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14 pages, 16102 KiB

Open AccessArticle

Effect of Ultrasonic Assistance on Properties of Ultra-High-Strength Steel in Laser-Arc Hybrid Welding

by Hua Liang, Xiaolong Shi and Yanzhou Li

Coatings 2025, 15(4), 389; https://doi.org/10.3390/coatings15040389 - 26 Mar 2025

Viewed by 2188

Abstract

To address the challenge of achieving an optimal balance between strength and toughness in ultra-high-strength steel welds, this study investigates ultrasonic vibration-assisted laser-arc hybrid welding. The influence of ultrasonic vibrations, applied to the lower surface of laser-arc hybrid welding specimens at powers ranging [...] Read more.

To address the challenge of achieving an optimal balance between strength and toughness in ultra-high-strength steel welds, this study investigates ultrasonic vibration-assisted laser-arc hybrid welding. The influence of ultrasonic vibrations, applied to the lower surface of laser-arc hybrid welding specimens at powers ranging from 60 W to 240 W, on various aspects of the weld, including macroscopic morphology, porosity, microstructure, and mechanical properties, was systematically examined. Experimental findings reveal that as ultrasonic power increases, weld porosity initially diminishes before rising again. Simultaneously, the fusion ratio of the weld gradually enhances, and the cross-sectional morphology of the weld transforms from a “goblet” shape to an “inverted triangle”, with the transition boundary between the arc zone and laser zone becoming less distinct. Furthermore, an increase in ultrasonic power leads to a gradual rise in the microhardness of the weld, and the mechanical properties of the weld joint exhibit an upward trend. Notably, at an ultrasonic power of 180 W, the weld attains a tensile strength of 1380 MPa and an impact toughness of 10.5 J, highlighting the potential of this technique in optimizing the welding characteristics of ultra-high-strength steel. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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29 pages, 10331 KiB

Open AccessArticle

Using Preexisting Surface Cracks to Prevent Thermal Fatigue Failure and Crack Delamination in FGM Thermal Barrier Coatings

by Kai-Chien Lo, Jenn-Kun Kuo, Pei-Hsing Huang and Chang-Yu Hsiao

Coatings 2025, 15(3), 362; https://doi.org/10.3390/coatings15030362 - 20 Mar 2025

Viewed by 406

Abstract

Thermal shock testing has long been employed to assess thermal barrier coatings (TBCs), with crack formation and propagation on TBC surfaces serving as important indicators of fracture toughness. In this study, the influence of preexisting cracks within TBC coatings was investigated. These cracks [...] Read more.

Thermal shock testing has long been employed to assess thermal barrier coatings (TBCs), with crack formation and propagation on TBC surfaces serving as important indicators of fracture toughness. In this study, the influence of preexisting cracks within TBC coatings was investigated. These cracks can help alleviate stress concentrations at the interface and within the thermally grown oxide (TGO) layers of the TBC model. In other words, surface crack propagation may eventually intersect the interface, leading to delamination and spallation. This research focused on modifying the volume fraction of functionally graded materials (FGMs) and optimizing preexisting surface cracks in TBCs to extend their lifespan before delamination occurs. The accuracy of the J-integral and displacement correlation technique (DCT) methods was evaluated for use in thermal shock testing simulations. The results showed that both the stress intensity factor (SIF) and interface tensile stress of preexisting cracks were significantly reduced when the volume fraction was set at N = 3. Furthermore, the SIF values demonstrated strong agreement with calculations using the J-integral and DCT methods. The SIF for preexisting cracks dropped to below 62.42% of the fracture toughness when the crack length was approximately 50% of the TBC coating thickness in FGM structures, with a crack density of 10 cracks per inch (CPI). Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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20 pages, 3945 KiB

Open AccessArticle

Nondestructive Evaluation of Aging Failure in Insulation Coatings by Ultrasonic Guided Wave Based on Signal Processing and Machine Learning

by Mengmeng Qiu and Xin Ge

Coatings 2025, 15(3), 347; https://doi.org/10.3390/coatings15030347 - 18 Mar 2025

Viewed by 413

Abstract

In the field of nondestructive evaluation (NDE) using ultrasonic guided waves, accurately assessing the aging failure of insulation coatings remains a challenging and prominent research topic. While the application of ultrasonic guided waves in material testing has been extensively explored in the existing [...] Read more.

In the field of nondestructive evaluation (NDE) using ultrasonic guided waves, accurately assessing the aging failure of insulation coatings remains a challenging and prominent research topic. While the application of ultrasonic guided waves in material testing has been extensively explored in the existing literature, there is still a significant gap in quantitatively evaluating the aging failure of insulation coatings. This study innovatively proposes an NDE method for assessing insulation coating aging failure by integrating signal processing and machine learning technologies, thereby effectively addressing both theoretical and practical gaps in this domain. The proposed method not only enhances the accuracy of detecting insulation coating aging failure but also introduces new approaches to non-destructive testing technology in related fields. To achieve this, an accelerated aging experiment was conducted to construct a cable database encompassing various degrees of damage. The effects of aging time, temperature, mechanical stress, and preset defects on coating degradation were systematically investigated. Experimental results indicate that aging time exhibits a three-stage nonlinear evolution pattern, with 50 days marking the critical inflection point for damage accumulation. Temperature significantly influences coating damage, with 130 °C identified as the critical threshold for performance mutation. Aging at 160 °C for 100 days conforms to the time-temperature superposition principle. Additionally, mechanical stress concentration accelerates coating failure when the bending angle is ≥90°. Among preset defects, cut defects were most destructive, increasing crack density by 5.8 times compared to defect-free samples and reducing cable life to 40% of its original value. This study employs Hilbert–Huang Transform (HHT) for noise reduction in ultrasonic guided wave signals. Compared to Fast Fourier Transform (FFT), HHT demonstrates superior performance in feature extraction from ultrasonic guided wave signals. By combining HHT with machine learning techniques, we developed a hybrid prediction model—HHT-LightGBM-PSO-SVM. The model achieved prediction accuracies of 94.05% on the training set and 88.36% on the test set, significantly outperforming models constructed with unclassified data. The LightGBM classification model exhibited the highest classification accuracy and AUC value (0.94), highlighting its effectiveness in predicting coating aging damage. This research not only improves the accuracy of detecting insulation coating aging failure but also provides a novel technical means for aviation cable health monitoring. Furthermore, it offers theoretical support and practical references for nondestructive testing and life prediction of complex systems. Future studies will focus on optimizing model parameters, incorporating additional environmental factors such as humidity and vibration to enhance prediction accuracy, and exploring lightweight algorithms for real-time monitoring. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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15 pages, 5642 KiB

Open AccessArticle

Effect of Partial Fibre Laser Processing on the Wear Resistance of NiCrMoFeCSiB Coatings

by Olegas Černašėjus, Jelena Škamat, Łukasz Gierz, Olga Zharkevich and Alexandra Berg

Coatings 2025, 15(3), 323; https://doi.org/10.3390/coatings15030323 - 11 Mar 2025

Viewed by 579

Abstract

Surface laser processing of metallic materials is known to be effective in improving wear resistance due to microstructure refinement and the associated hardening effect. However, the formation of cracks, which frequently accompanies such processing, remains a challenge. This work focusses on partial laser [...] Read more.

Surface laser processing of metallic materials is known to be effective in improving wear resistance due to microstructure refinement and the associated hardening effect. However, the formation of cracks, which frequently accompanies such processing, remains a challenge. This work focusses on partial laser processing of Ni-based protective coatings as a method that could potentially reduce the risk of crack formation due to lower overall heat input and retaining softer material portions that facilitate stress redistribution. A fibre-optic laser with a wavelength of λ = 976 nm and beam oscillation capability was used. After laser processing at 175 W power, a 250 mm/min processing rate, and a 2 mm oscillation amplitude, coating hardness increased by ~1.49 times reaching 713 ± 19 HV0.2 value. Preheating the samples to 400 °C inhibited crack formation but partially reduced the quenching effect, providing a ~30% increase in coating hardness (631 ± 16NV0.2). The resistance to dry sliding wear was increased by ~2 times and to abrasive wear—by ~2.9 times. Partial laser treatment of 25%, 50%, and 75% of the surface area enhanced the coating’s wear resistance by 1.29, 2.13, and 2.81 time, respectively, indicating that when the processed surface area reaches 50% or more, wear resistance is primarily determined by the hardened regions and to a greater extent than what is expected based on the proportion of the treated area. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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17 pages, 9632 KiB

Open AccessArticle

Wear and Corrosion Behavior of Diamond-like Carbon Coatings in Artificial Saliva

by Monika Madej, Katarzyna Piotrowska, Martin Vicen and Viera Zatkaliková

Coatings 2025, 15(3), 305; https://doi.org/10.3390/coatings15030305 - 5 Mar 2025

Viewed by 880

Abstract

This study investigates the properties of diamond-like carbon (DLC) coatings deposited onto a Ti6Al4V titanium alloy using plasma-assisted chemical vapor deposition (PACVD). The research encompasses adhesion tests, hardness, surface characterization, as well as corrosion and tribological evaluations. Artificial saliva was employed as both [...] Read more.

This study investigates the properties of diamond-like carbon (DLC) coatings deposited onto a Ti6Al4V titanium alloy using plasma-assisted chemical vapor deposition (PACVD). The research encompasses adhesion tests, hardness, surface characterization, as well as corrosion and tribological evaluations. Artificial saliva was employed as both the lubricating and corrosive medium. Microscopic examination revealed a uniform coating with a thickness of about 3.2 µm. Scratch test results indicated that the deposited DLC coating exhibited superior adhesion, lower frictional resistance, and reduced wear compared to the titanium alloy. The coating deposition increased the hardness of the Ti6Al4V alloy by about 75%. Friction coefficients, measured under dry and lubricated conditions, were approximately 80% lower for the DLC-coated samples. Corrosion studies revealed that both the coated and uncoated surfaces demonstrated typical passive behavior and high corrosion resistance in artificial saliva. For DLC coatings, the corrosion current density and the corrosion rate were reduced by 85%. Microscopic observations of wear tracks following tribological and scratch tests confirmed the inferior wear and scratch resistance of the titanium alloy relative to the DLC coating. Under both dry and lubricated conditions (with artificial saliva), the volumetric wear rate of the titanium alloy was over 90% higher than for the DLC coating. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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14 pages, 2422 KiB

Open AccessArticle

Effect of Welding Current on the Dilution and Mechanical Properties of Co–Cr Alloy Stellite-6 Coatings Applied to AISI 4130 Steel

by Elias Rocha Gonçalves Júnior, Bárbara Ferreira de Oliveira, Luis Augusto Hernandez Terrones, Noan Tonini Simonassi and Sergio Neves Monteiro

Coatings 2024, 14(12), 1591; https://doi.org/10.3390/coatings14121591 - 19 Dec 2024

Cited by 1 | Viewed by 832

Abstract

Coating welding with cobalt alloys on pipelines is crucial for the offshore industry due to its exceptional resistance to corrosion and wear. In this paper, two welding conditions with different currents were proposed to observe the behavior of the dissimilar joint. The microstructure, [...] Read more.

Coating welding with cobalt alloys on pipelines is crucial for the offshore industry due to its exceptional resistance to corrosion and wear. In this paper, two welding conditions with different currents were proposed to observe the behavior of the dissimilar joint. The microstructure, mechanical properties, and dilution of a dissimilar material consisting of AISI 4130 steel substrate coated with Stellite 6 alloy were analyzed. Firstly, samples were metallographically prepared for the evaluation of the weld bead and the coating phases using SEM, EDS, and XRD analyses. Then, microstructural characterization was performed qualitatively using confocal microscopy and quantitatively to determine the phase fraction volumes in the dendritic and interdendritic regions, as well as the resulting dilution. Results revealed that varying welding conditions did not significantly affect the hardness of the coatings, which remained within the alloy standard of 36-45 HRC, with microhardness varying by 3%–5% from one condition to another and phase fraction volume showing a variation of 5.6% between welding conditions. On the other hand, experimental results indicated a clear effect of welding current variation on dilution values, with 4.6% for condition 1 and 16.7% for condition 2, allowing for direct proportional relationships to be established, i.e., higher deposition current results in greater dilution. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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18 pages, 6430 KiB

Open AccessArticle

Analysis of Wear Mechanisms Under Cutting Parameters: Influence of Double Layer TiAlN/TiN PVD and TiCN/Al₂O₃ Chemical Vapor Deposition-Coated Tools on Milling of AISI D2 Steel

by Gustavo M. Minquiz, N. E. González-Sierra, Javier Flores Méndez, Ana C. Piñón Reyes, Mario Moreno Moreno, Alfredo Morales-Sánchez, José Alberto Luna López, Zaira Jocelyn Hernandez-Simon and Claudia Denicia Carral

Coatings 2024, 14(12), 1491; https://doi.org/10.3390/coatings14121491 - 27 Nov 2024

Cited by 1 | Viewed by 1300

Abstract

Tool selection is relevant because a wide variety of materials exhibit different machinability behaviors. Tool life during manufacturing is commonly associated with productivity. Insert developers have been using coatings on cutting tools to enhance their performance, with chemical vapor deposition (CVD) and physical [...] Read more.

Tool selection is relevant because a wide variety of materials exhibit different machinability behaviors. Tool life during manufacturing is commonly associated with productivity. Insert developers have been using coatings on cutting tools to enhance their performance, with chemical vapor deposition (CVD) and physical vapor deposition (PVD) being the two most used techniques. This study analyzed the cutting tool wear mechanism by machining AISI D2 steel using two different inserts of TiAlN/TiN PVD and TiCN/Al₂O₃ CVD as layers deposited on a carbide substrate. The two inserts were tested at three different cutting speeds, namely, low, medium, and high; these values were below the data suggested by the supplier catalog. The flank wear and rake face were analyzed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDX). The adhesion material, edge deformation, and abrasion were the main wear mechanisms before catastrophic damage occurred at the three different cutting speeds in the PVD cutting tool. Nevertheless, increasing the cutting speed reduced the tool life from 84% to 61% at high values compared to the medium values of PVD and CVD, respectively, where the medium value resulted in a balance between the material removal rate and tool life. The wear mechanism of the CVD tool was BUE and chipping; nevertheless, its craters were larger than those of the PVD. Compared to those configured for PVD, the CVD insert demonstrated the ability to machine D2 steel at twice the cutting speed with a workpiece surface roughness of 0.3 µm, in contrast to a variation of 0.6 to 0.15 µm with the PVD tool. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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19 pages, 10339 KiB

Open AccessArticle

The Effect of DLC Surface Coatings on Microabrasive Wear of Ti-22Nb-6Zr Obtained by Powder Metallurgy

by Silvio José Gobbi, Jorge Luiz de Almeida Ferreira, José Alexander Araújo, Paul André, Vinicius André Rodrigues Henriques, Vladimir Jesus Trava Airoldi and Cosme Roberto Moreira da Silva

Coatings 2024, 14(11), 1396; https://doi.org/10.3390/coatings14111396 - 4 Nov 2024

Viewed by 1118

Abstract

Titanium alloys have a high cost of production and exhibit low resistance to abrasive wear. The objective of this work was to carry out diamond-like carbon (DLC) coating, with dissimilar thicknesses, on Ti-22Nb-6Zr titanium alloys produced by powder metallurgy, and to evaluate its [...] Read more.

Titanium alloys have a high cost of production and exhibit low resistance to abrasive wear. The objective of this work was to carry out diamond-like carbon (DLC) coating, with dissimilar thicknesses, on Ti-22Nb-6Zr titanium alloys produced by powder metallurgy, and to evaluate its microabrasive wear resistance. The samples were compacted, cold pressed, and sintered, producing substrates for coating. The DLC coatings were carried out by PECVD (plasma-enhanced chemical vapor deposition). Free sphere microabrasive wear tests were performed using alumina (Al₂O₃) abrasive suspension. The DLC-coated samples were characterized by scanning electron microscopy (SEM), Vickers microhardness, coatings adhesion tests, confocal laser microscopy, atomic force microscopy (AFM), and Raman spectroscopy. The coatings did not show peeling-off or delamination in adhesion tests. The PECVD deposition was effective, producing sp2 and sp3 mixed carbon compounds characteristic of diamond-like carbon. The coatings provided good structural quality, homogeneity in surface roughness, excellent coating-to-substrate adhesion, and good tribological performance in microabrasive wear tests. The low wear coefficients obtained in this work demonstrate the excellent potential of DLC coatings to improve the tribological behavior of biocompatible titanium alloy parts (Ti-22Nb-6Zr) produced with a low modulus of elasticity (closer to the bone) and with near net shape, given by powder metallurgy processing. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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13 pages, 9558 KiB

Open AccessArticle

Influence of Si Content on the Microstructure, Wear Resistance, and Corrosion Resistance of FeCoNiCrAl_0.7Cu_0.3Si_x High Entropy Alloy

by Rui Xi and Yanzhou Li

Coatings 2024, 14(10), 1309; https://doi.org/10.3390/coatings14101309 - 13 Oct 2024

Cited by 4 | Viewed by 1093

Abstract

This study explores microstructure, wear, and corrosion resistance properties of FeCoNiCrAl_0.7Cu_0.3Si_x (x = 0, 0.2, 0.3, 0.5) high-entropy alloys. The FeCoNiCrAl_0.7Cu_0.3Si_x alloy contains FCC and BCC structures; as the x increases, the FeCoNiCrAl [...] Read more.

This study explores microstructure, wear, and corrosion resistance properties of FeCoNiCrAl_0.7Cu_0.3Si_x (x = 0, 0.2, 0.3, 0.5) high-entropy alloys. The FeCoNiCrAl_0.7Cu_0.3Si_x alloy contains FCC and BCC structures; as the x increases, the FeCoNiCrAl_0.7Cu_0.3Si_0.2, FeCoNiCrAl_0.7Cu_0.3Si_0.4, and FeCoNiCrAl_0.7Cu_0.3Si_0.5 high-entropy alloys transition to BCC structures. The morphological transition in FeCoNiCrAl_0.7Cu_0.3Si_x evolves from bamboo leaf-like intergranular features to a discontinuous intergranular structure as Si content increases. The hardness of these alloys gradually increases with higher Si content. The addition of Si promotes a uniform distribution of Cr within and between grains, reducing the intergranular segregation of Cu. Al and Ni show a consistent pattern of elemental distribution throughout the alloy. Wear measurements of FeCoNiCrAl_0.7Cu_0.3Si_x alloys demonstrate that adding Si enhances wear resistance, resulting in smoother wear surfaces with reduced deformation. The wear mechanism for all alloys is primarily abrasive, with no brittle fractures observed. Corrosion resistance is optimized when Si content is 0.2, with pitting corrosion being the primary corrosion form. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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13 pages, 7142 KiB

Open AccessArticle

Microstructure and Mechanical Properties of FeCoCrNiAl + WC Composite Coating Formed by Laser Cladding on H13

by Yali Gao, Shan Jiang, Sicheng Bai, Meng Jie, Dongdong Zhang and Yu Liu

Coatings 2024, 14(10), 1259; https://doi.org/10.3390/coatings14101259 - 1 Oct 2024

Cited by 2 | Viewed by 1019

Abstract

To enhance high-temperature wear resistance of H13 steel, laser cladding was used to prepare a high-entropy alloy + carbide composite coating. The microstructure and high-temperature wear resistance of the composite coating were systematically analyzed. The results indicate that the FeCoCrNiAl + WC composite [...] Read more.

To enhance high-temperature wear resistance of H13 steel, laser cladding was used to prepare a high-entropy alloy + carbide composite coating. The microstructure and high-temperature wear resistance of the composite coating were systematically analyzed. The results indicate that the FeCoCrNiAl + WC composite coating had a phase structure of BCC + FCC solid solutions, with a small amount of CFe15.1. The microstructure of the composite coating consisted of columnar and equiaxed grains. The microhardness of the FeCoCrNiAl + WC composite coatings was approximately 3.0–3.4 times that of H13. At wear temperatures of 823 K, compared with H13 steel, the wear volumes of composite coatings with different WC contents were reduced by 73.4%–80.2%. Among these, the FeCoCrNiAl + 10% WC composite coating showed the lowest wear volume. Furthermore, when wear temperatures increased from 623 K to 823 K, compared with H13 steel (108.37%), the increase in the wear volume of the FeCoCrNiAl + 10% WC coating was reduced to 90.82%, which indicates the FeCoCrNiAl + 10% WC coating had better high-temperature wear resistance. The wear mechanisms of the composite coating were abrasive and oxidative wear, while H13 steel exhibited abrasive wear, oxidative wear and fatigue wear. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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13 pages, 4392 KiB

Open AccessArticle

Aerosol-Deposited 8YSZ Coating for Thermal Shielding of 3YSZ/CNT Composites

by Maria Wiśniewska, Grzegorz Kubicki, Mateusz Marczewski, Volf Leshchynsky, Luca Celotti, Mirosław Szybowicz and Dariusz Garbiec

Coatings 2024, 14(9), 1186; https://doi.org/10.3390/coatings14091186 - 13 Sep 2024

Viewed by 2048

Abstract

High-temperature conditions are harmful for carbon nanotube-based (CNT-based) composites, as CNTs are susceptible to oxidation. On the other hand, adding CNTs to ceramics with low electrical conductivity, such as 3YSZ, is beneficial because it allows the production of complex-shaped samples with spark plasma [...] Read more.

High-temperature conditions are harmful for carbon nanotube-based (CNT-based) composites, as CNTs are susceptible to oxidation. On the other hand, adding CNTs to ceramics with low electrical conductivity, such as 3YSZ, is beneficial because it allows the production of complex-shaped samples with spark plasma sintering (SPS). A shielding coating system may be applied to prevent CNT oxidation. In this work, the 8YSZ (yttria-stabilized zirconia) thermal shielding coating system was deposited by aerosol deposition (AD) to improve the composite’s resistance to CNT degradation without the use of bond-coat sublayers. Additionally, the influence of the annealing process on the mechanical properties and microstructure of the composite was evaluated by nanoindentation, scratch tests, scanning electron microscopy (SEM), X-ray diffraction (XRD), flame tests, and light microscopy (LM). Annealing at 1200 °C was the optimal temperature for heat treatment, improving the coating’s mechanical strength (the first critical load increased from 0.84 N to 3.69 N) and promoting diffusion bonding between the compacted powder particles and the substrate. The deposited coating of 8YSZ increased the composite’s thermal resistance by reducing the substrate’s heating rate and preventing the oxidation of CNTs. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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16 pages, 13078 KiB

Open AccessArticle

Metallization of Carbon Fiber-Reinforced Plastics (CFRP): Influence of Plasma Pretreatment on Mechanical Properties and Splat Formation of Atmospheric Plasma-Sprayed Aluminum Coatings

by Christian Semmler, Willi Schwan and Andreas Killinger

Coatings 2024, 14(9), 1169; https://doi.org/10.3390/coatings14091169 - 11 Sep 2024

Cited by 1 | Viewed by 1439

Abstract

Carbon fiber-reinforced plastics (CFRPs) have broad applications as lightweight structural materials due to their remarkable strength-to-weight ratio. Aluminum is often used as a bond coating to ensure adhesion between CFRPs and further coatings with a higher melting temperature. However, challenges persist in optimizing [...] Read more.

Carbon fiber-reinforced plastics (CFRPs) have broad applications as lightweight structural materials due to their remarkable strength-to-weight ratio. Aluminum is often used as a bond coating to ensure adhesion between CFRPs and further coatings with a higher melting temperature. However, challenges persist in optimizing their surface properties and adhesion attributes for diverse applications. This investigation explores the impact of sandblasting and plasma pretreatment on CFRP surfaces and their influence on plasma-sprayed aluminum coatings. Two distinct CFRP substrates, distinguished by their cyanate ester and epoxy resin matrices, and two different aluminum powder feedstocks were employed. Plasma pretreatment induced micro-surface roughening in the range of 0.5 µm and significantly reduced the contact angles on polished specimens. Notably, on sandblasted specimens, plasma-activated surfaces displayed improved wetting behavior, which is attributed to the removal of polymeric fragments and augmented fiber exposure. Aluminum splats show a better interaction with carbon fibers compared to a polymeric matrix material. The impact of plasma activation on the coating adhesion proved relatively limited. All samples with plasma activation had deposition efficiencies that increased by 12.5% to 34.4%. These findings were supported by SEM single-splat analysis and contribute to a deeper comprehension of surface modification strategies tailored to CFRPs. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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17 pages, 9396 KiB

Open AccessArticle

Finite Element Simulation of Dry Wear of Prosthesis Made of UHMWPE and 316LVM Stainless Steel

by Tomas de la Mora Ramírez, Elías Crispín López, Daniel Maldonado Onofre, Elvis Coutiño Moreno, Noé López Perrusquia, Marco A. Doñu Ruíz and Christhopher René Torres San Miguel

Coatings 2024, 14(7), 876; https://doi.org/10.3390/coatings14070876 - 12 Jul 2024

Cited by 1 | Viewed by 1516

Abstract

The study of wear is currently one of the most important aspects of applied mechanics. The damage caused by this phenomenon involves the total replacement of parts in devices ranging from industrial machinery to biomedical implants. The focus of these work is aimed [...] Read more.

The study of wear is currently one of the most important aspects of applied mechanics. The damage caused by this phenomenon involves the total replacement of parts in devices ranging from industrial machinery to biomedical implants. The focus of these work is aimed at the analysis and prediction of mechanical wear in prostheses manufactured using UHMWPE materials and 316 LVM stainless steel by means of the finite element method using Abaqus^® software V. 2020. The wear mechanism between the surfaces of the UHMWPE material specimen and a 316 LVM stainless steel specimen was modeled using Archard’s wear theory to determine the parameters of damage, plastic deformation, and fatigue. The attrition process was discretized into several steps, including developing a program in Fortran code, and integrating a pre-established subroutine known as UMESHMOTION, followed by a Mesh update whenever contact nodes were deformed. For the simulation process, the variables of the thermal properties of conductivity, specific heat, and the parameters of the Johnson-Cook plastic model were taken into account. The simulation results were validated by laboratory tests. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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16 pages, 8455 KiB

Open AccessArticle

Insight into Microstructure Evolution and Corrosion Mechanisms of K₂ZrF₆/Al₂O₃-Doped Hot-Dip Aluminum/Micro-Arc Oxidation Coatings

by Shuliang Wang, Xiaofei Peng, Yi Yang, Shidong Wang, Mingyu Wu, Ping Hu and Chunyan Fu

Coatings 2023, 13(9), 1543; https://doi.org/10.3390/coatings13091543 - 4 Sep 2023

Cited by 2 | Viewed by 1738

Abstract

In this study, we investigated the impact of K₂ZrF₆/Al₂O₃ composite additives on the microstructure evolution and corrosion behavior of ceramic coatings formed through micro-arc oxidation (MAO) treatment on hot-dip aluminum-coated 316L stainless steel surfaces. Our findings [...] Read more.

In this study, we investigated the impact of K₂ZrF₆/Al₂O₃ composite additives on the microstructure evolution and corrosion behavior of ceramic coatings formed through micro-arc oxidation (MAO) treatment on hot-dip aluminum-coated 316L stainless steel surfaces. Our findings revealed the successful preparation of micro-arc oxidation ceramic coatings, presenting a dual-layer structure consisting of a porous micro-arc oxidation ceramic outer layer and a relatively dense/thick hot-dip aluminum inner layer. The incorporation of K₂ZrF₆/Al₂O₃ composite additives induced a self-sealing effect on the ceramic coating surface. Optimal coating performance was achieved with a composite additive concentration of 7.5 g/L, resulting in remarkable improvements not only in thickness, hardness, and surface smoothness but also in corrosion resistance. This research introduces a pioneering investigation of K₂ZrF₆/Al₂O₃ composite additives in the context of micro-arc oxidation technology, offering fresh perspectives and methodologies for the development of highly corrosion-resistant materials. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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11 pages, 18606 KiB

Open AccessArticle

Influence of Laser Power on Microstructure and Properties of Al-Si+Y₂O₃ Coating

by Yali Gao, Pengyong Lu, Sicheng Bai, Baolong Qin and Dongdong Zhang

Coatings 2023, 13(7), 1289; https://doi.org/10.3390/coatings13071289 - 23 Jul 2023

Cited by 7 | Viewed by 1635

Abstract

Al-Si/7.5 wt.%Y₂O₃ coatings were prepared on Mg alloy with laser cladding to enhance the wear and corrosion resistance of substrate. The influence of laser power on the microstructure and properties of the coating were discussed. The results uncovered that the [...] Read more.

Al-Si/7.5 wt.%Y₂O₃ coatings were prepared on Mg alloy with laser cladding to enhance the wear and corrosion resistance of substrate. The influence of laser power on the microstructure and properties of the coating were discussed. The results uncovered that the coatings consisted primarily of Mg₂Si, Mg₁₇Al₁₂, Mg₂Al₃, Al₄MgY, and α-Mg phases. Through calculation, it was observed that the crystal size decreased with the decrease in the laser power. Y₂O₃ gave the coating a better strengthening effect due to the fine-grain strengthening and hard-phase strengthening. The average hardness of the coating with laser power of 1100 W achieved 312 HV, which was approximately 4.2 times that of the substrate. The wear volume of the coating was 22.2% that of the substrate. Compared with Mg alloy, the self-corrosion potential of the coating increased by 1.09 V, and the self-corrosion current density decreased by three orders of magnitude. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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12 pages, 18818 KiB

Open AccessArticle

Abrasive Wear and Physical Properties of In-Situ Nano-TiC_x Reinforced Cu–Cr–Zr Composites

by Dongdong Zhang, Pengyong Lu, Xiya He and Yali Gao

Coatings 2023, 13(7), 1263; https://doi.org/10.3390/coatings13071263 - 18 Jul 2023

Cited by 3 | Viewed by 1403

Abstract

Cu–Cr–Zr alloys reinforced in situ with TiC_x nanoparticles were prepared via combustion synthesis and electromagnetic stirring casting. The microstructure of TiC_x/Cu-Cr-Zr composites with various contents was analyzed. The microhardness and Brinell hardness of the composites were determined; the average volumetric [...] Read more.

Cu–Cr–Zr alloys reinforced in situ with TiC_x nanoparticles were prepared via combustion synthesis and electromagnetic stirring casting. The microstructure of TiC_x/Cu-Cr-Zr composites with various contents was analyzed. The microhardness and Brinell hardness of the composites were determined; the average volumetric abrasive wear rate and worn surface of the composites were investigated; and the electrical, thermal conductivity and thermal expansion coefficients of the materials were discussed. The results indicated that the addition of TiC_x particles transformed the Cu–Cr–Zr matrix alloy microstructure from a dendritic to an equiaxed crystal, and the grain size was significantly refined as the amount added was increased. The composites with high TiCx content possessed higher hardness and abrasive wear resistance. The addition of TiC_x particles reduced the electrical and thermal conductivity and thermal expansion coefficients of the materials. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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10 pages, 5415 KiB

Open AccessArticle

Effect of Powder Recycling on the Organization and Mechanical Properties of GH4169 Alloy by Laser Metal Deposition

by Haibo Zhang, Jieshuai Li and Yingqiu Li

Coatings 2023, 13(3), 659; https://doi.org/10.3390/coatings13030659 - 22 Mar 2023

Cited by 6 | Viewed by 1849

Abstract

The purpose of this research is to prepare GH4 169 alloy specimens by laser metal deposition, by investigating the changes in powder morphology, powder particle size, and elemental content during the cycling process. As well as the pore defects and microstructure of deposited [...] Read more.

The purpose of this research is to prepare GH4 169 alloy specimens by laser metal deposition, by investigating the changes in powder morphology, powder particle size, and elemental content during the cycling process. As well as the pore defects and microstructure of deposited samples prepared from recycled powder, we analyzed the changes in powder properties during the cycling process and the effects of using recycled powder on the organization and properties of LMD-deposited specimens. It was shown that the average particle size of the powder increased with the increase in the size of powder recycling, from 59.861 µm in the original powder to 64.144 µm after four cycles, with the phenomenon of powder burnout and satellite ball. The elemental content of the powder changed with the increase in the number of cycles, among which the elemental content of Nb increased significantly from 4.31 wt% of the original powder to 7.97 wt% after four cycles, the proportion of Laves phase in the deposited samples increased, the porosity and pore size increased, the tensile strength of the specimen decreased from 1046 MPa of the original powder to 936 MPa, the tensile strength decreased by 10.5%, and the elongation was increased to 27% from 11% of the original powder. Powder recycling can lead to powder aging and reduce the mechanical properties of the laser metal deposited formed parts. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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12 pages, 7071 KiB

Open AccessArticle

Investigation of the Microstructure and Wear Properties of Laser Clad Al-Si Coatings Containing Different Y₂O₃ Contents

by Dongdong Zhang, Xiya He, Yali Gao and Baolong Qin

Coatings 2023, 13(2), 308; https://doi.org/10.3390/coatings13020308 - 30 Jan 2023

Cited by 11 | Viewed by 1851

Abstract

Y₂O₃-reinforced Al-Si alloy coatings were prepared on the surface of a Mg alloy by the laser cladding technique. The microstructure, hardness, and wear resistance of the coatings were analyzed using an X-ray diffractometer, a scanning electron microscope, an energy [...] Read more.

Y₂O₃-reinforced Al-Si alloy coatings were prepared on the surface of a Mg alloy by the laser cladding technique. The microstructure, hardness, and wear resistance of the coatings were analyzed using an X-ray diffractometer, a scanning electron microscope, an energy spectrometer, a Vickers hardness tester, and a friction wear tester. The effect of different additions of Y₂O₃ on the microstructure and properties of the coatings was investigated. The results indicate that the addition of Y₂O₃ leads to a significant refinement of the grain size and a denser microstructure of the coatings. Coatings with a high Y₂O₃ content provide superior hardness and wear resistance. With a Y₂O₃ content of 7.5 wt.%, the coating exhibits the finest grain size, highest hardness, and smallest wear volume. Excessive amounts of Y₂O₃, however, cause a reduction in the surface properties of the coating. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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13 pages, 4340 KiB

Open AccessArticle

Study on Anti-Scale and Anti-Corrosion of Polydopamine Coating on Metal Surface

by Xu-Liang Yu, Bing-Bing Wang, Zhi-Ming Xu and Wei-Mon Yan

Coatings 2023, 13(2), 306; https://doi.org/10.3390/coatings13020306 - 29 Jan 2023

Cited by 13 | Viewed by 3212

Abstract

Some surface coatings can protect metal surfaces and reduce scale deposition. Based on that, the biomimetic material polydopamine (PDA) can form a stable coating on many material surfaces; therefore, we propose an efficient one-step electroplating method for preparing anti-scale PDA coatings with high [...] Read more.

Some surface coatings can protect metal surfaces and reduce scale deposition. Based on that, the biomimetic material polydopamine (PDA) can form a stable coating on many material surfaces; therefore, we propose an efficient one-step electroplating method for preparing anti-scale PDA coatings with high stability. The scale deposition test showed that the deposition weight of calcium carbonate on the coating is less than that of carbon steel after immersing in a supersaturated solution of calcium carbonate for 12 h at 70 °C and 90 °C, with a coating scale-inhibition efficiency of 55.02% and 66.96%, respectively. By using molecular dynamics simulation, it was found that water adsorption layers exist near the metal’s surface, and the existence of water adsorption layers on the hydrophilic surface is the main reason for the initial deposition of calcium carbonate. The interaction energy between the PDA molecular layer and water is weaker (−5.69 eV) for the surface with the PDA coating, and there is no dense water adsorption layer on the coating, which leads to the low probability of calcium carbonate adsorption on the PDA coating surface. Therefore, PDA coating can inhibit the deposition of calcium carbonate on the surface. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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25 pages, 7115 KiB

Open AccessArticle

Laser Ablation of Copper Alloy under Varying Environmental Conditions to Achieve Purpose-Built Surface Structures

by Asadullah Dawood, Naveed Ahmed, Shazia Bashir, Asma Hayat, Syed Muhammad Abouzar Sarfraz and Ambreen Ayub

Coatings 2022, 12(12), 1972; https://doi.org/10.3390/coatings12121972 - 15 Dec 2022

Cited by 6 | Viewed by 2643

Abstract

In the manufacturing industry, surface structures and surface topographies present at functional areas of the mechanical parts play a vital role in various performance characteristics, such as corrosion resistance, weldability, and wear behaviors, etc. Copper–zinc alloys are extensively used in the manufacturing industry. [...] Read more.

In the manufacturing industry, surface structures and surface topographies present at functional areas of the mechanical parts play a vital role in various performance characteristics, such as corrosion resistance, weldability, and wear behaviors, etc. Copper–zinc alloys are extensively used in the manufacturing industry. Laser ablation has the potential to create a variety of surface structures on the ablated substrate. The size and geometry of such structures largely depend on the selection of process parameters and the ablation environment. In the present study, a copper–zinc alloy (95% Cu and 5% Zn) has been laser ablated under different gaseous and magnetic environments to realize a variety of micro-structuring at the ablation surfaces. The effect of plasma plume pressure on the geometry of the structures is deeply investigated through optical emission spectroscopy (OES) and scanning electron microscopy (SEM). By analytically evaluating thermal beta (βt), directional beta (βd), and containment radii (Rs) for the plasma of the Cu–Zinc alloy, the validity of magnetic confinement has been proven. In general, five types of microstructures are produced: micro-sized spherical cones, mounted ablated networks, cavities, pores, ridges, and ablation channels with uplifted cones. Moreover, it has been found that, under a magnetic environment, the geometry of the structures is distinct and well-defined compared to those structures achieved when the ablation is carried out without applying a magnetic field. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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15 pages, 22745 KiB

Open AccessArticle

Microstructure and Mechanical Properties of Ni-Based Alloy Composite Coating on Cr12MoV by Laser Cladding

by Yali Gao, Yan Tong, Li Guohui, Pengyong Lu and Dongdong Zhang

Coatings 2022, 12(11), 1632; https://doi.org/10.3390/coatings12111632 - 27 Oct 2022

Cited by 21 | Viewed by 2304

Abstract

Cr12MoV has been widely used in the manufacture of stamping and drawing dies. In the present study, an attempt was made to improve the mechanical properties of Cr12MoV by laser cladding Ni60 alloy reinforced by WC. X-ray diffraction (XRD), scanning electron microscopy (SEM), [...] Read more.

Cr12MoV has been widely used in the manufacture of stamping and drawing dies. In the present study, an attempt was made to improve the mechanical properties of Cr12MoV by laser cladding Ni60 alloy reinforced by WC. X-ray diffraction (XRD), scanning electron microscopy (SEM), a microhardness tester, and a friction and wear test prototype were used to analyze the macroscopic morphology, microstructure, and mechanical properties of the coating. The results showed that the coating mainly was composed of Cr-Fe-Ni, γ-(Fe, Ni), Cr₂₃C₆, Cr₇C₃, and W₂C phases. The cladding layer presented the dendritic eutectic structure enriched Cr, Fe, and Ni. Zigzag-shaped dendrites with thicknesses of 50~80 μm of the bonding zone ensured the strong metallurgical bonding. Due to solid solution strengthening, dispersion hardening, and grain refinement, the hardness of the coating reached 745 HV, which was 3.5 times that of the substrate. The wear volume of the coating was 14 × 10⁻³ mm³, which was 48% lower than that of the substrate (27 × 10⁻³ mm³). The coating had the abrasive wear; however, the substrate had the adhesive wear besides the abrasive wear. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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12 pages, 8720 KiB

Open AccessArticle

Research on Wear and Corrosion Resistance of Ni60-WC Coating Fabricated by Laser on the Preheated Copper Alloy

by Yu Liu, Tianhao Xu and Guohui Li

Coatings 2022, 12(10), 1537; https://doi.org/10.3390/coatings12101537 - 13 Oct 2022

Cited by 8 | Viewed by 2468

Abstract

The copper alloy is widely used to prepare pipes in ocean engineering. The surface is washed and corroded by seawater for a long time, which gradually shortens the service life of the condenser tube. In order to improve the wear and corrosion resistance [...] Read more.

The copper alloy is widely used to prepare pipes in ocean engineering. The surface is washed and corroded by seawater for a long time, which gradually shortens the service life of the condenser tube. In order to improve the wear and corrosion resistance of copper alloy, a Ni60-WC coating was fabricated on a preheated copper alloy by laser cladding. Experiments on the Ni60-WC coatings were carried out by SEM, XRD, Vickers-microhardness meter, wear tester and electrochemical workstation. The microstructure, phases, hardness, wear and corrosion resistance were investigated. The results show that from the top to bottom, the microstructures were columnar dendrites, dendritic crystals and grains, respectively. The wear rate of the Ni60-WC coating was only 4.9 × 10⁻⁵ mm³·N⁻¹·m⁻¹, which was only 1.14% of copper substrate. In addition, the corrosion current density was 2.34 × 10⁻⁷ mA·mm⁻², which was much lower than that of copper alloy substrate (1.14 × 10⁻⁶ mA·mm⁻²). The experimental results show that this Ni60-WC coating has a good metallurgical bonding and hardness, and it also has good wear and corrosion resistance, which is helpful to improve the service life of the condenser tube. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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24 pages, 80652 KiB

Open AccessArticle

Surface Structuring and Thin Film Coating through Additive Concept Using Laser Induced Plasma of Mg Alloy: A Comparison between the Presence and Absence of Transverse Magnetic Field (TMF)

by Asadullah Dawood, Shazia Bashir, Naveed Ahmed, Asma Hayat, Abdullah Yahia AlFaify, Syed Muhammad Abouzar Sarfraz, Shahab Ahmed Abbasi and Ateekh Ur Rehman

Coatings 2022, 12(9), 1316; https://doi.org/10.3390/coatings12091316 - 9 Sep 2022

Cited by 2 | Viewed by 2608

Abstract

In the present study, the influence of a 1.1 tesla Transverse Magnetic Field (TMF) on Laser-Induced Breakdown Spectroscopy (LIBS) of Mg-alloy plasma has been explored. The Mg plasma was produced using an Nd: YAG laser (1064 nm, 10 ns) at an intensity of [...] Read more.

In the present study, the influence of a 1.1 tesla Transverse Magnetic Field (TMF) on Laser-Induced Breakdown Spectroscopy (LIBS) of Mg-alloy plasma has been explored. The Mg plasma was produced using an Nd: YAG laser (1064 nm, 10 ns) at an intensity of 2 GW/cm². Inert gases of Ar, Ne, and He were filled as environmental gases at pressures ranging from 1 to 100 Torr. Optical emission spectra from laser-produced plasma were detected with the help of a spectrometer, and plasma parameters such as excitation temperature (T_exc) and electron number density (n_e) were evaluated. Enhancement in the Mg plasma’s T_exc and n_e in the presence of TMF was noticed under all experimental conditions, including different ambient gases with varying pressures and time delays (0.42 µs–9.58 µs). Plasma confinement by applied TMF was analytically evaluated through thermal beta (β_t) values, which were <1 under all circumstances. The highest T_exc and n_e values (17,259 K and 11.5 × 10¹⁷ cm⁻³) for Mg-alloy plasma were obtained with ambient Ar in TMF, while the lowest values (8793 K and 1.0 × 10¹⁷ cm⁻³) were obtained in presence of He gas in the absence of TMF. SEM analysis was used to determine the surface structure of laser-ablated Mg alloy in the presence and absence of TMF. It revealed that the formation of cones, cavities, and non-uniform melting are characteristic features of ambient Ar, while spikes and cavities are prominent features in Ne gas environments. Conical spikes and dendrites are distinct features when ambient He is present. In comparison with the field-free condition, distinct and well-defined structures were observed in the presence of TMF. By controlling LPP parameters, the surface structuring of Mg alloy can be controlled. The optimization and enhancement of LPP parameters make it a highly useful tool for thin film deposition, coatings of multilayers, and ion implantation/doping. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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Review

Jump to: Research

32 pages, 15315 KiB

Open AccessReview

Recent Advances in the Performance and Mechanisms of High-Entropy Alloys Under Low- and High-Temperature Conditions

by Rui Xi and Yanzhou Li

Coatings 2025, 15(1), 92; https://doi.org/10.3390/coatings15010092 - 15 Jan 2025

Cited by 1 | Viewed by 2295

Abstract

High-entropy alloys, since their development, have demonstrated great potential for applications in extreme temperatures. This article reviews recent progress in their mechanical performance, microstructural evolution, and deformation mechanisms at low and high temperatures. Under low-temperature conditions, the focus is on alloys with face-centered [...] Read more.

High-entropy alloys, since their development, have demonstrated great potential for applications in extreme temperatures. This article reviews recent progress in their mechanical performance, microstructural evolution, and deformation mechanisms at low and high temperatures. Under low-temperature conditions, the focus is on alloys with face-centered cubic, body-centered cubic, and multi-phase structures. Special attention is given to their strength, toughness, strain-hardening capacity, and plastic-toughening mechanisms in cold environments. The key roles of lattice distortion, nanoscale twin formation, and deformation-induced martensitic transformation in enhancing low-temperature performance are highlighted. Dynamic mechanical behavior, microstructural evolution, and deformation characteristics at various strain rates under cold conditions are also summarized. Research progress on transition metal-based and refractory high-entropy alloys is reviewed for high-temperature environments, emphasizing their thermal stability, oxidation resistance, and frictional properties. The discussion reveals the importance of precipitation strengthening and multi-phase microstructure design in improving high-temperature strength and elasticity. Advanced fabrication methods, including additive manufacturing and high-pressure torsion, are examined to optimize microstructures and improve service performance. Finally, this review suggests that future research should focus on understanding low-temperature toughening mechanisms and enhancing high-temperature creep resistance. Further work on cost-effective alloy design, dynamic mechanical behavior exploration, and innovative fabrication methods will be essential. These efforts will help meet engineering demands in extreme environments. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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39 pages, 9698 KiB

Open AccessReview

Technologies in Marine Antifouling and Anti-Corrosion Coatings: A Comprehensive Review

by Hua Liang, Xiaolong Shi and Yanzhou Li

Coatings 2024, 14(12), 1487; https://doi.org/10.3390/coatings14121487 - 26 Nov 2024

Cited by 5 | Viewed by 8147

Abstract

With the rapid development of marine engineering, effective antifouling and anti-corrosion technologies are essential for ensuring the safety and longevity of marine facilities. This review synthesizes current research on various coating technologies designed to combat marine biological fouling and corrosion. It analyzes the [...] Read more.

With the rapid development of marine engineering, effective antifouling and anti-corrosion technologies are essential for ensuring the safety and longevity of marine facilities. This review synthesizes current research on various coating technologies designed to combat marine biological fouling and corrosion. It analyzes the causes of marine biological fouling and corrosion, discusses their potential impacts on the safety of ships and marine structures, and emphasizes the need for effective protective systems. The review covers current antifouling coating technologies, including the preparation of low-surface-energy coatings, conductive coatings, biomimetic coatings, polysiloxane coatings, polyurea coatings, epoxy coatings, polyurethane coatings, and high-entropy alloy coatings. Anti-corrosion coatings are also discussed, with a focus on the characteristics of epoxy, polyurethane, and polyurea coatings, as well as metal-based coatings, alongside their corrosion resistance in marine environments. Based on existing research, the review summarizes ongoing challenges in marine antifouling and anti-corrosion coating technologies, and offers perspectives on future research directions and technological developments. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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36 pages, 2169 KiB

Open AccessReview

Review of Progress in Marine Anti-Fouling Coatings: Manufacturing Techniques and Copper- and Silver-Doped Antifouling Coatings

by Xiaolong Shi, Hua Liang and Yanzhou Li

Coatings 2024, 14(11), 1454; https://doi.org/10.3390/coatings14111454 - 15 Nov 2024

Cited by 2 | Viewed by 3858

Abstract

Marine biofouling presents numerous challenges, including increased drag, reduced efficiency, and ecological imbalance. This review presents an overview of recent advances in antifouling coatings. First, essential preparation techniques such as cold spray, plasma spray, magnetron sputtering, and laser cladding are introduced, including the [...] Read more.

Marine biofouling presents numerous challenges, including increased drag, reduced efficiency, and ecological imbalance. This review presents an overview of recent advances in antifouling coatings. First, essential preparation techniques such as cold spray, plasma spray, magnetron sputtering, and laser cladding are introduced, including the specific characteristics of each method. Next, the antifouling performance of Cu-doped and Ag-doped coating is analyzed. Emphasis is placed on the differences in coating composition, preparation methods, and their effects on antifouling and anticorrosion properties. The future development of antifouling technologies is also discussed, emphasizing the creation of multifunctional coatings, the optimization of coating microstructures for better performance, and the advancement of sustainable materials to minimize environmental impact. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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11 pages, 12070 KiB

Open AccessReview

Investigation of the Change in Roughness and Microhardness during Laser Surface Texturing of Copper Samples by Changing the Process Parameters

by Risham Singh Ghalot, Lyubomir Lazov, Emil Yankov and Nikolay Angelov

Coatings 2023, 13(11), 1970; https://doi.org/10.3390/coatings13111970 - 20 Nov 2023

Cited by 5 | Viewed by 1604

Abstract

The aim of this research is to achieve a high-quality and long-lasting laser marking of ammunition, which is of interest to the defense industry. The study is about the effects of speed, raster pitch and power on the roughness and microhardness of the [...] Read more.

The aim of this research is to achieve a high-quality and long-lasting laser marking of ammunition, which is of interest to the defense industry. The study is about the effects of speed, raster pitch and power on the roughness and microhardness of the marked areas of copper samples. The experiments were carried out with a fiber laser and a copper bromide laser—modern lasers widely used in industrial production. Laser power, scan speed and raster step were varied to determine their effects on the resulting microhardness and surface roughness. The lasers operate in different wavelength ranges, with the optical laser operating at 1064 nm in the near-infrared region and the copper bromide laser at 511 nm and 578 nm in the visible region, allowing the influence of wavelengths on the process to be investigated. The roughness and microhardness velocity dependence for three powers and two pulse durations for the fiber laser were obtained from the experimental data. The dependence of roughness and microhardness on the raster step for both types of lasers was also demonstrated. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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