Coatings

15 pages, 16156 KiB

Open AccessArticle

Microstructure and Wear Resistance of a Cr₇C₃ Reinforced Ni₃Al Composite Coating Prepared by Laser Cladding

by Zhenbo Liu, Fuxing Yin, Cuixin Chen, Lin Zhao, Lihua Fu, Yingkai Feng, Yang Cao, Yun Peng, Zhiling Tian and Changhai Li

Coatings 2022, 12(1), 105; https://doi.org/10.3390/coatings12010105 - 17 Jan 2022

Cited by 9 | Viewed by 3353

Abstract

Using Cr₇C₃/Ni₃Al alloyed powder and Cr₃C₂/Ni₃Al mixed powder, laser cladding was carried out to prepare a Cr₇C₃ reinforced Ni₃Al composite cladding layer. The microstructure and tribological [...] Read more.

Using Cr₇C₃/Ni₃Al alloyed powder and Cr₃C₂/Ni₃Al mixed powder, laser cladding was carried out to prepare a Cr₇C₃ reinforced Ni₃Al composite cladding layer. The microstructure and tribological properties of the cladding materials were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), and wear tests. The results indicate that the microstructure of the Cr₇C₃/Ni₃Al alloyed powder cladding layer contains mainly Ni₃Al, NiAl, and in situ-formed Cr₇C₃, whereas Cr₃C₂ occurs in the Cr₃C₂/Ni₃Al mixed powder cladding layer. The friction coefficient and wear loss of the alloyed powder cladding layer are about 0.1 and 0.75 mg, respectively, which are less than those of the mixed powder cladding layer (0.12 and 0.8 mg). Moreover, the alloyed powder cladding layer is much friendlier to its counterpart. The counterpart’s loss weight of the alloyed powder cladding layer decreases 42.2% than the mixed powder cladding layer. The reason can be attributed to the homogeneous distribution of fine in situ-formed Cr₇C₃ in the alloyed powder cladding materials, which can effectively separate the friction pair, improving the wear resistance of the cladding materials. Full article

(This article belongs to the Topic Laser Surface Modification of Cemented Carbides, Superalloys, Composites, and Alloys)

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28 pages, 5214 KiB

Open AccessArticle

Multi-Response Optimization of Surface Grinding Process Parameters of AISI 4140 Alloy Steel Using Response Surface Methodology and Desirability Function under Dry and Wet Conditions

by Rakesh Roy, Sourav Kumar Ghosh, Tanvir Ibna Kaisar, Tazim Ahmed, Shakhawat Hossain, Muhammad Aslam, Mosab Kaseem and Md Mahfuzur Rahman

Coatings 2022, 12(1), 104; https://doi.org/10.3390/coatings12010104 - 17 Jan 2022

Cited by 11 | Viewed by 3163

Abstract

The effect of four controllable input process parameters of AISI 4140 steel, cross-feed, workpiece velocity, wheel velocity, and the depth of cut were experimentally investigated under dry and wet conditions. Three responses, contact temperature, material removal rate (MRR), and machining cost during surface [...] Read more.

The effect of four controllable input process parameters of AISI 4140 steel, cross-feed, workpiece velocity, wheel velocity, and the depth of cut were experimentally investigated under dry and wet conditions. Three responses, contact temperature, material removal rate (MRR), and machining cost during surface grinding of AISI 4140 steel, were considered. The process was optimized using a recently developed combined methodology based on response surface methodology (RSM) and desirability functional approach (DFA). RSM generated the models of the responses for prediction while DFA solved these multi-response optimization problems. The DFA approach employed an objective function known as the desirability function, which converts an estimated response into a scale-free value known as desirability. The optimum parameter was attained at the maximum overall desirability. An analysis of variance (ANOVA) was conducted to confirm the model adequacy. From the results of the study, for equal weights of responses, the corresponding optimal values of the input parameters cross-feed, workpiece velocity, the wheel or cutting velocity and the depth of cut were found to be 6 mm/pass, 12 m/min, 15 m/s, and 0.095 mm respectively in wet conditions. The corresponding predicted output responses were: 134.55 °C for the temperature, and 7.366 BDT (Taka, Currency of Bangladesh) for the total cost with an overall desirability of 0.844. Confirmation testing of optimized parameters, i.e., checking the validity of optimal set of predicted responses with the real experimental run were conducted, and it was found that the experimental value for temperature and total cost were 140.854 °C and 8.36 BDT, respectively, with an overall desirability of 0.863. Errors of the predicted value from the experimental value for equal weightage scheme were 4.47% for the temperature and 7.37% for the total cost. It was also found that if the temperature was prioritized, then the wet condition dominated the overall desirability, which was expected. However, if the cost was given high weightage, dry condition achieved the highest overall desirability. This can be attributed to the cutting in the wet condition which was more expensive due to the application of cutting fluid. The proposed model was found to be new and highly flexible in the sense that there was always an option at hand to focus on a particular response if needed. Full article

(This article belongs to the Special Issue Recent Advances in Bioactive Film Coatings)

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11 pages, 3472 KiB

Open AccessArticle

Experimental Study of Black Cotton Soil Stabilization with Natural Lime and Pozzolans in Pavement Subgrade Construction

by Zihong Yin, Raymond Leiren Lekalpure and Kevin Maraka Ndiema

Coatings 2022, 12(1), 103; https://doi.org/10.3390/coatings12010103 - 17 Jan 2022

Cited by 13 | Viewed by 5574

Abstract

This study explores the engineering characteristics of Black cotton soil (BCS) stabilized with natural lime, volcanic ash (VA), and their mixtures. Based on the available literature, the stabilization of VA-BCS is limited. Laboratory tests conducted on stabilized BCS include the Atterbeg limits, the [...] Read more.

This study explores the engineering characteristics of Black cotton soil (BCS) stabilized with natural lime, volcanic ash (VA), and their mixtures. Based on the available literature, the stabilization of VA-BCS is limited. Laboratory tests conducted on stabilized BCS include the Atterbeg limits, the proctor test, the swell percent test, and the California bearing ratio (CBR). The results showed that adding VA and lime greatly improves the engineering characteristics of BCS. BCS stabilized with a mixture of VA and lime showed superior results. Adding 3% lime with 20% VA increased natural CBR values 10.76 times, reduced plasticity by 29%, and reduced swell percent by 88%. Stabilized BCS with 3% lime + 20% VA meets the minimum swell, plasticity, and strength requirements; thus, it can be used as an alternative to cutting and filling. Full article

(This article belongs to the Special Issue Functional Materials for Building and Pavement Coatings)

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22 pages, 1065 KiB

Open AccessReview

Nanocarriers for Sustainable Active Packaging: An Overview during and Post COVID-19

by Mihaela Stefana Pascuta and Dan Cristian Vodnar

Coatings 2022, 12(1), 102; https://doi.org/10.3390/coatings12010102 - 17 Jan 2022

Cited by 34 | Viewed by 5628 | Correction

Abstract

Lockdown has been installed due to the fast spread of COVID-19, and several challenges have occurred. Active packaging was considered a sustainable option for mitigating risks to food systems during COVID-19. Biopolymeric-based active packaging incorporating the release of active compounds with antimicrobial and [...] Read more.

Lockdown has been installed due to the fast spread of COVID-19, and several challenges have occurred. Active packaging was considered a sustainable option for mitigating risks to food systems during COVID-19. Biopolymeric-based active packaging incorporating the release of active compounds with antimicrobial and antioxidant activity represents an innovative solution for increasing shelf life and maintaining food quality during transportation from producers to consumers. However, food packaging requires certain physical, chemical, and mechanical performances, which biopolymers such as proteins, polysaccharides, and lipids have not satisfied. In addition, active compounds have low stability and can easily burst when added directly into biopolymeric materials. Due to these drawbacks, encapsulation into lipid-based, polymeric-based, and nanoclay-based nanocarriers has currently captured increased interest. Nanocarriers can protect and control the release of active compounds and can enhance the performance of biopolymeric matrices. The aim of this manuscript is to provide an overview regarding the benefits of released active compound-loaded nanocarriers in developing sustainable biopolymeric-based active packaging with antimicrobial and antioxidant properties. Nanocarriers improve physical, chemical, and mechanical properties of the biopolymeric matrix and increase the bioactivity of released active compounds. Furthermore, challenges during the COVID-19 pandemic and a brief post-COVID-19 scenario were also mentioned. Full article

(This article belongs to the Special Issue Innovations in Active Food Packaging during the Pandemic and into the 'New Normal')

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7 pages, 1314 KiB

Open AccessArticle

Structural and Electrical Properties of Atomic Layer Deposited PtRu Bimetallic Alloy Thin Films

by Hyun-Jae Woo, Woo-Jae Lee, Chang-Min Kim, Qimin Wang, Shihong Zhang, Yong-Jin Yoon and Se-Hun Kwon

Coatings 2022, 12(1), 101; https://doi.org/10.3390/coatings12010101 - 17 Jan 2022

Cited by 2 | Viewed by 2190

Abstract

The structural and electrical properties of PtRu bimetallic alloy (BA) thin films prepared via atomic layer deposition (ALD) were systemically investigated according to the film composition, which was controlled at a deposition temperature of 340 °C by changing the numbers of Pt and [...] Read more.

The structural and electrical properties of PtRu bimetallic alloy (BA) thin films prepared via atomic layer deposition (ALD) were systemically investigated according to the film composition, which was controlled at a deposition temperature of 340 °C by changing the numbers of Pt and Ru subcycles of a supercycle. As-deposited PtRu BA thin films exhibited weaker crystallinity than Pt₃₆Ru₆₄ when the Ru content was high. However, crystallinity improved, and the peak shifts became clearer after Ar heat treatment at 700 °C, reflecting the formation of well-mixed solid solutions. The electrical resistivity and work function also improved. The work function of PtRu BA thin films can be controlled between the work functions of Pt and Ru, and is only weakly dependent on the film composition in the single solid solution region. Full article

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10 pages, 2909 KiB

Open AccessArticle

Effect of UV Radiation on Structural Damage and Tribological Properties of Mo/MoS₂-Pb-PbS Composite Films

by Cuihong Han, Guolu Li, Guozheng Ma, Jiadong Shi, Zhen Li, Qingsong Yong and Haidou Wang

Coatings 2022, 12(1), 100; https://doi.org/10.3390/coatings12010100 - 17 Jan 2022

Cited by 6 | Viewed by 2054

Abstract

To investigate ultraviolet (UV) radiation effects on tribological properties of Mo/MoS₂-Pb-PbS film, ultraviolet (UV) radiation exposure tests were carried out for 20 h, 40 h, 60 h and 80 h by space UV radiation simulation device developed by our team, which [...] Read more.

To investigate ultraviolet (UV) radiation effects on tribological properties of Mo/MoS₂-Pb-PbS film, ultraviolet (UV) radiation exposure tests were carried out for 20 h, 40 h, 60 h and 80 h by space UV radiation simulation device developed by our team, which can reach 3 UV radiation intensity. The exposure time in test was equivalent to the radiation of 100 h, 200 h, 300 h and 400 h in the space. Then, the vacuum friction test of Mo/MoS₂-Pb-PbS thin film was performed under the 6 N load and 100 r/min, and friction test time of each sample was 20 min. By SEM, TEM, XPS the composition and morphology of Mo/MoS₂-Pb-PbS film surface after UV radiation were analyzed. UV radiation could change the microstructure significantly and relative content of S element and MoS₂ on the surface of the films decreased, and light mass loss of the films occurred. The tribological properties will also recover with the increase of sliding time, although the friction coefficient fluctuation of the film increased at the starting stage of the friction test. The damage of Mo/MoS₂-Pb-PbS under UV irradiation was mainly caused by the volatilization of the enriched S element in the surface layer due to the high temperature heating of UV irradiation. Full article

(This article belongs to the Special Issue Nanocomposite Films and Coatings for Aerospace Applications)

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18 pages, 7835 KiB

Open AccessArticle

Microstructure and Mechanical Properties of TiC/TiB Composite Ceramic Coatings In-Situ Synthesized by Ultrasonic Vibration-Assisted Laser Cladding

by Hangbiao Mi, Tao Chen, Zixin Deng, Shengchen Li, Jian Liu and Defu Liu

Coatings 2022, 12(1), 99; https://doi.org/10.3390/coatings12010099 - 15 Jan 2022

Cited by 13 | Viewed by 3351

Abstract

Laser cladding coating has many advantages in surface modification, such as a small heat-affected zone, and good metallurgical bonding. However, some serious problems such as pores, and poor forming quality still exist in the coating. To suppress these problems, a novel process of [...] Read more.

Laser cladding coating has many advantages in surface modification, such as a small heat-affected zone, and good metallurgical bonding. However, some serious problems such as pores, and poor forming quality still exist in the coating. To suppress these problems, a novel process of ultrasonic vibration-assisted laser cladding process was adopted to in-situ synthesize TiC/TiB composite ceramic coating on the surface of titanium alloy. Results showed that the introduction of ultrasonic vibration effectively improved the surface topography of the coating, reduced the number of pores in the coating, refined the crystal grains of the coating, decreased the residual tensile stress in the coating, and increased the micro-hardness of the coating. The tribological properties of the coating were significantly improved by the ultrasonic vibration, the wear resistance of the coating fabricated with ultrasonic vibration at power of 400 W increased about 1.2 times compared with the coating fabricated without ultrasonic vibration, and the friction coefficient decreased by 50%. Full article

(This article belongs to the Topic Laser Surface Modification of Cemented Carbides, Superalloys, Composites, and Alloys)

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15 pages, 12551 KiB

Open AccessArticle

Studying the Influence of Mica Particle Size on the Properties of Epoxy Acrylate/Mica Composite Coatings through Reducing Mica Particle Size by the Ball-Milled Method

by Yaling Da, Jianxing Liu, Zixian Gao and Xiangxin Xue

Coatings 2022, 12(1), 98; https://doi.org/10.3390/coatings12010098 - 15 Jan 2022

Cited by 10 | Viewed by 3242

Abstract

In this work, a series of epoxy acrylate (EA)/mica composite coatings were synthesized through introducing mica powders of different particle size into epoxy acrylate coatings and using an ultraviolet (UV) curing technique to investigate the influence of mica particle size on the coatings. [...] Read more.

In this work, a series of epoxy acrylate (EA)/mica composite coatings were synthesized through introducing mica powders of different particle size into epoxy acrylate coatings and using an ultraviolet (UV) curing technique to investigate the influence of mica particle size on the coatings. Mica powders of different particle sizes were obtained by ball-milling for 4, 8, 12, 16, and 20 h with a planetary high-energy ball mill. The particle size and morphologies of ball-milled mica powders were characterized by laser particle size analyzer and scanning electron microscopy (SEM). The results indicated that planetary ball-milling reduced the particle size of mica powders effectively. Mica powders that were un-ball-milled and ball-milled were added into the epoxy acrylate matrix by a blending method to synthesize the organic-inorganic UV curable coatings. The optical photographs of the coatings showed greater stability of liquid mixtures with smaller particle size fillers. The chemical structures of EA/mica composite coatings were investigated by Fourier transform infrared spectroscopy (FTIR), and the conversion rate of C=C bonds was calculated. The results indicated that the C=C conversion of coatings with mica powders of smaller particle sizes was higher. Tests of mechanical properties and tests using electrochemical impedance spectroscopy (EIS) showed that pencil hardness, impact resistance, and coating resistance were improved due to the reduction of mica powders particle size. Full article

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15 pages, 2039 KiB

Open AccessArticle

Silica-Supported Assemblage of Cu^II Ions with Carbon Dots for Self-Boosting and Glutathione-Induced ROS Generation

by Olga Bochkova, Alexey Dovjenko, Rustem Zairov, Kirill Kholin, Rinata Biktimirova, Svetlana Fedorenko, Irek Nizameev, Artem Laskin, Alexandra Voloshina, Anna Lyubina, Syumbelya Amerhanova, Amina Daminova, Vladimir Evtugyn, Tatiana Gerasimova and Asiya Mustafina

Coatings 2022, 12(1), 97; https://doi.org/10.3390/coatings12010097 - 15 Jan 2022

Cited by 9 | Viewed by 2237

Abstract

The present work introduces coordinative binding of Cu^II ions with both amino-functionalized silica nanoparticles (SNs) and green-emitting carbon dots (CDs) as the pregrequisite for the Cu^II-assisted self-assembly of the CDs at the surface of the SNs. The produced composite SNs [...] Read more.

The present work introduces coordinative binding of Cu^II ions with both amino-functionalized silica nanoparticles (SNs) and green-emitting carbon dots (CDs) as the pregrequisite for the Cu^II-assisted self-assembly of the CDs at the surface of the SNs. The produced composite SNs exhibit stable in time stimuli-responsive green fluorescence derived from the Cu^II-assisted assemblage of CDs. The fluorescence response of the composite SNs is sensitive to the complex formation with glutathione (GSH), enabling them to detect it with the lower limit of detection of 0.15 μM. The spin-trap-facilitated electron spin resonance technique indicated that the composite SNs are capable of self-boosting generation of ROS due to Cu^II→Cu^I reduction by carbon in low oxidation states as a part of the CDs. The intensity of the ESR signals is enhanced under the heating to 38 °C. The intensity is suppressed at the GSH concentration of 0.35 mM but is enhanced at 1.0 mM of glutathione, while it is suppressed once more at the highest intracellular concentration level of GSH (10 mM). These tendencies reveal the concentrations optimal for the scavenger or reductive potential of GSH. Flow cytometry and fluorescence and confocal microscopy methods revealed efficient cell internalization of SNs-NH₂-Cu^II-CDs comparable with that of “free” CDs. Full article

(This article belongs to the Special Issue Functional Coatings and Soft Matter: Insights from Nanomechanics and Surface Properties)

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13 pages, 5617 KiB

Open AccessArticle

Mo Contact via High-Power Impulse Magnetron Sputtering on Polyimide Substrate

by Yung-Lin Chen, Yi-Cheng Lin and Wan-Yu Wu

Coatings 2022, 12(1), 96; https://doi.org/10.3390/coatings12010096 - 14 Jan 2022

Cited by 2 | Viewed by 2828

Abstract

It has always been a huge challenge to prepare the Mo back contact of inorganic compound thin film solar cells (e.g., CIGS, CZTS, Sb₂Se₃) with good conductivity and adhesion at the same time. High-power impulse magnetron sputtering (HiPIMS) has [...] Read more.

It has always been a huge challenge to prepare the Mo back contact of inorganic compound thin film solar cells (e.g., CIGS, CZTS, Sb₂Se₃) with good conductivity and adhesion at the same time. High-power impulse magnetron sputtering (HiPIMS) has been proposed as one solution to improve the properties of the thin film. In this study, the HiPIMS technology replaced the traditional DC power sputtering technology to deposit Mo back contact on polyimide (PI) substrates by adjusting the experimental parameters of HiPIMS, including working pressure and pulse DC bias. When the Mo back contact is prepared under a working pressure of 5 mTorr and bias voltage of −20 V, the conductivity of the Mo back contact is 9.9 × 10⁻⁶ Ω·cm, the residual stress of 720 MPa, and the film still has good adhesion. Under the minimum radius of curvature of 10 mm, the resistivity change rate of Mo back contact does not increase by more than 15% regardless of the 1680 h or 1500 bending cycle tests, and the Mo film still has good adhesion in appearance. Experimental results show that, compared with traditional DC sputtering, HiPIMS coating technology has better conductivity and adhesion at the same time, and is especially suitable for PI substrates. Full article

(This article belongs to the Special Issue Thin Films and Coatings for Energy Application)

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14 pages, 7196 KiB

Open AccessArticle

Influence of Dolomite Rock Powder and Iron Tailings Powder on the Electrical Resistivity, Strength and Microstructure of Cement Pastes and Concrete

by Yang Liu, Wenru Hao, Wei He, Xia Meng, Yinlan Shen, Tao Du and Hui Wang

Coatings 2022, 12(1), 95; https://doi.org/10.3390/coatings12010095 - 14 Jan 2022

Cited by 13 | Viewed by 2659

Abstract

Dolomite rock powder (the waste stone residue in the production of machine-made sand and stone processing) and iron tailings powder formed by mineral processing industry are solid wastes, which occupy land resources, pollute the environment and release toxic substances without reasonable processing. The [...] Read more.

Dolomite rock powder (the waste stone residue in the production of machine-made sand and stone processing) and iron tailings powder formed by mineral processing industry are solid wastes, which occupy land resources, pollute the environment and release toxic substances without reasonable processing. The dolomite rock powder and iron tailings powder composing a large number of active substances could be advantageous to the cement-based materials. In this study, the electrical resistivity of cement paste and concrete was measured. Meanwhile, the influence of dolomite rock powder and iron tailings powder on the compressive strength of concrete was investigated. The electric flux of concrete was determined to estimate the chloride ion permeability. The scanning electron microscope (SEM) and X-ray diffraction were obtained to investigate the hydration of cement paste. Results showed the electrical resistivity of all specimens presented in this order: specimens with iron tailings < specimens with dolomite rock powder < blank specimens < specimens with ground granulated blast-furnace slag (GGBS) < specimens with fly ash. The correlation between electrical resistivity and curing age of cement paste or concrete has been deduced as a quadratic function. The addition of GGBS could improve the compressive strength of concrete. Meanwhile, when the other three types of mineral admixtures were added, 5% by mass ratio of the total binder materials was the optimum for the compressive strength. The curing ages, the fly ash, the GGBS and 5% dolomite rock powder or 5% iron tailings powder demonstrated a positive effect on the chloride ion impermeability. However, when higher dosages of dolomite rock powder or iron tailings powder were added, the effect was the opposite. Finally, the compactness of the microstructure and the Ca(OH)₂ of cement paste could be improved by a small dosage of dolomites or iron tailings (less than 5%). Full article

(This article belongs to the Special Issue Interface and Surface Modification for Durable Concretes)

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11 pages, 2548 KiB

Open AccessArticle

Plasma-Assisted MOCVD Growth of Non-Polar GaN and AlGaN on Si(111) Substrates Utilizing GaN-AlN Buffer Layer

by Pepen Arifin, Heri Sutanto, Sugianto and Agus Subagio

Coatings 2022, 12(1), 94; https://doi.org/10.3390/coatings12010094 - 14 Jan 2022

Cited by 9 | Viewed by 3058

Abstract

We report the growth of non-polar GaN and AlGaN films on Si(111) substrates by plasma-assisted metal-organic chemical vapor deposition (PA-MOCVD). Low-temperature growth of GaN or AlN was used as a buffer layer to overcome the lattice mismatch and thermal expansion coefficient between GaN [...] Read more.

We report the growth of non-polar GaN and AlGaN films on Si(111) substrates by plasma-assisted metal-organic chemical vapor deposition (PA-MOCVD). Low-temperature growth of GaN or AlN was used as a buffer layer to overcome the lattice mismatch and thermal expansion coefficient between GaN and Si(111) and GaN’s poor wetting on Si(111). As grown, the buffer layer is amorphous, and it crystalizes during annealing to the growth temperature and then serves as a template for the growth of GaN or AlGaN. We used scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD) characterization to investigate the influence of the buffer layer on crystal structure, orientation, and the morphology of GaN. We found that the GaN buffer layer is superior to the AlN buffer layer. The thickness of the GaN buffer layer played a critical role in the crystal quality and plane orientation and in reducing the cracks during the growth of GaN/Si(111) layers. The optimum GaN buffer layer thickness is around 50 nm, and by using the optimized GaN buffer layer, we investigated the growth of AlGaN with varying Al compositions. The morphology of the AlGaN films is flat and homogenous, with less than 1 nm surface roughness, and has preferred orientation in a-axis. Full article

(This article belongs to the Special Issue Thin Films and Nanostructures by MOCVD: Fabrication, Characterization and Applications)

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14 pages, 10096 KiB

Open AccessArticle

Cumulative Impact of Micropolar Fluid and Porosity on MHD Channel Flow: A Numerical Study

by Kottakkaran Sooppy Nisar, Aftab Ahmed Faridi, Sohail Ahmad, Nargis Khan, Kashif Ali, Wasim Jamshed, Abdel-Haleem Abdel-Aty and I. S. Yahia

Coatings 2022, 12(1), 93; https://doi.org/10.3390/coatings12010093 - 14 Jan 2022

Cited by 24 | Viewed by 2569

Abstract

The mass and heat transfer magnetohydrodynamic (MHD) flows have a substantial use in heat exchangers, electromagnetic casting, X-rays, the cooling of nuclear reactors, mass transportation, magnetic drug treatment, energy systems, fiber coating, etc. The present work numerically explores the mass and heat transportation [...] Read more.

The mass and heat transfer magnetohydrodynamic (MHD) flows have a substantial use in heat exchangers, electromagnetic casting, X-rays, the cooling of nuclear reactors, mass transportation, magnetic drug treatment, energy systems, fiber coating, etc. The present work numerically explores the mass and heat transportation flow of MHD micropolar fluid with the consideration of a chemical reaction. The flow is taken between the walls of a permeable channel. The quasi-linearization technique is utilized to solve the complex dynamical coupled and nonlinear differential equations. The consequences of the preeminent parameters are portrayed via graphs and tables. A tabular and graphical comparison evidently reveals a correlation of our results with the existing ones. A strong deceleration is found in the concentration due to the effect of a chemical reaction. Furthermore, the impact of the magnetic field force is to devaluate the mass and heat transfer rates not only at the lower but at the upper channel walls, likewise. Full article

(This article belongs to the Special Issue Nanofluidics: Interfacial Transport Phenomena)

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16 pages, 6905 KiB

Open AccessArticle

An Approach for Material Model Identification of a Composite Coating Using Micro-Indentation and Multi-Scale Simulations

by Pouya Shojaei, Riccardo Scazzosi, Mohamed Trabia, Brendan O’Toole, Marco Giglio, Xing Zhang, Yiliang Liao and Andrea Manes

Coatings 2022, 12(1), 92; https://doi.org/10.3390/coatings12010092 - 14 Jan 2022

Cited by 3 | Viewed by 2434

Abstract

While deposited thin film coatings can help enhance surface characteristics such as hardness and friction, their effective incorporation in product design is restricted by the limited understanding of their mechanical behavior. To address this, an approach combining micro-indentation and meso/micro-scale simulations was proposed. [...] Read more.

While deposited thin film coatings can help enhance surface characteristics such as hardness and friction, their effective incorporation in product design is restricted by the limited understanding of their mechanical behavior. To address this, an approach combining micro-indentation and meso/micro-scale simulations was proposed. In this approach, micro-indentation testing was conducted on both the coating and the substrate. A meso-scale uniaxial compression finite element model was developed to obtain a material model of the coating. This material model was incorporated within an axisymmetric micro-scale model of the coating to simulate the indentation. The proposed approach was applied to a Ti/SiC metal matrix nanocomposite (MMNC) coating, with a 5% weight of SiC nanoparticles deposited over a Ti-6Al-4V substrate using selective laser melting (SLM). Micro-indentation testing was conducted on both the Ti/SiC MMNC coating and the Ti-6Al-4V substrate. The results of the meso-scale finite element indicated that the MMNC coating can be represented using a bi-linear elastic-plastic material model, which was incorporated within an axisymmetric micro-scale model. Comparison of the experimental and micro-scale model results indicated that the proposed approach was effective in capturing the post-indentation behavior of the Ti/SiC MMNC coating. This methodology can also be used for studying the response of composite coatings with different percentages of reinforcements. Full article

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13 pages, 18084 KiB

Open AccessArticle

Effect of Graphene Nanoparticles Addition on Superconductivity of YBa₂Cu₃O₇_~_δ Synthesized via the Thermal Treatment Method

by Aliah Nursyahirah Kamarudin, Mohd Mustafa Awang Kechik, Siti Nabilah Abdullah, Hussein Baqiah, Soo Kien Chen, Muhammad Khalis Abdul Karim, Aima Ramli, Kean Pah Lim, Abdul Halim Shaari, Muralidhar Miryala, Masato Murakami and Zainal Abidin Talib

Coatings 2022, 12(1), 91; https://doi.org/10.3390/coatings12010091 - 13 Jan 2022

Cited by 8 | Viewed by 2807

Abstract

The development of high-temperature superconductor (HTS) YBa₂Cu₃O_7~δ (Y123) bulks in industrial applications were established years ago. It is one of the developments that currently attracts great attention especially in transportation, superconductor cables and wires. This study is focused [...] Read more.

The development of high-temperature superconductor (HTS) YBa₂Cu₃O_7~δ (Y123) bulks in industrial applications were established years ago. It is one of the developments that currently attracts great attention especially in transportation, superconductor cables and wires. This study is focused on the preparation of the Y123 bulk superconductors by the thermal treatment method due to the promising ways to develop high-quality Y123 superconductors with its simplicity, low cost, and relatively low reaction temperature used during the process. Y123 were added with graphene nanoparticles (x = (0.0–1.0) wt.%). Samples were then characterized by X-ray diffraction (XRD) analysis, field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), and alternating current susceptibility (ACS). It was found that Y123 confirmed that the majority of phases in all the XRD patterns was the orthorhombic crystal structure and the Pmmm space group with secondary phases belonged to Y₂Ba₁Cu₁O₅ (Y211). The highest T_c obtained when graphene nanoparticles were added in the Y123 sample was x = 1.0 wt.%, followed by x = 0.5 wt.% with 92.64 and 92.59 K, respectively. From the microstructure analysis, the average grain size significantly decreased to 4.754 µm at x = 0.5 wt.%. The addition of graphene nanoparticles had disturbed the grain growth of Y123, affecting the superconducting properties of the samples. On the other hand, the intergranular critical current density, J_cm, was found to increase with graphene nanoparticle addition and had the highest value at x = 1.0 wt.%, indicating that graphene nanoparticles acted as pinning centers in the Y123 matrix. Full article

(This article belongs to the Special Issue New Advance in Superconductor and Superconducting Thin Films)

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16 pages, 2022 KiB

Open AccessArticle

The Effects of a Gum Arabic-Based Edible Coating on Guava Fruit Characteristics during Storage

by Sherif Fathy El-Gioushy, Mohamed F. M. Abdelkader, Mohamed H. Mahmoud, Hanan M. Abou El Ghit, Mohammad Fikry, Asmaa M. E. Bahloul, Amany R. Morsy, Lo’ay A. A., Adel M. R. A. Abdelaziz, Haifa A. S. Alhaithloul, Dalia M. Hikal, Mohamed A. Abdein, Khairy H. A. Hassan and Mohamed S. Gawish

Coatings 2022, 12(1), 90; https://doi.org/10.3390/coatings12010090 - 13 Jan 2022

Cited by 39 | Viewed by 6310

Abstract

Guava is a nutritious fruit that has perishable behavior during storage. We aimed to determine the influences of some edible coatings (namely, cactus pear stem (10%), moringa (10%), and henna leaf (3%) extracts incorporated with gum Arabic (10%)), on the guava fruits’ properties [...] Read more.

Guava is a nutritious fruit that has perishable behavior during storage. We aimed to determine the influences of some edible coatings (namely, cactus pear stem (10%), moringa (10%), and henna leaf (3%) extracts incorporated with gum Arabic (10%)), on the guava fruits’ properties when stored under ambient and refrigeration temperatures for 7, 14, and 21 days. The results revealed that the coating with gum Arabic (10%) only, or combined with the natural plant extracts, exhibited a significant reduction in weight loss, decay, and rot ratio. Meanwhile, there were notable increases in marketability. Moreover, among all tested treatments, the application of gum Arabic (10%) + moringa extract (10%) was the superior treatment for most studied parameters, and exhibited for the highest values for maintaining firmness, total soluble solids, total sugars, and total antioxidant activity. Overall, it was suggested that coating guava with 10% gum Arabic combined with other plant extracts could maintain the postharvest storage quality of the cold-storage guava. Full article

(This article belongs to the Special Issue Coatings on Food Packaging and Shelf Life)

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12 pages, 1720 KiB

Open AccessArticle

Viscoelastic Properties, Rutting Resistance, and Fatigue Resistance of Waste Wood-Based Biochar-Modified Asphalt

by Ran Zhang, Haoxiang Wang, Jie Ji and Hainian Wang

Coatings 2022, 12(1), 89; https://doi.org/10.3390/coatings12010089 - 13 Jan 2022

Cited by 16 | Viewed by 2894

Abstract

The purpose of this study is to explore the viscoelastic properties, rutting resistance, and fatigue resistance of waste wood-based biochar-modified asphalt. The biochar with 2%, 4%, and 8% mixing amounts and two kinds of particle size, 75–150 μm and <75 μm, were used [...] Read more.

The purpose of this study is to explore the viscoelastic properties, rutting resistance, and fatigue resistance of waste wood-based biochar-modified asphalt. The biochar with 2%, 4%, and 8% mixing amounts and two kinds of particle size, 75–150 μm and <75 μm, were used as modifiers of petroleum asphalt. Meanwhile, in the control group, a graphite modifier with a particle size of 0–75 μm and mixing amount of 4% was used for comparison. Aged asphalts were obtained in the laboratory by the Rolling Thin Film Oven (RTFO) test and the Pressure Aging Vessel (PAV) test. The viscoelastic properties, rutting resistance, and fatigue resistance of biochar-modified asphalt were evaluated by phase angle, critical high temperature, and fatigue cracking index by the Dynamic Shear Rheometer (DSR) test. In addition, the micromorphology of biochar and graphite was compared and observed by using the scanning electron microscope (SEM). The results show that increasing the mixing amount of biochar gave a higher elastic property and significantly better rutting resistance of the modified asphalt at high temperature. Compared with graphite, the biochar has a rougher surface and more pores, which provides its higher specific surface area. Therefore, it is easier to bond with asphalt to form a skeleton network structure, then forming a more stable biochar–asphalt base structure. In this way, compared to graphite-modified asphalt, biochar-modified asphalt showed better resistance to rutting at high temperature, especially for the asphalt modified with biochar of small particle size. The critical high temperature T^(G*/sinδ) of 4% Gd, 4% WD, and 4% Wd was 0.31 °C, 1.57 °C, and 2.92 °C higher than that of petroleum bitumen. In addition, the biochar asphalt modified with biochar of small particle size had significantly better fatigue cracking resistance than the asphalt modified with biochar of large particle size. The fatigue cracking indexes for 2% Wd, 4% Wd, and 8% Wd were 29.20%, 7.21%, and 37.19% lower by average than those for 2% WD, 4% WD, and 8% WD at 13–37 °C. Therefore, the waste wood biochar could be used as the modifier for petroleum asphalt. After the overall consideration, the biochar-modified asphalt with 2%–4% mixing amount and particle size less than 75 μm was recommended. Full article

(This article belongs to the Special Issue Surface Characterization and Treatments in Transportation Infrastructure)

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12 pages, 2913 KiB

Open AccessArticle

Fabrication of an Immobilized Polyelectrolite Complex (PEC) Membrane from Pectin-Chitosan and Chromoionophore ETH 5294 for pH-Based Fish Freshness Monitoring

by Eka Safitri, Zatul Omaira, Nazaruddin Nazaruddin, Irfan Mustafa, Sitti Saleha, Rinaldi Idroes, Binawati Ginting, Muhammad Iqhrammullah, Sagir Alva and Maria Paristiowati

Coatings 2022, 12(1), 88; https://doi.org/10.3390/coatings12010088 - 13 Jan 2022

Cited by 5 | Viewed by 2834

Abstract

Considering the significance of its demand around the world, the accurate determination of fish freshness with a simple and rapid procedure has become an interesting issue for the fishing industry. Hence, we aimed to fabricate a new optical pH sensor based on a [...] Read more.

Considering the significance of its demand around the world, the accurate determination of fish freshness with a simple and rapid procedure has become an interesting issue for the fishing industry. Hence, we aimed to fabricate a new optical pH sensor based on a polyelectrolyte (PEC) membrane of pectin–chitosan and the active material chromoionophore ETH 5294. A trial-and-error investigation of the polymer compositions revealed that the optimum ratio of pectin to chitosan was 3:7. With an optimum wavelength region (λ) at 610 nm, the constructed sensor was capable of stable responses after 5 min exposure to phosphate-buffered solution. Furthermore, the obtained sensor achieved optimum sensitivity when the PBS concentration was 0.1 M, while the relative standard deviation values ranged from 2.07 to 2.34%, suggesting good reproducibility. Further investigation revealed that the sensor experienced decreased absorbance of 16.67–18.68% after 25 days of storage. Employing the optimum conditions stated previously, the sensor was tested to monitor fish freshness in samples that were stored at 4 °C and ambient temperature. The results suggested that the newly fabricated optical sensor could measure pH changes on fish skin after 25 h storage at room temperature (pH 6.37, 8.91 and 11.02, respectively) and 4 °C (pH 6.8, 7.31 and 7.92, respectively). Full article

(This article belongs to the Special Issue Optical Sensing Materials and Coatings)

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16 pages, 6266 KiB

Open AccessArticle

Epitaxial Growth and Optical Properties of Laser Deposited CdS Thin Films

by Atef S. Gadalla, Hamdan A. S. Al-shamiri, Saad Melhi Alshahrani, Huda F. Khalil, Mahmoud M. El Nahas and Mohamed A. Khedr

Coatings 2022, 12(1), 87; https://doi.org/10.3390/coatings12010087 - 13 Jan 2022

Cited by 10 | Viewed by 2320

Abstract

In this study, cadmium Sulfide (CdS) thin films were synthesized on quartz substrates using an infrared pulsed laser deposition (IR-PLD) technique under high vacuum (~10⁻⁶ Torr) conditions. X-ray diffraction was used to evaluate the structural features. According to X-ray analysis, the deposited [...] Read more.

In this study, cadmium Sulfide (CdS) thin films were synthesized on quartz substrates using an infrared pulsed laser deposition (IR-PLD) technique under high vacuum (~10⁻⁶ Torr) conditions. X-ray diffraction was used to evaluate the structural features. According to X-ray analysis, the deposited CdS films are crystalline and have a favored orientation on a plane (110) of an orthorhombic. The peak intensity and the average crystallite size increases with increasing the film thickness. After annealing at 300 °C, the orthorhombic phase transformed into a predominant hexagonal phase and the same result was obtained by SEM photographs as well. Spectrophotometric measurements of transmittance and reflectance of the CdS films were used to derive optical constants (n, k, and absorption coefficient α). The optical band gap energy was found to be 2.44 eV. The plasma plume formation and expansion during the film deposition have also been discussed. The photocurrent response as a function of the incident photon energy E (eV) at different bias voltages for different samples of thicknesses (85, 180, 220 and 340 nm) have been studied, indicating that the photocurrent increases by increasing both the film thickness and photon energy with a peak in the vicinity of the band edge. Thus, the prepared CdS films are promising for application in optoelectronic field. Full article

(This article belongs to the Special Issue 10th Anniversary of Coatings: Invited Papers for Thin Films Section)

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15 pages, 46567 KiB

Open AccessArticle

Process Simulation and Abrasion Behavior of Jet Electrodeposited Ni–TiN Nanocoatings

by Zhongguo Yang, Shujuan Yi, Longkui Cao, Songhao Tang and Qiang Li

Coatings 2022, 12(1), 86; https://doi.org/10.3390/coatings12010086 - 12 Jan 2022

Cited by 6 | Viewed by 2043

Abstract

In this work, we study jet-electrodeposited Ni–TiN composite nanocoatings (CNCs) for improving abrasion resistance as a function of various nozzle diameters. In addition, COMSOL software is utilized to simulate the process of jet electrodeposition, particularly the influence of spraying speed and pressure of [...] Read more.

In this work, we study jet-electrodeposited Ni–TiN composite nanocoatings (CNCs) for improving abrasion resistance as a function of various nozzle diameters. In addition, COMSOL software is utilized to simulate the process of jet electrodeposition, particularly the influence of spraying speed and pressure of the electrolyte on the abrasion resistance of coatings. Optimization of the nozzle diameter to obtain uniform and high-performance coatings showed that a Φ7 mm nozzle diameter generated the optimum spraying speed and spraying pressure, which results in good micro-hardness and abrasion resistance of the Ni–TiN CNCs. Under these conditions, the 45 steel substrates are coated with a compact layer of uniform and nano-sized TiN particles, which are responsible for the high abrasion resistance of our Ni–TiN CNCs. Our study may motivate researchers to study jet electrodeposition in order to obtain abrasion-resistant coatings. Full article

(This article belongs to the Special Issue State-of-the-Art on Coatings Research in Asia)

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15 pages, 6543 KiB

Open AccessArticle

Effects of Climate on Exterior Wood Coating Performance: A Comparison of Three Industrial Coatings in a Warm-Summer Mediterranean and a Semi-Arid Climate in Oregon, USA

by Kent Davis, Scott Leavengood and Jeffrey J. Morrell

Coatings 2022, 12(1), 85; https://doi.org/10.3390/coatings12010085 - 12 Jan 2022

Cited by 3 | Viewed by 2368

Abstract

Wood exposed in exterior applications degrades and changes color due to weathering and fungal growth. Wood coatings can reduce the effects of weathering by reducing the damaging effects of ultraviolet light, reducing water absorption, and slowing fungal growth on the surface. Coating performance [...] Read more.

Wood exposed in exterior applications degrades and changes color due to weathering and fungal growth. Wood coatings can reduce the effects of weathering by reducing the damaging effects of ultraviolet light, reducing water absorption, and slowing fungal growth on the surface. Coating performance depends on the blend of resins, oils, and pigments and varies considerably among different wood species and conditions. Specific information describing expected service for different wood species and exposure conditions is not commonly available; certain combinations may work well in one climate or on one timber species, but underperform elsewhere. This study compared the performance of three industrial wood coatings on two wood species for two temperate climates under natural weathering conditions. Most of the coatings/species combinations lost their protective properties within 12 to 15 months; however, fungal growth was more prevalent at the wetter site than at the drier site for several combinations. Film-forming coatings often peeled and cracked, while penetrating coatings weathered and changed color relatively uniformly during the study. While no coating was completely effective, the results illustrate the benefits of using coatings that promote the development of natural, uniform-patinaed wood surfaces. The findings also guide coating maintenance programs for mass timber structures exposed to natural weathering conditions. Full article

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12 pages, 3418 KiB

Open AccessArticle

Reduction of Surface Residual Lithium Compounds for Single-Crystal LiNi_0.6Mn_0.2Co_0.2O₂ via Al₂O₃ Atomic Layer Deposition and Post-Annealing

by Jiawei Li, Junren Xiang, Ge Yi, Yuanting Tang, Huachen Shao, Xiao Liu, Bin Shan and Rong Chen

Coatings 2022, 12(1), 84; https://doi.org/10.3390/coatings12010084 - 12 Jan 2022

Cited by 15 | Viewed by 4525

Abstract

Surface residual lithium compounds of Ni-rich cathodes are tremendous obstacles to electrochemical performance due to blocking ion/electron transfer and arousing surface instability. Herein, ultrathin and uniform Al₂O₃ coating via atomic layer deposition (ALD) coupled with the post-annealing process is reported [...] Read more.

Surface residual lithium compounds of Ni-rich cathodes are tremendous obstacles to electrochemical performance due to blocking ion/electron transfer and arousing surface instability. Herein, ultrathin and uniform Al₂O₃ coating via atomic layer deposition (ALD) coupled with the post-annealing process is reported to reduce residual lithium compounds on single-crystal LiNi_0.6Mn_0.2Co_0.2O₂ (NCM622). Surface composition characterizations indicate that LiOH is obviously reduced after Al₂O₃ growth on NCM622. Subsequent post-annealing treatment causes the consumption of Li₂CO₃ along with the diffusion of Al atoms into the surface layer of NCM622. The NCM622 modified by Al₂O₃ coating and post-annealing exhibits excellent cycling stability, the capacity retention of which reaches 92.2% after 300 cycles at 1 C, much higher than that of pristine NCM622 (34.8%). Reduced residual lithium compounds on NCM622 can greatly decrease the formation of LiF and the degree of Li⁺/Ni²⁺ cation mixing after discharge–charge cycling, which is the key to the improvement of cycling stability. Full article

(This article belongs to the Special Issue Surface Coating in Advanced Energy Storage Devices)

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15 pages, 1464 KiB

Open AccessArticle

The Combined Effect of Hot Water Treatment and Chitosan Coating on Mango (Mangifera indica L. cv. Kent) Fruits to Control Postharvest Deterioration and Increase Fruit Quality

by Hoda A. Khalil, Mohamed F. M. Abdelkader, A. A. Lo’ay, Diaa O. El-Ansary, Fatma K. M. Shaaban, Samah O. Osman, Ibrahim E. Shenawy, Hosam-Eldin Hussein Osman, Safaa A. Limam, Mohamed A. Abdein and Zinab A. Abdelgawad

Coatings 2022, 12(1), 83; https://doi.org/10.3390/coatings12010083 - 12 Jan 2022

Cited by 23 | Viewed by 5890

Abstract

The synergistic effect of dipping in 55 °C for 5 min of hot water (HW) and 1% chitosan coating during the storage of mango at 13 ± 0.5 °C and 85%–90% relative humidity for 28 days was investigated. The combined treatment significantly suppressed [...] Read more.

The synergistic effect of dipping in 55 °C for 5 min of hot water (HW) and 1% chitosan coating during the storage of mango at 13 ± 0.5 °C and 85%–90% relative humidity for 28 days was investigated. The combined treatment significantly suppressed the fruit decay percentage compared with both the single treatment and the control. In addition, the specific activities of key plant defense-related enzymes, including peroxidase (POD) and catalase (CAT), markedly increased. The increase occurred in the pulp of the fruits treated with the combined treatment compared to those treated with HW or chitosan alone. While the control fruits showed the lowest values, the combination of pre-storage HW treatment and chitosan coating maintained higher values of flesh hue angle (h°), vitamin C content, membrane stability index (MSI) percentage, as well as lower weight loss compared with the untreated mango fruits. The combined treatment and chitosan treatment alone delayed fruit ripening by keeping fruit firmness, lessening the continuous increase of total soluble solids (TSS), and slowing the decrease in titratable acidity (TA). The results showed that the combined application of HW treatment and chitosan coating can be used as an effective strategy to suppress postharvest decay and improve the quality of mango fruits. Full article

(This article belongs to the Special Issue Coatings on Food Packaging and Shelf Life)

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39 pages, 9904 KiB

Open AccessReview

Electron-Beam Synthesis of Dielectric Coatings Using Forevacuum Plasma Electron Sources (Review)

by Yury G. Yushkov, Efim M. Oks, Andrey V. Tyunkov and Denis B. Zolotukhin

Coatings 2022, 12(1), 82; https://doi.org/10.3390/coatings12010082 - 12 Jan 2022

Cited by 13 | Viewed by 3841

Abstract

This is a review of current developments in the field of ion-plasma and beam methods of synthesis of protective and functional dielectric coatings. We give rationales for attractiveness and prospects of creating such coatings by electron-beam heating and following evaporation of dielectric targets. [...] Read more.

This is a review of current developments in the field of ion-plasma and beam methods of synthesis of protective and functional dielectric coatings. We give rationales for attractiveness and prospects of creating such coatings by electron-beam heating and following evaporation of dielectric targets. Forevacuum plasma electron sources, operating at elevated pressure values from units to hundreds of pascals, make it possible to exert the direct action of an electron beam on low-conductive materials. Electron-beam evaporation of aluminum oxide, boron, and silicon carbide targets is used to exemplify the particular features of electron-beam synthesis of such coatings and their parameters and characteristics. Full article

(This article belongs to the Special Issue Electron-Ion-Plasma Technology Applied to Surface Engineering)

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10 pages, 1662 KiB

Open AccessFeature PaperArticle

Influence of Al Doping on the Morphological, Structural and Gas Sensing Properties of Electrochemically Deposited ZnO Films on Quartz Resonators

by Gergana Alexieva, Konstantin Lovchinov, Miroslav Petrov, Rositsa Gergova and Nikolay Tyutyundzhiev

Coatings 2022, 12(1), 81; https://doi.org/10.3390/coatings12010081 - 12 Jan 2022

Cited by 9 | Viewed by 1987

Abstract

The detection of hazardous gases at different concentration levels at low and room temperature is still an actual and challenging task. In this paper, Al-doped ZnO thin films are synthesized by the electrochemical deposition method on the gold electrodes of AT-cut quartz resonators, [...] Read more.

The detection of hazardous gases at different concentration levels at low and room temperature is still an actual and challenging task. In this paper, Al-doped ZnO thin films are synthesized by the electrochemical deposition method on the gold electrodes of AT-cut quartz resonators, vibrating at 10 MHz. The average roughness, surface morphology and gas sensing properties are investigated. The average roughness of Al-doped ZnO layers strongly depends on the amount of the doping agent Al₂(SO₄)₃ added to the solution. The structural dependence of these films with varying Al concentrations is evident from the scanning electron microscopy images. The sensing properties to ethanol and ammonia analytes were tested in the range of 0–12,800 ppm. In the analysis of the sensitivity to ammonia, a dependence on the concentration of the added Al₂(SO₄)₃ in the electrochemically deposited layers is also observed, as the most sensitive layer is at 3 × 10⁻⁵ M. The sensitivity and the detection limit in case of ammonia are, respectively, 0.03 Hz/ppm and 100 ppm for the optimal doping concentration. The sensitivity depends on the active surface area of the layers, with those with a more developed surface being more sensitive. Al-doped ZnO layers showed a good long-term stability and reproducibility towards ammonia and ethanol gases. In the case of ethanol, the sensitivity is an order lower than that for ammonia, as those deposited with Al₂(SO₄)₃ do not practically react to ethanol. Full article

(This article belongs to the Special Issue Thin Films and Structures for Optical Sensing)

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26 pages, 5270 KiB

Open AccessArticle

Synthesis, Properties and Aging of ICP-CVD SiC_xN_y:H Films Formed from Tetramethyldisilazane

by Maksim N. Chagin, Veronica S. Sulyaeva, Vladimir R. Shayapov, Aleksey N. Kolodin, Maksim N. Khomyakov, Irina V. Yushina and Marina L. Kosinova

Coatings 2022, 12(1), 80; https://doi.org/10.3390/coatings12010080 - 11 Jan 2022

Cited by 7 | Viewed by 2836

Abstract

Amorphous hydrogenated silicon carbonitride films were synthesized on Si(100), Ge(111), and fused silica substrates using the inductively coupled plasma chemical vapor deposition technique. 1,1,3,3-tetramethyldisilazane (TMDSN) was used as a single-source precursor. The effect of the precursor’s pressure in the initial gas mixture, the [...] Read more.

Amorphous hydrogenated silicon carbonitride films were synthesized on Si(100), Ge(111), and fused silica substrates using the inductively coupled plasma chemical vapor deposition technique. 1,1,3,3-tetramethyldisilazane (TMDSN) was used as a single-source precursor. The effect of the precursor’s pressure in the initial gas mixture, the substrate temperature, the plasma power, and the flow rate of nitrogen gas as an additional reagent on the film growth rate, element composition, chemical bonding, wettability of film surface, and the optical and mechanical properties of a-SiC_xN_y:H films was investigated. In situ diagnostic studies of the gas phase have been performed by optical emission spectroscopy during the film deposition process. The long-term stability of films was studied over a period of 375 days. Fourier-transform infrared (FTIR) and X-ray energy dispersive spectroscopy (EDX), and wettability measurements elucidated the oxidation of the SiC_xN_y:H films deposited using TMDSN + N₂ mixture. Films obtained from a mixture with argon had high stability and maintained the stability of element composition after long-term storage in ambient air. Full article

(This article belongs to the Special Issue Coatings and Thin Film for Chemical Vapor Deposition (CVD) Application)

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12 pages, 3947 KiB

Open AccessArticle

A Modeling Approach on the Correction Model of the Chromatic Aberration of Scanned Wood Grain Images

by Jingjing Mao, Zhihui Wu and Xinhao Feng

Coatings 2022, 12(1), 79; https://doi.org/10.3390/coatings12010079 - 11 Jan 2022

Cited by 6 | Viewed by 2361

Abstract

There always exists subjective and objective color differences between digital wood grain and real wood grain, making it difficult to replicate the color of natural timber. Therefore, we described a novel method of correcting the chromatic aberration of scanned wood grain to maximally [...] Read more.

There always exists subjective and objective color differences between digital wood grain and real wood grain, making it difficult to replicate the color of natural timber. Therefore, we described a novel method of correcting the chromatic aberration of scanned wood grain to maximally restore the objective color information of the real wood grain. A point-to-point correction model of chromatic aberration between the scanned wood grain and the measured wood grain was established based on Circle 1 by adjusting the three channels (

s R

,

s G

, and

s B

) of the scanned images. A conversion of the color space was conducted using the mutual conversion formulas. The color change of the scanned images before and after the correction was evaluated through the

L^{*} a^{*} b^{*}

color-mode-based

Δ E^{*}

. and the lαβ color-model-based CIQI (Color Image Quality Index) and CQE (Color Quality Enhancement). The experimental results showed that the chromatic aberration

Δ E^{*}

between the scanned wood grain and the measured wood grain decreased and the colorfulness index CIQI of the scanned wood grain increased for most wood specimens after the correction. The values of

Δ E^{*}

of the twenty kinds of wood specimens decreased by an average of 3.1 in Circle 1 and 2.3 in Circle 2, thus the correction model established based on Circle 1 was effective. The color of the scanned wood grain was more consistent with that of the originals after the correction, which would provide a more accurate color information for the reproductions of wood grain and had an important practical significance. Full article

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16 pages, 4763 KiB

Open AccessArticle

Study on Performance Optimization of Composite Natural Asphalt Modified Gussasphalt Mix

by Huadong Sun, Peng Jiang, Yongling Ding, Laixue Pang, Yinbin Liu, Yafei Wang and Xuhe Shang

Coatings 2022, 12(1), 78; https://doi.org/10.3390/coatings12010078 - 11 Jan 2022

Cited by 6 | Viewed by 2156

Abstract

In order to systematically study and develop a type of gussasphalt (GA) mix with superior performance, namely GA-10; the effect of Qingchuan Rock Asphalt (QRA) and Trinidad Lake asphalt (TLA) on the GA-10 mix was assessed based on the study of composite natural [...] Read more.

In order to systematically study and develop a type of gussasphalt (GA) mix with superior performance, namely GA-10; the effect of Qingchuan Rock Asphalt (QRA) and Trinidad Lake asphalt (TLA) on the GA-10 mix was assessed based on the study of composite natural asphalt modified gussasphalt (CNAMGA) binder. Various analytical tests were used to evaluate the engineering properties, thermal stability and microstructure of CNAMGA mix. The results indicate that the stability of QRA modified binder and TLA modified binder in the normal temperature range and the high temperature range have been improved, and the temperature susceptibility is reduced. The optimal asphalt–aggregate ratio of the GA mix is determined to be 9.7%, which has good high-temperature stability, low-temperature crack resistance and construction workability. The QRA mix has better high-temperature stability than the TLA mix, whereas the low-temperature cracking resistance of the TLA mix is better than that of the QRA mix. The two kinds of GA-10 mix have similar construction workability. The fact that the abundant fine aggregates wrapped in binder fill the coarse aggregates surface contributes to the better adhesion of the GA asphalt concrete. The distribution of aggregate and binder is relatively uniform with fewer pores, and the overall proportion of the binder is greater than that of aggregate. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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12 pages, 7339 KiB

Open AccessArticle

Impact of Multi-Walled CNT Incorporation on Dielectric Properties of PVDF-BaTiO₃ Nanocomposites and Their Energy Harvesting Possibilities

by Abu Sadat M. Iftekhar Uddin, Dongin Lee, Chanseob Cho and Bonghwan Kim

Coatings 2022, 12(1), 77; https://doi.org/10.3390/coatings12010077 - 10 Jan 2022

Cited by 22 | Viewed by 3596

Abstract

The current study investigated the fabrication of multi-walled carbon nanotubes (MWCNTs) adhering to Barium titanate (BaTiO₃) nanoparticles and poly(vinylidene fluoride) (PVDF) nanocomposites, as well as the impact of MWCNT on the PVDF-BaTiO₃ matrix in terms of dielectric constant and dielectric [...] Read more.

The current study investigated the fabrication of multi-walled carbon nanotubes (MWCNTs) adhering to Barium titanate (BaTiO₃) nanoparticles and poly(vinylidene fluoride) (PVDF) nanocomposites, as well as the impact of MWCNT on the PVDF-BaTiO₃ matrix in terms of dielectric constant and dielectric loss with a view to develop a high performance piezoelectric energy harvester in future. The capacity and potential of as-prepared nanocomposite films for the fabrication of high-performance flexible piezoelectric nanogenerator (PNG) were also investigated in this work. In particular, five distinct types of nanocomposites and films were synthesized: PB (bare PVDF–BaTiO₃), PBC-1 (PVDF–BaTiO₃-0.1 wt% CNT), PBC-2 (PVDF–BaTiO₃-0.3 wt% CNT), PBC-3 (PVDF–BaTiO₃-0.5 wt% CNT), and PBC-4 (PVDF–BaTiO₃-1 wt% CNT). The dielectric constant and dielectric loss increased as MWCNT concentration increased. Sample PBC-3 had the optimum dielectric characteristics of all the as-prepared samples, with the maximum output voltage and current of 4.4 V and 0.66 μA, respectively, with an applied force of ~2N. Fine-tuning the BaTiO₃ content and thickness of the PNGs is likely to increase the harvester’s performance even more. It is anticipated that the work would make it easier to fabricate high-performance piezoelectric films and would be a suitable choice for creating high-performance PNG. Full article

(This article belongs to the Special Issue Optical Thin Films: Preparation, Application and Development)

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18 pages, 4865 KiB

Open AccessArticle

Investigation of Accelerated Degradation Methods to Cause Blisters for Non-Defective Vinyl Ester Resin Glass Flake Organic Coatings

by Koya Tokutake, Shinji Okazaki and Shintaro Kodama

Coatings 2022, 12(1), 76; https://doi.org/10.3390/coatings12010076 - 10 Jan 2022

Cited by 3 | Viewed by 3003

Abstract

Organic coatings are applied as a corrosion prevention measure, but their effectiveness may degrade over time. In this study, the acceleration effects of typical degradation methods in non-defective vinyl ester resin organic coatings containing glass flakes such as high-temperature immersion and immersion in [...] Read more.

Organic coatings are applied as a corrosion prevention measure, but their effectiveness may degrade over time. In this study, the acceleration effects of typical degradation methods in non-defective vinyl ester resin organic coatings containing glass flakes such as high-temperature immersion and immersion in chemical accelerators are clarified using physiochemical techniques. Immersion in an acetic acid (AcOH) aqueous solution causes resin swelling, and the behaviors are quantitatively evaluated through gravimetric, thickness, and electrochemical impedance spectroscopy (EIS) measurements. Furthermore, a combined process of immersion in hydrofluoric acid and an AcOH aqueous solution reduces the electrical properties and eventually blisters the thick coating surface. This result suggests that an appropriate combination of the resin swelling and the glass degradation (glass dissolution and/or formation of the gap between glass and resin) decrease mechanical properties of the glass flake coating and causes blisters. In order to help the health diagnosis of the visually non-defective aged glass flake coating, the relationship between the electrical characteristic values and the invisible degradation by accelerated tests is finally indicated. Full article

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