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Engines and motive power systems
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Proceedings Papers
ITSC2024, Thermal Spray 2024: Proceedings from the International Thermal Spray Conference, 159-165, April 29–May 1, 2024,
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The method of simulating the wear performance under working conditions using a high-temperature ultra-high-speed wear testing machine was adopted to study the effect of feed rate variation on the wear behavior and scraping performance of the AlSi/hBN sealing coating and TC4 simulated blades. The macro and micro morphology of the coating and blades were analyzed by stereomicroscope and scanning electron microscope (SEM). The phase composition of the coating was analyzed by energy dispersive spectrometer (EDS) and X-ray diffraction. The results showed that, under the conditions of temperature of 450°C, line velocity of 300m/s, and feed depth of 500μm, the change in feed rate significantly affected the macro and micro morphology and wear mechanism of the AlSi/hBN sealing coating-TC4 simulated blades. At low feed rates, severe wear occurred, mainly manifested as grooving, adhesion transfer, and overheating mechanisms. At medium to high feed rates, good machinability was observed, mainly manifested as cutting and transfer of coating material to the blades.
Proceedings Papers
ITSC2024, Thermal Spray 2024: Proceedings from the International Thermal Spray Conference, 213-220, April 29–May 1, 2024,
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The H-class turbine, introduced nearly a decade ago, has reached a significant milestone with its 100th global sale. With 108 units sold and 91 in operation across four continents, accumulating over 3.2 million fired hours, the SGT5-8000H has established itself as a market leader, setting industry benchmarks for performance. Since its launch, the SGT5-8000H's output has increased from 375 MW to 450 MW, and combined cycle efficiency has surpassed 62%. To maintain optimal performance, the platform combustion system (PCS) of the SGT5-8000H has undergone refurbishment in Berlin since 2017. Beginning with a PCS from Samsun, Turkey, the process involves a detailed inspection, repair, recoating, and final assembly. Advanced technologies, such as blue light scanning, enhance efficiency and enable lifecycle assessments. Innovative repair methods, including 3D printed patch repairs using laser powder bed fusion (LPBF), reduce costs. Laser-based cutting and welding automation further minimizes heat input and distortion, ensuring the PCS's reliability and longevity. These technological advancements contribute to the SGT5-8000H's stable and dependable operation.
Proceedings Papers
ITSC2024, Thermal Spray 2024: Proceedings from the International Thermal Spray Conference, 319-324, April 29–May 1, 2024,
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Hexavalent chromium has been widely used in the coating industry and more specifically in gas turbine hot end component protection. UK REACH (registration, evaluation, authorization, and restriction of chemicals) have given an end date of September 2024 for the use of hexavalent chromium and as such, the industry must adapt to these regulations. Indestructible Paint LTD have developed a new aluminium diffused slurry coating, CFIPAL, that does not contain hexavalent chromium like its predecessor, IP1041. Both CFIPAL and IP1041 were deposited onto Nimonic 75 alloy and underwent metallurgical and chemical analysis which included scanning electron microscopy, energy dispersive spectroscopy, electron backscatter diffraction, hardness testing, contact angle testing, surface roughness testing and finally, salt spray corrosion testing. The results indicated that CFIPAL is a suitable alternative for hexavalent chromium-containing coatings, such as IP1041.
Proceedings Papers
ITSC2024, Thermal Spray 2024: Proceedings from the International Thermal Spray Conference, 704-711, April 29–May 1, 2024,
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Thermally sprayed abradable coatings are essential for improving the performance of gas turbine engines. They act as a protective barrier between the stationary casing and rotating blades. Though a lot of research has been done on abradable coatings, little attention has been paid to comprehending wear mechanisms in the abradable-blade tip interaction. The goal of this project is to create a cost-effective test rig that can evaluate different thermally sprayed abradable coatings and understand how they interact with titanium blade tips under application-relevant conditions. Blade tip velocity, incursion rates, incursion depths, reaction forces, and interfacial temperatures are some of the inputs and outputs that the testing rig can provide. Aiming to validate the rig, this study examined the wear behavior of aluminum, thermally sprayed polyester, and AlSi-40Polyester abradable coating. The reaction forces for aluminum and polyester were overall higher when compared to AlSi-40Polyester. However, thermally sprayed polyester showed the highest interfacial temperatures of all materials tested. The difference in the reaction forces and interfacial temperature correlates well with the different wear mechanisms and thermal conductivities. Overall, the equipment showed to be a promising pre-screening methodology to evaluate and develop novel thermal spray abradable coatings.
Proceedings Papers
ITSC 2022, Thermal Spray 2022: Proceedings from the International Thermal Spray Conference, 1-13, May 4–6, 2022,
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Environmental barrier coatings (EBCs) are required to protect SiC based composites in high temperature, steam containing combustion environments found in the latest generation of high efficiency gas turbine aeroengines. Ytterbium disilicate has shown promise as an environmental barrier coating, showing excellent phase stability at high temperature and a coefficient of thermal expansion close to that of SiC; however, its performance is dependent on the conditions under which the coating was deposited. In this work, a parametric study was undertaken to demonstrate how processing parameters using a widely used Praxair SG-100 atmospheric plasma spraying torch affect the phase composition, microstructure and mechanical properties of ytterbium disilicate environmental barrier coatings. Ytterbium disilicate coatings were deposited using 5 sets of spray parameters, varying arc current and secondary gas flow. The phases present in these coatings were quantified using X-ray diffraction with Rietveld refinement, and the level of porosity was measured. Using this data, the relationship between processing parameters and phase composition and microstructure was examined. Abradable coatings are used throughout gas turbine engines to increase efficiency in the compression and combustion phases of the turbine. Abradable coatings are soft enough to be worn away by turbine blade tips (without damaging the tip itself), allowing for tighter clearances to be used, limiting leakages and increasing efficiency. Using the optimum process parameter window determined in this work, a low density abradable Yb 2 Si 2 O 7 layer will be deposited in future research.
Proceedings Papers
ITSC 2022, Thermal Spray 2022: Proceedings from the International Thermal Spray Conference, 288-298, May 4–6, 2022,
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Hot section components of stationary gas turbines such as turbine blades are coated with thermal barrier coatings (TBCs) to increase the high thermal strain tolerance thereby the improvement of the performance for the gas turbines. TBCs represent high-performance ceramics and are mostly composed of yttria-stabilized zirconia (YSZ) in order to fulfil the function of thermal insulation. The microstructure of conventional TBCs should be porous to decrease heat conduction. Besides porous TBCs, the recently developed vertically segmented thermal barrier coatings (s-TBCs) feature outstanding thermal durability. In this work, process parameter development for atmospheric plasma spraying (APS) of s-TBCs is presented. Within the experiments, relevant process parameters such as powder feed rate, surface speed and pathway strategy have been optimized. The aim of this work is to achieve a combination of low internal residual stress and high adhesive tensile strength for s-TBCs. For the formation of vertical cracks, the heat input into the powder feedstock material and the substrate must be controlled precisely.
Proceedings Papers
ITSC 2022, Thermal Spray 2022: Proceedings from the International Thermal Spray Conference, 447-452, May 4–6, 2022,
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Repair methods are of great interest to the aeronautic industry, especially for turbines. Deposition techniques that can quickly and easily repair small localised areas of damage in Thermal Barrier Coatings (TBCs) on combustion chambers could be financially worthwhile. In a first approach, a Low-Power Plasma Reactor (LPPR) operating at low pressure (< 1000 Pa, 240 W) was tested to locally deposit effective Yttria partially Stabilised Zirconia (YSZ) as TBC; however, a vacuum chamber would be more difficult to implement on an industrial scale. For this reason, a new LPPR (< 1 kW) operating at atmospheric pressure with solution precursors was investigated. The precursors were injected in the plasma afterglow to be sprayed and deposited onto parts of combustion chambers. As the afterglow temperature was cooler than for most thermal spray processes, spray distance was less than 10 mm. As such, YSZ deposition could be performed locally in hard-to-reach areas. YSZ coating characteristics were studied by FTIR and SEM analyses. For example, YSZ coatings exhibited the expected stoichiometry, a precursor conversion of 98 mol%, good adherence, and a porosity evaluated at approximately 30 vol%. In addition, YSZ coating thickness could be greater than 200 μm.
Proceedings Papers
ITSC 2022, Thermal Spray 2022: Proceedings from the International Thermal Spray Conference, 1000-1005, May 4–6, 2022,
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Abradable seal coatings are widely employed in the gas turbine of aero-engine, which not only strength enough to resist the impact of external particles and airflow, but also excellent wear resistance. In the current study, we concentrate on APS sprayed Aluminum Bronze Polyester abradable coating that can be used in turbo engines both for seals and clearance control. A composite thermal spray powder, substantially in the form of clad particles each of which has coarse polyester powders and sub-particles of Cu-Al alloy powders, was prepared using mechanically clad process. Abradable seal coating was prepared by atmospheric plasma spraying. The microstructure, hardness, bonding strength, thermal shock resistance and corrosion resistance of coatings were researched. Properties of the coating were able to meet the application requirements. The coating microstructures and phase compositions were evaluated via SEM. The corrosion mechanisms of the coating were compared by analyzing the cross-sectional and top surface microstructures of the as-sprayed and eroded coatings.
Proceedings Papers
ITSC 2021, Thermal Spray 2021: Proceedings from the International Thermal Spray Conference, 307-314, May 24–28, 2021,
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As steam power plants continue to move towards higher operating temperatures in order to improve efficiency, materials exposed to the working fluid are subjected to accelerated degradations in the forms of surface oxidation and reduced mechanical properties. In this study, the oxidation behavior of two cobalt base alloys, CoCrMoSi (T14) and CoCrNiMoSi (T19), was evaluated in superheated steam (SHS, 0.1MPa) at 800 °C for up to 500 hours. After the exposure, both T14 and T19 alloys experienced weight gain caused by oxidation. Visual observation and SEM surface analysis revealed that T19 had greater extent of surface oxide spallation than that seen on T14. From the cross-sectional evaluation, however, a thin, adherent oxide layer was found to have formed on T19. T14 in fact had suffered from excessive internal oxidation and the surface oxide was uneven. Based on the results obtained so far, it is believed that the finer Laves phase combined with greater amount of Cr in alloy T19 have enabled the formation of a protective oxide layer and thus reduced the extent of internal oxidation. Due to the extensive oxidation ingress along the large Laves phase, it is concluded that T14 is not suitable for applications in SHS at 800 °C.
Proceedings Papers
Rodolpho F. Vaz, Anderson G.M. Pukasiewicz, Irene B.A.F. Siqueira, Gustavo B. Sucharski, André Chicoski ...
ITSC 2021, Thermal Spray 2021: Proceedings from the International Thermal Spray Conference, 431-439, May 24–28, 2021,
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FeMnCrSi alloys have been developed and studied over the past several years with an emphasis on their use as coatings on CA6NM stainless steel hydroturbine components. Much of the work conducted has focused on the optimization of cavitation resistance through chemical composition changes, the use of different thermal spraying (ASP, HVOF, HVAF) and welding (PTA) processes, and post-treatments such as shot-peening, cold working, and PTA remelting. The aim of this current work is to present a compilation of published articles that report on the research that has been done. Among the trends observed is that coating density and cavitation resistance improve with increasing particle velocity, particularly for HVOF-kerosene spraying. In regard to post-treatments, cold working was found to most effective, reducing cavitation mass loss (in PTA FeMnCrSi coatings) by a factor of nearly two.
Proceedings Papers
ITSC 2021, Thermal Spray 2021: Proceedings from the International Thermal Spray Conference, 695-699, May 24–28, 2021,
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Increasing operating temperature plays a critical role in improving the thermal efficiency of gas turbines. This paper assesses the capability of advanced thermal barrier coatings being developed for use in 1700 °C class gas turbines. Parts sprayed with these coatings were evaluated and found to have excellent durability and long-term reliability.
Proceedings Papers
ITSC 2019, Thermal Spray 2019: Proceedings from the International Thermal Spray Conference, 207-213, May 26–29, 2019,
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Thermal spray coatings are an effective means for improving the cavitation resistance of hydroturbine components, especially in on-site repair situations. In this study, WC-CoCr cermet coatings are deposited by HVOF spraying and their microstructure, hardness, and cavitation behavior are assessed. The coatings exhibit better cavitation resistance than stainless steel with an erosion mechanism that leaves wrinkles and craters that correspond to specific erosion stages.
Proceedings Papers
Anderson Gerlado Marenda Pukasiewicz, Gustavo Bavaresco Sucharski, Irene Bida de Araújo Fernandes Siqueira, Juliano de Andrade, Rodolpho Fernando Váz ...
ITSC 2019, Thermal Spray 2019: Proceedings from the International Thermal Spray Conference, 359-368, May 26–29, 2019,
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Hydraulic turbines, valves, and pumps operate in environments where they are exposed to cavitation phenomena and corrosion, which can result in mass loss, leading to reduced performance and failure. HVOF spraying has been used to repair eroded surfaces on such components and new alloys are being developed to reduce repair costs. This investigation assesses the cavitation resistance of FeMnCrSiNiB alloy coatings deposited by HVOF spraying. Corrosion rates and oxidation potentials are measured under different conditions and compared to stainless steel coatings normally used on water turbine runners.
Proceedings Papers
ITSC 2018, Thermal Spray 2018: Proceedings from the International Thermal Spray Conference, 84-91, May 7–10, 2018,
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Fabrication of Thermal Barrier Coatings (TBCs) with higher lifetime and relatively cheaper processes is of particular interest for gas turbine applications. Suspension Plasma Spray (SPS) is capable of producing coatings with porous columnar structure, and it is also a much cheaper process compared to the conventionally used Electron Beam Physical Vapor Deposition (EB-PVD). Although TBCs fabricated using SPS have lower thermal conductivity as compared to other commonly used processes, they are still not commercialized due to their poor lifetime expectancy. Lifetime of TBCs is highly influenced by the top coat microstructure. The objective of this work was to study the TBCs produced using axial SPS with different process parameters. The bond coat was deposited using High Velocity Air Fuel (HVAF) spray. Influence of the microstructure on lifetime of the coatings was of particular interest and it was determined by thermal cyclic fatigue testing. Thermal conductivity of the coatings was determined by laser flash analysis. The results show that axial SPS could be a promising method of producing TBCs for high temperature gas turbine applications.
Proceedings Papers
ITSC 2018, Thermal Spray 2018: Proceedings from the International Thermal Spray Conference, 355-360, May 7–10, 2018,
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Abradable coatings are typically applied on the compressor section of gas turbines to reduce air leakage and increase compressor performance. In pursuit of engine efficiency, the service temperatures of the components are higher than before. The use of nickel-graphite coating in compressor applications in higher temperature environments diminishes the abradable property of the coating. In the current study, a series of abradable coatings were prepared with combustion and plasma spray methods and tested at gas turbine conditions. Coating microstructure, hardness, abradability, and erosion resistance was investigated and compared against conventional nickel-graphite coating. In addition, coatings were aged to mimic the aging cycle in industrial gas turbines and compared to as-sprayed coating properties.
Proceedings Papers
ITSC 2018, Thermal Spray 2018: Proceedings from the International Thermal Spray Conference, 557-560, May 7–10, 2018,
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MCrAlY(M=Ni, Co, or Ni-Co)coatings with good high temperature oxidation resistance have attracted great interest. They are widely used in gas turbines as protecting layers, such as thermal barrier coatings and seal coatings. Among many methods developed for preparing MCrAlY coatings, electroplating has drawn great attention due to its perfect bond strength, precise controllability, good coating ability for complex shape and so on. In this paper, the MCrAlY coatings have been prepared by a composite plating way. During this process, the CrAlY particles are wrapped with Ni clad layer. The thickness of the composite coatings is controlled at 150- 200 μm. The plating tests results indicate that the density of the clad layers mainly depend on the electroplating time. After that, these coatings are heat treated under the vacuum condition to make elements diffuse, forming homogeneous M(Ni)CrAlY component. The high-temperature oxidation resistance tests of the prepared coatings show good antioxidant ability at 1000 °C under air condition.
Proceedings Papers
ITSC 2018, Thermal Spray 2018: Proceedings from the International Thermal Spray Conference, 727-731, May 7–10, 2018,
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The economic use of offshore wind turbines requires a reliable and long-lasting corrosion protection. Sophisticated multilayer coating systems consisting of a thermal spray coating – mainly ZnAl15, a sealer and several layers of organic coating – have been proven to provide such protection. Damages to these duplex-coatings can, however, not be prevented necessitating on-site repair. In case of severe damages, the remaining coating close to the damage is often removed and subsequently, the duplex coating is rebuilt from scratch. In the present study, two integrated coating removal and substrate pre-treatment methods are investigated. For this purpose, duplex-systems were produced, artificially damaged by milling and afterwards treated by either grit blasting or with a rotating steel-wire brush, i.e. a Monti Bristle Blaster. Afterwards, the duplex coating was re-applied in the considered area. To evaluate the influence of the pre-treatment method on the coatings’ corrosion protection potential, a 38 week-long salt spray test was used. The test revealed a pronounced influence of the pre-treatment method on the corrosion protection potential. In case of grit blasting, no substrate corrosion could be detected. The use of a Bristle Blaster, however, resulted in coating failure and some spots of red rust.
Proceedings Papers
ITSC 2017, Thermal Spray 2017: Proceedings from the International Thermal Spray Conference, 23-30, June 7–9, 2017,
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Suspension plasma spraying (SPS) process has attracted extensive effort and interest as a method to produce fine-structured and functional coatings. In particular, thermal barrier coating (TBC) applied by SPS process has gained increasing interest due to its potential for producing coatings that provide superior thermal protection of gas turbine hot-section components as compared to conventional APS-TBC and even EB-PVD TBC. The unique columnar architecture and nano- and submicron sized grains in a SPS-TBC coatings demonstrate some advantages in thermal shock durability, low thermal conductivity, and high-temperature sintering resistance. This work addresses some practical aspects of using the SPS process for TBC applications before it becomes a reliable industry method. The spray capability and applicability of SPS to achieve uniform thickness and microstructure on curved substrates was evaluated in designed spray trials to simulate industrial parts with complex configurations. The performance of SPS-TBCs in erosion, free falling ballistic impact, and indentation loading tests was evaluated to simulate SPS-TBC performance in turbine service conditions. The behaviors of SPS-TBCs in those tests were correlated to key test factors including grit incident angles, impact object sizes, indentation head shapes, and coating surface curvatures. Finally, a turbine blade was coated and sectioned to verify SPS sprayability in multiple critical sections. The SPS trials and test results demonstrate that SPS is promising for innovative TBCs, but some challenges need to be addressed before it becomes an economical and reliable industrial process, especially for gas turbine components.
Proceedings Papers
ITSC 2017, Thermal Spray 2017: Proceedings from the International Thermal Spray Conference, 104-107, June 7–9, 2017,
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The degradation mechanisms of machine parts are well-known facts, usually resulting in replacement of components. However, in some cases, for instance, parts for large ship engines, repair will often seem more attractive. Time-wise, the vessel’s down-time will be reduced and the investment will be lower. This paper describes repair work performed on valve stems from a 52-year-old ship engine. Due to this long time in operation, the stems were damaged by wear and were no longer functional. The requirements for the stems were scarcely documented stating only a few specific requirements; therefore a short study of the possibilities concerning rebuild material and application method was initiated. This paper illuminates the manufacturing process used; twin wire arc spraying with Monel as the rebuild material. Monel is chosen to meet the requirements for hardness and the subsequent high precision machining. In addition, the mechanical and metallurgical properties of the rebuild coating are examined in regard to adhesion, microstructure and hardness to interpret and support the functionality.
Proceedings Papers
ITSC 2017, Thermal Spray 2017: Proceedings from the International Thermal Spray Conference, 302-307, June 7–9, 2017,
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Cyclic oxidation failure of Atmospheric Plasma Sprayed Thermal Barrier Coatings systems (APS TBCs), commonly used to insulate hot sections in gas turbines, usually results from the spallation of the ceramic top coat. Consequently, in order to predict such spalling phenomena, understanding the mechanisms for cracks initiation and propagation in thermal barrier coatings is of utmost concern for engine-makers. Failure of the TBC is strongly related to the thermal and mechanical properties of each component of the multi-materials system (substrate, bond coat and ceramic) but also to the response of the TBC as a whole. The purpose of the work is to assess the mechanical behaviour of thick TBC using experimental approach for TBC standard lamellar, porous and microcracked microstructure (classically obtained through APS coatings). The experimental characterisation of the mechanical behaviour of the ceramic top coat of the TBC is addressed on specifically designed and prepared free-standing specimens using three points bending (3PB) tests and Small Punch Testing (SPT). The tests are performed on free-standing top coats made of YSZ in the as deposited states and for specimens that undergone isothermal aging at 1100°C for various durations (1h, 10h and 100h). The results of test performed at room temperature using both mechanical testing techniques are compared. This allows to show the evolution of mechanical properties after thermal aging. Tests performed at 850°C in the SPT ring show that the evolution of properties resulting from this aging may be different at room temperature as compare to 850°C.
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