Editorial

4 pages, 189 KiB

Open AccessEditorial

Research and Progress of Laser Cladding: Process, Materials and Applications

by Kaiming Wang, Zhenlin Zhang, Dingding Xiang and Jiang Ju

Coatings 2022, 12(10), 1382; https://doi.org/10.3390/coatings12101382 - 22 Sep 2022

Cited by 4 | Viewed by 1872

Laser cladding (LC) is a process in which materials with certain properties are added to the surface of a substrate [...] Full article

(This article belongs to the Special Issue Laser Cladding Coatings: Microstructure, Properties, and Applications)

Research

Jump to: Editorial, Review

21 pages, 10324 KiB

Open AccessEditor’s ChoiceArticle

Effect of Zn on Phase Evolution and Shear Resistance of Stainless Steel and Aluminum Alloy Interface by Laser Cladding

by Keyan Wang, Xianqing Yin, Chengxin Li and Kaiping Du

Coatings 2023, 13(7), 1267; https://doi.org/10.3390/coatings13071267 - 19 Jul 2023

Cited by 1 | Viewed by 895

Abstract

The connection between aluminum and iron alloys is of immense significance in the pursuit of lightweight industrial products. However, the Fe-Al interface’s inherent weakness restricts its widespread application. This study investigates the impact of Zn at the interface of Al-Fe laser cladding on [...] Read more.

The connection between aluminum and iron alloys is of immense significance in the pursuit of lightweight industrial products. However, the Fe-Al interface’s inherent weakness restricts its widespread application. This study investigates the impact of Zn at the interface of Al-Fe laser cladding on the phase and mechanical properties of the interface. Specifically, we examine the influence of the applied Zn powder layer and alloying Zn layer on the morphology of the Fe-based cladding layer. The inclusion of Zn enhances the spreadability of the Fe-based cladding layer. Additionally, we elucidate the effect of Zn on the composition and phase of the Fe-Al laser cladding interface. Notably, the affinity between Zn and the η phase surpasses that of the θ phase, and an increased Zn content significantly thickens the η phase. Shear tests reveal that the failure mode of shear fracture encompasses both brittle and ductile fractures. Density functional theory (DFT) calculations indicate that Zn has a limited effect on the strength of the η phase but reduces the enthalpy of formation of the η phase. Our findings demonstrate that the alloyed Zn layer initially facilitates the formation of a continuous and uniform η layer, while an increased Zn content enhances and stabilizes the shear strength of the interface. Full article

(This article belongs to the Special Issue Laser Cladding Coatings: Microstructure, Properties, and Applications)

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23 pages, 23317 KiB

Open AccessArticle

Influence of the Relative Position of Powder–Gas Jet and Laser Beam on the Surface Properties of Inconel 625 Coatings Produced by Extreme High-Speed Laser Material Deposition (EHLA)

by Matthias Brucki, Tobias Schmickler, Andres Gasser and Constantin Leon Häfner

Coatings 2023, 13(6), 998; https://doi.org/10.3390/coatings13060998 - 27 May 2023

Cited by 3 | Viewed by 1450

Abstract

Laser material deposition (LMD) is a widely used coating process in industry. However, to increase its economic appeal, higher process speeds are required. The solution to this challenge is an innovative modification known as extreme high-speed laser material deposition (EHLA). EHLA allows for [...] Read more.

Laser material deposition (LMD) is a widely used coating process in industry. However, to increase its economic appeal, higher process speeds are required. The solution to this challenge is an innovative modification known as extreme high-speed laser material deposition (EHLA). EHLA allows for an impressive increase in process speed from 2 m/min for conventional LMD to 500 m/min. With the ability to adjust process parameters, EHLA can generate tailor-made surface properties, expanding its potential application beyond current industrial uses. In this novel study, we explore the effects of relative positioning between tools (laser beam and powder–gas jet) and substrate on the surface properties of EHLA coatings. By laterally and axially offsetting the tools, the proportional energy coupling of the laser radiation into the powder–gas jet and substrate can be modified. Altering the position of the powder–gas jet can also affect the weld pool flow or number of particle attachments, thereby affecting surface properties. This approach allows for the adjustment of surface roughness over a wide range—from smooth, quasi-laser-polished surfaces to rough surfaces covered with particle adhesions. Full article

(This article belongs to the Special Issue Laser Cladding Coatings: Microstructure, Properties, and Applications)

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19 pages, 17846 KiB

Open AccessEditor’s ChoiceArticle

Effect of Scanning Strategies on Anisotropy of YCF104 Alloy Mechanical Properties by Laser Cladding

by Yu Zhao, Wenkai Shi, Liaoyuan Chen, Wenzheng Wu and Tianbiao Yu

Coatings 2023, 13(5), 842; https://doi.org/10.3390/coatings13050842 - 28 Apr 2023

Viewed by 973

Abstract

YCF104 alloy specimens were fabricated by laser cladding on #45 steel following three different scanning strategies. The microstructure, phase composition, friction coefficient, microhardness, tensile strength, and compressive strength of the specimens formed by different scanning strategies were investigated. The results show that the [...] Read more.

YCF104 alloy specimens were fabricated by laser cladding on #45 steel following three different scanning strategies. The microstructure, phase composition, friction coefficient, microhardness, tensile strength, and compressive strength of the specimens formed by different scanning strategies were investigated. The results show that the uniformity of laser remelting of solidified layers improved the uniformity of microstructure and refined the grains. The strengthening effect of the Fe–Cr/Mo solid solution was primarily responsible for the high strength. YCF104 cladding specimens exhibit brittle failure, and with the change of metallurgical bonding form in the overlap area, the compressive strength (the maximum value is 3235 MPa) and the tensile strength (specimen via strategy 3 is 527.44 MPa), there appears significant anisotropy. With the improvement of the uniformity of temperature distribution, the friction coefficient as well as the microhardness decreased when the GCr15 was used as the friction pair. The mechanical anisotropy of the coating is related to both the microstructure and metallurgical bonding strength in the overlap area. Full article

(This article belongs to the Special Issue Laser Cladding Coatings: Microstructure, Properties, and Applications)

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14 pages, 13488 KiB

Open AccessArticle

Effect of Mechanical Vibration on Microstructure and Properties of Laser Cladding WC-Reinforced Nickel-Based Alloy Coatings

by Zhongtang Gao, Congcong Ren, Jinzhou Li, Zhiming Gao, Lifei Du, Zhuhui Qiao and Chuanwei Zhang

Coatings 2023, 13(5), 840; https://doi.org/10.3390/coatings13050840 - 27 Apr 2023

Viewed by 1126

Abstract

Ni-WC composite coatings on 35CrMoV alloy surface were successfully prepared by mechanical vibration field-assisted laser cladding technology. Optical microscopy (OM) and scanning electron microscopy (SEM) were used to study the microstructure of the composite coatings without vibration and at different vibration frequencies; the [...] Read more.

Ni-WC composite coatings on 35CrMoV alloy surface were successfully prepared by mechanical vibration field-assisted laser cladding technology. Optical microscopy (OM) and scanning electron microscopy (SEM) were used to study the microstructure of the composite coatings without vibration and at different vibration frequencies; the phase composition of the cladding layer was studied by X-ray diffraction (XRD); and an energy dispersive spectrometer (EDS) was used for elemental plane scanning analysis. The grain growth trend under different convection directions was simulated. The wear resistance and mechanical properties of the composite coating were analyzed by friction and wear testing machine, three-dimensional surface profiler, and microhardness tester. The vibration field generated by the self-improved shaking table device is used to assist laser cladding. The effect of mechanical vibration on the quality of the cladding layer was studied. The results show that compared with the coating without mechanical vibration, an appropriate increase in vibration frequency contributes to the refinement of the grains. The original coarse dendrite structure becomes a fine needle-like structure, and the fine grain size gradually decreases. The application of vibration can improve the effect of grain refinement. The vibration makes the grain size distribution more uniform and the microhardness fluctuation of the cladding layer decreases. The experimental results show that mechanical vibration can improve the microstructure uniformity of the coating by selecting suitable vibration parameters. The average friction coefficient and wear width are reduced, and the microhardness is also increased. Full article

(This article belongs to the Special Issue Laser Cladding Coatings: Microstructure, Properties, and Applications)

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14 pages, 4700 KiB

Open AccessArticle

Gradient Coating of Laser Cladding TiB₂/Ti-Based Alloy on Titanium Alloy Surface

by Yinghua Lin, Haibo Wang, Mingxing Zhang, Hui Lin, Dengqiang Yan, Qinghua Lin, Xin Kang and Xinlin Wang

Coatings 2023, 13(4), 743; https://doi.org/10.3390/coatings13040743 - 06 Apr 2023

Cited by 7 | Viewed by 1553

Abstract

The technology of the TiB₂/TiB cladding layer addresses the issue of the insufficient wear resistance of cup-shaped parts composed of titanium alloy materials. In order to eliminate the cracking problem of laser cladding TiB₂/Ti-based alloy, 30%TiB₂/Ti-based alloy [...] Read more.

The technology of the TiB₂/TiB cladding layer addresses the issue of the insufficient wear resistance of cup-shaped parts composed of titanium alloy materials. In order to eliminate the cracking problem of laser cladding TiB₂/Ti-based alloy, 30%TiB₂/Ti-based alloy gradient coating was prepared on the surface of titanium alloy by laser cladding in this study. The results revealed that the microstructure of the matrix and the cladding layer is metallurgically bonded. The microstructures of the cladding layer appear as rod-like and coarse-grained features on the surface, and fine needle-like and small-grained morphologies inside. The fine needle-like TiB precipitated in situ from the melt has a flat interface with Ti and exhibits a low degree of interfacial mismatch, while the interface between small particle-like TiB and Ti is wavy and has a high degree of interfacial mismatch. The gradual increase in the amount of TiB is present from the surface to the bottom of the cladding layer, while the amount of unmelted TiB₂ particles decreases. The chemical structure of the cladding layer is mainly presented as TiB₂, TiB and α-Ti phases. The maximum hardness of the cladding layer is 725 HV_0.2, where it is more than twice the hardness of the substrate. The fretting wear resistance of the cladding layer is better than that of the titanium alloy substrate under low loads (50 N–100 N), while a high load (more than 150 N) triggers a reverse outcome. Full article

(This article belongs to the Special Issue Laser Cladding Coatings: Microstructure, Properties, and Applications)

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16 pages, 7654 KiB

Open AccessArticle

Effects of Process Parameters on Microstructure and High-Temperature Oxidation Resistance of Laser-Clad IN718 Coating on Cr5Mo Steel

by Zelin Xu, Fengtao Wang, Shitong Peng, Weiwei Liu and Jianan Guo

Coatings 2023, 13(1), 197; https://doi.org/10.3390/coatings13010197 - 15 Jan 2023

Cited by 2 | Viewed by 1652

Abstract

Cr5Mo steel with high thermal strength is frequently applied as the material for hydrocracking furnace tubes. Nonetheless, Cr5Mo tubes are prone to material failure in a high-temperature environment, threatening production safety. Considering that the IN718 nickel-base superalloy has favorable high-temperature oxidation resistance, the [...] Read more.

Cr5Mo steel with high thermal strength is frequently applied as the material for hydrocracking furnace tubes. Nonetheless, Cr5Mo tubes are prone to material failure in a high-temperature environment, threatening production safety. Considering that the IN718 nickel-base superalloy has favorable high-temperature oxidation resistance, the IN718 coating was fabricated on Cr5Mo substrate through laser cladding. The effect of process parameters on the high-temperature oxidation resistance of laser cladding IN718 coating was investigated. The results confirm that laser power and scanning speed affected the eutectic quantity precipitation of this layer, and the eutectic quantity precipitation was positively correlated with the mass gain of the coating. The high-temperature behavior of the coating could be divided into surface oxidation, intergranular corrosion, and material shedding. The scanning speed has a more significant impact on the high-temperature oxidation resistance. When the scanning speed is 15 mm/s, cracks originating in the heat-affected zone could exert a negative impact on the high-temperature oxidation resistance. Full article

(This article belongs to the Special Issue Laser Cladding Coatings: Microstructure, Properties, and Applications)

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16 pages, 6883 KiB

Open AccessEditor’s ChoiceArticle

High Temperature Oxidation and Oxyacetylene Ablation Properties of ZrB₂-ZrC-SiC Ultra-High Temperature Composite Ceramic Coatings Deposited on C/C Composites by Laser Cladding

by Kaijin Huang, Yahao Xia and Aihua Wang

Coatings 2023, 13(1), 173; https://doi.org/10.3390/coatings13010173 - 12 Jan 2023

Cited by 3 | Viewed by 1414

Abstract

In order to improve the high temperature oxidation and ablation resistance of C/C composites, ZrB₂-ZrC-SiC ultra-high temperature composite ceramic coatings were prepared on C/C composites by laser cladding using Zr, B₄C, and Si as raw materials. The microstructure of [...] Read more.

In order to improve the high temperature oxidation and ablation resistance of C/C composites, ZrB₂-ZrC-SiC ultra-high temperature composite ceramic coatings were prepared on C/C composites by laser cladding using Zr, B₄C, and Si as raw materials. The microstructure of the coating was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Air isothermal oxidation (1600 °C, 80 min) and oxyacetylene flame ablation (2400 kW/m², 300 s) were used to evaluate the high-temperature oxidation and ablation properties of the coating, respectively. The results show that the microstructure of laser cladding coating is a totem of black and white. The white part is mainly the first solidified high melting point ZrB₂ phase, and the black part is the latter solidified eutectic structure, which is mainly composed of ZrB₂(ZrB₁₂)-ZrC or ZrB₂(ZrB₁₂)-SiC two phases. After oxidation at 1600 °C and 80 min, the coating is mainly composed of ZrO₂ and ZrSiO₄ phases, and ZrSiO₄ is basically distributed among ZrO₂ particles. The high temperature oxidation and ablation properties of the coating are better than the C/C composite matrix, and the mass ablation rate of the coating is about 1/4 of the latter. Full article

(This article belongs to the Special Issue Laser Cladding Coatings: Microstructure, Properties, and Applications)

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13 pages, 2925 KiB

Open AccessArticle

Effect of Heat Treatment on Microstructure and Tribological Properties of Laser Cladding CeO₂/Ni60 Composite Coating on 35CrMoV Steel

by Zhiming Gao, Shuqing Zhang, Zhongtang Gao, Haibo Ren and Chuanwei Zhang

Coatings 2023, 13(1), 161; https://doi.org/10.3390/coatings13010161 - 11 Jan 2023

Viewed by 1069

Abstract

A Ni60 cladding layer with addition of 6.0% CeO₂ was prepared on 35CrMoV steel by laser cladding technology. The prepared sample was placed at 500 °C, 600 °C and 700 °C for 60 min to explore the effects of heat treatment on [...] Read more.

A Ni60 cladding layer with addition of 6.0% CeO₂ was prepared on 35CrMoV steel by laser cladding technology. The prepared sample was placed at 500 °C, 600 °C and 700 °C for 60 min to explore the effects of heat treatment on the tribological properties of the composite coating. The microstructure, phase composition, microhardness and tribological properties of the composite coating were characterized by optical microscopy and scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-Vickers hardness tester and MicroXAM-800 optical surface photometer, respectively. According to the above experimental results analysis, the main components of 6.0% CeO₂/Ni60 cladding layer are γ-(Fe,Ni),Cr₇C₃,Cr₂₃C₆,CrB, CrFeB and Cr₂Ni₃. By calculating the FWHM value and the left shift of the XRD diffraction peak, it is found that the coating grains are remarkably refined and the microstructure uniformity is significantly improved under the condition of heat treatment at 500 °C. The experimental results show that the Ni60 composite coating with 6.0% CeO₂ has the best friction and wear performance at 500 °C. The wearing quality of the composite coating at 500 °C was reduced by 43%. Full article

(This article belongs to the Special Issue Laser Cladding Coatings: Microstructure, Properties, and Applications)

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12 pages, 8484 KiB

Open AccessArticle

Effect of Cr₃C₂ Content on the Microstructure and Wear Resistance of Fe₃Al/Cr₃C₂ Composites

by Yingkai Feng, Jiguo Shan, Lin Zhao, Zhenbo Liu, Karin Gong and Changhai Li

Coatings 2022, 12(12), 1980; https://doi.org/10.3390/coatings12121980 - 17 Dec 2022

Cited by 3 | Viewed by 1282

Abstract

In this paper, an engine piston ring coating comprising composite material of Fe₃Al and Cr₃C₂ mixed powder was prepared by laser cladding onto carbon structural steel. The microstructure and tribological properties of the cladding materials were investigated through [...] Read more.

In this paper, an engine piston ring coating comprising composite material of Fe₃Al and Cr₃C₂ mixed powder was prepared by laser cladding onto carbon structural steel. The microstructure and tribological properties of the cladding materials were investigated through X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), and wear tests. The influence mechanism of the Cr₃C₂ content in cladding powder was studied. During the process of wear, the soft Fe₃Al/Fe₂AlCr matrix is first ground off, and the hard Cr₇C₃ phase initially supports the abrasive surface before being worn away into hard particles, resulting in abrasive wear. With the increase in Cr₃C₂ content, the hardness of the cladding layer increases, the proportion of the Cr₇C₃ phase increases, and the morphology changes from a sparse network to a dense floccule. Of the cladding layers with different Cr₃C₂ content, the 15 wt.% Cr₃C₂ cladding layer had the lowest friction coefficient, and the 25 wt.% Cr₃C₂ cladding layer had the lowest wear rate. The low wear rate of the 25 wt.% Cr₃C₂ cladding layer can be attributed to the fact that adhesive wear does not easily occur and the fine microstructure of the strengthening phase, which facilitates better separation in the grinding surfaces. Full article

(This article belongs to the Special Issue Laser Cladding Coatings: Microstructure, Properties, and Applications)

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16 pages, 8021 KiB

Open AccessArticle

Investigations on Microstructures and Properties of (Fe, Cr, W)₇C₃ Carbides by First Principles and Experiments

by Chao Chen, Junfa Wang, Yiyuan Ge and Lili Ma

Coatings 2022, 12(9), 1363; https://doi.org/10.3390/coatings12091363 - 18 Sep 2022

Cited by 1 | Viewed by 1244

Abstract

Tungsten doping is critical for the wear resistance and application of High-Chromium Cast Iron (HCCI). A series of investigations of (Fe, Cr, W)₇C₃ carbides were performed by first principles calculations and experimental analysis. The calculated results showed that with the [...] Read more.

Tungsten doping is critical for the wear resistance and application of High-Chromium Cast Iron (HCCI). A series of investigations of (Fe, Cr, W)₇C₃ carbides were performed by first principles calculations and experimental analysis. The calculated results showed that with the increase in tungsten content in M₇C₃, the equilibrium cell volumes and the density gradually increased, and the formation energy of M₇C₃ carbides gradually decreased. The TEM results showed that the (Fe, Cr, W)₇C₃ carbides were (Fe_3.27Cr_2.99W_0.74) C₃ with a hexagonal structure after adding 2.13 wt % tungsten into laser cladding coatings of High-Chromium Cast Iron with a composition of Fe-26.8 wt % Cr-3.62 wt % C. These results from calculations and in situ nanoindentation show that tungsten doping could improve the ductility and indentation modulus of (Fe, Cr)₇C₃ carbides, and the composition of (Fe, Cr, W)₇C₃ was expected to be a high hardness and softness material. The wear test results showed that the wear resistance of tungsten-bearing HCCI was better than ordinary HCCI. Full article

(This article belongs to the Special Issue Laser Cladding Coatings: Microstructure, Properties, and Applications)

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14 pages, 5417 KiB

Open AccessArticle

Crack Behavior of Ni60A Coating Prepared by Laser Cladding on a Tilted Substrate

by Bowen Shi, Xiaokai Mu, Huan Zhan, Linhui Deng, Tao Li and Hongchao Zhang

Coatings 2022, 12(7), 966; https://doi.org/10.3390/coatings12070966 - 07 Jul 2022

Cited by 3 | Viewed by 1294

Abstract

Almost all of the research on cracks in laser cladding is based, at present, on a horizontal substrate, which cannot be directly applied to prepare high performance coatings, especially high hardness coatings, on tilted substrate. In this work, the influence of the substrate’s [...] Read more.

Almost all of the research on cracks in laser cladding is based, at present, on a horizontal substrate, which cannot be directly applied to prepare high performance coatings, especially high hardness coatings, on tilted substrate. In this work, the influence of the substrate’s tilt angle on the crack behavior of high hardness Ni60A coating is studied, based on the laser intensity distribution and energy attenuation models on the tilted substrate. Results show that the cracking rate (the crack number in the unit’s cladding length) of the coating increases with the increasing substrate tilt angle, but the tilt angle has no significant influence on the crack mechanism. The different lap direction has a certain influence on the crack, and the coating prepared by downward lap cladding has a larger cracking rate due to the greater laser energy loss. Furthermore, with the increasing substrate tilt angle, the residual stress increases due to the decreased plastic flow, and the fracture strength decreases due to the decreased dilution rate, which results in the increase in the cracking rate of the Ni60A coating. This work will broaden the application of laser cladding technology on repairing complex parts such as gear and blades. Full article

(This article belongs to the Special Issue Laser Cladding Coatings: Microstructure, Properties, and Applications)

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14 pages, 5965 KiB

Open AccessFeature PaperArticle

The Effect of Process-Induced Porosity on Fatigue Properties of Ti6Al4V Alloy via High-Power Direct Energy Deposition

by Hang Lv, Zhenlin Zhang, Junjie Li, Yan Liu, Hui Chen, Huabing He, Jing Cheng and Yong Chen

Coatings 2022, 12(6), 822; https://doi.org/10.3390/coatings12060822 - 11 Jun 2022

Cited by 4 | Viewed by 1684

Abstract

Titanium alloy is widely used in the aviation sector and has become the most important structural material in aircraft manufacturing. However, manufacturing a large-scale titanium component owns a high buy-to-fly ratio due to its poor machinability and expensive price. Over the last decade, [...] Read more.

Titanium alloy is widely used in the aviation sector and has become the most important structural material in aircraft manufacturing. However, manufacturing a large-scale titanium component owns a high buy-to-fly ratio due to its poor machinability and expensive price. Over the last decade, the additive manufacturing (AM) technology has developed rapidly and has become a promising processing method for titanium alloys. In the future, in order to enhance processing efficiency and material utilization, a higher laser energy source is supposed to be applied in AM processes. Nevertheless, porosity within the AM fabricated part is the most important issue that restricts the application of AM technology. In the present work, two bulks with different porosities were fabricated using high-power direct energy deposition (HP-DED), and the high cycle fatigue (HCF) performance of the as-build part was tested and compared. The result shows that a lack of fusion (LOF), spherical pores and un-melted particles are the main porosity defects in the as-build part. The shape, size and location of the defect will have a synthetic effect on HCF performance. In addition, the unstable key-hole during the process will facilitate the formation of a pore, which consequently increases the porosity. Online monitoring and closed-loop feedback systems should be established for enhancing the process stability. Full article

(This article belongs to the Special Issue Laser Cladding Coatings: Microstructure, Properties, and Applications)

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20 pages, 7684 KiB

Open AccessArticle

Microstructure and Wear Behavior of TC4 Laser Cladding Modified via SiC and MoS₂

by Yan Liu, Junjie Li, Qian Xu, Yunhua Zhang, Xiulin Yan, Yong Chen and Huabing He

Coatings 2022, 12(6), 792; https://doi.org/10.3390/coatings12060792 - 07 Jun 2022

Cited by 5 | Viewed by 1689

Abstract

A TC4 composite coating reinforced by SiC ceramic phase and MoS₂ self-lubricating phase was prepared on a muzzle brake by laser cladding to improve its wear resistance properties. In this study, we investigated the microstructure and wear behavior of the composite coating. [...] Read more.

A TC4 composite coating reinforced by SiC ceramic phase and MoS₂ self-lubricating phase was prepared on a muzzle brake by laser cladding to improve its wear resistance properties. In this study, we investigated the microstructure and wear behavior of the composite coating. The results show that the composite coating consisted of equiaxed grains with grain sizes ranging from 102.39 to 255.31 μm on the surface and columnar grains on the bottom. The grains with mesh basket microstructure were mainly with α-Ti and β-Ti phases. When wearing against H70 brass, the main wear mechanism of the composite coating at room temperature was adhesive wear, while the wear mechanism was dominated by adhesive wear, oxidation wear, and slight abrasive wear at high temperature. Compared with TC4 coating without SiC and MoS₂, the wear rate of the composite coating was reduced by 15%–35% when the temperature was below 400 °C, and the wear rate was reduced by about 55% at 600 °C, resulting from the addition of SiC. Moreover, the friction coefficient of the composite coating was about 10%, which was 30% lower than that of the substrate and TC4 coating when the temperature was below 400 °C and at 600 °C due to the forming of the dense oxide film and the MoS₂ friction transfer film on the friction contact surface of the titanium-based composite coating. Full article

(This article belongs to the Special Issue Laser Cladding Coatings: Microstructure, Properties, and Applications)

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15 pages, 8357 KiB

Open AccessArticle

Prediction for Dilution Rate of AlCoCrFeNi Coatings by Laser Cladding Based on a BP Neural Network

by Yutao Li, Kaiming Wang, Hanguang Fu, Xiaohui Zhi, Xingye Guo and Jian Lin

Coatings 2021, 11(11), 1402; https://doi.org/10.3390/coatings11111402 - 18 Nov 2021

Cited by 15 | Viewed by 1872

Abstract

The dilution rate has a significant impact on the composition and microstructure of the coatings, and the dilution rate and process parameters have a complex coupling relationship. In this study, three process parameters, namely laser power, powder feeding rate, and scanning speed, were [...] Read more.

The dilution rate has a significant impact on the composition and microstructure of the coatings, and the dilution rate and process parameters have a complex coupling relationship. In this study, three process parameters, namely laser power, powder feeding rate, and scanning speed, were selected as variables to design the orthogonal experiment. The dilution rate and hardness data were obtained from AlCoCrFeNi coatings based on orthogonal experiments. Then, a BP neural network was used to establish a prediction model of the process parameters on the dilution rate. The established BP neural network exhibited good prediction of the dilution rate of AlCoCrFeNi coatings, and the average relative error between the predicted value and the experimental value was only 5.89%. Subsequently, the AlCoCrFeNi coating was fabricated with the optimal process parameters. The results show that the coating was well-formed without defects, such as cracks and pores. The microhardness of the AlCoCrFeNi coating prepared with the optimal process parameters was 521.6 HV_0.3. The elements were uniformly distributed in the microstructure, and the grain size was about 20–60 μm. The microstructure of the AlCoCrFeNi coating was only composed of the BCC phase without the existence of the FCC phase and intermetallic compounds. Full article

(This article belongs to the Special Issue Laser Cladding Coatings: Microstructure, Properties, and Applications)

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Review

Jump to: Editorial, Research

17 pages, 1908 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Corrosion of Laser Cladding High-Entropy Alloy Coatings: A Review

by Yusheng Liu, Dingding Xiang, Kaiming Wang and Tianbiao Yu

Coatings 2022, 12(11), 1669; https://doi.org/10.3390/coatings12111669 - 03 Nov 2022

Cited by 9 | Viewed by 2400

Abstract

Material corrosion is a common phenomenon. Severe corrosion not only causes material failure, but may also lead to unexpected catastrophic accidents. Therefore, reducing the loss caused by corrosion has become a problem faced by countries around the world. As a surface modification technology, [...] Read more.

Material corrosion is a common phenomenon. Severe corrosion not only causes material failure, but may also lead to unexpected catastrophic accidents. Therefore, reducing the loss caused by corrosion has become a problem faced by countries around the world. As a surface modification technology, laser cladding (LC) can be used to prepare coatings that can achieve metallurgical bonding with the substrate. High-entropy alloys (HEAs) are a new material with superior anti-corrosion ability. Therefore, HEA coatings prepared by LC have become a research hotspot to improve the anti-corrosive ability of material surfaces. In this work, the effects of LC process parameters, post-processing, and the HEA material system on the anti-corrosion ability of HEA coatings and their mechanisms are reviewed. Among them, the LC process parameters influence the anti-corrosion ability by affecting the macroscopic quality, dilution rate, and uniformity of the coatings. The post-processing enhances the anti-corrosion ability of the coatings by improving the internal defects and refining the grain structure. The anti-corrosion ability of the coatings can be improved by appropriately adding transition metal elements such as Ni, Cr, Co, and rare earth elements such as Ce and Y. However, the lattice distortion, diversification of phase composition, and uneven distribution caused by excess elements will weaken the corrosion protection of the coatings. We reviewed the impact of corrosion medium on the anti-corrosion ability of coatings, in which the temperature and pH value of the corrosion medium affect the quality of the passive film on the surface of the coatings, thereby affecting the anti-corrosion ability of the coatings. Finally, to provide references for future research, the development trend of preparing HEA coatings by LC technology is prospected. Full article

(This article belongs to the Special Issue Laser Cladding Coatings: Microstructure, Properties, and Applications)

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