Coatings

16 pages, 1294 KiB

Open AccessArticle

A Comparative Clinical Study of the Self-Adhering Flowable Composite Resin Vertise Flow and the Traditional Flowable Composite Resin Premise Flowable

by Aleksander Maj, Agata Trzcionka, Henryk Twardawa and Marta Tanasiewicz

Coatings 2020, 10(8), 800; https://doi.org/10.3390/coatings10080800 - 18 Aug 2020

Cited by 7 | Viewed by 3896

Abstract

Background. The aim of this research was to carry out a comparative clinical study of a self-adhesive, light-curing composite material called Vertise Flow and a traditional flow material called Premise flowable used in combination with dedicated bonding systems. In order to standardize the [...] Read more.

Background. The aim of this research was to carry out a comparative clinical study of a self-adhesive, light-curing composite material called Vertise Flow and a traditional flow material called Premise flowable used in combination with dedicated bonding systems. In order to standardize the clinical environment, the stability of oral hygiene (analyzed with the oral hygiene index and the approximal plaque index) was taken into consideration. Methods. The study involved 37 patients with 64 fillings. They were distributed into three groups: 22 fillings in Group I, 22 fillings in Group II and 20 fillings in Group III. In Group I (G I), Vertise Flow material was applied without the use of an etching agent or a bonding system; in Group II (G II), Premise flowable material was applied without the use of an etching agent, but with the use of the OptiBond All-In-One seventh-generation bonding system; in Group III (G III), Premise flowable material was applied after etching and treatment of the hard tooth tissues using a fifth-generation OptiBond Solo Plus bonding system. Then, at appropriate time intervals (0, i.e., right after filling and after 6, 12 and 24 months), the fillings were subjected to clinical evaluation, conducted according to the Ryge scale criteria with the use of registration by means of a fluorescent high-intensity visible light beam produced by a camera (Vista Proof). Results. The quality of fillings performed with the use of comparable materials was subjected to clinical evaluation using the Ryge scale of fillings after 6, 12, and 24 months; the examination showed significant differences between the tested materials. The Vertise Flow material used without an etching agent or a bonding system (G I) presented the weakest results with respect to marginal adaptation and smoothness among those evaluated in this study. The intensification of the degradation continued over time until the final clinical observation at 24 months. The results confirmed that the best quality was achieved with the Premise flowable material after etching and treatment of the hard tooth tissues using a fifth-generation OptiBond Solo Plus bonding system (G III) relative to others for all time points during the observation. Conclusions. The used preparation scheme and bonding system have an impact on the final quality of the composite filling. There is a need to carry out a qualitative clinical evaluation of dental restorative materials under uniform conditions using evaluation scales. Full article

(This article belongs to the Special Issue Surface Properties of Dental Materials and Instruments)

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16 pages, 8282 KiB

Open AccessArticle

Detection of Organic Substances by a SERS Method Using a Special Ag-Poly(Chloro-P-Xylylene)-Ag Sandwich Substrate

by Irina Boginskaya, Aliia Gainutdinova, Alexey Gusev, Karen Mailyan, Anton Mikhailitsyn, Marina Sedova, Artem Vdovichenko, Ilya Ryzhikov, Sergei Chvalun and Andrey Lagarkov

Coatings 2020, 10(8), 799; https://doi.org/10.3390/coatings10080799 - 18 Aug 2020

Cited by 8 | Viewed by 2644

Abstract

Spectroscopy based on surface enhanced Raman scattering (SERS) is widely used as a method with extremely high sensitivity for molecular and chemical analysis. We have developed thin-film sandwich structures, in which, when used as sensitive elements for detecting organic compounds at low concentrations, [...] Read more.

Spectroscopy based on surface enhanced Raman scattering (SERS) is widely used as a method with extremely high sensitivity for molecular and chemical analysis. We have developed thin-film sandwich structures, in which, when used as sensitive elements for detecting organic compounds at low concentrations, high-amplitude spectra of surface enhanced Raman scattering are observed. Using gas-phase cryochemical synthesis and thermal sputtering in vacuum, SERS active sandwich structures Ag–poly(chloro-p-xylylene)–Ag (Ag–PCPX–Ag) were obtained. In the process of creating sandwich structures, the upper silver film takes the form of a complex island topology with submicron sizes. A series of samples were made with different thicknesses of the polymer and upper silver layers. SERS spectra of the analyte chemically adsorbed on the film surface were obtained, demonstrating a significant amplification (up to 10⁴) compared with the control sample. The dependence of the gain on the silver concentration is characterized by a maximum polymer layer thickness of 600 nm and a 30 nm thick upper silver layer. A selective amplification of the low molecular weight compound spectra with respect to proteins was observed. A semi-empirical model is proposed that is in good agreement with the experimental results. Full article

(This article belongs to the Special Issue Functional Nanofilms: From Fundamentals to Applications)

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Graphical abstract

11 pages, 5091 KiB

Open AccessArticle

The Effect of the Metal Phase on the Compressive and Tensile Stresses Reduction in the Superhard Nitride Coatings

by Alexey O. Volkhonsky, Igor V. Blinkov and Dmitry S. Belov

Coatings 2020, 10(8), 798; https://doi.org/10.3390/coatings10080798 - 18 Aug 2020

Cited by 2 | Viewed by 2373

Abstract

The influence of the compressive and tensile stresses forming in the nanostructured Ti–Al–N coatings during deposition on their physical-mechanical properties was studied. The modifying influence of metal components (Ni and Cu) introduction into Ti–Al–N coatings, which do not interact with nitrogen and have [...] Read more.

The influence of the compressive and tensile stresses forming in the nanostructured Ti–Al–N coatings during deposition on their physical-mechanical properties was studied. The modifying influence of metal components (Ni and Cu) introduction into Ti–Al–N coatings, which do not interact with nitrogen and have limited solubility with the nitride phase, was also under research. Coatings were deposited on WC–(6 wt.%)Co carbide cutting inserts with an arc-PVD method using a cathodic vacuum arc evaporation apparatus. The introduction of Ni and Cu to the composition leads to the reduction of nitride phases grain size in both investigated coatings from 120 to 10–12 nm for Ti–Al–Cu–N and to 15–18 nm for Ti–Al–Ni–N. Thus, the hardness increases from 29 to 43 and 51 GPa for the mentioned above coatings, respectively. Meanwhile, Ti–Al–Cu–N and Ti–Al–Ni–N coatings are characterized by tensile stresses about 0.12–0.32 MPa against the much higher value of compressive stresses in Ti–Al–N coatings (4.29–5.31 GPa). The modification of Ti–Al–N coatings also leads to the changing of their destruction mechanism during the scratch-test. The critical loads characterizing the emergence of the first cracks in the coatings and complete abrasion of the coating (L_c1 and L_c3) were determined. They had the value of 20; 22 N (L_c1) and 64; 57 N (L_c3) for Ti–Al–Ni–N; Ti–Al–Cu–N coatings, respectively. The L_c1 parameter for Ti–Al–N coatings was much lower and was equal to 11 N. Along with those, Ti–Al–N coatings destructed according to the adhesion mechanism when the critical load was 35 N. In addition, the decreasing level of compressive stresses in Ti–Al–Cu–N and Ti–Al–Ni–N coatings as compared to that in the Ti–Al–N coating, their crack resistance during multi-cycle shock-dynamic impact test was significantly higher. The results can indicate that high hardness and crack resistance of the coatings is to a greater extent determined by coatings nanostructuring, not the stresses value. In addition, it confirms the possibility to obtain coatings with low stresses value while maintaining their superhardness. Full article

(This article belongs to the Section Plasma Coatings, Surfaces & Interfaces)

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10 pages, 6312 KiB

Open AccessArticle

A Modeling and Experimental Study on the Growth of VCSEL Materials Using an 8 × 6 Inch Planetary MOCVD Reactor

by Yudan Gou, Jun Wang, Yang Cheng, Yintao Guo, Xiao Xiao and Shouhuan Zhou

Coatings 2020, 10(8), 797; https://doi.org/10.3390/coatings10080797 - 18 Aug 2020

Cited by 7 | Viewed by 3546

Abstract

VCSEL (vertical cavity surface emitting laser) is a promising optoelectronic device, but its high manufacturing cost limits its scope of applications. Growing on larger size wafers is an effective way to reduce the cost. However, the growth rate uniformity needs to be optimized [...] Read more.

VCSEL (vertical cavity surface emitting laser) is a promising optoelectronic device, but its high manufacturing cost limits its scope of applications. Growing on larger size wafers is an effective way to reduce the cost. However, the growth rate uniformity needs to be optimized to ensure the uniformity of the devices’ performance over the wafers. This paper investigates the factors which influence the growth rate uniformity using an 8 × 6 inch planetary reactor through experiments and simulations. At a carrier gas flow rate of 37 slm, an AsH₃ flow rate of 600 sccm, an AsH₃ flow rate ratio of 100:500, and a ceiling temperature of 175 °C, the growth rate uniformity of the AlGaAs layer with a relative standard deviation of 0.16%, 1σ, was obtained over the 6-inch wafers. The uniformity of the DBR stop band center and VCSEL quantum well wavelength with standard deviations of 0.142% and 0.023%, 1σ, were received over the 6-inch wafers, respectively. Based on the optimized results, 99.95% of VCSEL devices with wavelengths of 940 ± 5 nm were realized over the 6-inch wafers. Full article

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

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12 pages, 2445 KiB

Open AccessArticle

Effects of Bias Voltages on the Structural, Mechanical and Oxidation Resistance Properties of Cr–Si–N Nanocomposite Coatings

by Yanxiong Xiang, Lingling Huang and Changwei Zou

Coatings 2020, 10(8), 796; https://doi.org/10.3390/coatings10080796 - 18 Aug 2020

Cited by 10 | Viewed by 2676

Abstract

Cr–Si–N nanocomposite coatings were deposited by multi-arc ion plating under different bias voltages. The influences of bias voltage on composition, microstructure, surface morphology and mechanical properties of Cr–Si–N nanocomposite coatings were investigated in detail. The HR-TEM, XRD, and XPS results confirmed the formation [...] Read more.

Cr–Si–N nanocomposite coatings were deposited by multi-arc ion plating under different bias voltages. The influences of bias voltage on composition, microstructure, surface morphology and mechanical properties of Cr–Si–N nanocomposite coatings were investigated in detail. The HR-TEM, XRD, and XPS results confirmed the formation of nanocomposite structure of nanocrystalline of CrN embedded into the amorphous phase of Si₃N₄. The particle radius of CrN can be calculated from the half-width of the diffraction peak of CrN (200) and the value was about 20–60 nm. In addition, no diffraction peaks of CrSi₂, Cr₃Si, or Si₃N₄ were found in all the Cr–Si–N coatings. With the increasing of bias voltages from 0 to −200 V, the number and size of large droplets on the coating surface decreased, and the growth mode of the coatings changed from loose to dense. However, with the increasing of bias voltages from 0 to −200 V, the micro-hardness of the coatings increased and then decreased, reaching its maximum value at negative bias voltages of 100 V. It was found that the friction coefficient of Cr–Si–N coatings is almost the same except for the Cr–Si–N coatings deposited under bias voltage of 0 V. When the oxidation temperature was at 800 °C, the Cr–Si–N coating was only partially oxidized. However, with the increase of oxidation temperature to 1200 °C, the surface of the coating was completely covered by the oxide generated. The results showed that the bias voltages used in multi-arc ion plating had effects on the structure, mechanical, and high temperature oxidation resistance properties of Cr–Si–N nanocomposite coatings. Full article

(This article belongs to the Special Issue Plasma Surface Engineering)

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13 pages, 4847 KiB

Open AccessArticle

Effects of Process Parameters and CrCl₃ Concentration on the Structure, Surface Morphology, Composition and Corrosion Resistance of Electrodeposited NiCrP Amorphous Alloy Coatings

by Jingjing Xiao, Jinku Yu, Fuyu Guo, Qi Qiao, Haibo Yang and Yanqing Guo

Coatings 2020, 10(8), 795; https://doi.org/10.3390/coatings10080795 - 17 Aug 2020

Cited by 3 | Viewed by 2798

Abstract

Herein, NiCrP amorphous alloy coatings were prepared on copper substrates by electrodeposition. The aim of this paper is to replace Cr⁶⁺ with Cr³⁺ to prepare NiCrP amorphous alloy coating, which can reduce environmental pollution. By studying the influence of pH, temperature [...] Read more.

Herein, NiCrP amorphous alloy coatings were prepared on copper substrates by electrodeposition. The aim of this paper is to replace Cr⁶⁺ with Cr³⁺ to prepare NiCrP amorphous alloy coating, which can reduce environmental pollution. By studying the influence of pH, temperature (T), current density (D_K), and CrCl₃ concentration on the structure, surface morphology, composition, and corrosion resistance of the alloy coatings, the optimum bath formulation and process parameters were determined as follows: 25 g·L⁻¹ NiSO₄·6H₂O, 100 g·L⁻¹ CrCl₃·6H₂O, 20 g·L⁻¹ NaH₂PO₂·H₂O, 80 g·L⁻¹ Na₃C₆H₅O₇·2H₂O (sodium citrate), 40 g·L⁻¹ H₃BO₃, 50 g·L⁻¹ NH₄Cl, 1 g·L⁻¹ KF, 5 g·L⁻¹ C₇H₅O₃NS (saccharin), 0.05 g·L⁻¹ C₁₂H₂₅SO₄Na (sodium dodecyl sulfate), and 40 mL·L⁻¹ HCOOH and T: 30 °C, D_K: 15 A·dm⁻², and pH: 3.5, respectively. NiCrP amorphous alloy coatings with high corrosion resistance were prepared under the abovementioned conditions. The crystal cells of the coating surface are uniform and fine. The corrosion resistance of the NiCrP amorphous alloy coatings was characterized by polarization curves, electrochemical impedance spectroscopy, and an immersion corrosion test and compared with that of the NiP amorphous alloy coating. The results show that Ni91.9P8.1 and Ni83.5Cr8.3P8.2 corrosion potential and corrosion current density are −0.68, −0.44 V, and 36, 7 μA·cm⁻² in 3.5 wt.% NaCl, respectively. With Ni91.9P8.1 and Ni83.5Cr8.3P8.2, the maximum weight loss is 61.67 and 15.42 mg·dm⁻² in a 1 mol·L⁻¹ HCl, respectively. The corrosion resistance of the NiCrP amorphous alloy coatings in 3.5 wt.% NaCl and 1 mol·L⁻¹ HCl solutions is better than that of the NiP alloy coating. Full article

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

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23 pages, 12049 KiB

Open AccessArticle

Thin SiNC/SiOC Coatings with a Gradient of Refractive Index Deposited from Organosilicon Precursor

by Hieronim Szymanowski, Katarzyna Olesko, Jacek Kowalski, Mateusz Fijalkowski, Maciej Gazicki-Lipman and Anna Sobczyk-Guzenda

Coatings 2020, 10(8), 794; https://doi.org/10.3390/coatings10080794 - 17 Aug 2020

Cited by 13 | Viewed by 4018

Abstract

In this work, optical coatings with a gradient of the refractive index are described. Its aim was to deposit, using the RF PECVD method, films of variable composition (ranging from silicon carbon-oxide to silicon carbon-nitride) for a smooth change of their optical properties [...] Read more.

In this work, optical coatings with a gradient of the refractive index are described. Its aim was to deposit, using the RF PECVD method, films of variable composition (ranging from silicon carbon-oxide to silicon carbon-nitride) for a smooth change of their optical properties enabling a production of the filter with a refractive index gradient. For that purpose, two organosilicon compounds, namely tetramethyldisilazane and hexamethyldisilazane, were selected as precursor compounds. The results reveal better optical properties of the materials obtained from the latter source. Depending on whether deposited in pure oxygen atmosphere or under conditions of pure nitrogen, the refractive index of the coatings amounted to 1.65 and to 2.22, respectively. By using a variable composition N₂/O₂ gas mixture, coatings of intermediate magnitudes of “n” were acquired. The optical properties were investigated using both UV-Vis absorption spectroscopy and variable angle spectroscopic ellipsometry. The chemical structure of the coatings was studied with the help of Fourier transform infrared and X-ray photoelectron spectroscopies. Finally, atomic force microscopy was applied to examine their surface topography. As the last step, a “cold mirror” type interference filter with a gradient of refractive index was designed and manufactured. Full article

(This article belongs to the Special Issue Functional Ceramic Coatings)

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21 pages, 6560 KiB

Open AccessArticle

Structure and Properties of AlCrN Coatings Deposited Using Cathodic Arc Evaporation

by Bogdan Warcholinski, Adam Gilewicz, Piotr Myslinski, Ewa Dobruchowska and Dawid Murzynski

Coatings 2020, 10(8), 793; https://doi.org/10.3390/coatings10080793 - 15 Aug 2020

Cited by 37 | Viewed by 4806

Abstract

Al–Cr–N coatings were formed at various nitrogen pressures, substrate bias voltages and substrate temperatures using cathodic arc evaporation. The relationship between technological parameters and properties of the coatings was investigated. The phase and chemical composition of the coatings, roughness, hardness, adhesion and thermal [...] Read more.

Al–Cr–N coatings were formed at various nitrogen pressures, substrate bias voltages and substrate temperatures using cathodic arc evaporation. The relationship between technological parameters and properties of the coatings was investigated. The phase and chemical composition of the coatings, roughness, hardness, adhesion and thermal stability were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDX), micro-indenter, Rockwell, scratch tester and thermomechanical methods. The corrosion resistance of selected coatings was also investigated. XRD analysis indicates that the coatings crystallize in a cubic structure and show preferential orientation (200) CrN. With the increase of nitrogen pressure, the preferential orientation changes to (111). EDX analysis shows that as nitrogen pressure increases, the Al/(Al + Cr) rate decreases. Microscopic observations indicate that the number of macroparticles reduces as nitrogen pressure increases. As a result, the surface roughness parameter Ra of the coatings decreases. The effects of deposition temperature, nitrogen pressure and substrate bias voltage on the mechanical and tribological properties of the coatings were investigated. It was found that the above parameters influence the mechanical properties in different ways. The hardness and adhesion of coatings formed at higher temperatures was lower. Coatings formed under a higher nitrogen pressure or substrate bias voltage were characterized by higher hardness and better wear resistance. Full article

(This article belongs to the Special Issue Coatings Deposited by Cathodic Arc and Magnetron Sputtering Process)

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15 pages, 8877 KiB

Open AccessArticle

A Fully Inkjet-Printed Strain Sensor Based on Carbon Nanotubes

by Hsuan-Ling Kao, Cheng-Lin Cho, Li-Chun Chang, Chun-Bing Chen, Wen-Hung Chung and Yun-Chen Tsai

Coatings 2020, 10(8), 792; https://doi.org/10.3390/coatings10080792 - 14 Aug 2020

Cited by 30 | Viewed by 4347

Abstract

A fully inkjet-printed strain sensor based on carbon nanotubes (CNTs) was fabricated in this study for microstrain and microcrack detection. Carbon nanotubes and silver films were used as the sensing layer and conductive layer, respectively. Inkjet-printed CNTs easily undergo agglomeration due to van [...] Read more.

A fully inkjet-printed strain sensor based on carbon nanotubes (CNTs) was fabricated in this study for microstrain and microcrack detection. Carbon nanotubes and silver films were used as the sensing layer and conductive layer, respectively. Inkjet-printed CNTs easily undergo agglomeration due to van der Waals forces between CNTs, resulting in uneven films. The uniformity of CNT film affects the electrical and mechanical properties. Multi-pass printing and pattern rotation provided precise quantities of sensing materials, enabling the realization of uniform CNT films and stable resistance. Three strain sensors printed eight-layer CNT film by unidirectional printing, rotated by 180° and 90° were compared. The low density on one side of eight-layer CNT film by unidirectional printing results in more disconnection and poor connectivity with the silver film, thereby, significantly increasing the resistance. For 180° rotation eight-layer strain sensors, lower sensitivity and smaller measured range were found because strain was applied to the uneven CNT film resulting in non-uniform strain distribution. Lower resistance and better strain sensitivity was obtained for eight-layer strain sensor with 90° rotation because of uniform film. Given the uniform surface morphology and saturated sheet resistance of the 20-layer CNT film, the strain performance of the 20-layer CNT strain sensor was also examined. Excluding the permanent destruction of the first strain, 0.76% and 1.05% responses were obtained for the 8- and 20-layer strain sensors under strain between 0% and 3128 µε, respectively, which demonstrates the high reproducibility and recoverability of the sensor. The gauge factor (GF) of 20-layer strain sensor was found to be 2.77 under strain from 71 to 3128 µε, which is higher than eight-layer strain sensor (GF = 1.93) due to the uniform surface morphology and stable resistance. The strain sensors exhibited a highly linear and reversible behavior under strain of 71 to 3128 µε, so that the microstrain level could be clearly distinguished. The technology of the fully inkjet-printed CNT-based microstrain sensor provides high reproducibility, stability, and rapid hardness detection. Full article

(This article belongs to the Special Issue Multilayer and Functional Graded Coatings)

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14 pages, 3196 KiB

Open AccessArticle

RF/DC Magnetron Sputtering Deposition of Thin Layers for Solar Cell Fabrication

by Slawomir Gulkowski and Ewelina Krawczak

Coatings 2020, 10(8), 791; https://doi.org/10.3390/coatings10080791 - 14 Aug 2020

Cited by 13 | Viewed by 5295

Abstract

Thin film Cu(In,Ga)Se₂ (CIGS)-based solar cells with relatively high efficiency and low material usage might become a promising alternative for crystalline silicon technology. The most challenging task nowadays is to decrease the PV module fabrication costs by application of easily scalable industrial [...] Read more.

Thin film Cu(In,Ga)Se₂ (CIGS)-based solar cells with relatively high efficiency and low material usage might become a promising alternative for crystalline silicon technology. The most challenging task nowadays is to decrease the PV module fabrication costs by application of easily scalable industrial process. One of the possible solutions is the usage of magnetron sputtering system for deposition of all structures applied in CIGS-based photovoltaic device. The main object of these studies was fabrication and characterization of thin films deposited by sputtering technique. Structural and electrical properties of the sputtered films were analyzed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray Powder Diffraction (XRD), and four-point probe resistivity measurements. The presented findings revealed technological parameters for which sheet resistance of molybdenum (Mo) back contact decreased up to 0.3 Ω/□ and to even 0.08 Ω/□ in case of aluminum layer. EDS analysis provided evidence for the appropriate stoichiometry of CIGS absorber (with CGI and GGI equal to 0.96 and 0.2, respectively). XRD characterization confirmed high-quality chalcopyrite polycrystalline structure of Cu(In,Ga)Se₂ film fabricated at relatively low substrate temperature of 400 °C. Characteristic XRD peaks of hexagonal-oriented structures of sputtered CdS and i-ZnO layers were noticed. Full article

(This article belongs to the Section Thin Films)

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9 pages, 1113 KiB

Open AccessCommunication

Copper-Silver Alloy Coated Door Handles as a Potential Antibacterial Strategy in Clinical Settings

by Nicole Ciacotich, Lasse Kvich, Nicholas Sanford, Joseph Wolcott, Thomas Bjarnsholt and Lone Gram

Coatings 2020, 10(8), 790; https://doi.org/10.3390/coatings10080790 - 14 Aug 2020

Cited by 3 | Viewed by 4325

Abstract

Coating surfaces with a copper-silver alloy in clinical settings can be an alternative or complementary antibacterial strategy to other existing technologies and disinfection interventions. A newly developed copper-silver alloy coating has a high antibacterial efficacy against common pathogenic bacteria in laboratory setups, and [...] Read more.

Coating surfaces with a copper-silver alloy in clinical settings can be an alternative or complementary antibacterial strategy to other existing technologies and disinfection interventions. A newly developed copper-silver alloy coating has a high antibacterial efficacy against common pathogenic bacteria in laboratory setups, and the purpose of this study is to determine the antibacterial efficacy of this copper-silvery alloy in real-world clinical settings. Two field trials were carried out at a private clinic and a wound care center. Door handles coated with the copper-silver alloy had a lower total aerobic plate count (1.3 ± 0.4 Log CFU/cm² and 0.8 ± 0.3 Log CFU/cm², CFU stands for Colony Forming Units) than the reference uncoated material on-site (2.4 ± 0.4 Log CFU/cm² for the stainless steel and 1.7 ± 0.4 Log CFU/cm² for the satin brass). The copper-silver alloy did not selectively reduce specific bacterial species. This study points to the possibility of a successful long-term implementation of the copper-silver alloy coating as an antibacterial strategy. Full article

(This article belongs to the Special Issue Antibacterial Coatings and Biofilm)

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10 pages, 2423 KiB

Open AccessArticle

Study of the Static and Microwave Magnetic Properties of Nanostructured BaFe_12−xTi_xO₁₉

by Polina A. Zezyulina, Dmitry A. Petrov, Konstantin N. Rozanov, Denis A. Vinnik, Sergey S. Maklakov, Vladimir E. Zhivulin, Andrey Yu. Starikov, Daria P. Sherstyuk and Santiranjan Shannigrahi

Coatings 2020, 10(8), 789; https://doi.org/10.3390/coatings10080789 - 14 Aug 2020

Cited by 4 | Viewed by 2298

Abstract

The effect of Ti substitution on the microwave and magnetostatic properties of nanostructured hexagonal BaFe_12−xTi_xO₁₉ ferrite composites is studied. The microwave permeability is measured in the frequency range of 0.1–22 GHz by a coaxial technique. An analysis [...] Read more.

The effect of Ti substitution on the microwave and magnetostatic properties of nanostructured hexagonal BaFe_12−xTi_xO₁₉ ferrite composites is studied. The microwave permeability is measured in the frequency range of 0.1–22 GHz by a coaxial technique. An analysis of the magnetostatic data is made by the law of approach to saturation. The ferrimagnetic resonance frequencies calculated from the magnetostatic data are consistent with those obtained from the microwave measurements. The natural ferrimagnetic resonance frequencies are located in the frequency range of 15 to 22 GHz, depending on the substitution level x. An increase in the amount of substitution elements results in a low-frequency shift of the ferrimagnetic resonance frequency for samples with x < 1. With x rising from 1 to 2.5, the resonance frequency increases. The results of the study demonstrate that the tailored optimization of the nano-structure of a functional material is a robust tool to fine-tune its microwave magnetic properties. The ferrites under study are promising materials to be applied as functional coatings intended to control electromagnetic interference in microwave devices. Full article

(This article belongs to the Special Issue Functional Nanofilms: From Fundamentals to Applications)

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16 pages, 3730 KiB

Open AccessArticle

ZnO Nanostructured Thin Films via Supersonic Plasma Jet Deposition

by Chiara Carra, Elisa Dell’Orto, Vittorio Morandi and Claudia Riccardi

Coatings 2020, 10(8), 788; https://doi.org/10.3390/coatings10080788 - 13 Aug 2020

Cited by 11 | Viewed by 3064

Abstract

Zinc Oxide nanostructured thin films were grown by a novel plasma assisted vapour deposition method, which aims to combine the versatility of deposition processes that are mediated by plasma with the capability to control particles diffusion and nucleation. For this purpose, the proposed [...] Read more.

Zinc Oxide nanostructured thin films were grown by a novel plasma assisted vapour deposition method, which aims to combine the versatility of deposition processes that are mediated by plasma with the capability to control particles diffusion and nucleation. For this purpose, the proposed approach spatially separates into two different vacuum chambers the creation of zinc oxide from a metalorganic precursor from the actual film growth, thanks to the extraction of a supersonic jet of plasma seeded by the precursor fragments. The characterization of the reactor in different plasma conditions has been carried out by means of optical emission spectroscopy (OES). ZnO films with different degrees of purity, thickness uniformity, as well as different morphologies can be obtained varying the deposition parameters. The samples profiles have been collected in order to evaluate deposition rates and films uniformity. The as-prepared as well as annealed thin films were characterized by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) to evaluate their chemical composition and purity. According to Raman analyses, the annealed samples are high-purity wurtzite-type crystalline zinc oxide films. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) confirm a surface morphology characterized by columnar structures. Full article

(This article belongs to the Section Plasma Coatings, Surfaces & Interfaces)

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10 pages, 4068 KiB

Open AccessArticle

Addition of Si₃N₄ Strengthens SiC Coatings via Heat Treatment with Nitrogen Gas onto Carbon/Carbon Composites

by Zuli Mao and Li Yang

Coatings 2020, 10(8), 787; https://doi.org/10.3390/coatings10080787 - 13 Aug 2020

Cited by 3 | Viewed by 2829

Abstract

We report the synthesis of SiC/Si₃N₄ coatings on carbon/carbon composites via pack cementation and heat treatment with nitrogen gas, the latter of which improves the coating wear resistance. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) [...] Read more.

We report the synthesis of SiC/Si₃N₄ coatings on carbon/carbon composites via pack cementation and heat treatment with nitrogen gas, the latter of which improves the coating wear resistance. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) are used to analyse the microstructure, surface morphology, chemical states and elemental distribution, respectively, of SiC and SiC/Si₃N₄ coatings. In addition, we analyse the tribological behaviour of the SiC and SiC/Si₃N₄ coatings and the related microstructure and wear mechanisms. The results show that SiC/Si₃N₄ coatings are compact and contain the three phases: Si₃N₄, SiC and C. Additionally, specimens with the SiC/Si₃N₄ coating have smaller, more stable friction coefficients and less weight loss than specimens with only the SiC coating. Adhesive wear and abrasive wear are the main wear mechanisms contributing to the higher friction coefficient of the SiC coating. Furthermore, with the SiC/Si₃N₄ coating, adhesive wear is the main wear mechanism causing a high friction coefficient at the initial stage of frictional wear. In the subsequent stages of frictional wear, the graphite in the SiC/Si₃N₄ coating generates a thin lubricating film that decreases the friction coefficient. Full article

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9 pages, 3016 KiB

Open AccessArticle

Thermal Stability, Hardness, and Corrosion Behavior of the Nickel–Ruthenium–Phosphorus Sputtering Coatings

by Yu-Cheng Hsiao and Fan-Bean Wu

Coatings 2020, 10(8), 786; https://doi.org/10.3390/coatings10080786 - 13 Aug 2020

Cited by 1 | Viewed by 2498

Abstract

Nickel–ruthenium–phosphorus, Ni–Ru–P, alloy coatings were fabricated by magnetron dual-gun co-sputtering from Ni–P alloy and Ru source targets. The composition variation and related microstructure evolution of the coatings were manipulated by the input power modulation. The as-prepared Ni–Ru–P alloy coatings with a Ru content [...] Read more.

Nickel–ruthenium–phosphorus, Ni–Ru–P, alloy coatings were fabricated by magnetron dual-gun co-sputtering from Ni–P alloy and Ru source targets. The composition variation and related microstructure evolution of the coatings were manipulated by the input power modulation. The as-prepared Ni–Ru–P alloy coatings with a Ru content less than 12.2 at.% are amorphous/nanocrystalline, while that with a high Ru content of 52.7 at.% shows a feature of crystallized Ni, Ru, and Ru₂P mixed phases in the as-deposited state. The crystallized phases for high Ru content Ni–Ru–P coatings are stable against annealing process up to 600 °C. By contrast, the amorphous/nanocrystalline Ni–Ru–P thin films withstand a heat-treated temperature up to 475 °C and then transform into Ni(Ru) and Ni_xP_y crystallized phases at an annealing temperature over 500 °C. The surface hardness of the Ni–Ru–P films ranges from 7.2 to 12.1 GPa and increases with the Ru content and the annealing temperatures. A highest surface hardness is found for the 550 °C annealed Ni–Ru–P with a high Ru content of 52.7 at.%. The E_corr values of the heat-treated amorphous/nanocrystalline Ni–Ru–P coatings become more negative, while with a high Ru content over 27.3 at.% the Ni–Ru–P films show more negative E_corr values after annealing process. The pitting corrosion feature is observed for the amorphous/nanocrystalline Ni–Ru–P coatings when tested in a 3.5M NaCl solution. Severer pitting corrosion is found for the 550 °C annealed Ni–Ru–P coatings. The development of Ni(Ru) and Ni_xP_y crystallized phases during annealing is responsible for the degeneration of corrosion resistance. Full article

(This article belongs to the Special Issue Multilayer and Functional Graded Coatings)

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12 pages, 982 KiB

Open AccessArticle

Effect of MF-Coated Epoxy Resin Microcapsules on Properties of Waterborne Wood Coating on Basswood

by Xiaoxing Yan and Yijuan Chang

Coatings 2020, 10(8), 785; https://doi.org/10.3390/coatings10080785 - 12 Aug 2020

Cited by 11 | Viewed by 3165

Abstract

In this paper, melamine–formaldehyde (MF) was used as the wall material, and epoxy resin was used as the core material to prepare microcapsules. The optical properties, mechanical properties and ageing resistance of waterborne topcoat were investigated by adding different mass fractions of microcapsules [...] Read more.

In this paper, melamine–formaldehyde (MF) was used as the wall material, and epoxy resin was used as the core material to prepare microcapsules. The optical properties, mechanical properties and ageing resistance of waterborne topcoat were investigated by adding different mass fractions of microcapsules into the waterborne topcoat. Through scanning electron microscopy and infrared spectroscopy analysis, the prepared microcapsules of core-wall ratio of 0.50 were more uniform. It was found that when the mass fraction of microcapsules is less than 10.0% and the core–wall ratio is 0.50, the original color difference of the coating can be maintained. With the increase in microcapsule mass fraction, the gloss of the topcoat film gradually decreases. The mass fraction of the microcapsule of 4.0% with the core–wall ratio of 0.50 can maintain the original gloss of 30.0 GU. The topcoat film with the MF-coated epoxy resin microcapsules of the core–wall ratio of 0.50 has high impact resistance, adhesion and hardness. The results showed that the gloss loss and color difference of the coating with the MF-coated epoxy microcapsules were the lowest when the mass fraction of microcapsules was 4.0%, indicating that microcapsules can improve the stability of coating. These results lay a technical foundation for the development and application of high-performance wood coatings. Full article

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20 pages, 5538 KiB

Open AccessArticle

Encapsulation of Grapefruit Essential Oil in Emulsion-Based Edible Film Prepared by Plum (Pruni Domesticae Semen) Seed Protein Isolate and Gum Acacia Conjugates

by Chen Li, Jiliu Pei, Xiaohui Xiong and Feng Xue

Coatings 2020, 10(8), 784; https://doi.org/10.3390/coatings10080784 - 12 Aug 2020

Cited by 29 | Viewed by 4795

Abstract

A dry-heated Maillard reaction was used to prepare plum seed protein isolate and gum acacia conjugates. Emulsion-based edible films (EBEF) were prepared by the encapsulation of grapefruit essential oil using conjugates solution as the continuous phase. The conjugates formed from 3 days of [...] Read more.

A dry-heated Maillard reaction was used to prepare plum seed protein isolate and gum acacia conjugates. Emulsion-based edible films (EBEF) were prepared by the encapsulation of grapefruit essential oil using conjugates solution as the continuous phase. The conjugates formed from 3 days of dry heating showed a significant improvement in emulsifying properties due to the unfolding of protein, as confirmed by structure analysis. The droplet size, electrical charge, and viscosity of emulsions increased with the increasing essential oil concentration, and all emulsions exhibited ‘gel’-like behavior. The water vapor barrier property, surface hydrophobicity, mechanical properties, and thermal stability of the films were improved as the essential oil content increased in the range of 1–4% due to enhancement in intermolecular interaction and compatibility, as well as a denser microstructure. Furthermore, all films exhibited an inhibitory effect against E. coli, while their radical scavenging activity depended on the release rate from films. The results obtained in this work confirmed that EBEF could be used as a novel food active packaging in the near future. Full article

(This article belongs to the Special Issue Green Polymer Coatings and Films for Food and Health Applications)

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14 pages, 2633 KiB

Open AccessArticle

Enhanced Corrosion Protection of Epoxy/ZnO-NiO Nanocomposite Coatings on Steel

by Muna Ibrahim, Karthik Kannan, Hemalatha Parangusan, Shady Eldeib, Omar Shehata, Mohammad Ismail, Ranin Zarandah and Kishor Kumar Sadasivuni

Coatings 2020, 10(8), 783; https://doi.org/10.3390/coatings10080783 - 12 Aug 2020

Cited by 62 | Viewed by 5722

Abstract

ZnO-NiO nanocomposite with epoxy coating on mild steel has been fabricated by the sol–gel assisted method. The synthesized sample was used to study corrosion protection. The analysis was performed by electrochemical impedance spectroscopy in 3.5% NaCl solution. The structural and morphological characterization of [...] Read more.

ZnO-NiO nanocomposite with epoxy coating on mild steel has been fabricated by the sol–gel assisted method. The synthesized sample was used to study corrosion protection. The analysis was performed by electrochemical impedance spectroscopy in 3.5% NaCl solution. The structural and morphological characterization of the metal oxide nanocomposite was carried out using XRD and SEM with Energy Dispersive Absorption X-ray (EDAX) analysis. XRD reveals the ZnO-NiO (hexagonal and cubic) structure with an average ZnO-NiO crystallite size of 26 nm. SEM/EDAX analysis of the ZnO-NiO nanocomposite confirms that the chemical composition of the samples consists of: Zn (8.96 ± 0.11 wt.%), Ni (10.53 ± 0.19 wt.%) and O (80.51 ± 3.12 wt.%). Electrochemical Impedance Spectroscopy (EIS) authenticated that the corrosion resistance has improved for the nanocomposites of ZnO-NiO coated along with epoxy on steel in comparison to that of the pure epoxy-coated steel. Full article

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32 pages, 596 KiB

Open AccessReview

Electrodeposited Biocoatings, Their Properties and Fabrication Technologies: A Review

by Andrzej Zielinski and Michal Bartmanski

Coatings 2020, 10(8), 782; https://doi.org/10.3390/coatings10080782 - 12 Aug 2020

Cited by 30 | Viewed by 5299

Abstract

Coatings deposited under an electric field are applied for the surface modification of biomaterials. This review is aimed to characterize the state-of-art in this area with an emphasis on the advantages and disadvantages of used methods, process determinants, and properties of coatings. Over [...] Read more.

Coatings deposited under an electric field are applied for the surface modification of biomaterials. This review is aimed to characterize the state-of-art in this area with an emphasis on the advantages and disadvantages of used methods, process determinants, and properties of coatings. Over 170 articles, published mainly during the last ten years, were chosen, and reviewed as the most representative. The most recent developments of metallic, ceramic, polymer, and composite electrodeposited coatings are described focusing on their microstructure and properties. The direct cathodic electrodeposition, pulse cathodic deposition, electrophoretic deposition, plasma electrochemical oxidation in electrolytes rich in phosphates and calcium ions, electro-spark, and electro-discharge methods are characterized. The effects of electrolyte composition, potential and current, pH, and temperature are discussed. The review demonstrates that the most popular are direct and pulse cathodic electrodeposition and electrophoretic deposition. The research is mainly aimed to introduce new coatings rather than to investigate the effects of process parameters on the properties of deposits. So far tests aim to enhance bioactivity, mechanical strength and adhesion, antibacterial efficiency, and to a lesser extent the corrosion resistance. Full article

(This article belongs to the Special Issue Recent Developments of Electrodeposition Coating)

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10 pages, 9541 KiB

Open AccessArticle

A Study of the Optical Properties and Fabrication of Coatings Made of Three-Dimensional Photonic Glass

by Chih-Ling Huang

Coatings 2020, 10(8), 781; https://doi.org/10.3390/coatings10080781 - 12 Aug 2020

Cited by 14 | Viewed by 3257

Abstract

Photonic crystals employ optical properties based on optical, physical, chemical, and material science. Nanosilica particles have a high specific surface area and are widely used in nanotechnology research and biomedical applications. In this study, nanosilica particles were fabricated by sol–gel methods, and the [...] Read more.

Photonic crystals employ optical properties based on optical, physical, chemical, and material science. Nanosilica particles have a high specific surface area and are widely used in nanotechnology research and biomedical applications. In this study, nanosilica particles were fabricated by sol–gel methods, and the particle sizes of the silica nanoparticles were 280, 232, and 187 nm, based on dynamic light scattering. The silica nanoparticle suspension solution was heated to boiling for fast evaporation processing for self-assembly to fabricate three-dimensional photonic glass for structural color coatings. The sample had an adjustable structural color (red: 640 nm, green: 532 nm, and blue: 432 nm). The microstructures of various structure-colored samples were arranged, but there was a disordered solid arrangement of silica nanoparticles. These were not perfect opal-based photonic crystals. Compared to opal-based photonic crystals, the arrangement of silica nanoparticles was a glassy structure with a short-range order. Due to the accumulation of silica nanoparticle aggregates, samples displayed a stable colloidal film, independent of the viewing angle. In our study, the fast solvent evaporation in the self-assembly process led to the formation of a colloidal amorphous array, and it fitted the requirement for non-iridescence. Non-iridescent photonic glass with various colors was obtained. This type of color coating has wide potential applications, including reflective displays, colorimetric sensors, textiles, and buildings. Full article

(This article belongs to the Special Issue Thin Films and Coatings by Sol-Gel Chemistry: Synthesis, Characterization and Applications)

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10 pages, 3244 KiB

Open AccessFeature PaperArticle

Analysis of Metal-Insulator Crossover in Strained SrRuO₃ Thin Films by X-ray Photoelectron Spectroscopy

by Andrea Nardi, Chiara Bigi, Sandeep Kumar Chaluvadi, Regina Ciancio, Jun Fujii, Ivana Vobornik, Giancarlo Panaccione, Giorgio Rossi and Pasquale Orgiani

Coatings 2020, 10(8), 780; https://doi.org/10.3390/coatings10080780 - 11 Aug 2020

Cited by 7 | Viewed by 3736

Abstract

The electronic properties of strontium ruthenate

{SrRuO}_{3}

perovskite oxide thin films are modified by epitaxial strain, as determined by growing on different substrates by pulsed laser deposition. Temperature dependence of the transport properties indicates that tensile strain deformation of the

{SrRuO}_{3}

[...] Read more.

The electronic properties of strontium ruthenate

{SrRuO}_{3}

perovskite oxide thin films are modified by epitaxial strain, as determined by growing on different substrates by pulsed laser deposition. Temperature dependence of the transport properties indicates that tensile strain deformation of the

{SrRuO}_{3}

unit cell reduces the metallicity of the material as well as its metal-insulator-transition (MIT) temperature. On the contrary, the shrinkage of the Ru–O–Ru buckling angle due to compressive strain is counterweighted by the increased overlap of the conduction Ru-4d orbitals with the O-2p ones due to the smaller interatomic distances resulting into an increased MIT temperature, i.e., a more conducting material. In particular, in the more metallic samples, the core level X-ray photoemission spectroscopy lineshapes show the occurrence of an extra-peak at the lower binding energies of the main Ru-3d peak that is attributed to screening, as observed in volume sensitive photoemission of the unstrained material. Full article

(This article belongs to the Special Issue Advance in Perovskite Thin Films)

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22 pages, 3405 KiB

Open AccessArticle

Marine Antibiofouling Properties of TiO₂ and Ti-Cu-O Films Deposited by Aerosol-Assisted Chemical Vapor Deposition

by Caroline Villardi de Oliveira, Julie Petitbois, Fabienne Faÿ, Frédéric Sanchette, Frédéric Schuster, Akram Alhussein, Odette Chaix-Pluchery, Jean-Luc Deschanvres and Carmen Jiménez

Coatings 2020, 10(8), 779; https://doi.org/10.3390/coatings10080779 - 11 Aug 2020

Cited by 7 | Viewed by 3727

Abstract

The actual interest in developing light-induced catalytic coatings to act as an antibiofouling alternative has recently prompted interest in the incorporation of Cu into TiO₂ films, working as a visible light sensitizer catalyst. TiO₂ and new Ti-Cu-O films with Cu contents [...] Read more.

The actual interest in developing light-induced catalytic coatings to act as an antibiofouling alternative has recently prompted interest in the incorporation of Cu into TiO₂ films, working as a visible light sensitizer catalyst. TiO₂ and new Ti-Cu-O films with Cu contents ranging between 16% and 75% Cu/(Cu + Ti) are deposited by aerosol-assisted metalorganic chemical vapor deposition at a substrate temperature of 550 °C. The films are composed of TiO₂ anatase phase, mixed with Cu₂O when including Cu in the composition. Pure TiO₂ films’ morphologies are characterized by the formation of microflower-like structures with nanometric petals, which induce a high specific surface. These features are not present in Ti-Cu-O films. A UV-Visible study revealed that the optical band gap energy decreases with increasing Cu content. Interestingly, Ti-Cu-O films presented a highly photo-catalytic activity in the orange-G degradation. Marine biofouling field tests in Lorient’s Harbor in France and in vitro tests were carried out in order to evaluate the antifouling performance of the films, revealing that topography and chemical composition can act differently on different species. Field tests revealed that TiO₂ microflowers reduced the fouling coverage. Besides, Ti-Cu-O films with 16 at.% Cu presented lower fouling coverage than films containing 58 at.% Cu. In vitro tests using two diatoms (P. tricornutum and N. perminuta) showed that the spaces between microflowers play a significant role in the adhesion of diatoms: microalgae adhere less when spaces are bigger than their cells, compared to when spaces are of the same size as cells. Films containing Cu did not alter N. perminuta growth nor adhesion, while they affected P. tricornutum by lowering its growth rate and adhesion without noticeable toxicity. Indeed, Cu-Ti-O is a very promising non-toxic fouling release film for marine and industrial applications. Full article

(This article belongs to the Special Issue Novel Marine Antifouling Coatings)

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16 pages, 6475 KiB

Open AccessArticle

Preparation and Self-Repairing Properties of MF-Coated Shellac Water-Based Microcapsules

by Yijuan Chang and Xiaoxing Yan

Coatings 2020, 10(8), 778; https://doi.org/10.3390/coatings10080778 - 10 Aug 2020

Cited by 17 | Viewed by 2884

Abstract

A self-repairing microcapsule was prepared by emulsion polymerization using melamine formaldehyde resin (MF) as wall material, and a mixture of shellac solution and water-based coating as core material. The orthogonal experiment was carried out through five factors and four levels. The effects of [...] Read more.

A self-repairing microcapsule was prepared by emulsion polymerization using melamine formaldehyde resin (MF) as wall material, and a mixture of shellac solution and water-based coating as core material. The orthogonal experiment was carried out through five factors and four levels. The effects of W_core:W_wall, W_emulsifier:W_core, stirring rate, W_shellac:W_coating, W_{emulsifier solution}:W_core on the output and coverage rate of microcapsules were studied. The stirring rate has a great influence on the preparation process of the MF-coated shellac water-based microcapsules. When the W_core:W_wall is 0.8:1, W_emulsifier:W_core is 3:100, stirring rate is 600 rpm, W_shellac:W_coating is 1:1, W_{emulsifier solution}:W_core is 9:1, the prepared microcapsules have the best shape and size. With the increase in concentration of microcapsules, the color difference and gloss of paint film decreased gradually. The tensile strength, scanning electron microscopy (SEM), infrared spectroscopy and repair effects of the paint film were analyzed. When the concentration of microcapsules was 5.0–10.0%, the comprehensive performance of the paint film was better, providing a technical reference for the self-repairing coatings. Full article

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10 pages, 204 KiB

Open AccessEditorial

Recent Trends in Coatings and Thin Film: Modeling and Application

by Rahmat Ellahi

Coatings 2020, 10(8), 777; https://doi.org/10.3390/coatings10080777 - 10 Aug 2020

Cited by 10 | Viewed by 3064

Abstract

This special issue took this opportunity to invite researchers to contribute their original research work and review articles to this Special Issue on “Recent Trends in Coatings and Thin Film: Modeling and Application” to be published in Coatings. The goal of this Special [...] Read more.

This special issue took this opportunity to invite researchers to contribute their original research work and review articles to this Special Issue on “Recent Trends in Coatings and Thin Film: Modeling and Application” to be published in Coatings. The goal of this Special Issue was to address challenges and current issues that either advance the state-of-the-art of experimental, numerical, and theoretical methodologies, or extends the bounds of existing methodologies to new contributions that are related to coatings and thin film containing whichever, magnetic, multiphase, material science, nanotechnology, surfaces, interfaces, and mechanical sensing properties. In response to the call for papers, a total of 58 papers were submitted for possible publication. After comprehensive peer review, only 27 papers qualified for acceptance for final publication. The rest of 31 papers could not be accommodated. The submissions may have been technically correct, but were not considered appropriate for the scope of this special issue. The authors are from 17 geographically distributed countries, such as China, Spain, Romania, Turkey, Saudi Arabia, Pakistan, Malaysia, Abu Dhabi, UAE, Vietnam, Korea, Taiwan, Thailand, Lebanon, Egypt, India, and Kuwait, etc. This reflects the great impact of the proposed topic and the effective organization of the guest editorial team of this Special Issue. Full article

(This article belongs to the Special Issue Recent Trends in Coatings and Thin Film–Modeling and Application)

17 pages, 2850 KiB

Open AccessArticle

Robustness of Surface Roughness against Low Number of Picture Elements and Its Benefit for Scaling Analysis

by Wenmeng Zhou, Xinghui Li, Feng Feng, Timing Qu, Junlong Huang, Xiang Qian, Huiting Zha and Pingfa Feng

Coatings 2020, 10(8), 776; https://doi.org/10.3390/coatings10080776 - 10 Aug 2020

Cited by 10 | Viewed by 2802

Abstract

Surface roughness is widely used in the research of topography, and the scaling characteristics of roughness have been noticed in many fields. To rapidly obtain the relationship between root-mean-squared roughness (

R q

) and measurement scale (L) could be helpful [...] Read more.

Surface roughness is widely used in the research of topography, and the scaling characteristics of roughness have been noticed in many fields. To rapidly obtain the relationship between root-mean-squared roughness (

R q

) and measurement scale (L) could be helpful to achieve more understandings of the surface property, particularly the

R q

-L curve could be fitted to calculate the fractal dimension (D). In this study, the robustness of

R q

against low number of picture elements was investigated. Artificial surfaces and the surfaces of two actual samples (a silver thin film and a milled workpiece) were selected. When the number of picture elements was lowered,

R q

was found to be stable within a large portion of the concerned scope. Such a robustness property could validate the feasibility of

R q

-L curve obtained by segmenting a single morphological picture with roughness scaling extraction (RSE) method, which was proposed in our previous study. Since the traditional roughness (TR) method to obtain

R q

-L curves was based on multiple pictures, which used a fixed number of picture elements at various L, RSE method could be significantly more rapid than TR method. Moreover, a direct comparison was carried out between RSE method and TR method in calculating the

R q

-L curve and D, and the credibility and accuracy of RSE method with flatten order 1 and 2 was verified. Full article

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21 pages, 13368 KiB

Open AccessArticle

Electrodeposition of Photocatalytic Sn–Ni Matrix Composite Coatings Embedded with Doped TiO₂ Particles

by Eleni Rosolymou, Stella Spanou, Caterina Zanella, Dimitris S. Tsoukleris, Susanne Köhler, Peter Leisner and Evangelia A. Pavlatou

Coatings 2020, 10(8), 775; https://doi.org/10.3390/coatings10080775 - 9 Aug 2020

Cited by 10 | Viewed by 3837

Abstract

Direct current electrodeposited Sn–Ni/TiO₂ nanostructured coatings were produced by embedding two different doped types of TiO₂ particles within the alloy matrix, a commercially available doped carbon-based and doped N,S-TiO₂ particles. The structural characteristics of the composite coatings have been correlated [...] Read more.

Direct current electrodeposited Sn–Ni/TiO₂ nanostructured coatings were produced by embedding two different doped types of TiO₂ particles within the alloy matrix, a commercially available doped carbon-based and doped N,S-TiO₂ particles. The structural characteristics of the composite coatings have been correlated with the effect of loading, type of particles in the electrolytic bath, and the applied current density. Regardless of the type of doped particles TiO₂, increasing values of applied current density resulted in a reduction of the co-deposition percentage of TiO₂ particles and an increase of Tin content into the alloy matrix. The application of low current density values accompanied by a high load of particles in the bath led to the highest codeposition percentage (~3.25 wt.%) achieved in the case of embedding N,S-TiO₂ particles. X-ray diffraction data demonstrated that in composite coatings the incorporation of the different types of TiO₂ particles in the alloy metal matrix modified significantly the nano-crystalline structure in comparison with the pure coatings. The best photocatalytic behavior under visible irradiation was revealed for the composite coatings with the highest co-deposition percentage of doped N,S-TiO₂ particles, that also exhibited enhanced wear resistance and slightly reduced microhardness compared to pure ones. Full article

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

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15 pages, 10100 KiB

Open AccessArticle

Microstructure Control and Friction Behavior Prediction of Laser Cladding Ni35A+TiC Composite Coatings

by Xu Huang, Chang Liu, Hao Zhang, Changrong Chen, Guofu Lian, Jibin Jiang, Meiyan Feng and Mengning Zhou

Coatings 2020, 10(8), 774; https://doi.org/10.3390/coatings10080774 - 9 Aug 2020

Cited by 5 | Viewed by 2660

Abstract

The premise of surface strengthening and repair of high valued components is to identify the relationship between coating formulation, structure, and properties. Based on the full factorial design, the effects of process parameters (laser power, scanning speed, gas-powder flow rate, and weight fraction [...] Read more.

The premise of surface strengthening and repair of high valued components is to identify the relationship between coating formulation, structure, and properties. Based on the full factorial design, the effects of process parameters (laser power, scanning speed, gas-powder flow rate, and weight fraction of TiC) on the phase composition, microstructure, and element distribution of Ni35A/TiC cladding layer were investigated, followed by the cause identification of wear behavior. Through ANOVA, the correlation was established with good prediction accuracy (R² = 0.9719). The most important factors affecting the wear rate of the cladding layer were recognized as laser power and particle ratio with a p-value < 0.001. The cladding layer was mainly comprised of Ni₃Fe and TiC_0.957. The excessive laser power would enhance the process of convection-diffusion of the melt pool, increase dilution, and improve wear volume. High laser power facilitates renucleation and growth of the hard phase, especially the complete growth of secondary axis dendrite for the top region. Increased TiC significantly changes the microstructure of the hard phase into a non-direction preferable structure, which prevents stress concentration at tips and further improves the mechanical properties. The research results are a valuable support for the manipulation of microstructure and prediction of wear behavior of composite cladding layer. Full article

(This article belongs to the Special Issue Additively Manufactured Coatings)

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9 pages, 3227 KiB

Open AccessArticle

Measuring the Wall Thickness of a Trailing Arm Using Ultrasonic Measurement Model

by Feng Chen, Siqi Chen, Rongfan Zhang, Yongsheng Shi and Liangyao Gu

Coatings 2020, 10(8), 773; https://doi.org/10.3390/coatings10080773 - 8 Aug 2020

Viewed by 2610

Abstract

Trailing arms are widely used in the automobiles’ suspension system, and effective detection of their wall thickness is essential to ensure their mechanical properties and to evaluate the casting process. In this work, an ultrasonic measurement model (UMM) is firstly established with consideration [...] Read more.

Trailing arms are widely used in the automobiles’ suspension system, and effective detection of their wall thickness is essential to ensure their mechanical properties and to evaluate the casting process. In this work, an ultrasonic measurement model (UMM) is firstly established with consideration of the curvature and thickness of the trailing arm, then the UMM is introduced to predict the theoretical ultrasonic waveforms with different hypothetical thicknesses of the trailing arm. Next, the experimental ultrasonic waveforms are collected and matched with the predicted theoretical waveforms by using the correlation matching algorithm. The hypothetical thickness with the best match is regarded as the wall thickness of the trailing arm. Finally, an automatic ultrasonic experiment was conducted on a trailing arm with a 5-degrees of freedom (DOF) manipulator, in which the ultrasonic beam can radiate into a trailing arm at normal incidence. The results are compared with those determined by the micrometer and microscope, showing that their relative errors are controlled within 0.08 mm, which reveals the effectiveness of the present method. The method can also work for wall thickness measurements of curved components with CAD models. Full article

(This article belongs to the Special Issue Advanced Nondestructive Evaluation and Characterization of Surface)

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14 pages, 14010 KiB

Open AccessArticle

Effect of Slit Channel Width of a Shim Embedded in Slot-Die Head on High-Density Stripe Coating for OLEDs

by Dongkyun Shin, Jinyoung Lee and Jongwoon Park

Coatings 2020, 10(8), 772; https://doi.org/10.3390/coatings10080772 - 8 Aug 2020

Cited by 8 | Viewed by 4984

Abstract

With an attempt to achieve high-density fine organic stripes for potential applications in solution-processable organic light-emitting diodes (OLEDs), we have performed slot-die coatings using a shim with slit channels in various shapes (rectangular-shaped narrow, rectangular-shaped wide, and reversely tapered channels) in the presence [...] Read more.

With an attempt to achieve high-density fine organic stripes for potential applications in solution-processable organic light-emitting diodes (OLEDs), we have performed slot-die coatings using a shim with slit channels in various shapes (rectangular-shaped narrow, rectangular-shaped wide, and reversely tapered channels) in the presence of narrow µ-tips. Based on hydraulic-electric circuit analogy, we have analyzed the fluid dynamics of an aqueous poly (3,4-ethylenedioxythiophene): poly (4-styrenesulfonate) (PEDOT:PSS). It is observed that the coating speed can be increased and the stripe width can be reduced using a shim with rectangular-shaped wide slit channels. It is attributed that the hydraulic resistance is decreased and thus more fluid can reach a substrate through µ-tips. This behavior is consistent with the simulation result of the equivalent electrical circuit with a DC voltage source representing a pressure source. Using the shim with 150-µm-wide slit channels, we have successfully fabricated 200 PEDOT:PSS stripes within the effective coating width (150 mm) and 160 OLED stripes (34 stripes per inch) with the luminance of 325 cd/m² at 5 V. Full article

(This article belongs to the Special Issue Design, Fabrication, and Characterization of Thin Films for Photonic Applications)

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15 pages, 4687 KiB

Open AccessArticle

Investigation on High Temperature Rheological Behaviors and Fatigue Performance of Trans-Polyoctenamer-Activated Crumb Rubber Modified Asphalt Binder

by Yan Mu, Feng Ma, Jiasheng Dai, Chen Li, Zhen Fu, Tiantian Yang and Meng Jia

Coatings 2020, 10(8), 771; https://doi.org/10.3390/coatings10080771 - 7 Aug 2020

Cited by 10 | Viewed by 2865

Abstract

Asphalt binders have been modified with Crumb rubber (CR) as an effort to fulfil the demand for the development of eco-friendly and sustainable pavements. The objective of this study was to investigate the high temperature rheological behaviors and fatigue performance of crumb rubber [...] Read more.

Asphalt binders have been modified with Crumb rubber (CR) as an effort to fulfil the demand for the development of eco-friendly and sustainable pavements. The objective of this study was to investigate the high temperature rheological behaviors and fatigue performance of crumb rubber modified asphalt (CRMA) binder activated using trans-polyoctenamer (TOR). Long-term and short-term aging tests were performed on samples by thin film oven test (TFOT) and pressure aging vessel (PAV). Rotational viscosity (RV), softening point, and dynamic shear rheometer (DSR) tests were conducted to characterize the rheological and physical performance. A linear amplitude sweep (LAS) test was employed to evaluate the fatigue performance. The results show that TOR-activated CRMA is more capable of hardening the matrix bitumen and improving its high-temperature viscoelastic properties after TFOT. The high temperature viscoelasticity is significantly better than styrene-butadiene-styrene block (SBS) modified asphalt (SBSMA) and CRMA. TOR-activated CRMA exhibits strong rutting resistance, but it is more likely to generate fatigue cracks under the violent advancement of complex modulus. Therefore, TOR active agent has a negative impact on the fatigue performance of CRMA. SBSMA exhibited superior fatigue resistance. The viscosity temperature index (VTS) of TOR-activated CRMA and CRMA was basically identical; the TOR did not significantly improve the temperature sensitivity of CRMA. Full article

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