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13 pages, 4004 KiB

Open AccessArticle

Effects of Copper Content on the Microstructural, Mechanical and Tribological Properties of TiAlSiN–Cu Superhard Nanocomposite Coatings

by Sung-Bo Heo, Wang Ryeol Kim, Jun-Ho Kim, Su-Hyeon Choe, Daeil Kim, Jae-Hun Lim and In-Wook Park

Coatings 2022, 12(12), 1995; https://doi.org/10.3390/coatings12121995 - 19 Dec 2022

Cited by 3 | Viewed by 1568

Abstract

The effects of the Cu content on the microstructural, mechanical and tribological properties of the TiAlSiN–Cu coatings were investigated in an effort to improve the wear resistance with a good fracture toughness for cutting tool applications. A functionally graded TiAlSiN–Cu coating with various [...] Read more.

The effects of the Cu content on the microstructural, mechanical and tribological properties of the TiAlSiN–Cu coatings were investigated in an effort to improve the wear resistance with a good fracture toughness for cutting tool applications. A functionally graded TiAlSiN–Cu coating with various copper (Cu) contents was fabricated by a filtered cathodic arc ion plating technique using four different (Ti, TiAl₂, Ti₄Si, and Ti₄Cu) targets in an argon-nitrogen atmosphere. The results showed that the TiAlSiN–Cu coatings are a nanocomposite consisting of (Ti,Al)N nano-crystallites (~5 to 7 nm) embedded in an amorphous matrix, which is a mixture of TiO_x, AlO_x, SiO_x, SiN_x, and CuO_x phase. The addition of Cu atoms into the TiAlSiN coatings led to the formation of an amorphous copper oxide (CuO_x) phase in the coatings. The maximum nanohardness (H) of ~46 GPa, H/E ratio of ~0.102, and adhesion bonding strength between coating and substrate of ~60 N (L_C2) were obtained at a Cu content ranging from 1.02 to 2.92 at.% in the TiAlSiN–Cu coatings. The coating with the lowest friction coefficient and best wear resistance was also obtained at a Cu content of 2.92 at.%. The formation of the amorphous CuO_x phase during coating growth or sliding test played a key role as a smooth solid-lubricant layer, and reduced the average friction coefficient (~0.46) and wear rate (~10 × 10⁻⁶ mm³/N·m). Full article

(This article belongs to the Special Issue Multifunctional Coatings and Lubrication)

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13 pages, 10109 KiB

Open AccessArticle

In Situ Preparation of Nano-Cu/Microalloyed Gradient Coating with Improved Antifriction Properties

by Jinquan Sun, Dongrui Wang, Jie Yang, Fujie Li, Lingli Zuo, Feng Ge and Yunbo Chen

Coatings 2022, 12(9), 1336; https://doi.org/10.3390/coatings12091336 - 14 Sep 2022

Cited by 3 | Viewed by 1128

Abstract

In order to solve the failure problem between the crankshaft and the connecting rod friction pair, nano-Cu/microalloyed gradient coating was prepared on the surface of the crankshaft by in situ gaseous nitriding process. Electron probe analysis confirmed the change of delamination after the [...] Read more.

In order to solve the failure problem between the crankshaft and the connecting rod friction pair, nano-Cu/microalloyed gradient coating was prepared on the surface of the crankshaft by in situ gaseous nitriding process. Electron probe analysis confirmed the change of delamination after the in situ nitriding process, and the formed coating included three layers: the upper layer is a nano-copper layer, the middle is a microalloyed layer (containing Cu, N, and Fe elements), and the bottom is a nitriding diffusion layer. The change of profile hardness curve was analyzed by microhardness test. The bonding force between the coating and the substrate was analyzed by the scratch test. The friction and wear test showed that the nano-Cu/microalloyed coating could achieve the effect of antifriction. Moreover, self-lubricating and antifriction mechanisms of nano-copper coating were proposed. These results indicated that the in situ gaseous nitriding process could provide a new surface modification technique for the precision friction pairs. Full article

(This article belongs to the Special Issue Multifunctional Coatings and Lubrication)

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19 pages, 12001 KiB

Open AccessArticle

The Effect of TiN, TiAlN, TiCN Thin Films Obtained by Reactive Magnetron Sputtering Method on the Wear Behavior of Ti6Al4V Alloy: A Comparative Study

by Şengül Danışman, Durmuş Odabaş and Muharrem Teber

Coatings 2022, 12(9), 1238; https://doi.org/10.3390/coatings12091238 - 25 Aug 2022

Cited by 11 | Viewed by 2447

Abstract

Titanium-based alloys have gained worldwide application over the past century. However, their low wear resistance remains an unresolved challenge for the Ti6Al4V alloy, which has significant industrial use. Therefore, it is an integral part in material selection and surface treatment in friction-wear applications. [...] Read more.

Titanium-based alloys have gained worldwide application over the past century. However, their low wear resistance remains an unresolved challenge for the Ti6Al4V alloy, which has significant industrial use. Therefore, it is an integral part in material selection and surface treatment in friction-wear applications. Tribological properties are not only material parameters but also system parameters where test conditions are essential. Hardness, roughness and contact conditions of coatings, which are especially important in surface treatments, affect wear modes. In this study, titanium nitride, titanium aluminum nitride and titanium carbon nitride coatings were obtained by unbalanced reactive magnetron sputtering to improve the weak tribological properties of Ti6Al4V alloy. The wear behavior was studied at room temperature in dry conditions. Wear tests were conducted under different loads and different sliding rates, which were followed by comparative analyses of their wear resistances. While the coated samples showed higher wear resistance than the uncoated Ti6Al4V alloy, the lowest wear track width was observed in TiN coating. Depending on the surface properties of the coatings, adhesion, abrasion and oxidation wear mechanisms were observed. It was concluded that a TiN coating could be a material of choice for applications where triple abrasive wear is dominant. Full article

(This article belongs to the Special Issue Multifunctional Coatings and Lubrication)

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11 pages, 5215 KiB

Open AccessArticle

Superhydrophobic Composite Coating with Excellent Mechanical Durability

by Cheng Ke, Yifan Fang, Zheng Zhou, Guohong Wang, Yongjia Liu, Wei Wu, Lishuang Xiao, Mengzhuo Zhang, Haibao Hu and Jianxi Liu

Coatings 2022, 12(2), 185; https://doi.org/10.3390/coatings12020185 - 31 Jan 2022

Cited by 8 | Viewed by 3410

Abstract

Superhydrophobic surfaces have great potential for self-cleaning, anti-icing, and drag-reducing because of their water repellency property. However, their super-hydrophobicity is destroyed under mechanical abrasion due to the vulnerability of the delicate surface textures. Here, we demonstrate a strategy to create a robust superhydrophobic [...] Read more.

Superhydrophobic surfaces have great potential for self-cleaning, anti-icing, and drag-reducing because of their water repellency property. However, their super-hydrophobicity is destroyed under mechanical abrasion due to the vulnerability of the delicate surface textures. Here, we demonstrate a strategy to create a robust superhydrophobic surface using MXene and fluoridated silica as functional fillers in epoxy resin. The fluoridated silica produces low surface energy, MXene serves as a wear-resistant phase and epoxy resin is the binding matrix. The composite coating demonstrates a self-cleaning effect to remove particles from the superhydrophobic surface by rolling water droplets. Moreover, the coating exhibits excellent mechanical durability by standing abrasion to maintain super-hydrophobicity. The superhydrophobic composite coating has the advantages of low cost and feasibility and has the potential for expandable industrial promotion. Full article

(This article belongs to the Special Issue Multifunctional Coatings and Lubrication)

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10 pages, 3780 KiB

Open AccessArticle

Fluid Characteristics Analysis of the Lubricating Oil Film and the Wear Experiment Investigation of the Sliding Bearing

by Fengming Du, Changduo Chen and Kaiguang Zhang

Coatings 2022, 12(1), 67; https://doi.org/10.3390/coatings12010067 - 07 Jan 2022

Cited by 14 | Viewed by 2329

Abstract

The sliding bearing is an important component in machines. The characteristics of the oil film fluid of the sliding bearing is the key factor affecting lubrication, which will affect the wear and reliability of the sliding bearing. Herein, the lubricating oil of the [...] Read more.

The sliding bearing is an important component in machines. The characteristics of the oil film fluid of the sliding bearing is the key factor affecting lubrication, which will affect the wear and reliability of the sliding bearing. Herein, the lubricating oil of the sliding bearing is studied, the oil film flow model considering the cavitation effect is established, the pressure and temperature distribution of the oil film under different rotational speeds is explored, and its influence on oil film pressure and temperature are analyzed. Furthermore, wear tests are carried out to measure the wear amount of the bearing bush under different rotational speeds, and the influence of the fluid characteristics of the lubricating oil film on bearing wear is explored. The simulation and experimental study in this paper can provide a reference for the design of sliding bearings. Full article

(This article belongs to the Special Issue Multifunctional Coatings and Lubrication)

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28 pages, 15982 KiB

Open AccessArticle

Wettability, Microhardness, Wear and Corrosion Resistance of Ni–Co–P–BN(h)–Al₂O₃ Binary Nanocomposite Coatings Surface with Varying Long-Pulse Laser Parameters

by Yin Zhang, Min Kang, Nyambura Samuel Mbugua, Bertrand Vigninou Gbenontin, Meifu Jin and Jiping Zhu

Coatings 2021, 11(12), 1467; https://doi.org/10.3390/coatings11121467 - 29 Nov 2021

Cited by 2 | Viewed by 1600

Abstract

In this study, Ni–Co–P–BN(h)–Al₂O₃ binary nanocomposite coatings were fabricated on steel C1045 substrates by jet electrodeposition. The samples were then processed using self-made laser processing equipment to investigate the influence of long-pulse laser processing parameters variation on samples’ surface morphology, [...] Read more.

In this study, Ni–Co–P–BN(h)–Al₂O₃ binary nanocomposite coatings were fabricated on steel C1045 substrates by jet electrodeposition. The samples were then processed using self-made laser processing equipment to investigate the influence of long-pulse laser processing parameters variation on samples’ surface morphology, roughness and wettability. Additionally, the properties of samples before and after laser processing were analyzed and characterized. The results showed that the surface morphologies, surface roughness and wettability of samples were affected by laser output power, pulse width and spot-to-spot distance variation. A convex dome was formed on the samples’ surface at a low laser output power and a suitable pulse width, while a dimple was formed on the samples’ surface at a high laser output power. The surface roughness and water contact angle of samples increased with the rise in laser output power or pulse width. The water contact angle decreased with the rise in the spot-to-spot distance, and the water contact angle reached a maximum value of 139.8° with a laser output power of 50 W, a pulse width of 100 µs and a spot-to-spot distance of 150 µm. The samples after laser processing exhibited a higher wettability, microhardness and wear resistance compared to those of the normal samples. The microhardness of the heat-affected zone reached a maximum value of 812.1 HV_0.1, and the wear scar width of the samples reached a minimum value of 360.5 µm. However, after laser processing, the samples’ seawater corrosion resistance decreased slightly. Full article

(This article belongs to the Special Issue Multifunctional Coatings and Lubrication)

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24 pages, 14276 KiB

Open AccessArticle

Impacting Droplet Can Mitigate Dust from PDMS Micro-Post Array Surfaces

by Abba Abdulhamid Abubakar, Bekir Sami Yilbas, Mubarak Yakubu, Hussain Al-Qahtani, Ghassan Hassan and Johnny Ebaika Adukwu

Coatings 2021, 11(11), 1377; https://doi.org/10.3390/coatings11111377 - 10 Nov 2021

Cited by 1 | Viewed by 1621

Abstract

In this paper, the impact mechanisms of a water droplet on hydrophobized micro-post array surfaces are examined and the influence of micro-post arrays spacing on the droplet behavior in terms of spreading, retraction, and rebounding is investigated. Impacting droplet behavior was recorded using [...] Read more.

In this paper, the impact mechanisms of a water droplet on hydrophobized micro-post array surfaces are examined and the influence of micro-post arrays spacing on the droplet behavior in terms of spreading, retraction, and rebounding is investigated. Impacting droplet behavior was recorded using a high-speed facility and flow generated in the droplet fluid was simulated in 3D geometry accommodating conditions of the experiments. Micro-post arrays were initially formed lithographically on silicon wafer surfaces and, later, replicated by polydimethylsiloxane (PDMS). The replicated micro-post arrays surfaces were hydrophobized through coating by functionalized nano-silica particles. Hydrophobized surfaces result in a contact angle of 153° ± 3° with a hysteresis of 3° ± 1°. The predictions of the temporal behavior of droplet wetting diameter during spreading agree with the experimental data. Increasing micro-post arrays spacing reduces the maximum spreading diameter on the surface; in this case, droplet fluid penetrated micro-posts spacing creates a pinning effect while lowering droplet kinetic energy during the spreading cycle. Flow circulation results inside the droplet fluid in the edge region of the droplet during the spreading period; however, opposing flow occurs from the outer region towards the droplet center during the retraction cycle. This creates a stagnation zone in the central region of the droplet, which extends towards the droplet surface onset of droplet rebounding. Impacting droplet mitigates dust from hydrophobized micro-post array surfaces, and increasing droplet Weber number increases the area of dust mitigated from micro-post arrays surfaces. Full article

(This article belongs to the Special Issue Multifunctional Coatings and Lubrication)

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Review

Jump to: Research

23 pages, 7540 KiB

Open AccessReview

New Progress in the Application of Flame-Retardant Modified Epoxy Resins and Fire-Retardant Coatings

by Shuang Sun, Qiangliang Yu, Bo Yu and Feng Zhou

Coatings 2023, 13(10), 1663; https://doi.org/10.3390/coatings13101663 - 22 Sep 2023

Cited by 2 | Viewed by 2202

Abstract

Due to the enhancement of people’s environmental awareness, flame-retardant epoxy resin (EP) tends to be non-toxic, efficient, and multi-functional, and its development is systematic. At present, many new flame retardants or intrinsic modification methods reported in studies can effectively improve the flame retardability [...] Read more.

Due to the enhancement of people’s environmental awareness, flame-retardant epoxy resin (EP) tends to be non-toxic, efficient, and multi-functional, and its development is systematic. At present, many new flame retardants or intrinsic modification methods reported in studies can effectively improve the flame retardability and thermal stability of EP. However, many aspects still need to be further improved. In this review, the flame-retardant mechanism and method of flame-retardant epoxy resins are briefly analyzed. The research progress of the flame-retardant modification of epoxy resin by physical addition and chemical reaction is summarized and discussed. Furthermore, the research trend of flame-retardant epoxy resin in the field of fire-protective coatings is discussed, and future problems in this field are put forward. This work may provide some new insights for the design of multi-functional integrated epoxy resin fireproof coatings. Full article

(This article belongs to the Special Issue Multifunctional Coatings and Lubrication)

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