bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal Barrier Coatings on Surfaces with Micro-Machined Roughness Profiles
Authors: Seiler P. , Bäker M. , Rösler J. , Schweda M. , Beck T. 
Published: November 2022

Abstract
Thermal barrier coating systems are used to enhance the temperature resistance of hot section components in gas turbines. The coatings protect the underlying nickel based components and consist of the bond coat (BC) the thermal barrier coating (TBC) and a thermally grown oxide (TGO) between the BC and TBC. The coating systems fail in service at or near the TBC/TGO interface. To study the failure mechanisms a simplified coating system is introduced which consists of a MCrAlY bond-coat material as the substrate, a TGO, and a yttria-stabilised zirconia TBC as a topcoat. The TBC is applied by atmospheric plasma spraying on top of specimens with defined roughness profiles, manufactured by a micromachining process. The main advantage of micro-machining is a defined interfacial roughness between the TBC and the BC in contrast to sandblasted specimens. Furthermore, a FEM simulation of the coating system was developed which approximates the interface by sinusoidal functions. This simplified model system and additional FEM calculations show the influence of varying the interfacial roughness between the BC and the TBC.
Effect of Hardness in Blasted Substrate Surface on Adhesive Strength of Sprayed Coatings
Authors: Maruyama T. , Kishita T. , Kobayashi T. 
Published: November 2022

Abstract
The effect of the hardness in the substrate surface blasted by a grit blasting process on the adhesive strength of Zn-Al sprayed coatings is investigated to find the adhesive strength is improved by work hardening of the substrate surface. The adhesive strength between a substrate of a carbon steel and sprayed coatings of Zn-Al alloy sprayed by a wire flame spraying process is measured. The substrate is roughened by the grit blasting process with white alumina girt in various blasting angles and blasting time. The hardness is measured in around 20 micro-meter depth from the substrate surface. The adhesive strength increases with increasing the hardness even if the surface roughness is almost same. There is the definite correlation between the adhesive strength and the hardness rather than the surface roughness.
Net Energy Return (EROEI) of Thermal Barrier Coatings in Turbine Engines
Authors: Bardi U. , Borri C. , Giolli C. , Giorgetti A. , Meneghetti S. , Nocivelli J. , Scrivani A. 
Published: November 2022

Abstract
Thermal barrier coatings (TBC) are normally based on yttria partially stabilised zirconia (YPSZ) coatings and are commonly used coatings in the high temperature, combustion region of gas turbines. TBC permit to increase the temperature of combustion, increasing the thermodynamic efficiency of the engine. Therefore, an engine equipped with TBC can produce a larger amount of energy over its lifetime. This increase in produced energy can be compared with the energy needed for the manufacturing and installation of TBC. The comparison can be performed in terms of the “energy return” (or “energy returned for energy invested”, EROI or EROEI). The qualitative analysis performed in the present study indicates that this return is large in comparison to that of other energy producing systems.
Impact of Particle Size Distribution on the TBC Coating Deposition and Performance
Authors: Li L. , Belov V. 
Published: November 2022

Abstract
Thermal barrier coatings (TBCs) functioning in the aviation and power generation industries have heavily relied on plasma sprayed yttria stabilized zirconia (YSZ) on MCrAlY bond coated engine components. Among those factors which may impact the repeatability and reliability of a TBC coating, powder feedstock is one of the most important while being the challenging to control constituents as it is difficult to keep the powder chemistry, morphology and size distribution exact the same from lot to lot, year after year. In this study the authors systematically vary the size distribution of one type of commercial YSZ powder to explore the effect of the size distribution on the TBC deposition and the coating performance. Deposition rate and efficiency are quantitatively compared for those experimental powders. The coating microstructures and performances for different sizing are also evaluated analytically. Understanding the impact of the powder variation on the coating deposition and performance is essential to determine the quality control standards.
Phase Stability and Thermal Conductivity of Plasma Sprayed Scandia, Yttria-Stabilized Zirconia TBCs
Authors: Li Q. , Gong S. , Liu H. , Yang W. , Li S. 
Published: November 2022

Abstract
Zirconia stabilized with a combination of scandia and yttria (ScYSZ) powder for plasma spraying was synthesized by chemical coprecipitation process in the experiment, and the ScYSZ powder contains 7.0mol% scandia and 1.5mol% yttria. The microstructure, phase stability and thermal conductivity of plasma sprayed ScYSZ thermal barrier coatings (TBCs) were investigated. The results revealed that the ScYSZ TBCs had excellent stability to retain single metastable tetragonal t′phase even after high temperature (1500 °C) exposure for 300 hours and did not undergo a tetragonal-to-monoclinic phase transition upon cooling. Furthermore, the ScYSZ TBCs had lower thermal conductivity than 3.5-4.5mol% yttria-stabilized zirconia TBCs currently used in gas turbine engine industry. ScYSZ TBCs could be developed as a novel TBCs for advanced gas turbine engines.
Plasma Sprayed Zirconium Thermal Diffusion Behavior
Authors: Hollis K. J. 
Published: November 2022

Abstract
Zirconium (Zr) metal is of interest for chemical corrosion protection and nuclear reactor core applications. Inert chamber plasma spraying has been used to produce thin Zr coatings on stainless steel (SS) substrates. The coatings were deposited while using transferred arc (TA) cleaning/heating at 5 different current levels. In order to better understand thermal diffusion governed processes, the coating porosity, grain size and interdiffusion with the substrate were measured as a function of TA current. Low porosity (3.5% to &lt; 0.5%), recrystallization with fine equiaxed grain size (3-8 µm diameter) and varying elemental diffusion distance (0-50 µm) from the coating substrate interface were observed. In addition, the coatings were low in oxygen content compared to the wrought SS substrates. The Zr coatings sprayed under these conditions look promising for highly demanding applications.
Deposition of Surface-Melted YSZ Particles by Flame Spraying
Authors: Li C.-J. , Wang X.-M. , Li C.-X. , Yang G.-J. 
Published: November 2022

Abstract
It is usually difficult to deposit effectively spray particles with a much limited melting in thermal spraying. In the present study, flame spraying was employed to produce yttria-stabilized zirconia (YSZ) particles at a limited melting. The melting degree of YSZ particles was controlled by flame combustion intensity and flying distance of spray particles within gas flame. The velocity of spray particles was quantitatively measured. The effects of spray distance and acetylene flow rate on the particle velocity, and deposition behavior were examined. The surface morphology of deposited particles was characterized by scanning electron microscopy. The bonding between deposited YSZ particles and YSZ substrate was examined from cross section. The spray particles in different melting states were obtained by changing flame spray parameters. The deposition experiment revealed that the YSZ particles at different melting states from only surface layer melted state, semi-melted state to substantially melted state can be successfully deposited on YSZ substrate by controlling substrate temperature. As a result, YSZ surfaces with different morphologies of particles from a near spherical shape, hat-on-frustum shape and hat-shape with different neck sizes, to a pancake shape and well spread disk shape have been created.
Influence of HVOF Spraying Parameters on the Wear Resistance of Al-SiC Composites Coatings Deposited on ZE41A Magnesium Alloy
Authors: López A. J. , Rams J. , Torres B. , Rodrigo P. , Campo M. 
Published: November 2022

Abstract
High velocity oxygen fuel has been used as fabrication technique for manufacturing aluminium coatings reinforced with different weight percents of silicon carbide particles on Mg-Zn alloys used as substrates. The aim of the investigation is to improve the tribological performance of the ZE41A magnesium alloy. The parameters of the thermal projection system have been optimized in order to maximize the SiC particles incorporation in the aluminium matrix of the coating. Pin-on-disc tests were developed to characterize the tribological behavior of the different specimens. Minor degradation of the magnesium alloy was achieved after . Composite coatings with thicknesses of about 120 µm, reinforced with about 10 wt.% and with high adhesion to the substrate were achieved. After the coating parameters were optimized, the wear rate of the magnesium with the composite coatings decreased by two orders of magnitude in comparison to that of the uncoated magnesium alloy.
Investigation of In-Flight Particle Characteristics of HVOF Sprayed MCrAlY Coatings
Authors: Saechua W. , Zhang D. , Voisey K. T. , McCartney D. G. 
Published: November 2022

Abstract
The MCrAlY type coatings provide oxidation protection and good adhesion between the ceramic topcoat and the substrate. The high velocity oxy fuel (HVOF) process is currently being introduced to make the bond coats instead of conventional low pressure plasma spraying due to lower cost. In this research, the METJET-III HVOF liquid fuel system was used to produce MCrAlY coatings and the Tecnar DPV2000 was used to investigate in-flight particle temperature, velocity and diameter. To examine the coating-build, the wipe test was used to reveal the particle deformation on the substrate with different spraying parameters and correlated impact behaviour with particle properties. It was found that increasing of total fuel plus oxygen flow rate, percent stoichiometry and stand-off distances did not dramatically change the particle temperature. Increasing of percent stoichiometry and stand off distance led to reduction in particle velocity while increasing of the total fuel plus oxygen flow rate led to increase in the particle velocity. The average particle velocity below 640 m/s seems to make less splat formation than the average particle velocity above 750 m/s. Compiling results of the coating microstructure, the splat formation and the in-flight particle measurements revealed the effect of spraying parameters on the coating characteristics.
Effect of Substrate Roughness on Splat Formation of a Thermally Sprayed Polymer Coating
Authors: Alamara K. , Saber-Samandari S. , Berndt C. C. 
Published: November 2022

Abstract
Polypropylene (PP) was flame sprayed onto rough mild steel substrates at room temperature (RT) that was preheated at 70 °C, 120 °C, and 170 °C. Single solidified droplets (splats) were collected and analysed to understand how processing variables influenced the thermal spray coating characteristics. The splat morphology was characterized in detail using optical and scanning electron microscopy (SEM). The splats exhibited a disk-like shape with a large central viscous core and a fully melted wide rim with a thin edge. The splat size increased with increasing substrate temperature. A unique flat microstructure was observed on the surface of the splat deposited onto the RT substrate, whereas a flowing pattern appeared on the splat surfaces deposited onto the preheated substrates and the pattern increased by increasing the substrate temperature. The results of this study revealed improved splat-substrate adhesion by heating the substrate from RT to 170 °C. On the basis of the result, the influence of substrate parameters on splat morphologies was employed to establish a relationship between the microstructural characteristics and processing variables of flame sprayed polymeric coatings.
The Influence of CMAS Attack on the Lifetime of Thermal Barrier Coatings
Authors: Steinke T. , Jarligo M. O. , Mack D. E. , Vaßen R. , Stöver D. 
Published: November 2022

Abstract
Oxide compounds basically composed of calcium, magnesium, aluminum and silicon cations also known as CMAS, can be deposited on the surface of thermal barrier coatings (TBC) of gas turbine blades. Under certain operation conditions these compounds have been found to aggressively degrade the TBC, hence affecting the thermo-mechanical properties of the underlying component. Detailed investigation on the interaction of CMAS and the atmospheric plasma sprayed (APS) yttria-stabilized zirconia (YSZ) TBC was performed in a burner rig test facility under thermal gradient cycling conditions and at the same time CMAS deposition. This novel and unique test approach promises a coating screening and characterization test under service conditions. Variable exposure times at approximately 1250°C/1050°C surface/substrate temperatures were applied. The lifetime of the TBC was indicated by the number of thermal cycles until significant spallation occurred. X-ray spectroscopy and microstructural analyses were conducted on the cycled samples to determine the effect of thermo-chemical interactions. It was found that with extended heating period of 10 times the standard cycle, the number of sustainable load alternations heating/cooling was reduced. Interaction of CMAS and YSZ induces formation of glassy soda-silicate phase. Thermal cycling of thermo-physically mismatched TBC and glass melt causes crack formation and coating failure.
Microstructural Investigation of Thermally Sprayed Ceramic Coatings by Laser Acoustic Surface Waves
Authors: Barbosa M. , Schneider D. , Puschmann R. , Toma F.-L. , Berger L.-M. 
Published: November 2022

Abstract
Young’s modulus is not only one of the important mechanical properties of thermally sprayed coatings but also a sensitive indicator of the coating’s microstructural defects. The ceramic coatings studied in this work were based on Al2O3, TiO2 and Cr2O3 and prepared by APS (Atmospheric Plasma Spraying), HVOF (High Velocity Oxy Fuel spraying) and suspension-HVOF spraying. The Young’s modulus was systematically studied by laser acoustic surface waves, which is a non-destructive, fast and reliable technique, using two different devices: a tabletop tester for samples and small components (LAwave) and a hand-held portable device. For oxide coatings, it was observed that the results distinctly vary depending on the spray technology. A comparison with the values derived from the instrumented indentation test shows that for most investigated ceramic coatings lower values were measured by laser acoustics. This is due to the influence of the pores and defects in the coatings. The LAwave results are expected to be close to the effective modulus of the material, due to the larger material volume evaluated during the test, which takes the coating defects into consideration.
Modeling Properties of HVOF Thermally Sprayed WC-Co Coatings Based on Particle-in-Flight Characteristics
Authors: Tillmann W. , Hussong B. , Kuhnt S. , Rudak N. , Weinert H. 
Published: November 2022

Abstract
Numerous factors, such as the spray parameters and non-predictable conditions, during the spraying process influence the properties of thermally sprayed coatings. However, the condition of the particles at the moment of impact on the substrate is the most crucial factor for the morphology and the mechanical properties of a coating. Thus, nowadays particle analyzing systems are employed in order to explain the relation between the process parameters and the properties of a layer. Yet, modeling of thermal spray processes is conducted disregarding particle parameters and only correlating process parameters with layer properties. This article presents a new approach on process modeling, for relating spray parameters to particle-inflight conditions. The modeling of the particle properties in relation to the process parameters shall allow conducting targeted adjustments during the running process, to optimize particle properties. This method will enable to influence coating properties during the spraying process, eliminating the influence of unpredictable environmental or process-related disturbances. In a series of experiments, spray beam properties were measured in an HVOF thermal spray process with agglomerated and sintered WC-Co powder. Spray parameters were correlated to the particle-in-flight conditions, which were measured by utilizing two particle analyzing systems.
Injection Optimization of Composite Powders using Laser Based Particle Visualization
Authors: Crawford D. , Gansert R. , Wright D. 
Published: November 2022

Abstract
Laser Based Particle Visualization instruments such as SprayCam provide a unique picture into the radial injection of powders in APS processes. Traditional injection optimization methods utilizing these instruments involve optimization of particle temperature and velocity while measuring the particle plume position in the plasma. The goal of these optimization techniques is to ensure maximum energy transfer to materials with a high melting point and a low thermal conductivity, such as is typical for materials applied as thermal barrier coatings. Conversely, optimizing energy transfer of composite powders with a low melting point and a high thermal conductivity, such as Al-8Si-20BN, has very little effect, thus it is difficult to optimize the injection process of this material in the traditional fashion. In addition, these materials have a tendency to bounce off the plasma rather than penetrate it due to their low inertia, resulting in low deposition efficiencies. A new method of injection optimization of these powders is proposed utilizing Laser Based Particle Visualization Techniques to view the injection from above in order to maximize powder injection into the plasma. A real-time examination of particle plume width inside the plasma will be conducted, varying an array of torch conditions while deposition efficiency is monitored.
WC-Co/Metal Multi-Layer Coatings by Warm Spray Deposition
Authors: Watanabe M. , Komatsu M. , Kuroda S. 
Published: November 2022

Abstract
WC-Co/copper coatings with 8 layers were fabricated by warm spray deposition in order to investigate the effect of ductile layer inclusion on their fracture behavior. Bending strength, work of fracture, and surface hardness of freestanding coatings were examined by three point bending tests after removal of the substrates. The multilayered samples showed nonlinear stress-strain curves due to cracks in the WC-Co layers and plastic elongation of the copper layers. The multilayered samples with lower volume fraction of copper showed even lower bending strength than the monolithic samples of WC-Co and copper and no beneficial feature in mechanical performance was found. On the other hand, the samples containing higher volume fraction of copper exhibited more than twice higher work of fracture and moderately better bending strength than the monolithic WC-Co coatings, while the surface hardness was almost identical among all samples instead of the monolithic copper. The ductility of copper layers and the plastic constraint by the intact WC-Co layers attributed to enhance their mechanical properties. It has been concluded that cermet/metal laminate coatings can be one alternative approach to further improvement of the mechanical properties of thermal sprayed cermet coatings.
Tribological Properties of HVOF Sprayed Nanostructured Composite Coatings
Authors: Żórawski W. , Burakowski T. , Skrzypek S. 
Published: November 2022

Abstract
Nanostructured materials are of particular scientific interest because of their physical and mechanical properties, which are superior to those of conventional materials. They are more widely used in various industrial applications mainly due to decreasing production costs. The work is concerned with a study of the tribological properties of a HVOF sprayed composite of nanostructured WC12Co mixed with nanostructured Fe3O4, having the properties of solid lubricant. The coatings were sprayed by means of a Hybrid Diamond Jet system. A T-01 ball on disc tribological tester was used to study their resistance to wear and determine the coefficient of friction on the basis of friction force obtained in the course of continuous measurement at a set load. Result of investigations were compared with properties of coatings sprayed with standard WC12Co/ Fe3O4. The microstructures and compositions of the nanostructured powders and coatings were analyzed by scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray analysis. Their phase composition was studied using a Bruker D8 Advance diffractometer.
Characterisation of Inconel 625 Coatings Deposited by Cold Spray
Authors: Pontarollo A. , Vezzù S. , Trentin A. , Rech S. , Guidolin M. , Cafissi A. , Peretti C. , Molinas B. 
Published: November 2022

Abstract
The high strength nickel alloys, and in particular Inconel type alloys, are extensively used in several applications, such as aeronautics and petroleum industry, thanks to the combination of their high mechanical properties and their thermal and chemical resistance. In particular Inconel 625 is already used in oil pipelines and pipelines of large thermal plants, and the possibility to replace high cost bulk Inconel parts with Inconel coated steel parts is of great interest. On this context the first topic to allow the use of coated parts instead of bulk Inconel is the capability to provide high corrosion and thermal resistance. The aim of this study is to investigate the capability of Coldspray in the deposition of high strength materials, such as hard nickel alloys, for corrosion protection, and to compare the corrosion behaviour of Coldspray coatings with commercial HVOF deposited coatings. Inconel 625 coatings were deposited by using CGT Kinetic3000 deposition system with nitrogen as carrier gas on AISI316L flat substrates. The coating thickness ranges between 0.3 and 1.0 mm. Different feedstock materials were used and the effect of powder size distribution on the growth capability, as well on coating microstructure and porosity, were evaluated. The corrosion behaviour of Coldspray coatings were studied by electrochemical potentiondynamic analysis and compared with the behaviour of commercially available coatings deposited by HVOF that could be considered as a high-quality benchmark. In particular, the effects of the different coating microstructures due to the different deposition processes were related with the corrosion resistance. Further development and key features are finally outlined in order to candidate the Coldspray as promising technology for the deposition of high-strength nickel alloys.