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Properties and Applications of Surfaces/Components Engineered Using Thermal Spray, Welding, and Directed High Energy Beam Technologies

A special issue of Coatings (ISSN 2079-6412). This special issue belongs to the section "Surface Characterization, Deposition and Modification".

Deadline for manuscript submissions: 30 June 2024 | Viewed by 27262

Special Issue Editors

Dr. Ramachandran Chidambaram Seshadri

E-Mail Website
Guest Editor
Department of Materials Science and Engineering, Stony Brook University, Stony Brook, NY 11794, USA
Interests: surface engineering research and development
Dr. A.K. Lakshminarayanan

E-Mail Website
Guest Editor
Department of Mechanical Engineering, SSN College of Engineering, Chennai, India
Interests: materials joining research and development

Special Issue Information

Dear Colleagues,

Surface engineering refers to treatment of the surface and near-surface regions of a material by a comprehensive array of technologies to allow the surface to perform functions that are distinct from those functions demanded from the bulk of the material. There are two key categories of surface engineering approaches that can be used to enhance the surface properties of the bulk materials. These are surface coatings and surface modification. Surface coating processes involve depositing a layer of molten, semi-molten, or solid state material onto a substrate. One of the main functions of surface coating is to alter and fortify the surface functions instead of ameliorating the composition of the bulk material (thermal/ cold spraying). Surface modification procedures can be categorized as hardening by flame/ arc weld-hardfacing, induction, directed high energy beams (lasers/ electron beams), severe plastic deformation via shot peen/ friction stirring/ friction surfacing, ion implantation, and diffusion treatments. Surface modification treatments also can be combined with surface coating processes. This amalgamation augments the benefits of surface coatings and surface modification, thus achieving explicit requirements and aptness for purpose. Surface engineering is also interconnected to additive manufacturing in cases where the materials are joined in an incremental layered fashion to make parts using a few of the aforementioned deposition processes from a three-dimensional model data. This special issue on the “Properties and Applications of Surfaces/ Components Engineered using Thermal Spray, Welding, and Directed High Energy Beam Technologies”, provides a forum for the publication of refereed material on both the theory and practice of these important enabling technologies, embracing science, technology and engineering. Coverage includes design, surface modification strategies, 3D component manufacturing, process control, characterization, properties of the final system or component, including quality control and non-destructive examination.

Dr. Ramachandran Chidambaram Seshadri
Dr. A.K. Lakshminarayanan
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Coatings is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (17 papers)

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Research

16 pages, 1744 KiB  
Article
Quasi-Isotropy Structure and Characteristics of the Ultrasonic-Assisted WAAM High-Toughness Al Alloy
by Wei Luo, Peng Xu, Ming Zhang and Jiangshan Li
Coatings 2024, 14(5), 551; https://doi.org/10.3390/coatings14050551 (registering DOI) - 28 Apr 2024
Viewed by 73
Abstract
Wire Arc Additive Manufacturing (WAAM) has emerged as a highly promising method for the production of large-scale metallic structures; nonetheless, the presence of microstructural inhomogeneities, anisotropic properties, and porosity defects within WAAM Al alloys has substantially hindered their broader application. To surmount these [...] Read more.
Wire Arc Additive Manufacturing (WAAM) has emerged as a highly promising method for the production of large-scale metallic structures; nonetheless, the presence of microstructural inhomogeneities, anisotropic properties, and porosity defects within WAAM Al alloys has substantially hindered their broader application. To surmount these obstacles, ultrasonic-assisted WAAM was applied in the fabrication of thin-wall structures utilizing 7075 Al alloy. This study investigates the effects of ultrasonic-assisted Wire Arc Additive Manufacturing (WAAM) on the structural and mechanical properties of 7075 Al alloy specimens. Microstructural analysis showed a significant refinement in grain distribution, with the average grain size notably reduced, enhancing the material’s homogeneity. Porosity across the specimens was quantified, showing a decrease in values from the upper (0.02151) to the middle (0.01347) and lower sections (0.01785), correlating with the rapid cooling effects of WAAM. Mechanical testing revealed that ultrasonic application contributes to a consistent hardness pattern, with measurements averaging 70.71 HV0.1 horizontally and 71.23 HV0.1 vertically, and significantly impacts tensile strength; the horizontally oriented specimen exhibited a tensile strength of 236.03 MPa, a yield strength of 90.29 MPa, and an elongation of 31.10% compared to the vertically oriented specimen which showed reduced mechanical properties due to the presence of defects such as porosity and cracks. The fracture morphology analysis confirmed a predominantly ductile fracture mode, supported by the widespread distribution of dimples on the fracture surface. The integration of ultrasonic vibrations not only refined the grain structure but also modified the secondary phase distribution, enhancing the quasi-isotropic properties of the alloy. These results underline the potential of ultrasonic-assisted WAAM in improving the performance of the 7075 Al alloy for critical applications in the aerospace and automotive industries, suggesting a promising direction for future research and technological advancement in additive manufacturing processes. Full article
(This article belongs to the Special Issue Properties and Applications of Surfaces/Components Engineered Using Thermal Spray, Welding, and Directed High Energy Beam Technologies)
15 pages, 10709 KiB  
Article
Numerical Simulation and Mechanical Properties of 6063/6082 Dissimilar Joints by Laser Welding
by Shuwan Cui, Fuyuan Tian, Suojun Zhang, Hongfeng Cai and Yunhe Yu
Coatings 2023, 13(12), 2049; https://doi.org/10.3390/coatings13122049 - 05 Dec 2023
Cited by 2 | Viewed by 1045
Abstract
In this paper, the laser welding process of 6082-T6 and 6063-T6 dissimilar aluminum alloys with a thickness of 2.5 mm was numerically simulated by using a rotary surface Gauss heat source and the flow state of the weld pool was analyzed. The microstructure [...] Read more.
In this paper, the laser welding process of 6082-T6 and 6063-T6 dissimilar aluminum alloys with a thickness of 2.5 mm was numerically simulated by using a rotary surface Gauss heat source and the flow state of the weld pool was analyzed. The microstructure and mechanical properties of the welded joint (WJ) with a laser power of 1.75 kW were also studied. The results show that the recoil pressure in the molten pool tends to be stable with the increase in welding power, and the surface tension was the main driving force affecting the liquid metal flow in the molten pool. Under the action of 1.75 kW of laser power, the macromorphology of the weld was complete, continuous, and clear. The weld metal zone (WMZ) near both sides of the fusion line (FL) was columnar in microstructure, and the center of the WMZ was dominated by equiaxed crystals. The average microhardness of WMZ was 73.46 HV, which was lower than the base material zone (BM) and heat-affected zone (HAZ). The fracture region of the tensile specimen was located in HAZ on the 6063-T6 side of WJ, showing ductile fracture characteristics with a tensile strength of 180.8 MPa and elongation of 4.04%. Full article
(This article belongs to the Special Issue Properties and Applications of Surfaces/Components Engineered Using Thermal Spray, Welding, and Directed High Energy Beam Technologies)
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16 pages, 13630 KiB  
Article
Effect of Ultrasonic Treatment on Microstructure and Properties of 2000 MPa Ultra-High-Strength Steel-Welded Joints
by Qibao Chu, Gang Wang, Ren Yuan and Xiangyu Xu
Coatings 2023, 13(12), 1995; https://doi.org/10.3390/coatings13121995 - 24 Nov 2023
Viewed by 677
Abstract
The microstructure and mechanical properties of ultra-high-strength steel weld joints were examined for the effect of ultrasonic treatment. ER120S-G welding wire is necessary for welding 4 mm thick ultra-high-strength steel. After that, the weld toe region underwent different parameters of the ultrasonic stress [...] Read more.
The microstructure and mechanical properties of ultra-high-strength steel weld joints were examined for the effect of ultrasonic treatment. ER120S-G welding wire is necessary for welding 4 mm thick ultra-high-strength steel. After that, the weld toe region underwent different parameters of the ultrasonic stress relief process. As a means of surface treatment for weld seams, noticeable grain refinement and the formation of a fine-grained layer were observed in the weld toe region after ultrasonic treatment. The blind hole method was used to measure residual stresses in the weld seam, which indicated a transition from tensile stress to compressive stress in the treated portion of the joint. Different ultrasonic treatment processes resulted in a significant increase in hardness values near the weld toe region during hardness testing. The hardness of the weld joint that was treated with ultrasound increased initially but then stabilized after increasing the frequency. The ultrasound-treated joints showed a significant improvement in both tensile strength and fracture elongation, as demonstrated in the tensile tests. Full article
(This article belongs to the Special Issue Properties and Applications of Surfaces/Components Engineered Using Thermal Spray, Welding, and Directed High Energy Beam Technologies)
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20 pages, 28986 KiB  
Article
Advanced Analyses of Heating Elements Manufactured by an Optimized Arc Spraying Process
by Michél Hauer, Benjamin Ripsch, Andreas Gericke, Werner Krömmer and Knuth-Michael Henkel
Coatings 2023, 13(10), 1701; https://doi.org/10.3390/coatings13101701 - 27 Sep 2023
Viewed by 734
Abstract
Heating elements in the automotive industry are currently produced by several thermal spray processes and materials. However, simpler spraying technologies such as arc spraying are investigated regarding technological suitability as a cost-effective alternative to plasma spraying in the production process of these components. [...] Read more.
Heating elements in the automotive industry are currently produced by several thermal spray processes and materials. However, simpler spraying technologies such as arc spraying are investigated regarding technological suitability as a cost-effective alternative to plasma spraying in the production process of these components. Thus, several mixtures and combinations of alternative pressurizing gases and further modifications of an arc spray process were examined in this study. Consequently, coatings based on NiCr were produced, since this alloy is typical for heating elements. Coating properties were investigated by SEM, EDS, and resistivity measurements. The results demonstrate reduced oxygen content and improved morphology compared with the industrially used plasma-sprayed coatings. Additionally, the improved microstructure affects the surface quality and specific resistivity of the coatings positively. This allowed for laser texturing the arc-sprayed coatings successfully. It must be considered a drawback, though, that cracks partially appeared in the underlying coatings. In contrast, the temperature coefficients of resistance and the resistivities of the heating elements were superior to the conventional coatings, which can lay the foundation for a future industrial application. To further investigate this and to minimize the influence of potential sample preparation issues on the analysis results, different methods of cross-sectioning, i.e., in detail hot mounting, cold mounting, and ion beam polishing, were evaluated. Full article
(This article belongs to the Special Issue Properties and Applications of Surfaces/Components Engineered Using Thermal Spray, Welding, and Directed High Energy Beam Technologies)
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15 pages, 15728 KiB  
Article
Thermal Cycling, Microstructure, and Mechanical Properties of Al-Mg-Si-Cu Alloy Bobbin Tool Friction Stir Welded Joints Based on Thermal Index
by Yi Li, Zhigang Zhou, Li Yin, Dingyao Fu, Haiyi Jiang, Yunxin Yang, Jie Lu and Fuming Jin
Coatings 2023, 13(9), 1607; https://doi.org/10.3390/coatings13091607 - 14 Sep 2023
Cited by 2 | Viewed by 959
Abstract
The two main process parameters of Bobbin tool friction stir welding (BT-FSW) are ω (rotational speed) and v (traverse speed). Both of these factors have a significant effect on heat input, microstructure, and mechanical properties. At present, most studies on friction stir welding [...] Read more.
The two main process parameters of Bobbin tool friction stir welding (BT-FSW) are ω (rotational speed) and v (traverse speed). Both of these factors have a significant effect on heat input, microstructure, and mechanical properties. At present, most studies on friction stir welding adopt the control variable method to study the thermal cycling during the welding process and the mechanical properties of joints, and there are few studies on changing the two process parameters at the same time, because it can be difficult to assess the correlation between heat input and mechanical properties when changing both factors at the same time. In this study, the w/v ratio is defined as the thermal index, which is a characteristic value of heat input. The study uses ABAQUS 6.5 software to establish a BT-FSW CEL (coupled Eulerian–Lagrangian) thermal coupling model. This model explores the relationship between joint thermal cycles, microstructure, and mechanical properties for different w and v values with the same w/v ratio. The results show that increasing rotational and traverse speeds under the same w/v ratio leads to an increase in the peak temperature of the nugget zone (NZ). However, the peak temperature of the thermo-mechanically affected zone (TMAZ) and heat-affected zone (HAZ) remained almost constant. Joint strength was highest at a rotational speed of 750 r/min and a traverse speed of 650 mm/min, with a yield strength of 227 MPa. As rotational and traverse speeds increased, the recrystallized grain content of the NZ showed an increasing trend followed by a decreasing trend. The recrystallized grain content of the advancing side thermo-mechanically affected zone (AS-TMAZ) and retreating side thermo-mechanically affected zone (RS-TMAZ) showed a decreasing trend. Joint hardness had a “W” shaped distribution, with the highest average hardness value found in the NZ. Full article
(This article belongs to the Special Issue Properties and Applications of Surfaces/Components Engineered Using Thermal Spray, Welding, and Directed High Energy Beam Technologies)
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13 pages, 5753 KiB  
Article
Effects of Ti/N Ratio on Coarse-Grain Heat-Affected Zone Microstructure Evolution and Low-Temperature Impact Toughness of High Heat Input Welding Steel
by Jin Liu, Jiaji Wang, Fengya Hu, Kuijun Fu, Zhiqiang Zhang and Yumin Wu
Coatings 2023, 13(8), 1347; https://doi.org/10.3390/coatings13081347 - 31 Jul 2023
Cited by 1 | Viewed by 783
Abstract
Coarse-grain heat-affected zone (CGHAZ) properties of steel deteriorate when it is welded using high heat input, which always restricts the promotion and use of high heat input welding steel. TiN particles significantly inhibit the growth of austenite and improve the microstructure and properties [...] Read more.
Coarse-grain heat-affected zone (CGHAZ) properties of steel deteriorate when it is welded using high heat input, which always restricts the promotion and use of high heat input welding steel. TiN particles significantly inhibit the growth of austenite and improve the microstructure and properties of high heat input welding steel. Effects of different Ti/N ratios on the CGHAZ microstructure and properties of high heat input welding steel were studied using welding thermal simulations and in situ observations. Results showed that a higher Ti/N ratio led to the abnormal growth of austenite grains and promoted the nucleation and growth of lath ferrite, which made the microstructure of the CGHAZ heterogeneous. In contrast, austenite grains were more uniform at a lower Ti/N ratio. Thus, the microstructure was refined, the brittle structure was reduced, and the properties of the CGHAZ were improved. In addition, when Ti/N = 5.85, the impact absorption energy of the CGHAZ obviously fluctuated. However, when Ti/N = 2.82, the impact absorption energy of the CGHAZ was higher and more stable. These results provided a new idea for the development of high heat input welding steel based on TiN theory. Full article
(This article belongs to the Special Issue Properties and Applications of Surfaces/Components Engineered Using Thermal Spray, Welding, and Directed High Energy Beam Technologies)
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14 pages, 48011 KiB  
Article
Improvement of Microstructure and Sliding Wear Property of Cold-Sprayed FeAl Intermetallic Compound Coating by Annealing Treatment
by Hongtao Wang, Fenghui An, Xiaobo Bai, Hailong Yao, Mengxian Zhang, Qinyu Chen, Gangchang Ji and Chidambaram Seshadri Ramachandran
Coatings 2023, 13(7), 1260; https://doi.org/10.3390/coatings13071260 - 18 Jul 2023
Cited by 2 | Viewed by 702
Abstract
Nanograin Fe(Al) solid solution alloy coating was firstly produced through cold-spraying technology using mechanically alloyed powder. Then, the above-mentioned coating was annealed at different temperatures to explore its influence on the phase constitution, microstructure, microhardness and dry sliding wear property of the coatings. [...] Read more.
Nanograin Fe(Al) solid solution alloy coating was firstly produced through cold-spraying technology using mechanically alloyed powder. Then, the above-mentioned coating was annealed at different temperatures to explore its influence on the phase constitution, microstructure, microhardness and dry sliding wear property of the coatings. Results exhibited that an FeAl phase appeared in the coatings after 500 °C treatment and remained stable with increasing annealing temperature. The annealing temperature had a considerable effect on the microstructure, microhardness and wear behavior of the FeAl coating. The existing laminated structure in the as-sprayed coating gradually faded away with increasing temperature and finally obtained a dense coating microstructure with no particle interface when annealed above 950 °C. Nanograin began to evidently grow at temperatures over 800 °C. The microhardness of the FeAl coating stayed at 400 Hv0.1 at temperatures below 800 °C, then it quickly dropped to 300 Hv0.1 at 950 °C and remained nearly unchangeable up to 1100 °C. The dry sliding wear mechanism of the FeAl coating annealed at low temperatures below 700 °C was mainly delamination of the oxide layer and showed a high wear rate within the order of magnitude range of 10−4, whereas FeAl coatings annealed at high temperatures above 950 °C were worn by microploughing and little oxidation and exhibited very low wear rates within the order of magnitude range of 10−6. Full article
(This article belongs to the Special Issue Properties and Applications of Surfaces/Components Engineered Using Thermal Spray, Welding, and Directed High Energy Beam Technologies)
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15 pages, 6083 KiB  
Article
Key Parameters and Optimal Design of a Split Induction Coil for T-Shaped Pipe Brazing
by Zhenlin Zhang, Ziheng Yang, Pu Xie, Yue Zhao, Jiguo Shan, Yan Liu, Aiping Wu, Sida Ma, Lei Zhang and Hui Chen
Coatings 2023, 13(5), 940; https://doi.org/10.3390/coatings13050940 - 17 May 2023
Viewed by 1284
Abstract
The heat exchanger made up of several T-shaped joints is a critical component in energy equipment. A split induction coil was designed for T-shaped aluminum pipe brazing, and the Taguchi method was combined with multi-physical simulation to solve the multi-factor optimization of the [...] Read more.
The heat exchanger made up of several T-shaped joints is a critical component in energy equipment. A split induction coil was designed for T-shaped aluminum pipe brazing, and the Taguchi method was combined with multi-physical simulation to solve the multi-factor optimization of the split coil. The results showed that the multi-physical simulation model had high precision. The melting of filler metal was almost consistent with the spatial distribution of the temperature field, and the average simulation error was approximately 5.753 °C. The optimal coil parameters were obtained with a turn number of 3.5, a turn space of 7 mm, a heating distance of 15.6 mm, a coil diameter of 8 mm, and a coil length of 9 mm. Three well-formed T-shaped joints could be obtained at one time via the optimal split coil. During the induction brazing, the skin effects and the proximity effects induced a high magnetic field intensity around the joint, which had a significant relationship with the coil length and coil diameter. The high magnetic field intensity promoted a high eddy current density in this place, and as a result, the high Joule heat could be generated around the joint. In addition, the significant decrease in the heating rate at high temperatures promoted the homogenization of the temperature and the melting and filling of the filler metal as well as avoided local overheating. Full article
(This article belongs to the Special Issue Properties and Applications of Surfaces/Components Engineered Using Thermal Spray, Welding, and Directed High Energy Beam Technologies)
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15 pages, 2824 KiB  
Article
Optimizing Friction Welding Parameters in AISI 304 Austenitic Stainless Steel and Commercial Copper Dissimilar Joints
by R. Paventhan, D. Thirumalaikumarasamy, Venkata Charan Kantumuchu, Omar Shabbir Ahmed, Mohamed Abbas, Ahmad Aziz Alahmadi, Mamdooh Alwetaishi, Ali Nasser Alzaed and Chidambaram Seshadri Ramachandran
Coatings 2023, 13(2), 261; https://doi.org/10.3390/coatings13020261 - 22 Jan 2023
Cited by 2 | Viewed by 1577
Abstract
By using fusion welding to weld AISI 304 austenitic stainless steel (ASS) and commercial copper, the creation of brittle intermetallic in the weld region that compromises the strength of the joints is the primary challenge. However, friction welding is a suitable method for [...] Read more.
By using fusion welding to weld AISI 304 austenitic stainless steel (ASS) and commercial copper, the creation of brittle intermetallic in the weld region that compromises the strength of the joints is the primary challenge. However, friction welding is a suitable method for joining these two materials because no obvious defects are produced at the joints. The joint strength is significantly influenced by the friction-welding-process variables including the pressure of friction, pressure of forging, time of friction, and time of forging. Throughout this study, a central composite factorial design-based empirical relationship-building effort was carried out to determine the tensile strengths of friction-welded AISI 304 austenitic stainless steels (ASS) and commercial copper alloys dissimilar joints from the process variables. The process conditions were optimized employing response surface methods in order to attain the joint’s optimum tensile strength. This research revealed that the greatest tensile strength of the joint created with the friction pressure of 60 MPa, forging pressure of 60 MPa, friction duration of 4 s, and forging time of 4 s, correspondingly, was 489 MPa. As a result, the intermetallic formation at the interface could be identified. Full article
(This article belongs to the Special Issue Properties and Applications of Surfaces/Components Engineered Using Thermal Spray, Welding, and Directed High Energy Beam Technologies)
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15 pages, 8500 KiB  
Article
Jointing of CFRP/5083 Aluminum Alloy by Induction Brazing: Processing, Connecting Mechanism, and Fatigue Performance
by Kang Guo, Guoqing Gou, Hang Lv and Meile Shan
Coatings 2022, 12(10), 1559; https://doi.org/10.3390/coatings12101559 - 16 Oct 2022
Cited by 88 | Viewed by 2063
Abstract
Carbon fiber reinforced polymer (CFRP) is widely used in the lightweight design of high-speed trains due to its high specific strength. In order to further reduce the weight of the high-speed train body, it is necessary to study the joining process and fatigue [...] Read more.
Carbon fiber reinforced polymer (CFRP) is widely used in the lightweight design of high-speed trains due to its high specific strength. In order to further reduce the weight of the high-speed train body, it is necessary to study the joining process and fatigue properties of CFRP/aluminum alloys (CFRP/Al) structure. In this work, the CFRP plate and 5083P-O aluminum plate were successfully connected by an induction brazing method. The optimum parameters of induction brazing were determined to be an induction temperature of 290 °C, a normal pressure of 200 kPa, and a holding time of 5 s. After the 5083 plate was pre-anodized, the tensile strength of the CFRP/5083 joint reached a maximum value of 176.5 MPa. The anodization process introduced more surface micro-structures on the 5083 plate, leading to a better wetting behavior between CFRP and oxide film. Meanwhile, a new chemical bond, Al-O-C, was also formed at the interface of the CFRP/5083 joint. The fatigue limit of the CFRP/5083 joint was calculated to be 71.68 MPa through high-cycle fatigue (HCF) testing. The fatigue cracks initiated from the interface of CFRP/oxide film, and then propagated to base metal. Finally, the oxide film was peeled off from the base metal under shear stress, which contributed to the fracture of the CFRP/5083 joint. The bonding strength between CFRP and 5083 aluminum alloy is far from the conventional welded joints. Therefore, feasible approaches should be proposed to obtain a more robust bonding between CFRP and aluminum alloy in the future. Full article
(This article belongs to the Special Issue Properties and Applications of Surfaces/Components Engineered Using Thermal Spray, Welding, and Directed High Energy Beam Technologies)
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23 pages, 5091 KiB  
Article
Investigating the Water Jet Erosion Performance of HVOF-Sprayed WC-10Co Coatings on 35CrMo Steel Utilizing Design of Experiments
by Daniel C. Ribu, Rajamony Rajesh, Duraisamy Thirumalaikumarasamy, Chidambaram Seshadri Ramachandran, C. Ahamed Saleel, Abdul Aabid, Muneer Baig and Bahaa Saleh
Coatings 2022, 12(4), 482; https://doi.org/10.3390/coatings12040482 - 02 Apr 2022
Cited by 7 | Viewed by 2172
Abstract
To enhance the surface of a material with the desired qualities for diverse applications in service, a variety of thermal and thermo-chemical surface treatment processes are used. Due to the high-velocity impact inherent in the process, high-velocity oxy-fuel (HVOF) spray is now frequently [...] Read more.
To enhance the surface of a material with the desired qualities for diverse applications in service, a variety of thermal and thermo-chemical surface treatment processes are used. Due to the high-velocity impact inherent in the process, high-velocity oxy-fuel (HVOF) spray is now frequently employed in industrial applications for its ability to generate a high-quality coating with appropriate hardness and low oxide content. In this investigation, a high-velocity oxy-fuel (HVOF) thermal spraying process was utilized to coat WC-10Co powders on a 35CrMo steel substrate. A water jet erosion test was also used to examine the substrate and coated samples’ erosion behavior. The erosion rate was systematically investigated using water jet variables such as the angle of impingement, water jet velocity, standoff distance, and erodent discharge. For the development of multiple regression models, experiments were performed utilizing the central composite rotatable design and the response surface methodology. The angle of impingement had the most impact on the rate of coating erosion, leading to the water jet velocity, standoff distance, and erodent discharge. Full article
(This article belongs to the Special Issue Properties and Applications of Surfaces/Components Engineered Using Thermal Spray, Welding, and Directed High Energy Beam Technologies)
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15 pages, 14376 KiB  
Article
Stability Study of Dielectric Properties of Plasma-Sprayed BaTiO3
by Pavel Ctibor, Libor Straka, František Lukáč and Josef Sedláček
Coatings 2022, 12(3), 355; https://doi.org/10.3390/coatings12030355 - 07 Mar 2022
Viewed by 1631
Abstract
Barium titanate coatings were, for the first time, sprayed by a high feed-rate plasma torch with water stabilization of the plasma. Two power levels of the torch were applied for spraying to cover steel substrates. Various substrate preheating levels from 125 °C to [...] Read more.
Barium titanate coatings were, for the first time, sprayed by a high feed-rate plasma torch with water stabilization of the plasma. Two power levels of the torch were applied for spraying to cover steel substrates. Various substrate preheating levels from 125 °C to 377 °C were used to modify cooling conditions. Microstructure and phase composition including crystallinity quantification were observed. Dielectric measurements proved that the relative permittivity between 300 and 400 coatings is too temperature sensitive over 170 °C but fits the requirements of the EIA temperature coefficient between room temperature and 170 °C. Simultaneously, the loss tangent remains rather low, between 0.02 and 0.07, in a broad range of temperatures and frequencies. Annealing was performed in air to heal the oxygen deficiency, but only modified the microstructure insignificantly. The dielectric properties of as-sprayed and annealed samples were discussed, with the main finding that the temperature coefficient of permittivity was improved by annealing. This study contributes to the search for the suitability of plasma-sprayed BaTiO3 coatings for application in the electrical industry, namely by the optimization of conditions for high feed-rate spraying. Full article
(This article belongs to the Special Issue Properties and Applications of Surfaces/Components Engineered Using Thermal Spray, Welding, and Directed High Energy Beam Technologies)
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14 pages, 3726 KiB  
Article
Comparison of Aqueous and Gelled 3.5% NaCl Electrolytes for Assessing the Corrosion Resistance of Thermal Spray Stainless-Steel Coatings in Electrochemical Corrosion Tests
by Pia Kutschmann, Maximilian Grimm, Thomas Lindner, Kerstin Raffaela Ernst, Olga Schwabe, Christian Pluta and Thomas Lampke
Coatings 2022, 12(3), 344; https://doi.org/10.3390/coatings12030344 - 06 Mar 2022
Cited by 4 | Viewed by 1890
Abstract
Corrosion testing with gel electrolytes gained attention in the past decade due to the advantage of almost non-destructive and in situ electrochemical measurements of bulk materials. Regarding thermal spray coatings, gel electrolytes offered the opportunity to prevent the infiltration of the typical microstructural [...] Read more.
Corrosion testing with gel electrolytes gained attention in the past decade due to the advantage of almost non-destructive and in situ electrochemical measurements of bulk materials. Regarding thermal spray coatings, gel electrolytes offered the opportunity to prevent the infiltration of the typical microstructural features such as pores and microcracks. Using the example of stainless-steel AISI 316L coatings deposited by high velocity air fuel (HVAF) spraying on mild and stainless-steel substrates, the electrochemical corrosion behavior was analyzed in 3.5% NaCl electrolytes in an aqueous and gelled state. In this context, potentiodynamic polarization tests were carried out in a three-electrode corrosion cell, which was adapted for gel electrolyte testing. Gelling was realized with a technical gelatin. The characteristic corrosion values, such as open circuit potential, corrosion potential, and corrosion current density, revealed for the gelled state that the influence of the substrate material used could be eliminated and thus, the coatings itself could be characterized. In contrast, the coating specific microstructure and substrate material significantly affected the potentiodynamic polarization curve in the 3.5% NaCl aqueous electrolyte. Optical microscopy of the coating surfaces and cross-sections proved that the corrosion attack caused by aqueous electrolytes could be mimicked with the gel electrolyte. Full article
(This article belongs to the Special Issue Properties and Applications of Surfaces/Components Engineered Using Thermal Spray, Welding, and Directed High Energy Beam Technologies)
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20 pages, 40493 KiB  
Article
Optimisation of HVOF Spray Process Parameters to Achieve Minimum Porosity and Maximum Hardness in WC-10Ni-5Cr Coatings
by Pradeep Raj Rajendran, Thirumalaikumarasamy Duraisamy, Ramachandran Chidambaram Seshadri, Ashokkumar Mohankumar, Sathiyamoorthy Ranganathan, Guruprasad Balachandran, Kaliyamoorthy Murugan and Laxmi Renjith
Coatings 2022, 12(3), 339; https://doi.org/10.3390/coatings12030339 - 04 Mar 2022
Cited by 18 | Viewed by 2878
Abstract
High-velocity oxy-fuel (HVOF) spray coating plays a major role in many surface treatment methods, which tend to improve erosion and corrosion resistance properties. HVOF is well known for its dense and high-quality coating ability. This is due to the less in-flight exposure time, [...] Read more.
High-velocity oxy-fuel (HVOF) spray coating plays a major role in many surface treatment methods, which tend to improve erosion and corrosion resistance properties. HVOF is well known for its dense and high-quality coating ability. This is due to the less in-flight exposure time, which tends to have less oxide content because of its high-velocity properties. Among the number of process parameters, porosity and hardness are predominant factors while considering wear rate and corrosion behaviour analysis. The current study aims to optimise HVOF process parameters to obtain low levels of porosity and high hardness values in the WC-10Ni-5Cr coating sprayed on 35 Mo Cr steel. The flow rates of oxygen, LPG, coating powder feed rate and spray distance are selected in this study as these have a superior influence on the final condition of the coating. Statistical tools such as the design of experiments (DoE), analysis of variants and response surface methodology (RSM) were used to achieve the desired results. As per the result analysis, the oxygen flow rate has a higher effect on the porosity value and microhardness value of the coating. Full article
(This article belongs to the Special Issue Properties and Applications of Surfaces/Components Engineered Using Thermal Spray, Welding, and Directed High Energy Beam Technologies)
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7 pages, 4727 KiB  
Article
The Influence of Polymeric Sealing Treatment on the Wear Performance of PEO Coating Deposited on AZ31 Mg Alloy
by Qun Wang, Sisi Tu, Yuqin Rao and Ramachandran Chidambaram Seshadri
Coatings 2022, 12(2), 182; https://doi.org/10.3390/coatings12020182 - 30 Jan 2022
Cited by 2 | Viewed by 2249
Abstract
A plasma electrolytic oxidation (PEO) coating fabricated on AZ31 Mg alloy was sealed with polymeric sealant. The sealant penetrated into the PEO coating and filled the micropores and microcracks of the coating. The effect of the sealant treatment on the sliding wear behavior [...] Read more.
A plasma electrolytic oxidation (PEO) coating fabricated on AZ31 Mg alloy was sealed with polymeric sealant. The sealant penetrated into the PEO coating and filled the micropores and microcracks of the coating. The effect of the sealant treatment on the sliding wear behavior of the PEO coating was investigated by systematically varying the axial wear loads applied onto the unsealed and sealed PEO coatings. The results of the sliding wear tests revealed that the polymeric sealing treatment enhanced the wear resistance of the Mg-based PEO coating by reducing the wear rate and by improving the load-bearing capacity. Full article
(This article belongs to the Special Issue Properties and Applications of Surfaces/Components Engineered Using Thermal Spray, Welding, and Directed High Energy Beam Technologies)
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14 pages, 8986 KiB  
Article
Enhancing the Corrosion Resistance of Low Pressure Cold Sprayed Metal Matrix Composite Coatings on AZ31B Mg Alloy through Friction Stir Processing
by Ashokkumar Mohankumar, Thirumalaikumarasamy Duraisamy, Ramachandran Chidambaramseshadri, Thirumal Pattabi, Sathiyamoorthy Ranganathan, Murugan Kaliyamoorthy, Guruprasad Balachandran, Deepak Sampathkumar and Pradeep Raj Rajendran
Coatings 2022, 12(2), 135; https://doi.org/10.3390/coatings12020135 - 24 Jan 2022
Cited by 11 | Viewed by 2528
Abstract
To improve the corrosion resistance of Mg alloy, Al alloy/alumina metal matrix composite (MMC) coatings were formed by low pressure cold spraying (LPCS) technology followed by post friction stir processing. The phase structure, microstructure, and corrosion properties of the cold-sprayed metal matrix composite [...] Read more.
To improve the corrosion resistance of Mg alloy, Al alloy/alumina metal matrix composite (MMC) coatings were formed by low pressure cold spraying (LPCS) technology followed by post friction stir processing. The phase structure, microstructure, and corrosion properties of the cold-sprayed metal matrix composite coatings before and after friction stir processing were investigated. The effect of the friction stir process (FSP) on the corrosion characteristics of MMC coatings at 3.5 weight percent of NaCl solution was explored using a Tafel polarisation plot. Microstructural studies were examined to investigate the electrochemical behaviour of the cold spray (CS) and FSPed MMC coatings. The results demonstrated that an enhancement in corrosion protection of the MMC deposits occurred at the 1st and 2nd runs of FSP, with superior corrosion performance observed at the 2nd run of FSP. The enhanced surface state is the primary enhancement mechanism of the electrochemical properties of the FSPed MMC coatings. For the higher run of FSP (3rd run), the electrochemical performance of the specimens was lower owing to the amalgamate action of the enhanced surface state with the aggravated interface of interior deposits. Full article
(This article belongs to the Special Issue Properties and Applications of Surfaces/Components Engineered Using Thermal Spray, Welding, and Directed High Energy Beam Technologies)
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16 pages, 6923 KiB  
Article
The Study on Feasibility and Welding Characteristics of GMAW Surfacing Remanufacturing of H13 Steel Cutter Ring of TBM Hob
by Moyun Zhang, Shihai He, Boyan Jiang, Xuming Yao and Kui Zhang
Coatings 2021, 11(12), 1559; https://doi.org/10.3390/coatings11121559 - 18 Dec 2021
Cited by 9 | Viewed by 2329
Abstract
As H13 steel is a common material for cutters of Tunnel Boring Machine (TBM), the research on surfacing remanufacturing performance is of great value. In this paper, the phase composition of the surfacing layer of H13 steel after gas metal arc welding (GMAW) [...] Read more.
As H13 steel is a common material for cutters of Tunnel Boring Machine (TBM), the research on surfacing remanufacturing performance is of great value. In this paper, the phase composition of the surfacing layer of H13 steel after gas metal arc welding (GMAW) was analyzed by exploring the precipitation of hard phase in the molten pool, and the microstructure evolution of the surfacing layer was revealed. Then, we carried out simulation modeling analysis on H13 steel surfacing remanufacturing. Results show that: (1) the surfacing layer is combined with the base metal by physical metallurgy without obvious defects such as pores, inclusions and cracks in the surfacing layer; (2) the hardness of the surfacing layer is 60 HRC, which is about 1.5 times of that of the base metal; (3) the stress is mainly concentrated in the arc starting and ending points, followed by the external constraints on both sides of the surfacing layer; (4) the deformation of surfacing layer is slight, which does not affect the forming quality of base metal, while the deformation of base metal is relatively severe. This paper verifies the feasibility of H13 steel remanufacturing from experimental and simulation, providing theoretical basis for future engineering practice. Full article
(This article belongs to the Special Issue Properties and Applications of Surfaces/Components Engineered Using Thermal Spray, Welding, and Directed High Energy Beam Technologies)
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