Coatings

2024

Jump to: 2022, 2021

11 pages, 10901 KiB

Open AccessArticle

Studies on the Morphological and Mechanical Properties of TiZrHfNiCuCo Metallic Coatings Deposited by DC Magnetron Sputtering

by Young-Soon Kim, Hae-Jin Park, Jin-Oh Seo, Ji-Woo Shin, Sung-Hwan Hong and Ki-Buem Kim

Coatings 2024, 14(9), 1179; https://doi.org/10.3390/coatings14091179 - 12 Sep 2024

Viewed by 568

Abstract

This research aimed to investigate the effects of input power and gas flow rate on the composition, microstructure, and mechanical properties of TiZrHfNiCuCo metallic coatings. These metallic coatings were deposited on a p-type Si wafer using a direct current magnetron sputtering system with [...] Read more.

This research aimed to investigate the effects of input power and gas flow rate on the composition, microstructure, and mechanical properties of TiZrHfNiCuCo metallic coatings. These metallic coatings were deposited on a p-type Si wafer using a direct current magnetron sputtering system with varying input powers (100–300 W) and Ar flow rates (5–20 sccm). It was observed that increasing input power and decreasing Ar flow rate led to TiZrHfNiCuCo metallic coatings with higher hardness and smoother surfaces. The experiment resulted in the formation of a metallic amorphous coating. This study describes the mechanism by which the mechanical properties of the TiZrHfNiCuCo coating change according to sputtering parameters. Based on these results, the effects of sputter variables, such as input power and gas flow rate properties, on the properties of coatings are discussed. Full article

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9 pages, 5402 KiB

Open AccessCommunication

Oxidation Behavior of Lightweight Al_0.2CrNbTiV High Entropy Alloy Coating Deposited by High-Speed Laser Cladding

by Tianhui Chen, Zhijiang Bi, Ji Zhou, Ruohui Shuai, Zhihai Cai, Liyan Lou, Haidou Wang and Zhiguo Xing

Coatings 2024, 14(9), 1104; https://doi.org/10.3390/coatings14091104 - 1 Sep 2024

Viewed by 578

Abstract

High-temperature oxidation resistance is the major influence on the high-temperature service stability of refractory high entropy alloys. The oxidation behavior of lightweight Al_0.2CrNbTiV refractory high entropy alloy coatings with different dilution ratios at 650 °C and 800 °C deposited by high-speed [...] Read more.

High-temperature oxidation resistance is the major influence on the high-temperature service stability of refractory high entropy alloys. The oxidation behavior of lightweight Al_0.2CrNbTiV refractory high entropy alloy coatings with different dilution ratios at 650 °C and 800 °C deposited by high-speed laser cladding was analyzed in this paper. The oxidation kinetic was analyzed, the oxidation resistance mechanism of the Al_0.2CrNbTiV coating was clarified with the analysis of the formation and evolution of the oxidation layer, and the effect of the dilution rate on high-temperature performances was revealed. The results showed that the oxide layer was mainly composed of rutile oxides (Ti, Cr, Nb)O₂ after isothermal oxidation at 650 °C and 800 °C for 50 h. The Al_0.2CrNbTiV coating in low dilution exhibited better oxidation performance at 650 °C, due to the dense oxide layer formed with the synergistic growth of fine AlVO₃ particles and (Ti, Cr, Nb)O₂, and higher percentage of Cr, Nb in (Ti, Cr, Nb)O₂ strengthened the lattice distortion effect to inhibit the penetration of oxygen. The oxide layer formed at 800 °C for the Al_0.2CrNbTiV coating was relatively loose, but the oxidation performance of the coating in high dilution improved due to the precipitation of Cr₂Nb-type Laves phases along grain boundaries, which inhibits the diffusion of oxygen. Full article

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14 pages, 4202 KiB

Open AccessArticle

On Low-Velocity Impact Response and Compression after Impact of Hybrid Woven Composite Laminates

by Yumin Li, Yongxing Jin, Xueting Chang, Yan Shang and Deng’an Cai

Coatings 2024, 14(8), 986; https://doi.org/10.3390/coatings14080986 - 5 Aug 2024

Viewed by 1037

Abstract

This paper aims to study the low-velocity impact (LVI) response and compression after impact (CAI) performance of carbon/aramid hybrid woven composite laminates employed in marine structures subjected to different energy impacts. The study includes a detailed analysis of the typical LVI responses of [...] Read more.

This paper aims to study the low-velocity impact (LVI) response and compression after impact (CAI) performance of carbon/aramid hybrid woven composite laminates employed in marine structures subjected to different energy impacts. The study includes a detailed analysis of the typical LVI responses of hybrid woven composite laminates subjected to the impact with three different energies, as well as a comparative analysis of cracks and internal delamination damage within impact craters. Additionally, the influence of different impact energies on the residual compressive strength of hybrid woven composite laminate is investigated through CAI tests and a comparative analysis of internal delamination damage is also conducted. The results indicate that as the impact energy increases, the impact load and CAI strength show a decreasing trend, while impact displacement and impact dent show an increasing trend. The low-velocity impact tests revealed a range of failure modes observed in the hybrid woven composite laminates. Depending on the specific combination of fiber materials and their orientations, the laminates exhibited different failure mechanisms. Buckling failures were observed in the uppermost composite layers of laminates with intermediate modulus systems. In contrast, laminates with higher modulus systems showed early damage in the form of delamination within the top surface layers. Full article

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18 pages, 5483 KiB

Open AccessArticle

Enhanced Analysis of Ice Accretion on Rotating Blades of Horizontal-Axis Wind Turbines Using Advanced 3D Scanning Technology

by Zhen Lei, Yuxiao Dong, Qinghui Wang, Hailin Li, Yexue Han and Fang Feng

Coatings 2024, 14(8), 970; https://doi.org/10.3390/coatings14080970 - 2 Aug 2024

Viewed by 882

Abstract

This study investigated the meteorological conditions leading to ice formation on wind turbines in a coastal mountainous area. An enhanced ice formation similarity criterion was developed for the experimental design, utilizing a scaled-down model of a 1.5 MW horizontal-axis wind turbine in icing [...] Read more.

This study investigated the meteorological conditions leading to ice formation on wind turbines in a coastal mountainous area. An enhanced ice formation similarity criterion was developed for the experimental design, utilizing a scaled-down model of a 1.5 MW horizontal-axis wind turbine in icing wind tunnel tests. Three-dimensional ice shapes on the rotating blades were obtained and scanned using advanced 3D laser measurement technology. Post-processing of the scanned data facilitated the construction of solid models of the ice-covered blades. This study analyzed the maximum ice thickness, ice-covered area, and dimensionless parameters such as the maximum dimensionless ice thickness and dimensionless ice-covered area along the blade. Under the experimental conditions, the maximum ice thickness reached 0.5102 m, and the ice-covered area extended up to 0.5549 m². The dimensionless maximum ice thickness and dimensionless ice-covered area consistently increased along the blade direction. Our analysis of 3D ice shape characteristics and the ice volume under different test conditions demonstrated that wind speed and the liquid water content (LWC) are critical factors affecting ice formation on blade surfaces. For a constant tip speed ratio, higher wind speeds and a greater LWC resulted in increased ice volumes on the blade surfaces. Specifically, increasing the wind speed can augment the ice volume by up to 57.2%, while increasing the LWC can enhance the ice volume by up to 149.2% under the experimental conditions selected in this study. Full article

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17 pages, 22285 KiB

Open AccessArticle

Effects of Wind Speed and Heat Flux on De-Icing Characteristics of Wind Turbine Blade Airfoil Surface

by Ting Zhang, Yangyang Lian, Zhi Xu and Yan Li

Coatings 2024, 14(7), 852; https://doi.org/10.3390/coatings14070852 - 7 Jul 2024

Cited by 1 | Viewed by 1107

Abstract

The icing on wind turbines reduces their aerodynamic performance and can cause other safety issues. Accordingly, in this paper, the de-icing characteristics of a wind turbine blade airfoil under different conditions are investigated using numerical simulation. The findings indicate that when the de-icing [...] Read more.

The icing on wind turbines reduces their aerodynamic performance and can cause other safety issues. Accordingly, in this paper, the de-icing characteristics of a wind turbine blade airfoil under different conditions are investigated using numerical simulation. The findings indicate that when the de-icing time is 10 s, the peak ice thickness on the leading edge of the airfoil surface decreases from 0.28 mm to 0.068 mm and from 0.77 mm to 0.45 mm at low (5 m/s) and high (15 m/s) wind speeds, respectively. This is due to the fact that the ice melting rate is much greater than the icing rate at low wind speeds, while the icing rate increases at high wind speeds. When the de-icing time is 20 s, ice accretion on the leading edge of the airfoil is completely melted. At a low heat flux (8000 W/m²) and high heat flux (12,000 W/m²), the peak ice thickness decreases by 31.2% and 64.9%, respectively. With an increase in de-icing time and heat flux, the peak thickness of runback ice increases. This is due to an increase in runback ice as a result of more ice melting on the leading edge of the airfoil. The surface temperature in the ice-free area is significantly higher than that in the ice-melting area, due to high thermal resistance in the ice-free area. This study will provide guidance for the thermal distribution and coating layout of a wind turbine blade airfoil to make the anti-/de-icing technology more efficient and energy-saving. Full article

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2022

Jump to: 2024, 2021

13 pages, 3406 KiB

Open AccessArticle

Electroplating on Al6082 Aluminium: A New Green and Sustainable Approach

by Andrea Comparini, Ivan Del Pace, Walter Giurlani, Roberta Emanuele, Margherita Verrucchi, Marco Bonechi and Massimo Innocenti

Coatings 2023, 13(1), 13; https://doi.org/10.3390/coatings13010013 - 22 Dec 2022

Cited by 7 | Viewed by 4146

Abstract

Aluminium and its alloys are interesting for many applications because they are very light, cheap, and unlimitedly recyclable. Despite being a promising base material for the fashion-jewellery sector, their tendency to form a passivating film makes them difficult to be galvanized, even more [...] Read more.

Aluminium and its alloys are interesting for many applications because they are very light, cheap, and unlimitedly recyclable. Despite being a promising base material for the fashion-jewellery sector, their tendency to form a passivating film makes them difficult to be galvanized, even more when recycled aluminium contains impurities of refractory elements. Indeed, the most common processes for galvanising aluminium are often expensive and not environmentally sustainable because they involve the use of cyanides. In this work we focussed on the pre-treatments and electroplating on Al6082 aluminium which is largely used for fashion-jewellery applications. The objective of the present study was to assess whether Al6082 series aluminium is suitable a as base material for the fashion market; therefore, we investigated the effectiveness of plating pre-treatments and the success of electroless zinc deposition using an innovative alkaline cyanide-free zincate solution. After the electroplating, adhesion between the deposited layers was evaluated both with cross-sectional scanning electron microscope (SEM) analysis as well as with an adhesion evaluation test (ISO2819:2018): no detachments confirmed the positive test outcomes and thereby highlighted that Al6082 can be exploited as base material in the fashion-jewellery market. Full article

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11 pages, 1439 KiB

Open AccessArticle

Impact of Throughflow and Coriolis Force on the Onset of Double-Diffusive Convection with Internal Heat Source

by Kallu Vetty Muhammed Rafeek, Gudala Janardhana Reddy, Ravi Ragoju, Gundlapally Shiva Kumar Reddy and Mikhail A. Sheremet

Coatings 2022, 12(8), 1096; https://doi.org/10.3390/coatings12081096 - 2 Aug 2022

Cited by 5 | Viewed by 1510

Abstract

The present research examines the joint influence of throughflow and Coriolis force on the onset of double-diffusive convection with an internal heat source modelled by Darcy’s law. The BVP4C routine in MATLAB R2020a is used to solve the eigenvalue problem numerically. Critical Rayleigh [...] Read more.

The present research examines the joint influence of throughflow and Coriolis force on the onset of double-diffusive convection with an internal heat source modelled by Darcy’s law. The BVP4C routine in MATLAB R2020a is used to solve the eigenvalue problem numerically. Critical Rayleigh numbers are obtained for designated values of governing parameters. The effect of the internal heat source parameter, Taylor number, Darcy number, and Peclet number on the system’s stability is investigated. The internal heat source parameter has a destabilizing influence on the system, according to our findings. The reason behind this observation is that the presence of an internal heat source in the porous medium may cause more molecular diffusion inside the medium. The Taylor number, on the other hand, stabilizes the system for both upward and downward throughflow because rotation introduces vorticity into the fluid. Thus, the fluid moves with higher velocity in horizontal planes. The velocity of the fluid perpendicular to the planes reduces as a result of this motion. Thus, the onset of convection is delayed. Full article

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11 pages, 1803 KiB

Open AccessFeature PaperArticle

Optimisation of Thiourea Concentration in a Decorative Copper Plating Acid Bath Based on Methanesulfonic Electrolyte

by Lorenzo Fabbri, Walter Giurlani, Giulia Mencherini, Antonio De Luca, Maurizio Passaponti, Emanuele Piciollo, Claudio Fontanesi, Andrea Caneschi and Massimo Innocenti

Coatings 2022, 12(3), 376; https://doi.org/10.3390/coatings12030376 - 12 Mar 2022

Cited by 14 | Viewed by 4888

Abstract

The role of thiourea as an organic additive in the nucleation and growth mechanism was studied for copper deposition and its application in the decorative electroplating and fashion accessory industries. The bath was designed to reduce the environmental and ecological impacts using methanesulfonic [...] Read more.

The role of thiourea as an organic additive in the nucleation and growth mechanism was studied for copper deposition and its application in the decorative electroplating and fashion accessory industries. The bath was designed to reduce the environmental and ecological impacts using methanesulfonic acid as electrolyte as an alternative to alkaline cyanide baths. We evaluated the nucleation and growth mechanism of copper exploiting voltametric and chronoamperometric measurements with a brightener concentration ranging from 0 to 90 ppm. We used the Scharifker–Hills model to estimate the type of nucleation mechanism after progressive addition of thiourea. Scanning electron microscope was employed for surface analysis and morphological characterisation of the nuclei. We verified that progressive nucleation is a key step in the obtainment of a shiny and homogeneous copper film, but an excess of thiourea could cause parasitic adsorption reactions on the surface of the substrate. X-ray fluorescence spectroscopy was used for the thickness determination of the copper deposits and the electrodeposition efficiency correlated to thiourea concentration. Finally, the optimal concentration of thiourea was assessed to be 60 ppm for the used formulation of copper plating. Full article

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20 pages, 5239 KiB

Open AccessEditor’s ChoiceArticle

Verification of the Influence of Particle Shape on the Chemical Resistance of Epoxy Coating and Use of Waste Glass as the Filler

by Jana Hodná, Jakub Hodul, Rostislav Drochytka and Michaela Seidlová

Coatings 2022, 12(3), 309; https://doi.org/10.3390/coatings12030309 - 24 Feb 2022

Cited by 6 | Viewed by 2908

Abstract

The use of suitable secondary raw materials as fillers in progressive, protective agents primarily intended for horizontal concrete construction is very effective not only from the ecological but also from the economic point of view. The impact of using various types of waste [...] Read more.

The use of suitable secondary raw materials as fillers in progressive, protective agents primarily intended for horizontal concrete construction is very effective not only from the ecological but also from the economic point of view. The impact of using various types of waste glass as fillers on the mechanical parameters of epoxy coatings was experimentally verified. Assessing the dependency of the coating’s chemical resistance on the shape of the used filler’s particles was the main aim of the performed research. A solvent-free epoxy suitable for a chemically aggressive environment was selected for the experiment. These were epoxy coatings filled with a micro filler based on raw materials such as glass flakes and silica flour. Three tested formulations containing fillers with different particle shapes and characteristics were exposed to H₂SO₄, HCl, CH₂O₂ and NaOH at concentrations of 5% and 30% and evaluated after 60, 90 and 120 days. The chemical resistance assessment was carried out not only visually but also using a scanning electron microscope (SEM). Thanks to the use of the waste glass as a coating filler, tensile properties and hardness improved, and its use did not negatively affect the chemical resistance and adhesion of the epoxy coatings. It was found that the shape of the filler particles influences the resistance of the coating against a chemically aggressive environment. The epoxy coating containing pre-treated waste windshield glass (shards) showed even better properties than the reference coating. Full article

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2021

Jump to: 2024, 2022

20 pages, 3840 KiB

Open AccessArticle

The Coriolis Effect on Thermal Convection in a Rotating Sparsely Packed Porous Layer in Presence of Cross-Diffusion

by Suman Shekhar, Ravi Ragoju, Gudala Janardhana Reddy and Mikhail A. Sheremet

Coatings 2022, 12(1), 23; https://doi.org/10.3390/coatings12010023 - 27 Dec 2021

Cited by 11 | Viewed by 2440

Abstract

The effect of rotation and cross-diffusion on convection in a horizontal sparsely packed porous layer in a thermally conducting fluid is studied using linear stability theory. The normal mode method is employed to formulate the eigenvalue problem for the given model. One-term Galerkin [...] Read more.

The effect of rotation and cross-diffusion on convection in a horizontal sparsely packed porous layer in a thermally conducting fluid is studied using linear stability theory. The normal mode method is employed to formulate the eigenvalue problem for the given model. One-term Galerkin weighted residual method solves the eigenvalue problem for free-free boundaries. The eigenvalue problem is solved for rigid-free and rigid-rigid boundaries using the BVP4c routine in MATLAB R2020b. The critical values of the Rayleigh number and corresponding wave number for different prescribed values of other physical parameters are analyzed. It is observed that the Taylor number and Solutal Rayleigh number significantly influence the stability characteristics of the system. In contrast, the Soret parameter, Darcy number, Dufour parameter, and Lewis number destabilize the system. The critical values of wave number for different prescribed values of other physical parameters are also analyzed. It is found that critical wave number does not depend on the Soret parameter, Lewis number, Dufour parameter, and solutal Rayleigh number; hence critical wave number has no impact on the size of convection cells. Further critical wave number acts as an increasing function of Taylor number, so the size of convection cells decreases, and the size of convection cells increases because of Darcy number. Full article

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20 pages, 3159 KiB

Open AccessArticle

Magnetized Dissipative Soret Effect on Chemically Reactive Maxwell Fluid over a Stretching Sheet with Joule Heating

by Suresha Suraiah Palaiah, Hussain Basha, Gudala Janardhana Reddy and Mikhail A. Sheremet

Coatings 2021, 11(5), 528; https://doi.org/10.3390/coatings11050528 - 29 Apr 2021

Cited by 10 | Viewed by 2155

Abstract

The present research paper deals with the study of heat and mass transfer characteristics of steady viscous incompressible two-dimensional Maxwell fluid flow past a stretching sheet under the influence of magnetic field and the Soret effect. A well-known non-Newtonian Maxwell fluid flow model [...] Read more.

The present research paper deals with the study of heat and mass transfer characteristics of steady viscous incompressible two-dimensional Maxwell fluid flow past a stretching sheet under the influence of magnetic field and the Soret effect. A well-known non-Newtonian Maxwell fluid flow model is used to differentiate it from the Newtonian fluids. The present physical problem gives the set of highly nonlinear-coupled partial differential equations that are not amenable to any of the direct techniques. The resultant nonlinear system of partial differential equations is reduced to a set of nonlinear ordinary differential equations by using suitable similarity transformations. Due to the inadequacy of analytical techniques, a bvp4c MATLAB function is used to solve the developed nonlinear system of equations. The simulated results are shown for various values of physical parameters in the flow regime. Additionally, the numerical values of skin-friction coefficient, heat, and mass transfer rates are calculated and tabularized. From the present investigation, it is observed that the normal and axial velocity profiles decreased for the enhancing values of the magnetic parameter. Increasing the Prandtl and Schmidt numbers reduces the temperature and concentration profiles in the flow region, respectively. Increasing the Maxwell fluid parameter decreases the velocity profile and magnifies the temperature field. Additionally, increasing the Soret number increases the concentration profile in the flow regime. Comparison of current similarity solutions with available results indicates the accuracy and guarantee of the present numerical results and the used method. Full article

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2024

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