Coatings

16 pages, 6813 KiB

Open AccessArticle

Study on the Wear Performance of Surface Alloy Coating of Inner Lining Pipe under Different Load and Mineralization Conditions

by Yuntao Xi, Yucong Bi, Yang Wang, Lan Wang, Shikai Su, Lei Wang, Liqin Ding, Shanna Xu, Haitao Liu, Xinke Xiao, Ruifan Liu and Jiangtao Ji

Coatings 2024, 14(10), 1274; https://doi.org/10.3390/coatings14101274 - 4 Oct 2024

Abstract

Testing was carried out in this study to evaluate the friction and wear performance of 45# steel inner liner pipes with cladding, along with four different types of centralizing materials (45# steel, nylon, polytetrafluoroethylene (PTFE), and surface alloy coating) in oil field conditions. [...] Read more.

Testing was carried out in this study to evaluate the friction and wear performance of 45# steel inner liner pipes with cladding, along with four different types of centralizing materials (45# steel, nylon, polytetrafluoroethylene (PTFE), and surface alloy coating) in oil field conditions. Under dry-friction conditions, the coefficients of friction and rates of wear are significantly higher than their counterparts in aqueous solutions. This is attributed to the lubricating effect provided by the aqueous solution, which reduces direct friction between contact surfaces, thereby lowering wear. As the degree of mineralization in the aqueous solution increases, the coefficient of friction tends to decrease, indicating that an elevated level of mineralization enhances the lubricating properties of the aqueous solution. The wear pattern in an aqueous solution is similar to that in dry-friction conditions under different loads, but with a lower friction coefficient and wear rate. The coating has played an important role in protecting the wear process of 45# steel, and the friction coefficient and wear rate of tubing materials under various environmental media have been significantly reduced. In terms of test load, taking into account the friction coefficient and wear rate, the suggested order for centralizing materials for lining oil pipes with the surface alloy coating is as follows: (i) surface alloy coating, (ii) nylon, (iii) PTFE, and (iv) 45# steel. Full article

(This article belongs to the Special Issue Anti-corrosion and Anti-wear Coatings: Fundamentals, Technologies, and Applications)

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19 pages, 1240 KiB

Open AccessArticle

Calcium Carbonate Deposition Model Supporting Multiple Operating Conditions Based on the Phase-Field Method for Free-Surface Flows

by Jianbing Lv, Zuru Chen, Li Feng, Chen Liang, Jia Li and Jingkai Huang

Coatings 2024, 14(10), 1273; https://doi.org/10.3390/coatings14101273 - 4 Oct 2024

Abstract

The drainage systems of tunnels situated in limestone regions frequently encounter crystallization blockages. Numerous studies have addressed this issue, and their findings identified factors such as the flow velocity and temperature as influencing the crystallization process. However, these studies could not predict the [...] Read more.

The drainage systems of tunnels situated in limestone regions frequently encounter crystallization blockages. Numerous studies have addressed this issue, and their findings identified factors such as the flow velocity and temperature as influencing the crystallization process. However, these studies could not predict the occurrence of crystallization. Regarding theoretical approaches, most studies have focused on full-pipe operations or have solely considered flow-field dynamics without including simulations of the chemical reactions and mass transfers. This study introduces a mass-transfer model for drainage pipes based on a two-phase flow (water and air) with a free surface and non-full pipe flow that simulates the crystallization deposition process in drainage pipes. This model can predict the deposition conditions at varying flow velocities and intuitively visualize the crystallization process under the influence of various factors. The impact of flow velocity on the overall crystallization deposition process can be directly analyzed through simulations developed using this model. The results show that under conditions of incomplete pipe flow with no pressure at the outlet, the weight of the deposition first increases and then decreases within a certain velocity. This model can depict the variations within a 30 d period. Full article

16 pages, 4961 KiB

Open AccessArticle

The Influence of Magnetic Field Orientation on the Efficacy and Structure of Ni-W-SiC Coatings Produced by Magnetic Field-Assisted Electrodeposition

by Hongbin Zhang, Zhiping Li, Lixin Wei and Fafeng Xia

Coatings 2024, 14(10), 1272; https://doi.org/10.3390/coatings14101272 - 4 Oct 2024

Abstract

This study presents a novel approach to enhancing the performance of Ni-W-SiC coatings through magnetic field-assisted electrodeposition, with a specific focus on the influence of magnetic field orientation. The coatings were evaluated for their structure, surface topology, roughness, corrosion resistance, and wear resistance. [...] Read more.

This study presents a novel approach to enhancing the performance of Ni-W-SiC coatings through magnetic field-assisted electrodeposition, with a specific focus on the influence of magnetic field orientation. The coatings were evaluated for their structure, surface topology, roughness, corrosion resistance, and wear resistance. The results indicated that the perpendicular magnetic orientation of the coating, obtained at a magnetic field value equal to 0.3 T (S1), showed the largest content of SiC, with a minimal grain size of Ni-W, measuring 84.7 nm with smooth, fine, and dense surface architecture. The S1 coating’s surface roughness, as revealed by AFM images, was 24.46 nm, significantly less than that of the coatings produced with 0 T (S0) and 0.3 T (S2) magnetic inductions. XRD results revealed that the Ni-W grains’ predominant growth direction shifted from the planar direction of (200) to the (111) direction, due to the application of a magnetic field oriented perpendicularly. In addition, the S1 coating had an outstanding corrosion resistance. Furthermore, S1, among all coatings, had the highest value of hardness, along with the lowest coefficient of friction and higher wear resistance. This work sets the stage for future advancements in surface engineering, demonstrating the potential of magnetic field orientation as a tool for material enhancement. Full article

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15 pages, 2879 KiB

Open AccessArticle

Magnetic Prediction of Doped Two-Dimensional Nanomaterials Based on Swin–Resnet

by Yu Zhang, Chuntian Zhou, Fengfeng Liang, Guangjie Liu and Jinlong Zhu

Coatings 2024, 14(10), 1271; https://doi.org/10.3390/coatings14101271 - 3 Oct 2024

Abstract

Magnetism is an important property of doped two-dimensional nanostructures. By introducing dopant atoms or molecules, the electronic structure and magnetic behavior of the two-dimensional nanostructures can be altered. However, the complexity of the doping process requires different strategies for the preparation and testing [...] Read more.

Magnetism is an important property of doped two-dimensional nanostructures. By introducing dopant atoms or molecules, the electronic structure and magnetic behavior of the two-dimensional nanostructures can be altered. However, the complexity of the doping process requires different strategies for the preparation and testing of various types, layers, and scales of doped two-dimensional materials using traditional techniques. This process is resource-intensive, inefficient, and can pose safety risks when dealing with chemically unstable materials. Deep learning-based methods offer an effective solution to overcome these challenges and improve production efficiency. In this study, a deep learning-based method is proposed for predicting the magnetism of doped two-dimensional nanostructures. An image dataset was constructed for deep learning using a publicly available database of doped two-dimensional nanostructures. The ResNet model was enhanced by incorporating the Swin Transformer module, resulting in the Swin–ResNet network architecture. A comparative analysis was conducted with various deep learning models, including Resnet, Res2net, ResneXt, and Swin Transformer, to evaluate the performance of the optimized model in predicting the magnetism of doped two-dimensional nanostructures. The optimized model demonstrated significant improvements in magnetism prediction, with a best accuracy of 0.9. Full article

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15 pages, 5202 KiB

Open AccessArticle

Sunlight-Driven Photodegradation of RB49 Dye Using TiO₂-P25 and TiO₂-UV100: Performance Comparison

by Fatima Zaaboul, Moisés Canle, Chaimaa Haoufazane, Juan Arturo Santaballa, Belkheir Hammouti, Khalil Azzaoui, Shehdeh Joedh, Aomar Hadjadj and Abderrahim El Hourch

Coatings 2024, 14(10), 1270; https://doi.org/10.3390/coatings14101270 - 3 Oct 2024

Abstract

By combining measurements of photocatalysis under solar irradiation with measurements of total organic carbon, we have compared the performance of two TiO₂-based photocatalysts in the photodegradation of the dye Reactive Blue 49 (RB49). TiO₂-P25 and TiO₂-UV100 commercial [...] Read more.

By combining measurements of photocatalysis under solar irradiation with measurements of total organic carbon, we have compared the performance of two TiO₂-based photocatalysts in the photodegradation of the dye Reactive Blue 49 (RB49). TiO₂-P25 and TiO₂-UV100 commercial photocatalysts were tested within a concentration ranging from 0.5 to 4 g/L. The dye solution concentration was varied from 10 to 50 mg/L and its pH was increased from 3 to 9. Extensive characterization of the photocatalysts was performed using Fourier-transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction. TiO₂-UV100 proved to be more active in adsorbing RB49 dye than TiO₂-P25. At low dye concentrations, the adsorption equilibrium is reached in 15 min. This time increases to 1 h at higher concentrations. The photocatalytic degradation of aqueous RB49 under sunlight was monitored by UV-Vis spectrophotometry. The apparent rate constant of dye photodegradation with TiO₂-UV100 is twice that of TiO₂-P25. The total organic carbon (TOC) analysis showed a removal of around 98% with TiO₂-UV100 and only 85% with TiO₂-P25 after 3 h of solar irradiation. Over five photocatalytic cycles of 3 h, TiO₂-UV100 maintained a more stable and higher efficient photocatalytic performance. All our results converge toward a better photocatalytic performance of TiO₂-UV100 for the photodegradation of RB49 dye and indicate that the most decisive factor is its greater capacity to adsorb the pollutant. Full article

(This article belongs to the Special Issue Surface and Interface Characteristics of Pavements: New Perspectives and Applications)

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14 pages, 4155 KiB

Open AccessArticle

Flexible Piezoelectric 0–3 PZT@C/PDMS Composite Films for Pressure Sensor and Limb Motion Monitoring

by Chungang Li, Chao Li, Yingzi Wang, Yaoting Zhao, Fengzhen Yang, Gensheng Dong, Xiujuan Lin, Shifeng Huang and Changhong Yang

Coatings 2024, 14(10), 1269; https://doi.org/10.3390/coatings14101269 - 3 Oct 2024

Abstract

The flexible piezoelectric pressure sensor is essential in areas such as machine sensing and human activity monitoring. Here, 0-dimensional PZT piezoelectric ceramic nanoparticles with carbon coating were synthesized by a surface-modified technique. The excellent electrical conductivity of the carbon shell causes redistribution and [...] Read more.

The flexible piezoelectric pressure sensor is essential in areas such as machine sensing and human activity monitoring. Here, 0-dimensional PZT piezoelectric ceramic nanoparticles with carbon coating were synthesized by a surface-modified technique. The excellent electrical conductivity of the carbon shell causes redistribution and accumulation of mobile charges in the carbon layer, resulting in a greatly increased piezoelectric effect by inducing an enhanced electric field. A series of organic–inorganic composite films were prepared by the spin-coating method using polydimethylsiloxane (PDMS) as the matrix. The as-fabricated flexible PZT@C/PDMS composite film with 40 wt% PZT@C powder exhibits an excellent output voltage of ~74 V, a peak of output current ~295 nA, as well as a big sensitivity of 5.26 V N⁻¹. Moreover, the composite film can be used as a pressure sensor to detect changes in force as well as for monitoring limb movements such as finger flexion, wrist flexion, and pedaling. This study reveals the promising applications of flexible 40%PZT@C/PDMS composite film for limb motion monitoring and pressure sensing. Full article

(This article belongs to the Special Issue Advances in Deposition and Surface Modification of Oxide Thin Films and Nanocoatings)

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11 pages, 3512 KiB

Open AccessArticle

Spraying Power Effect on Micro-Structure and Mechanical Property of TaSi₂ Coating Prepared by Supersonic Air Plasma Spraying for SiC-Coated C/C Composites

by Fei Liu, Hejun Li, Qiangang Fu, Bolun Ji, Lihao Chen, Bilin Zhang, Wei Zhang and Xinhai He

Coatings 2024, 14(10), 1268; https://doi.org/10.3390/coatings14101268 - 3 Oct 2024

Abstract

In order to further improve the oxidation resistance of SiC-coated C/C composites used in extreme environments, TaSi₂ coatings were deposited on the surfaces of SiC-coated C/C composites by supersonic air plasma spraying (SAPS) with different spraying power parameters, under other fixed parameter [...] Read more.

In order to further improve the oxidation resistance of SiC-coated C/C composites used in extreme environments, TaSi₂ coatings were deposited on the surfaces of SiC-coated C/C composites by supersonic air plasma spraying (SAPS) with different spraying power parameters, under other fixed parameter (gas flow, power feed rate, spraying distance and nozzle diameter) conditions. The micro-structures and phase characteristics of the TaSi₂ coatings prepared with the four kinds of spraying powers (40 kW, 45 kW, 50 kW and 55 kW) were analyzed. Also, the inter-facial bonding strengths and fracture modes between the four TaSi₂ coatings and the SiC coating were studied. The results showed that with an increase in the spraying power, the morphologies of the TaSi₂ coatings appeared from loose to dense to loose. When the spraying power was 50 kW, the deposition rate reached a maximum of 39.8%. The TaSi₂ coating presented an excellent micro-structure without obvious pores and microcracks, and its inter-facial bonding strength was 15.3 ± 2.3 N. Meanwhile, the fracture surface of the sample exhibited a brittle characteristic. Full article

(This article belongs to the Special Issue Trends in Coatings and Surface Technology, 2nd Edition)

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12 pages, 3090 KiB

Open AccessArticle

Ultrasound-Activated Multifunctional Bioactive Calcium Phosphate Composites for Enhanced Osteosarcoma Treatment

by Mingjie Wang, Dong Xu, Chunfeng Xu, Menghong Li, Chang Du and Yuelian Liu

Coatings 2024, 14(10), 1267; https://doi.org/10.3390/coatings14101267 - 2 Oct 2024

Abstract

Bone defects caused by surgical interventions and the challenges of tumor recurrence and metastasis due to residual cancer cells significantly complicate the treatment of osteosarcoma (OS). To address these complex clinical challenges, we propose an innovative therapeutic strategy that centers on an ultrasound-activated [...] Read more.

Bone defects caused by surgical interventions and the challenges of tumor recurrence and metastasis due to residual cancer cells significantly complicate the treatment of osteosarcoma (OS). To address these complex clinical challenges, we propose an innovative therapeutic strategy that centers on an ultrasound-activated multifunctional bioactive calcium phosphate (BioCaP) composite. A modified curcumin (mcur)-mediated wet biomimetic mineralization process was used to develop an anticancer-drug-integrated multifunctional BioCaP (mcur@BioCaP), exploring its potential biological effects for OS treatment activated by ultrasound (US). The mcur@BioCaP demonstrates a drug dose-dependent, tailorable alteration in its micro/nanostructure. The US stimulus significantly enhanced this composite to generate reactive oxygen species (ROS) in cancer cells. The results show that the OS cell viability of the mcur@BioCaP with US is 62.2% ± 6.3%, the migration distance is 63.9% ± 6.6%, and the invaded OS cell number is only 57.0 ± 3.7 OS cells per version, which were all significantly lower than US or mcur@BioCaP alone, suggesting that the anticancer, anti-migratory and anti-invasive effects of mcur@BioCaP on OS 143B cells were amplified by ultrasonic stimulation. This amplification can be attributed to the US-activated ROS production from the drug molecules, which regulates the wet biomimetic mineralization of the multifunctional composite. Furthermore, mcur@BioCaP with US increased calcium nodule formation by 1.8-fold, which was significantly higher than mcur@BioCaP or US group, indicating its potential in promoting bone regeneration. The anticancer and osteogenic potentials of mcur@BioCaP were found to be consistent with the mcur concentration in the multifunctional composite. Our research provides a novel therapeutic approach that leverages a multifunctional biomimetic mineral and ultrasonic activation, highlighting its potential applications in OS therapy. Full article

(This article belongs to the Special Issue Latest Trends in Coatings of Medical Implants)

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20 pages, 10749 KiB

Open AccessArticle

A Simulation Study on the Effect of Filament Spacing on the Temperature Field Uniformity of an HFCVD System

by Cen Hao, Fuming Deng, Quanbin Du, Zhiyu Min, Qing Lei, Lei Wang and Liang Zhang

Coatings 2024, 14(10), 1266; https://doi.org/10.3390/coatings14101266 - 2 Oct 2024

Abstract

Hot-filament chemical vapor deposition (HFCVD) has become the most widely used ways of preparing diamond film-coated tools due to the simple equipment used, its convenient operation, and its low cost. In the production process of an actual factory, a large number of coated [...] Read more.

Hot-filament chemical vapor deposition (HFCVD) has become the most widely used ways of preparing diamond film-coated tools due to the simple equipment used, its convenient operation, and its low cost. In the production process of an actual factory, a large number of coated tools need to be prepared in batches. Factors such as the hot-filament arrangement often affect the uniformity of coating on tools, making the performance of the tools prepared in the same batch unstable. This article uses ANSYS R15.0 software software in the context of computational fluid dynamics (CFD) to calculate the temperature field in the HFCVD system, and study the effect of filament spacing on the uniformity of the temperature field of the surface of the substrate. It was found that when the distance between filaments was 14 mm, 10 mm, 10 mm, 8 mm, 8 mm, the temperature field on the surface of the substrate was the most uniform. The experiments are consistent with the results of the simulation, indicating that simulation research has practical significance. Full article

(This article belongs to the Collection Hard Protective Coatings on Tools and Machine Elements)

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24 pages, 8725 KiB

Open AccessArticle

Application Study of Acoustic Reflectivity Based on Phased Array Ultrasonics in Evaluating Lubricating Oil Film Thickness

by Fei Shang, Huilin Chen, Bo Sun, Shaofeng Wang, Yongquan Han, Wenjing Liu, Fengchun Miao and Zhendong Liu

Coatings 2024, 14(10), 1265; https://doi.org/10.3390/coatings14101265 - 2 Oct 2024

Abstract

Bearings play a key role in rolling mills, and the uniformity of their lubricant film directly affects the degree of wear of bearings and the safety of equipment. Due to long-term stress, the lubricant film inside the bearing is not uniformly distributed, resulting [...] Read more.

Bearings play a key role in rolling mills, and the uniformity of their lubricant film directly affects the degree of wear of bearings and the safety of equipment. Due to long-term stress, the lubricant film inside the bearing is not uniformly distributed, resulting in uneven wear between the journal and the shaft tile, which increases the potential safety hazards in production. Traditional disassembly inspection methods are complex and time-consuming. Ultrasonic nondestructive testing technology, which has the advantages of nondestructive and adaptable, has become an effective means of assessing the thickness of the oil film in bearings. In this study, an experimental platform for calibrating the lubricant film thickness in bearings was constructed for the first time, and the acoustic characteristics of different thicknesses of the oil film were measured using ultrasonic detection equipment to verify the accuracy of the simulation process. The experimental results show that after discrete Fourier transform processing, the main features of the frequency channels of the reflected acoustic signals of different thicknesses of the oil film are consistent with the finite element simulation results, and the errors of the oil film thicknesses calculated from the reflection coefficients are within 10% of the set thicknesses, and the measurement ranges cover from 5 μm to 250 μm. Therefore, the above method can realize the accurate measurement of the thicknesses of the oil film in bearings. Full article

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12 pages, 2084 KiB

Open AccessArticle

Preparation of Tung Oil-Modified Raw Lacquer Films and Application for Mechanical Carving Technique

by Tong Wu and Wei Xu

Coatings 2024, 14(10), 1264; https://doi.org/10.3390/coatings14101264 - 2 Oct 2024

Abstract

Raw lacquer, known for its superior performance as a natural liquid coating, boasts excellent physical and mechanical properties as well as durability, making it widely used in manufacturing. However, the high hardness of the lacquer film upon complete curing poses challenges for carving [...] Read more.

Raw lacquer, known for its superior performance as a natural liquid coating, boasts excellent physical and mechanical properties as well as durability, making it widely used in manufacturing. However, the high hardness of the lacquer film upon complete curing poses challenges for carving and mechanical engraving. Therefore, it is necessary to study the curing process of lacquer films to obtain films suitable for carving or mechanical engraving. This study involves the preparation of raw lacquer with varying amounts of tung oil added, followed by the measurement of film drying time, surface roughness, glossiness, hardness, and adhesion on substrates to determine the optimal drying conditions. Additionally, SEM analysis of the carved surfaces and FT-IR analysis were used to investigate the impact of tung oil addition on lacquer carving performance and its variation. The results indicate that tung oil, to a certain extent, contributes to a smoother lacquer film but adversely affects film hardness and adhesion to Prunus serotina. However, with an increase in the amount of refined tung oil to 15%, the film exhibits improved glossiness, smoother carving tool marks, and reduced debris, thereby validating the feasibility of mechanical carving of tung oil-modified raw lacquer to some extent. Full article

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14 pages, 5157 KiB

Open AccessArticle

Research on the Optimal Protection Parameters of Graphene Composite Conductive Coatings Combined with Impressed Current Cathodic Protection Technology in Marine Atmospheric Environments

by Jiezhen Hu, Dahai Liu, Peichang Deng, Juyu Shangguan, Guo Zheng and Jingrong Yang

Coatings 2024, 14(10), 1263; https://doi.org/10.3390/coatings14101263 - 1 Oct 2024

Abstract

Based on the principle of a micropore-filling electrolyte, a graphene composite conductive coating combined with impressed current cathodic protection (ICCP) technology was constructed and applied in a marine atmospheric environment. To further explore the optimal protection parameters of the graphene composite conductive coating [...] Read more.

Based on the principle of a micropore-filling electrolyte, a graphene composite conductive coating combined with impressed current cathodic protection (ICCP) technology was constructed and applied in a marine atmospheric environment. To further explore the optimal protection parameters of the graphene composite conductive coating combined with ICCP technology in a marine atmospheric environment, the effects of the coating damage area (A), impressed voltage (B), and distance from the contact point (C) on the protective performance of the coating were investigated via orthogonal experiments. The optimal protection voltage and effective protection distance were verified by super-depth-of-field morphology observations and electrochemical tests. The orthogonal experimental results show that the primary and secondary orders affecting the protective performance of the conductive graphene composite coating are as follows: applied voltage (B) > coating damage area (A) > distance from the point of contact (C). The optimal protective parameters of the coating in the marine atmospheric environment are an applied voltage of 0.7 V, a damage rate of ≤1%, and a distance from the point of contact of 190 mm. The experimental results show that the corrosion potential of the sample is the highest under an applied voltage of 0.7 V, and the corrosion products do not diffuse to the surface of the coating. When the polarization resistance (R_p) values at 110 mm and 190 mm from the negative electrode at the point of contact are greater, the corrosion rate is lower, and the coating protection performance is better. Full article

(This article belongs to the Special Issue Research Progress on Coatings Degradation and Atmospheric Corrosion of Metal Surfaces)

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13 pages, 4183 KiB

Open AccessArticle

Optimization of Joining Parameters in Pulsed Tungsten Inert Gas Weld Brazing of Aluminum and Stainless Steel Based on Response Surface Methodology

by Huan He, Xu Tian, Xiaoyang Yi, Pu Wang, Zhiwen Guo, Ao Fu and Wenzhen Zhao

Coatings 2024, 14(10), 1262; https://doi.org/10.3390/coatings14101262 - 1 Oct 2024

Abstract

Combining aluminum and steel offers a promising solution for reducing structural weight and fuel consumption across various industries. Pulse in tungsten inert gas (TIG) weld brazing effectively suppresses interfacial brittle intermetallics and enhances joint strength by influencing pool stirring and heat input during [...] Read more.

Combining aluminum and steel offers a promising solution for reducing structural weight and fuel consumption across various industries. Pulse in tungsten inert gas (TIG) weld brazing effectively suppresses interfacial brittle intermetallics and enhances joint strength by influencing pool stirring and heat input during aluminum-to-steel joining. However, optimizing the pulsed TIG weld brazing process is challenging due to its numerous welding parameters. This study established statistical models for Al/steel joint strength without reinforcement using response surface methodology (RSM) based on central composite design (CCD). The models’ adequacy and significance were verified through analysis of variance (ANOVA). The four welding parameters influence weld strength in the following descending order: pulse on time > base current > pulse current > pulse frequency. Additionally, interactions between pulse current and pulse frequency, and between pulse on time and base current, were observed. Numerical optimization using RSM determined the optimal pulsed GTA weld brazing parameters for aluminum and stainless steel. With these optimized parameters, the joint strength reached 155.73 MPa, and the intermetallic compound (IMC) thickness was reduced to 3.4 μm. Full article

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11 pages, 11165 KiB

Open AccessArticle

Effect of Trace Bismuth on Deformation Behavior of Ultrahigh-Purity Copper during Hot Compression

by Haitao Liu, Yunxiao Hua, Weiqiang Li, Zhenguo Hou, Jincan Dong and Yong Liu

Coatings 2024, 14(10), 1261; https://doi.org/10.3390/coatings14101261 - 1 Oct 2024

Abstract

The effect of trace Bi impurities on the flow stress, microstructure evolution, and dynamic recrystallization (DRX) of the ultrahigh-purity copper was systematically investigated by a hot compression test at 600 °C. The results show that the peak stress of the ultrahigh-purity copper gradually [...] Read more.

The effect of trace Bi impurities on the flow stress, microstructure evolution, and dynamic recrystallization (DRX) of the ultrahigh-purity copper was systematically investigated by a hot compression test at 600 °C. The results show that the peak stress of the ultrahigh-purity copper gradually decreases with increasing Bi content. Trace Bi impurities can refine the microstructure of ultrahigh-purity copper. However, the refinement effect of 50 wt ppm Bi is much more significant than that of 140 wt ppm Bi during the hot deformation. This effect is ascribed to the higher concentration of Bi at GBs, which induces severe GB cracks that reduces the driving force for the nucleation of DRX grains. In addition, the introduction of Bi inhibits the DRX of the ultrahigh-purity copper and transforms its DRX process from the discontinuous dynamic recrystallization (DDRX) to the coexistence of DDRX and continuous dynamic recrystallization (CDRX) mechanisms. Full article

(This article belongs to the Special Issue Surface Modification of Advanced Transition Metal-Based Materials for Electrochemical Energy Storage)

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32 pages, 6198 KiB

Open AccessReview

A Review on Preparation of Palladium Oxide Films

by Petre Badica and Adam Lőrinczi

Coatings 2024, 14(10), 1260; https://doi.org/10.3390/coatings14101260 - 1 Oct 2024

Abstract

Fabrication aspects of PdO thin films and coatings are reviewed here. The work provides and organizes the up-to-date information on the methods to obtain the films. In recent years, the interest in Pd oxide for different applications has increased. Since Pd can be [...] Read more.

Fabrication aspects of PdO thin films and coatings are reviewed here. The work provides and organizes the up-to-date information on the methods to obtain the films. In recent years, the interest in Pd oxide for different applications has increased. Since Pd can be converted into PdO, it is instructive to pay attention to the preparation of the pure and the alloyed Pd films, heterostructures, and nanoparticles synthesized on different substrates. The development of PdO films is presented from the early reports on coatings’ formation by oxidation of Pd foils and wires to present technologies. Modern synthesis/growth routes are gathered into chemical and physical categories. Chemical methods include hydrothermal, electrochemical, electroless deposition, and coating methods, such as impregnation, precipitation, screen printing, ink jet printing, spin or dip coating, chemical vapor deposition (CVD), and atomic layer deposition (ALD), while the physical ones include sputtering and cathodic arc deposition, laser ablation, ion or electron beam-induced deposition, evaporation, and supersonic cluster beam deposition. Analysis of publications indicates that many as-deposited Pd or Pd-oxide films are granular, with a high variety of morphologies and properties targeting very different applications, and they are grown on different substrates. We note that a comparative assessment of the challenges and quality among different films for a specific application is generally missing and, in some cases, it is difficult to make a distinction between a film and a randomly oriented, powder-like (granular), thin compact material. Textured or epitaxial films of Pd or PdO are rare and, if orientation is observed, in most cases, it is obtained accidentally. Some practical details and challenges of Pd oxidation toward PdO and some specific issues concerning application of films are also presented. Full article

(This article belongs to the Special Issue Advances of Nanoparticles and Thin Films)

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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

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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15 pages, 4890 KiB

Open AccessArticle

Surface Tribological Properties Enhancement Using Multivariate Linear Regression Optimization of Surface Micro-Texture

by Zhenghui Ge, Qifan Hu, Haitao Zhu and Yongwei Zhu

Coatings 2024, 14(10), 1258; https://doi.org/10.3390/coatings14101258 - 1 Oct 2024

Abstract

This work aims to provide a comprehensive understanding of the structural impact of micro-texture on the properties of bearing capacity and friction coefficient through numerical simulation and theoretical calculation. Compared to the traditional optimization method of single-factor analysis (SFA) and orthogonal experiment, the [...] Read more.

This work aims to provide a comprehensive understanding of the structural impact of micro-texture on the properties of bearing capacity and friction coefficient through numerical simulation and theoretical calculation. Compared to the traditional optimization method of single-factor analysis (SFA) and orthogonal experiment, the multivariate linear regression (MLA) algorithm can optimize the structure parameters of the micro-texture within a wider range and analyze the coupling effect of the parameters. Therefore, in this work, micro-textures with varying texture size, area ratio, depth, and geometry were designed, and their impact on the bearing capacity and friction coefficient was investigated using SFA and MLA algorithms. Both methods obtained the optimal structures, and their properties were compared. It was found that the MLA algorithm can further improve the friction coefficient based on the SFA results. The optimal friction coefficient of 0.070409 can be obtained using the SFA method with a size of 500 µm, an area ratio of 40%, a depth of 5 µm, and a geometry of the slit, having a 10.7% reduction compared with the texture-free surface. In comparison, the friction coefficient can be further reduced to 0.067844 by the MLA algorithm under the parameters of size of 600 µm, area ratio of 50%, depth of 9 µm, and geometry of the slit. The final optimal micro-texture surface shows a 15.6% reduction in the friction coefficient compared to the texture-free surfaces and a 4.9% reduction compared to the optimal surfaces obtained by SFA. Full article

(This article belongs to the Special Issue Advances in Measurement and Data Analysis of Surfaces with Functionalized Coatings)

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14 pages, 11397 KiB

Open AccessArticle

Study of Hot-Dip Aluminium Plating Based on Micro-Morphology and Coating Bond Strength

by Chen Zhang, Bingying Wang, Xiaoyong Sun, Lin Liu, Enyang Liu, Haodong Guo, Lu Yin, Junze Yang and Jialei Ma

Coatings 2024, 14(10), 1257; https://doi.org/10.3390/coatings14101257 - 1 Oct 2024

Abstract

Hydrogen barrier coatings with Al₂O₃ as the main component are a good choice for solving the hydrogen embrittlement problem during hydrogen transportation in long-distance pipelines. However, the difference in the coefficients of thermal expansion between the substrate and the Al [...] Read more.

Hydrogen barrier coatings with Al₂O₃ as the main component are a good choice for solving the hydrogen embrittlement problem during hydrogen transportation in long-distance pipelines. However, the difference in the coefficients of thermal expansion between the substrate and the Al₂O₃ coating limits its further utilisation and development. In this study, rare earth oxides were added to the molten aluminium solution, and a Fe-Al transition layer was introduced on the surface of X80 steel by hot-dip plating to solve the thermal mismatch. Here, the microstructure and bonding strength of the hot-dip aluminium layer were investigated. It is found that the hot-dip aluminium coating consists of the outermost aluminium-rich layer and the inner Fe-Al alloy layer, and the microstructure of the two will change with the change in dip plating parameters. The best overall performance of the hot-dip aluminium layer was obtained from X80 steel substrate at a dip plating temperature of 700 °C and a dip plating time of 5 min. This coating has a good interface, moderate thickness, and a bond strength of 49 N. This study provides a reference value for solving the thermal mismatch between the steel substrate and the Al₂O₃ hydrogen barrier coating generated by subsequent anodising. Full article

(This article belongs to the Special Issue Ceramic Materials and Coatings: Materials, Fabrication, and Applications)

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17 pages, 5303 KiB

Open AccessArticle

Fluorescent Nanocomposites of Cadmium Sulfide Quantum Dots and Polymer Matrices: Synthesis, Characterization, and Sensing Application

by Paula Méndez, Karla Ramírez, Alex Lucero, Johny Rodríguez and Betty López

Coatings 2024, 14(10), 1256; https://doi.org/10.3390/coatings14101256 - 1 Oct 2024

Abstract

Fluorescent materials for sensing have gained attention for the visual detection of different substances as metals and pesticides for environmental monitoring. This work presents fluorescent nanocomposites in solution, film, and paper obtained without capping and stabilizing agents, coming from quantum dots of cadmium [...] Read more.

Fluorescent materials for sensing have gained attention for the visual detection of different substances as metals and pesticides for environmental monitoring. This work presents fluorescent nanocomposites in solution, film, and paper obtained without capping and stabilizing agents, coming from quantum dots of cadmium sulfide (CdS QDs) and anionic–cationic polymer matrices. Fluorescent films were formed by casting and fluorescent paper by impregnation from the solutions. The optical properties of CdS QDs in solution showed absorption between 418 and 430 nm and a maximum emission at 460 nm. TEM analysis evidenced particle size between 3 and 6 nm and diffraction patterns characteristic of CdS nanocrystals. Infrared spectra evidenced changes in the wavenumber in the fluorescent films. The band gap values (2.95–2.82 eV) suggested an application for visible transmitting film. Fluorescent solutions by UV-vis and fluorescence evidenced a chemical interaction with glyphosate standard between 1 and 100 µg/mL concentrations. The analysis of red, green, and blue color codes (RGB) evidenced a color response of the fluorescent paper at 10 and 100 µg/mL, but the fluorescent films did not show change. Nanocomposites of chitosan and pectin, in solution and on paper, exhibited a behavior “turn-on” sensor, while carboxymethylcellulose had a “turn-off” sensor. This methodology presents three fluorescent materials with potential applications in visual sensing. Full article

(This article belongs to the Special Issue Organic and Polymeric Materials: Synthesis, Properties and Applications)

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