were prepared for this phenomenon to suppress secondary electron emissions. The graphene coating was prepared on the polyimide surface through chemical vapor deposition (CVD). Scanning electron microscope images (SEM), X-ray photoelectron spectrometer images (XPS), Raman spectroscopy, atomic force microscopy (AFM), and other analytical methods were used to characterize the properties of the prepared materials. The C1s XPS fine spectra and Raman curve analyses showed that the material has an abundant sp2 hybridized structure, and the sp2 structure can reduce secondary electron emissions. The C, O, and N contents in the tested samples were 65.85, 20.47, and 13.68 at.%, respectively. It was examined that the graphene coating had an inhibitory effect on the secondary electron emissions of polyimide materials, and the secondary electron emission yield (SEY) was significantly reduced. The results of secondary electron tests showed that the maximum SEY (δmax) of the polyimide material decreased from 1.72 to 1.52 after the preparation of the graphene coating. The mechanism of using a graphene coating to reduce the SEY of polyimide was analyzed from experimental and theoretical perspectives. The results of this study can provide research ideas for polyimide thin film materials in aerospace, particle gas pedals, and other applications. Full article

(This article belongs to the Special Issue Carbon and Carbon-Based Composite Thin Films/Coatings: Synthesis, Properties and Applications)

► Show Figures

Figure 1

10 pages, 7354 KiB

Open AccessEditor’s ChoiceArticle

Tribo-Catalytic Degradation of Methyl Orange Solutions Enhanced by Silicon Single Crystals

by Xiaodong Cui, Zhiyu Guo, Hua Lei, Xuchao Jia, Chenyue Mao, Lujie Ruan, Xiaoyuan Zhou, Zhu Wang, Feng Chen and Wanping Chen

Coatings 2023, 13(10), 1804; https://doi.org/10.3390/coatings13101804 - 20 Oct 2023

Cited by 1 | Viewed by 1782

Abstract

Coating materials on the bottoms of reactors/beakers has emerged as an effective method to regulate tribo-catalytic reactions. In this study, silicon single crystals were coated on the bottoms of glass beakers, in which 30 mg/L methyl orange (MO) solutions suspended with alumina nanoparticles [...] Read more.

Coating materials on the bottoms of reactors/beakers has emerged as an effective method to regulate tribo-catalytic reactions. In this study, silicon single crystals were coated on the bottoms of glass beakers, in which 30 mg/L methyl orange (MO) solutions suspended with alumina nanoparticles were subjected to magnetic stirring using Teflon magnetic rotary disks. With a gentle rotating speed of 400 rpm for the Teflon disks, the MO solutions were changed from yellow to colorless and the characteristic absorption peak of MO at 450 nm in the UV-Vis spectrum disappeared entirely within 120 min. Mass spectrometry tests were further performed to gain insights into the degradation process, which suggested that the degradation was initiated with the cleavage of the nitrogen-nitrogen double bond in ionized MO molecules by the attack of •OH radicals. Through comparison experiments, we established that the observed degradation was related to the friction between alumina and silicon during magnetic stirring, and hydroxyl and superoxide radicals were formed from the friction, according to electron paramagnetic resonance analysis. It is proposed that electron-hole pairs are excited in silicon single crystals through friction with alumina, which diffuse to the surface of the single crystals and result in the degradation. Full article

(This article belongs to the Special Issue Advanced Materials for Electrocatalysis and Energy Storage)

► Show Figures

Figure 1

0 pages, 24607 KiB

Open AccessArticle

Study on the Rapid Degradation Performance of Salix/Wheat Straw Fiber Degradable Film

by Yuehui Liang, Qian Zhang, Bo Wang, Zhanpeng Liang and Xin Wang

Coatings 2023, 13(10), 1803; https://doi.org/10.3390/coatings13101803 - 20 Oct 2023

Cited by 2 | Viewed by 1010 | Correction

Abstract

The preparation of biodegradable mulch film to replace non-degradable mulch film is of great significance for reducing the harm of non-degradable agricultural mulch film to the environment. However, there are few studies on the degradation performance and degradation mechanisms of degradable cellulose mulch. [...] Read more.

The preparation of biodegradable mulch film to replace non-degradable mulch film is of great significance for reducing the harm of non-degradable agricultural mulch film to the environment. However, there are few studies on the degradation performance and degradation mechanisms of degradable cellulose mulch. Therefore, the wet papermaking process was adopted in this work. Salix fiber and wheat straw fiber were used as raw materials. A Salix/wheat straw fiber degradable film was prepared by adding cationic polyacrylamide, alkyl ketene dimer, and paraffin emulsion. The degradation process of cellulose film was studied using a UV degradation test and an acid-base degradation test system. The results showed that after 40 days of UV degradation, the degradation rate of Salix/wheat straw fiber degradable film could reach 6.66%. The tensile strength could still maintain 2.878 KN/m. The results of the brightness change index (

Δ

L) and color overall change index (

Δ E

) showed that the surface of the Salix/wheat straw fiber degradable film had been successfully partially degraded. After 4 days of alkaline degradation, the degradation rate could reach 11.89%. After 4 days of acid degradation, the degradation rate could reach 14.64%. At the same time, the specific degradation process of Salix/wheat straw fiber degradable film was further studied by infrared spectroscopy and scanning electron microscopy. This work provides a new method for the study of agricultural degradable cellulose mulch, which is of great significance for the future development of agricultural mulch. Full article

(This article belongs to the Special Issue Polymer Films/Membranes: Structure, Properties, and Applications)

► Show Figures

Figure 1

17 pages, 9768 KiB

Open AccessEditor’s ChoiceArticle

Experimental Evaluation of the Properties of Asphalt Binders Modified with Calcium Sulfate Anhydrous Whiskers and Polyester Fibers

by Taotao Fan, Chundi Si and Junfeng Gao

Coatings 2023, 13(10), 1802; https://doi.org/10.3390/coatings13101802 - 20 Oct 2023

Viewed by 772

Abstract

The use of waste calcium sulfate whiskers in pavement construction is cost-effective and beneficial to the environment. In this paper, modified asphalt binders are prepared by adding calcium sulfate anhydrous whiskers (ACSW, 9 wt.%,11 wt.%, and 13 wt.% by weight of asphalt binder) [...] Read more.

The use of waste calcium sulfate whiskers in pavement construction is cost-effective and beneficial to the environment. In this paper, modified asphalt binders are prepared by adding calcium sulfate anhydrous whiskers (ACSW, 9 wt.%,11 wt.%, and 13 wt.% by weight of asphalt binder) and polyester fibers (4 wt.%,6 wt.%, and 8 wt.% by weight of asphalt binder). The viscosity-temperature, rheological, and low-temperature properties of the modified asphalt binder were evaluated using the Brookfield rotational viscosity test, the dynamic shear rheometer (DSR) test, the bending beam rheometer (BBR) test, and the force ductility test. The results demonstrated that the addition of the ACSW and polyester fiber could improve the anti-deformation and low-temperature properties of the asphalt binders, but reduce their viscosity-temperature properties to some extent. The modified asphalt binder with 11 wt.% ACSW and 8% polyester fiber showed the best anti-deformation property, while the 11 wt.% ACSW and 6 wt.% polyester fiber modified asphalt binder had a better low-temperature performance. The force ductility test was more suitable than the BBR test to characterize the low-temperature properties of the modified asphalt binders. The Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) tests were conducted to study the functional groups and micro-structure of the modified asphalt binders, and the results indicated that no new functional groups were generated and that the interaction between the ACSW, polyester fiber, and asphalt binder was a physical adsorption and interleaving process. Full article

(This article belongs to the Special Issue Novel Cleaner Materials for Pavements)

► Show Figures

Figure 1

9 pages, 4166 KiB

Open AccessArticle

Crosstalk Reduction in High-Density Radio Frequency Printed Circuit Boards: Leveraging FR4 Coating Layers

by Vaidotas Barzdenas and Aleksandr Vasjanov

Coatings 2023, 13(10), 1801; https://doi.org/10.3390/coatings13101801 - 20 Oct 2023

Viewed by 813

Abstract

The escalating component density in radio frequency (RF) systems presents a growing challenge related to the coupling of adjacent microstrip lines in high-density printed circuit boards (PCBs). As a result, to tackle this prominent issue, there is a continuous pursuit of innovative techniques [...] Read more.

The escalating component density in radio frequency (RF) systems presents a growing challenge related to the coupling of adjacent microstrip lines in high-density printed circuit boards (PCBs). As a result, to tackle this prominent issue, there is a continuous pursuit of innovative techniques to effectively minimize the coupling effects among closely spaced microstrip lines. This paper proposes a reduction in the coupling of adjacent lines by utilizing a coating (stiffener) layer, which is commonly used in rigid-flex PCB fabrication. For this purpose, a reference 50 Ohm coupled line performance was compared to three coupled lines with track widths of 1.39 mm, 1.30 mm, and 1.25 mm, respectively, all at a fixed distance between the tracks. These decreasing widths were used to achieve the same 50 Ohm impedance for the coupled lines when covered with different coating layers. Each of these three coupled lines was covered with different coating (stiffener) layers, measuring 0.1 mm, 0.3 mm, and 0.5 mm in thickness, respectively. The manufactured device under test (DUT) structures underwent time-domain reflectometry (TDR) and S-parameter measurements. The TDR measurements of the DUT structures with coating layers demonstrated excellent conformity to the 50 Ohm reference coupled line. Meanwhile, the S21 measurements indicated a significant decrease in the crosstalk. For example, for a coating layer thickness of 0.3 mm, the crosstalk decreased by approximately 5–6 dB within the frequency range up to 5 GHz. When the coating layer thickness was 0.5 mm, the crosstalk decreased by approximately 10 dB or more. Full article

► Show Figures

Figure 1

13 pages, 2680 KiB

Open AccessArticle

Fabrication of Cr₂AlB₂ and Cr₄AlB₄ MAB Phase Coatings by Magnetron Sputtering and Post-Annealing

by Ke Jia, Guojing Wang, Shasha Lv, Yan Li, Shengjie Du and Zhengcao Li

Coatings 2023, 13(10), 1800; https://doi.org/10.3390/coatings13101800 - 20 Oct 2023

Viewed by 806

Abstract

Cr₂AlB₂ and Cr₄AlB₄ are members of the MAB phases that exhibit unique properties of both metals and ceramics. However, despite these unique characteristics, Cr₂AlB₂ and Cr₄AlB₄ phase coatings have not been [...] Read more.

Cr₂AlB₂ and Cr₄AlB₄ are members of the MAB phases that exhibit unique properties of both metals and ceramics. However, despite these unique characteristics, Cr₂AlB₂ and Cr₄AlB₄ phase coatings have not been widely investigated. In this study, Cr₂AlB₂ and Cr₄AlB₄ MAB phase coatings were fabricated by magnetron sputtering at room temperature and post-annealing. A composite target, consisting of a phase-pure disc-shaped CrB target overlapped by uniformly dispersed fan-shaped Al slices, was placed parallel to the substrates. The Al content of the coatings was adjusted by altering the areal proportion of the Al slices. MAB phases have crystallized upon post-annealing the as-deposited coatings on Al₂O₃(0001) substrates in Ar. The phase compositions and morphologies of the crystalline coatings were found to be dependent on the Al content and the annealing temperature. As-deposited coatings with a Cr:Al:B ratio close to 2:1:2 could crystallize as pure and dense Cr₂AlB₂ phases within the temperature range of 650–800 °C; higher annealing temperatures resulted in the decomposition of Cr₂AlB₂, while crystallization at lower temperatures was not evident from X-ray diffraction. As-deposited coatings with a Cr:Al:B ratio close to 3:1:3, despite containing a relatively higher Al content than required by the stoichiometry of Cr₄AlB₄, exhibited insufficient crystallization of Cr₄AlB₄ with unknown phases below 840 °C. Higher annealing temperatures resulted in the coexistence of Cr₄AlB₄ and CrB, indicating that achieving phase-pure and well-crystallized Cr₄AlB₄ coatings proved challenging, possibly due to the inevitable loss of Al during annealing. The configuration of the composite target and the substrates provides a promising strategy for fabricating phase-pure and dense Cr₂AlB₂ coatings. Full article

► Show Figures

Figure 1

15 pages, 3962 KiB

Open AccessArticle

Study of Asphalt Behavior on Pre-Wet Aggregate Surface Based on Molecular Dynamics Simulation and Surface Energy Theory

by Yaoxi Cao, Yanhua Wang, He Li and Wuxing Chen

Coatings 2023, 13(10), 1799; https://doi.org/10.3390/coatings13101799 - 20 Oct 2023

Viewed by 752

Abstract

The improvement of the performance of asphalt mixtures has been studied by scholars. This research proposes a new asphalt–mineral interface formation method, which is a pre-wet bitumen–mineral mixture. The formation process of the pre-wet asphalt–mineral interface was simulated by molecular dynamics simulation software. [...] Read more.

The improvement of the performance of asphalt mixtures has been studied by scholars. This research proposes a new asphalt–mineral interface formation method, which is a pre-wet bitumen–mineral mixture. The formation process of the pre-wet asphalt–mineral interface was simulated by molecular dynamics simulation software. The diffusion coefficient, concentration distribution, and interfacial energy of the asphalt on the surface of the pre-wet mineral material and non-pre-wet mineral material were compared and analyzed. The simulation results show that the mineral surface diffusion rate of the asphalt after pre-wetting is increased by more than 50%, and the concentration in the X, Y, and Z directions is reduced by 0.8%, 4.6%, and 7.8%, respectively. At the same time, the interface energy between the bitumen and the pre-wet mineral was increased by more than 8%. The results of the molecular dynamics model are verified based on the surface energy theory and contact angle test. The experimental results show that the contact angle of the asphalt is smaller and the diffusion performance is better after pre-wetting. At the same time, the interface adhesion work between the asphalt and wet mineral surface increased by 4.3% in a dry environment, and the peeling work decreased by 41.1% in a water environment. Therefore, the author believes that the pre-wetting technology of the asphalt mixture has a certain feasibility and practicability. Full article

► Show Figures

Figure 1

14 pages, 23632 KiB

Open AccessArticle

Polychromy in the Iberian Sculptures of Cerrillo Blanco: Analytical Study, Historical Context and State of Conservation

by Julio Romero-Noguera, María Belén Ruiz-Ruiz, María Teresa Doménech-Carbó and Fernando Bolívar-Galiano

Coatings 2023, 13(10), 1798; https://doi.org/10.3390/coatings13101798 - 20 Oct 2023

Viewed by 758

Abstract

In the environs of the city of Ipolca, today’s town of Porcuna (Jaén), the Iberian civilisation left behind one of the most outstanding sculptural ensembles of Antiquity, made up of 27 groups of figures and hundreds of fragments dating from the 7th to [...] Read more.

In the environs of the city of Ipolca, today’s town of Porcuna (Jaén), the Iberian civilisation left behind one of the most outstanding sculptural ensembles of Antiquity, made up of 27 groups of figures and hundreds of fragments dating from the 7th to the 2nd centuries BC. Despite its great relevance, there are very few scientific studies that serve as a basis for understanding the many questions that remain about how they were made, their significance, and their relationship to the culture that gave rise to them. This article studies the polychrome techniques used in the sculptures and puts them into context in Iberian art. The research has been carried out on original pieces from the Archaeological Museum of Jaén using stereoscopic optical microscopy (SOM), petrographic microscopy (PM), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX). Full article

(This article belongs to the Special Issue Materials Characterization and Surface Analysis for Cultural Heritage)

► Show Figures

Figure 1

25 pages, 5993 KiB

Open AccessArticle

Surface Modifications of Superparamagnetic Iron Oxide Nanoparticles with Polyvinyl Alcohol, Chitosan, and Activated Carbon or Graphite as Methylene Blue Adsorbents—Comparative Study

by Linh Doan, Tu M. D. Nguyen, Tan M. Le, Khanh G. Huynh and Tran P. T. Quach

Coatings 2023, 13(10), 1797; https://doi.org/10.3390/coatings13101797 - 20 Oct 2023

Cited by 1 | Viewed by 971

Abstract

Adsorption is a popular technique and has been investigated with many different materials for removing synthetic dyes from textile wastewater. This study compares the methylene blue (MB) adsorption capabilities of surface-modified superparamagnetic iron oxide nanoparticles, (SPION) using polyvinyl alcohol (PVA) and chitosan (CS), [...] Read more.

Adsorption is a popular technique and has been investigated with many different materials for removing synthetic dyes from textile wastewater. This study compares the methylene blue (MB) adsorption capabilities of surface-modified superparamagnetic iron oxide nanoparticles, (SPION) using polyvinyl alcohol (PVA) and chitosan (CS), combined with two carbon materials, activated carbon (AC) and graphite (GR), respectively. After 9 days, depending on the initial MB loading concentration (0.015 mg/mL, 0.02 mg/mL, and 0.025 mg/mL), the MB adsorption capacities onto SPION/PVA/CS/AC and SPION/PVA/CS/GR were 7.6 ± 0.2–22.4 ± 0.05 and 6.9 ± 0.02–22.4 ± 0.05 mg/g, respectively. The cumulative release percentages of SPION/PVA/CS/AC and SPION/PVA/CS/GR after 30 days were 63.24 ± 8.77%–22.10 ± 2.59% and 91.29 ± 12.35%–24.42 ± 1.40%, respectively. Additionally, both SPION/PVA/CS/AC and SPION/PVA/CS/GR can both fit the Freundlich isotherm model. The adsorption and desorption kinetics can be fitted to the pseudo-second-order linear and zeroth-order models, respectively. At 0.020 mg/mL MB initial loading, out of SPION/PVA/CS/AC, SPION/PVA/CS/GR, and SPION/PVA/CS/GO, SPION/PVA/CS/AC is the most economical adsorbent. Compared to SPION/PVA/AC, SPION/PVA/CS/AC is less economical. Since CS has antimicrobial properties, antimicrobial activities should be investigated to conclude which adsorbent is more promising: SPION/PVA/AC or SPION/PVA/CS/AC. Full article

► Show Figures

Figure 1

16 pages, 4725 KiB

Open AccessArticle

The Corrosion Behavior of Different Silver Plating Layers as Electrical Contact Materials in Sulfur-Containing Environments

by Bingkun Yang, Yun Chen, Wenkui Hao, Yu Han, Qiang Zhang, Yujie Li, Xiaofang Wang, Luyao Huang and Yiliang Lu

Coatings 2023, 13(10), 1796; https://doi.org/10.3390/coatings13101796 - 20 Oct 2023

Cited by 2 | Viewed by 1707

Abstract

Isolation switching devices are vital components in power grids. During their operational lifespan, these devices are prone to corrosion failure in atmospheric environments. To enhance conductivity and corrosion resistance, silver plating is applied to the contact surface of high-voltage switches. Common methods include [...] Read more.

Isolation switching devices are vital components in power grids. During their operational lifespan, these devices are prone to corrosion failure in atmospheric environments. To enhance conductivity and corrosion resistance, silver plating is applied to the contact surface of high-voltage switches. Common methods include graphite-Ag (G-Ag) coating, graphene-Ag (Gr-Ag) coating, and Ag-Sn coating. In this article, the corrosion resistance performance of silver plating, G-Ag coating, Gr-Ag coating, and Ag-Sn coating was studied. Firstly, adhesion tests were conducted on the plating layers. Subsequently, immersion experiments were performed to evaluate the corrosion resistance of the samples. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and laser confocal microscopy were used to analyze the morphology and elemental composition of the samples. Raman spectroscopy was used to analyze corrosion products. An electrochemical workstation was employed to study the electrochemical behavior of the samples. The adhesion results indicate that the adhesion of the plating layers is excellent. The immersion and electrochemical results showed the corrosion resistance order of the four Ag coatings was Ag-Sn coating > Gr-Ag coating > Ag coating > G-Ag coating. Full article

(This article belongs to the Special Issue Microstructure and Corrosion Behavior of Metallic Materials)

► Show Figures

Figure 1

17 pages, 12782 KiB

Open AccessArticle

Thermal–Fluid–Solid Coupling Analysis on the Effect of Cooling Gas Temperature on the Fatigue Life of Turbine Blades with TBCs

by Yingtao Chen, Ziliang Zhang, Yanting Ai, Peng Guan, Yudong Yao and Hongwei Liu

Coatings 2023, 13(10), 1795; https://doi.org/10.3390/coatings13101795 - 20 Oct 2023

Viewed by 915

Abstract

The application of thermal barrier coatings (TBCs) can increase the blade’s operating temperature and fatigue life. Previous studies have neglected the effects of cooling gas temperature variations on the temperature field, stress field, and fatigue life of blades and TBCs. For this reason, [...] Read more.

The application of thermal barrier coatings (TBCs) can increase the blade’s operating temperature and fatigue life. Previous studies have neglected the effects of cooling gas temperature variations on the temperature field, stress field, and fatigue life of blades and TBCs. For this reason, this paper considers the inhomogeneity of the high-temperature gas inlet temperature, the internal cooling gas temperature, the periodicity of the external flow field, etc., and establishes a finite element model of the gas turbine blade with TBCs. Then, the life of the blade and the TBCs is predicted based on the Ncode 2020R2. Finally, the effect of the cooling gas temperature on the temperature, stresses, and life of the blade and the TBCs is analyzed. The results show that the fatigue life of the TBCs is lower than that of the blade, and the low-life region of the TBCs is located at the leading edge of the blade, which is consistent with the TBCs shedding region of the real blade and verifies the accuracy of the life prediction method in this paper. The fatigue life of the blade and TBCs firstly increases and then decreases with the increase in the cooling gas temperature, and the trend of the stress changes in the opposite direction. When the cooling gas temperature is increased from 573 K to 873 K, the minimum life of the blade is increased by 358.5%, and that of the TBCs is increased by 138.7%. The conclusions can provide guidance for the design of long-life turbine blades with TBCs. Full article

► Show Figures

Figure 1

10 pages, 917 KiB

Open AccessArticle

Highly Improved PID Stability for Cu(In,Ga)Se₂ Solar Modules Due to a Filled P1 Groove

by Oliver Salomon, Erwin Lotter and Jan-Philipp Becker

Coatings 2023, 13(10), 1794; https://doi.org/10.3390/coatings13101794 - 19 Oct 2023

Cited by 1 | Viewed by 814

Abstract

Two types of Cu(In,Ga)Se₂ (CIGS) thin-film solar modules, differing only in the patterning procedures, were exposed to a high voltage (1 kV) across the thickness of the soda-lime glass substrate. Both module types utilized a cell stack, and in particular, a molybdenum [...] Read more.

Two types of Cu(In,Ga)Se₂ (CIGS) thin-film solar modules, differing only in the patterning procedures, were exposed to a high voltage (1 kV) across the thickness of the soda-lime glass substrate. Both module types utilized a cell stack, and in particular, a molybdenum back contact, which was optimized for CIGS solar cells with enhanced stability against potential-induced degradation (PID). A standard module with regular patterning lines for monolithic interconnection consists of P1, P2, and P3 lines, with P1 separating the back contact, P2 establishing the contact between the front contact TCO of one cell to the Mo back contact of the next cell, and P3 isolating the front contact from one cell to the next cell. However, modules employing this cell stack with regular patterning lines P1, P2, and P3 suffered considerably from PID while modules with a P1 groove filled with an insulator showed greatly enhanced stability similar to the pure single cell without P1 patterning. PID manifests once a specific quantity of charge has been transmitted through the soda-lime glass substrate, while the molybdenum back contact of the cell functions as the cathode, maintaining a negative bias relative to the substrate’s backside. As a consequence of PID, sodium is increased in the adsorber for susceptible cells. Therefore, inhibiting sodium transport through the P1 groove by filling it with an insulating material enhances the PID stability of the modules considerably. As a result, the modules with a filled P1 groove showed similar stability to the single solar cells with an improved PID stable cell stack, while modules without a filled P1 patterning were much more susceptible to PID, although a cell stack with greatly enhanced PID stability was used. In summary, the presented strategy to fill the P1 groove offers a viable and novel path to improved PID stability of CIGS modules. Full article

(This article belongs to the Section Thin Films)

► Show Figures

Figure 1

15 pages, 12789 KiB

Open AccessArticle

The Tribological Properties of Low-Sulfur and Low-Phosphorus Halogen-Free Ionic Liquids as Lubricants for the Nickel-Based Alloy Inconel 690

by Bian Guo, Mengnan Liu, Yan Li, Jianming Zheng, Xubo Li, Chao Peng, Zhangshuai Jing, Feizhou Li and Qiangliang Yu

Coatings 2023, 13(10), 1793; https://doi.org/10.3390/coatings13101793 - 19 Oct 2023

Viewed by 791

Abstract

In this study, we synthesized three low-sulfur and low-phosphorus ionic liquids (ILs). These were N₈₈₈₁₆P₈, P₈₈₈₁₆P₈, and P₈₈₈₁₆DOSS. The viscosity and thermal stability of the three ILs were analyzed. The tribological properties and [...] Read more.

In this study, we synthesized three low-sulfur and low-phosphorus ionic liquids (ILs). These were N₈₈₈₁₆P₈, P₈₈₈₁₆P₈, and P₈₈₈₁₆DOSS. The viscosity and thermal stability of the three ILs were analyzed. The tribological properties and lubrication mechanisms of the three ILs were investigated as lubricants for a carbide ball–Inconel 690 nickel-based alloy friction pair and compared at 50 °C and 150 °C. The wear spots of the carbide ball and nickel-based alloy disc samples were characterized using SEM and EDS. The experimental results revealed that P₈₈₈₁₆P₈ had excellent tribological properties. The lubrication mechanism of P₈₈₈₁₆P₈ as a lubricant for the carbide ball–Inconel 690 nickel-based alloy friction pair was investigated using XPS. The excellent friction reduction and anti-wear properties of P₈₈₈₁₆P₈ could be attributed to the tribo-chemistry between P₈₈₈₁₆P₈ and Inconel 690 as well as the formation of a tribo-film on the wear-spot surface. This high-performance IL, suitable for carbide ball–Inconel 690 contact, will be applied to a cutting process of Inconel 690. Full article

► Show Figures

Figure 1

19 pages, 21095 KiB

Open AccessArticle

Fabrication of Superhydrophobic Coatings by Using Spraying and Analysis of Their Anti-Icing Properties

by Lei Fan, Mingyong Xia, Jian Liu, Bo Li, Tao Zhu, Yingying Zhao, Linbo Song and Yuan Yuan

Coatings 2023, 13(10), 1792; https://doi.org/10.3390/coatings13101792 - 19 Oct 2023

Cited by 2 | Viewed by 1086

Abstract

Ice accumulation on glass insulators is likely to cause faults such as flashover, tripping and power failure, which interfere with the normal operation of the power grid. Accordingly, superhydrophobic coatings with great anti-icing potential have received much attention. In this study, three superhydrophobic [...] Read more.

Ice accumulation on glass insulators is likely to cause faults such as flashover, tripping and power failure, which interfere with the normal operation of the power grid. Accordingly, superhydrophobic coatings with great anti-icing potential have received much attention. In this study, three superhydrophobic coatings (PTFE, Al₂O₃ and SiO₂) were successfully prepared on glass surfaces by using one-step spraying. The microscopic morphology, wettability, anti-icing and anti-glaze icing properties of the superhydrophobic coatings were comparatively analyzed. The results indicated that the PTFE coating had a densely distributed rough structure, showing a contact angle of 165.5° and a sliding angle of 3.1°. The water droplets on the surface could rebound five times. Compared with the Al₂O₃ and SiO₂ coatings, the anti-icing performance of the PTFE coating was significantly improved. The freezing time was far more than 16 times that of glass (4898.7 s), and the ice adhesion strength was 9 times lower than that of glass (27.5 kPa). The glaze icing test in the artificial climate chamber showed that the icing weight of the PTFE coating was 1.38 g, which was about 32% lower than that of the glass. In addition, the icing/melting and abrasion cycles destroyed the low-surface-energy substances and nanostructures on the surface, leading to the degradation of the anti-icing durability of the PTFE coatings. However, the PTFE coating still maintained excellent hydrophobicity and anti-icing properties after UV irradiation for up to 624 h. The superhydrophobic coatings prepared in this work have promising development prospects and offer experimental guidance for the application of anti-icing coatings on glass insulators. Full article

(This article belongs to the Special Issue Durability of Transmission Lines)

► Show Figures

Figure 1

12 pages, 6512 KiB

Open AccessArticle

Biodegradable Conductive Layers Based on a Biopolymer Polyhydroxybutyrate/Polyhydroxyvalerate and Graphene Nanoplatelets Deposited by Spray-Coating Technique

by Sandra Lepak-Kuc, Katarzyna Wójkowska, Dorota Biernacka, Aleksandra Kądziela, Tomasz Tadeusz Murawski, Daniel Janczak and Małgorzata Jakubowska

Coatings 2023, 13(10), 1791; https://doi.org/10.3390/coatings13101791 - 19 Oct 2023

Viewed by 1043

Abstract

In light of the growing concern for environmental protection and the alarming amount of waste produced due to hygiene regulations, this study suggests a biodegradable and eco-friendly solution that could make a significant contribution to the preservation of our planet. The developed solution [...] Read more.

In light of the growing concern for environmental protection and the alarming amount of waste produced due to hygiene regulations, this study suggests a biodegradable and eco-friendly solution that could make a significant contribution to the preservation of our planet. The developed solution was based on a polyhydroxybutyrate/polyhydroxyvalerate biopolymer, which has been tested regarding its physicochemical parameters and possible use in printed electrically conductive structures. Graphene nanoplatelets have been used as the conductive functional phase, due to literature reports of their potential use in biomedical applications and due to the potential of providing cytocompatibility in electrical structures by carbon nanomaterials. Prepared composites have been spray-coated onto PET film and paper substrates and then subjected to electrical, adhesion and optical measurements. In order to establish the conductivity of the developed composite, its resistance, layer thickness and surface topography were measured. Optical parameters have been specified using scanning electron microscopy (SEM) imaging and spectrophotometry. The conducted research opens a wide path for the use of the polyhydroxybutyrate/polyhydroxyvalerate biopolymer with graphene nanoplatelets in biomedical applications, ensuring good conductivity, biocompatibility and stability. Full article

(This article belongs to the Special Issue Trends in Coatings and Surface Technology)

► Show Figures

Graphical abstract

15 pages, 5078 KiB

Open AccessArticle

Authentication of Roasted Coffee Beans via LIBS: Statistical Principal Component Analysis

by Fatemah H. Alkallas, Ayman M. Mostafa, Effat A. Rashed, Amira Ben Gouider Trabelsi, M. A. I. Essawy and Reham A. Rezk

Coatings 2023, 13(10), 1790; https://doi.org/10.3390/coatings13101790 - 18 Oct 2023

Cited by 1 | Viewed by 962

Abstract

Great efforts are constantly being made by industry-specific coffee agencies to standardize the certification of coffee quality. In consequence, international trade requires quick and reliable analyses because of their high cost, the risk of misclassification, the difficulty of large-scale analysis, and, most importantly, [...] Read more.

Great efforts are constantly being made by industry-specific coffee agencies to standardize the certification of coffee quality. In consequence, international trade requires quick and reliable analyses because of their high cost, the risk of misclassification, the difficulty of large-scale analysis, and, most importantly, the subjectivity generated by tasters. A powerful analytical method that can be used to accurately evaluate and identify coffee varieties is Laser-Induced Breakdown Spectroscopy (LIBS). In this study, it provided a quick, cost-effective, and residue-free method commonly used in laboratories for direct analysis, determining multi-elemental composition, and exploring the organic composition of roasted coffee. The mineral composition of eight varieties of pure roasted coffee was determined using a pulsed nanosecond laser produced from a Nd:YAG laser at 1064 nm. The most important spectral variables for coffee variety identification were sequestered using LIBS coupled with a chemometric-tool-based principal component analysis (PCA). The nine main wavelengths chosen corresponded to the elements of C(I), Mg(II, I), Ca(II), Fe(I), K(I), H(I), and O(I), in addition to the CN group. The overall findings indicated that using LIBS to identify coffee varieties is feasible based on a simple, quick, and eco-friendly strategy without the requirement for complex preparation or wasting time in preparation. Such studies can help to protect the coffee market and businesses by certifying product quality. Using LIBS and full statistical illustrations with PCA, the prevention of unfair competition, protection of consumers, and determination of coffee quality can be achieved. Full article

► Show Figures

Figure 1

15 pages, 3728 KiB

Open AccessArticle

The 2′,4′-Dichloro-chalcone Inhibits the In Vitro Growth and Pathogenicity of Fusarium tricinctum and Trichothecium roseum by Activating Cyanide-Resistant Respiration

by Fupeng Zhu, Yan Zhu, Yuanshou Zhao, Fu Chen, Wenjun Sheng, Wei Zhang, Pengqing Wang, Jiangwen Deng, Yunyu Sun, Weibing Zhang and Yongcai Li

Coatings 2023, 13(10), 1789; https://doi.org/10.3390/coatings13101789 - 18 Oct 2023

Viewed by 839

Abstract

Chalcones are a class of flavonoids possessing antimicrobial properties and have potential for use as coatings of plant products for the control of postharvest diseases. The effects of 2′,4′-dichloro-chalcone on the in vitro growth and in vivo pathogenicity of Fusarium tricinctum and Trichothecium [...] Read more.

Chalcones are a class of flavonoids possessing antimicrobial properties and have potential for use as coatings of plant products for the control of postharvest diseases. The effects of 2′,4′-dichloro-chalcone on the in vitro growth and in vivo pathogenicity of Fusarium tricinctum and Trichothecium roseum were investigated. First, 1 µM of 2′,4′-dichloro-chalcone strongly inhibited the mycelial growth and conidial production of F. tricinctum (32.3%) and T. roseum (65.2%) in vitro. Meanwhile, the cell membrane permeability was increased by 25% and 22.5% and the accumulation of reactive oxygen species was increased by 41.7 and 65.4%, respectively, of F. tricinctum and T. roseum. This treatment also significantly inhibited the total respiration rate and activated the cyanide-resistant respiratory pathway in both pathogens. The expression level of AOX was enhanced in F. tricinctum and T. roseum by 52.76 and 39.13%, respectively. This treatment also significantly inhibited the expansion of potato dry rot from F. tricinctum (48.6%) and apple rot spot from T. roseum (36.2%). Therefore, 2′,4′-dichloro-chalcone has potential use as an alternative safety method in the control of postharvest diseases by F. tricinctum and T. roseum in agricultural practices. Full article

(This article belongs to the Special Issue Bio-Based and Bio-Inspired Polymers and Composites)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Coatings, Volume 13, Issue 10 (October 2023) – 158 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI