{"title":"Multiple Electrodes and Cascaded Nozzles: A Review of the Evolution of Modern Plasma Spray Torches","authors":"Georg Mauer","doi":"10.1007/s11666-024-01909-x","DOIUrl":"10.1007/s11666-024-01909-x","url":null,"abstract":"<div><p>Conventional one-cathode/anode plasma spray guns are susceptible to aging. One reason is the large power density, especially at the arc roots on the cathode tip and the anode wall. Anode wear results in a thinner boundary layer and a reduced arc root motion, which increases the local thermal load. This also results in a voltage drop, and thus a reduction in power level when the power source is operated in a constant current mode. In addition to electrode wear, the instantaneous arc morphology and the time-dependent voltage waveform are strongly correlated to each other, especially when hydrogen or nitrogen is used as secondary plasma gas. Such arc dynamics are a major phenomenon that broadens the distribution of particle in-flight characteristics. The inevitable wear of electrodes and the inherent power fluctuations were the starting point for the development of new concepts for modern plasma spray guns. Multi-electrode plasma torches were developed to improve operational stability and lifetime. They became popular due to their good stability and high-power plasma jet, even when operated with inert gases only. In this context, cascaded torch nozzles were introduced, which effectively limit the axial movements of the anodic arc attachment. Such a design includes a stack of neutrodes in front of the anode, which are electrically insulated from each other. Since the arc is more stable, the power demand is virtually constant and the treatment of the feedstock particles is more uniform than with the conventional non-cascaded torches. In this review, the mechanisms leading to electrode wear and arc fluctuations in single-cathode/anode plasma guns are explained. Some concepts of multi-electrode torches and cascaded torch nozzles are presented. Examples of experimental results obtained by diagnostic methods are also given.</p></div>","PeriodicalId":679,"journal":{"name":"Journal of Thermal Spray Technology","volume":"34 2-3","pages":"484 - 494"},"PeriodicalIF":3.2,"publicationDate":"2024-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11666-024-01909-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143688388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Plasma Spraying of Ceramic Coating with All Interfaces Bonded Chemically through a Ceramic Bond Coat Thermally Grown on Metal Substrate","authors":"Peng-Yan Shi, Ya-Long Zhang, Xiao-Tao Luo, Kang-Wei Xu, Shu-Feng Xie, Ling-Jie Chen, Jiu-Jing Song, Rou Chen, Chang-Jiu Li","doi":"10.1007/s11666-024-01907-z","DOIUrl":"10.1007/s11666-024-01907-z","url":null,"abstract":"<div><p>Plasma-sprayed ceramic coatings are widely used for corrosion protection of metallic parts in industries. However, conventional ceramic coatings bond to metal substrates mainly through mechanical interlocking, with a tensile adhesion lower than 40 MPa, which limits their high-load applications. In this study, a new strategy to enhance the adhesion of coatings to a level over 100 MPa is proposed through introducing a ceramic bond coat to create chemical bonding throughout all the interfaces within the coating system. The experimental approval is made using titanium (Ti) as a typical substrate and Al<sub>2</sub>O<sub>3</sub>-13TiO<sub>2</sub> (AT13) as a typical coating material. The ceramic bond coat on Ti substrate was introduced by thermal growing under different oxidation conditions. The AT13 coating was deposited at 300 °C which was determined following the critical bonding temperature theory. It is found that the chemical bonding for all interfaces between ceramic layers was achieved by dynamic wetting of spreading molten splats ensured by the critical bonding temperature concept. The tensile test was modified by reducing the effective contact area of AT13 ceramic coatings to the substrate, and the adhesion of the ceramic coating prepared by the new method ranged from 105 to 121 MPa. This study provides a new technological approach for the application of plasma-sprayed ceramic coatings in high-load environments.</p></div>","PeriodicalId":679,"journal":{"name":"Journal of Thermal Spray Technology","volume":"34 2-3","pages":"908 - 919"},"PeriodicalIF":3.2,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143688412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Anis Chergui, Cédric Lebot, Vincent Rat, Gilles Mariaux, Alain Denoirjean, Olivier Messé, Benoît Changeux
{"title":"Physical Mechanisms in Plasma Spray Processing of Suspensions","authors":"Anis Chergui, Cédric Lebot, Vincent Rat, Gilles Mariaux, Alain Denoirjean, Olivier Messé, Benoît Changeux","doi":"10.1007/s11666-024-01905-1","DOIUrl":"10.1007/s11666-024-01905-1","url":null,"abstract":"<div><p>Suspension plasma spraying (SPS) is increasingly studied to produce finely structured coatings with columnar microstructures promising for thermal barrier coatings in aerospace application, especially. However, this process involves many parameters and complex phenomena with large spans of timescales and space scales, such as droplet breakup, liquid droplet evaporation and various physical phenomena occurring within the suspension droplet, making it difficult to master. The aim of this work is to supply a prior analysis to select the dominant physical phenomena and their sequence according to droplet properties and plasma conditions. Thus, this study provides a detailed analysis of these mechanisms, their significance and characteristic timescales, as well as the effects of plasma flow and droplet suspension properties on droplet/submicronic particle behavior. Additionally, the main governing forces acting between the different continuous and discrete phases (plasma, liquid, submicronic particles) are investigated. The results show that droplet breakup occurs much faster than other mechanisms, while the diffusion of submicron particles within droplets, mainly controlled by convection, is the longest. Furthermore, the importance of considering the lift force on droplet transport within the plasma stream is highlighted, particularly in the high-gradient region of the plasma jet.</p></div>","PeriodicalId":679,"journal":{"name":"Journal of Thermal Spray Technology","volume":"34 2-3","pages":"735 - 752"},"PeriodicalIF":3.2,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143688404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Thermomechanical Deformation Response in Cold Sprayed SiCp/Al Composites: Strengthening, Microstructure Characterization and Thermomechanical Properties","authors":"L. Gyansah, Tianying Xiong, Raffaella Sesana","doi":"10.1007/s11666-024-01910-4","DOIUrl":"10.1007/s11666-024-01910-4","url":null,"abstract":"<div><p>SiC<sub>p</sub>/pure Al composites with different SiC<sub>p</sub> fractions (20, 30 and 40 wt.%) were cold sprayed followed by hot axial-compression tests at deformation temperatures of 473 K (200 °C) to 673 K (400 °C), leading to failure of specimens through routine crack propagation in their multiphase. The plastic deformation behavior of the coating with respect to the SiC<sub>p</sub> contents and the deformation temperatures were studied at strain rate 1 s<sup>−1</sup>. As-sprayed and post-failure specimens were analyzed by x-ray computed tomography (XCT), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Quasi-static thermomechanical testing results revealed that compressive strength (UCS = 228 MPa) was the highest in the deposits that were compressed at 473 K compared to those of the as-sprayed, while the as-sprayed exhibited a compressive strength of 182.8 MPa related to the increment in SiC<sub>p</sub> fractions. Strength-plasticity synergy was promoted by dynamic recrystallization (DRX) through strengthening and refinement of the grains. The DRX degree depends relevantly on grain refinement, higher deformation temperature and the pinning effects of the interfaces promoted by the ultrafine grain structures (UFG). Reconstructed XCT data revealed different crack propagation mechanisms. A single-plane shear crack with multi-laminates fracture morphology yields relatively through the as-sprayed and as-deformed at 473 K deposits, while a multiphase plane shear cracks preeminently existed in high temperature deformed deposits resulting in multiphase-interface delaminations. Three pertinent strengthening mechanisms, videlicet, SiC<sub>p</sub> dispersed strengthening, refined grain strengthening and dislocation strengthening existed in the gradient microstructure, and their detailed contributions to the thermomechanical properties were discussed.</p></div>","PeriodicalId":679,"journal":{"name":"Journal of Thermal Spray Technology","volume":"34 1","pages":"203 - 218"},"PeriodicalIF":3.2,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Novel FeNiCrMoCBPNb High-Entropy Amorphous Coatings Prepared by Atmospheric Plasma Spraying with Excellent Corrosion and Wear Properties","authors":"Zhijun Guo, Yangzi Ye, Zhenjie Zhou, Qianqian Wang, Baosen Zhang, Baolong Shen","doi":"10.1007/s11666-024-01901-5","DOIUrl":"10.1007/s11666-024-01901-5","url":null,"abstract":"<div><p>Designing and fabricating Fe-based amorphous coatings with excellent wear and corrosion resistance as surface protection materials are essential to improve the service life of marine equipment. In this work, by adding 1 at.% Nb, a novel Fe<sub>34</sub>Ni<sub>20</sub>Cr<sub>20</sub>Mo<sub>5</sub>B<sub>4</sub>C<sub>4</sub>P<sub>12</sub>Nb<sub>1</sub> high-entropy amorphous alloy with enhanced glass-forming ability and excellent corrosion resistance was designed. The Fe<sub>34</sub>Ni<sub>20</sub>Cr<sub>20</sub>Mo<sub>5</sub>B<sub>4</sub>C<sub>4</sub>P<sub>12</sub>Nb<sub>1</sub> composition was adopted to prepare gas-atomized powders, which were then used as feedstock to prepare coatings using atmospheric plasma spraying (APS) technology with different input power. Higher spraying power was found to lead to denser coating, but more formation of oxides and lower amorphous content. The coating-35 kW input power exhibited the best corrosion resistance in 3.5 wt.% NaCl solution and high hardness of 519 ± 21 HV. The dry sliding wear rate of the coating-35 kW at 20 N and 20 mm/s was 8.3 × 10<sup>−7</sup> mm<sup>3</sup>/(N m), and the friction coefficient of the coating was 0.17 and kept relatively steady throughout the sliding test. This work guided designing Fe-based high-entropy amorphous coatings from both the composition aspect and the coating preparation technology.</p></div>","PeriodicalId":679,"journal":{"name":"Journal of Thermal Spray Technology","volume":"34 1","pages":"394 - 408"},"PeriodicalIF":3.2,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hao-Zheng Wang, Xin Zhang, Cao Cheng-ming, Lu Ren, Jiqiang Li
{"title":"Research on the Influence of Laser Power on the Microstructure and Performance of Fe-Based Coating","authors":"Hao-Zheng Wang, Xin Zhang, Cao Cheng-ming, Lu Ren, Jiqiang Li","doi":"10.1007/s11666-024-01904-2","DOIUrl":"10.1007/s11666-024-01904-2","url":null,"abstract":"<div><p>For the poor working environment, there would easily be sprocket tooth nest corrosion wear failure of mining sprocket, based on coaxial powder feeding method, this study prepares Fe-based alloy cladding on the surface of 42CrMo, which further improves the performance of the substrate. The effects of laser power on the dilution rate, microstructure, hardness and corrosion resistance of Fe-based alloy coating and the effect of heat treatment on the tensile properties of the cladding layer were studied. The results show that, with the increase in laser power, the grain size of the cladding layer becomes larger. When the laser power is greater than 1900 W, the cladding layer generates Fe<sub>2</sub>B and Cr<sub>23</sub>C<sub>6</sub>; the average hardness of the coating with laser power of 1600 W is the highest, which is 586.86 HV. Electrochemical experiments show that the 1800 W coating has excellent corrosion resistance, high corrosion potential (− 0.42 V) and minimum corrosion current density (2.65 × 10<sup>−6</sup>A·cm<sup>−2</sup>). EDS results show that no obvious corrosion area is found on the surface of the 1800 W cladding layer. This excellent performance is attributed to the formation of a dense Cr<sub>2</sub>O<sub>3</sub> passivation film on the surface of the cladding layer. The tensile test shows that the coating heat treated at 700 °C has the best tensile properties.</p></div>","PeriodicalId":679,"journal":{"name":"Journal of Thermal Spray Technology","volume":"34 1","pages":"316 - 336"},"PeriodicalIF":3.2,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Martin Zawischa, Stefan Makowski, Filofteia-Laura Toma
{"title":"Fast and Nondestructive Mechanical Characterization of Thermally Sprayed and Laser Cladded Coatings: Automated Surface Acoustic Wave Spectroscopy as a New Tool for Quality Control and Research","authors":"Martin Zawischa, Stefan Makowski, Filofteia-Laura Toma","doi":"10.1007/s11666-024-01899-w","DOIUrl":"10.1007/s11666-024-01899-w","url":null,"abstract":"<div><p>Laser-induced surface acoustic wave spectroscopy (LISAWS) allows quick and nondestructive evaluation of the elastic properties such as the Young’s modulus of coatings, surfaces and surface-near bulk materials. Furthermore, the mechanical weakening due to cracks and pores can be evaluated, as they influence the propagation of surface waves as well. This makes the method a fast, accurate and versatile tool for surface characterization, and it is increasingly used in research and development, and quality control. The short measurement time of the LISAWS method allows the time-efficient distribution of the effective Young's modulus over the coated surface to be determined. For this purpose, an industrial LAwave measurement system was automated to allow for processing of a larger number of samples and fast mappings. The investigated coating materials were thermally sprayed Al<sub>2</sub>O<sub>3</sub> insulation coatings and WC-reinforced 316L steel coatings on brake disks produced by laser cladding, respectively. For the Al<sub>2</sub>O<sub>3</sub> coatings, the correlation between the Young's modulus and its areal distribution is shown for different process parameters, such as spray gun movement direction or spray distance, and compared with results from pull-off tests. For the WC/316L-coated brake disks, the distribution of the wave velocity over the coated surfaces or the two coated sides of different disks with varying coating qualities is used to assess the coating quality and homogeneity.</p></div>","PeriodicalId":679,"journal":{"name":"Journal of Thermal Spray Technology","volume":"34 2-3","pages":"928 - 938"},"PeriodicalIF":3.2,"publicationDate":"2024-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11666-024-01899-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143688508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Geoffrey Darut, Timothé Ferrasse, Sophie Costil, Bernard Bouteiller, Marie-Camille Auscher
{"title":"Improved Adhesion of Plasma-Sprayed Zirconia Coatings on Textured Alumina Substrates","authors":"Geoffrey Darut, Timothé Ferrasse, Sophie Costil, Bernard Bouteiller, Marie-Camille Auscher","doi":"10.1007/s11666-024-01900-6","DOIUrl":"10.1007/s11666-024-01900-6","url":null,"abstract":"<div><p>Coating adhesion by thermal spraying method requires sufficient surface roughness of the substrate. The scale of the roughness must be adapted to the spread particle thickness size to optimize their mechanical attachment after spreading and cooling, particularly in the case of plasma spraying. Grit blasting is the most common process used to create the surface asperities required for coating bonding. However, to further increase adhesion, the use of laser texturing for metallic substrates is beneficial and is already well documented in literature. In the case of ceramic substrates such as alumina, grit blasting with corundum particles is no longer effective in creating a roughness of a few micrometers. Laser texturing therefore appears to be a potential candidate for generating adhesion in coatings. In this work, adhesion mechanisms of YSZ coatings produced by atmospheric plasma spraying (APS) on a textured alumina bulk substrate were investigated. The influence of substrate surface texturing by two different lasers (pulsed and continuous) on YSZ monolayer was studied. The lasers create an adapted surface profile to generate adhesion of YSZ coatings. For the pulsed laser, the depth of the holes must reach 100 µm, while for the continuous laser, the arithmetic mean surface roughness (Sa) value must exceed 25 µm. YSZ monolayer reaches a maximum adhesion of 4.8 MPa. Al<sub>2</sub>O<sub>3</sub> and Y<sub>2</sub>O<sub>3</sub> materials were selected as potential bond coats to increase YSZ topcoat adhesion on textured surfaces. The use of a bond coat with the same surface profile can improve adhesion, particularly with yttria, to reach a maximum value of 13.2 MPa. Surface texturing combined with the use of a bond coat is an appropriate approach for creating adhesion of a ceramic coating to a ceramic substrate.</p></div>","PeriodicalId":679,"journal":{"name":"Journal of Thermal Spray Technology","volume":"34 2-3","pages":"703 - 713"},"PeriodicalIF":3.2,"publicationDate":"2024-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143688510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Riddhi Joshi, Benjamin Boesl, Arvind Agarwal, Tony Thomas
{"title":"Desktop Manufacturing of Plasma-Sprayed Coating and Computational Estimation of its Mechanical Properties","authors":"Riddhi Joshi, Benjamin Boesl, Arvind Agarwal, Tony Thomas","doi":"10.1007/s11666-024-01851-y","DOIUrl":"10.1007/s11666-024-01851-y","url":null,"abstract":"<div><p>Traditional optimization of plasma-sprayed coatings involves resource-intensive experimental iterations of spraying parameters. This study presents a novel computational protocol for designing and manufacturing ceramic (e.g., Al<sub>2</sub>O<sub>3</sub>) coatings, reducing the need for extensive experiments. A computational fluid dynamics approach is adopted to simulate the morphology of Al<sub>2</sub>O<sub>3</sub> powder feedstock splats. These simulated splats are then stochastically arranged to construct three-dimensional (3D) representations of plasma-sprayed Al<sub>2</sub>O<sub>3</sub> coatings. The effective elastic modulus of the coating is computed using finite element analysis of the simulated microstructure. The introduced \"Desktop Manufacturing Protocol\" showcases a significant reduction in the requisite plasma spraying experiments, offering an optimized coating with desired microstructure and mechanical properties. This integrated computational approach not only streamlines the coating development process but also provides insights into the intricate relationships between spraying parameters, microstructure, and overall coating performance.</p></div>","PeriodicalId":679,"journal":{"name":"Journal of Thermal Spray Technology","volume":"33 8","pages":"2686 - 2697"},"PeriodicalIF":3.2,"publicationDate":"2024-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142844854","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Numerical and Experimental Studies on the In-Situ Measurement of Thermal Conductivity of the Thermal Barrier Coating","authors":"Ningning Liu, Ruifeng Dou, Zhi Wen, Xunliang Liu","doi":"10.1007/s11666-024-01895-0","DOIUrl":"10.1007/s11666-024-01895-0","url":null,"abstract":"<div><p>The thermal conductivity of thermal barrier coating (TBC) materials can be measured using transient and steady-state methods. It is crucial to evaluate the high-temperature thermal insulation performance of TBC materials. Although several steady-state methods exist for obtaining in situ TBC thermal conductivity at high temperatures, they are limited by heating methods and heat flux measurement instruments. In this study, a transient-state method is proposed, which does not have these limitations. Numerical simulations indicate that this method accurately predicts the temperature-dependent thermal conductivity of TBC materials in situ. The experimental results align well with existing literature. This method has potential applications for monitoring TBC failures, such as sintering, cracking, and peeling.</p></div>","PeriodicalId":679,"journal":{"name":"Journal of Thermal Spray Technology","volume":"34 1","pages":"460 - 476"},"PeriodicalIF":3.2,"publicationDate":"2024-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455536","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}