bluuebunny/crossref_metadata_2025_split huggingface dataset:
Technology Advances in Compressor and Turbine Abradables
Authors: Wilson S. , Sporer D. , Dorfman M.R. 
Published: September 2022

Abstract
Abradable seals have been used in jet engines since the late 1960's. Today they are seeing applications in low pressure and high pressure sections of compressors as well as the high pressure turbine module of jet engines. Clearance control systems using abradable coatings are also gaining ever more attention in industrial and steam turbine applications. Thermal spraying is a relatively simple and cost effective means to apply abradable seals. Abradable coatings work by minimizing gaps between rotating and stationary components by allowing the rotating parts to cut into the stationary ones. Typically plasma and combustion spray processes are used for applying abradable coatings. The types of coatings employed in the HP turbine are zirconia based abradable material systems with polymer and, in some cases, solid lubricant additions such as hexagonal boron nitride. The coatings are designed to work at service temperatures of up to 1200°C. Types of matrix materials used in the low and high pressure sections of the compressor are aluminum-silicon, nickel and MCrAlY based systems. These compressor type systems typically also contain fugitive phases of polymer and/or solid lubricants such as hexagonal boron nitride or graphite. Operating temperature, depending on the material of choice, can be up to 750°C. Regardless of the specific application, fugitive phases and porosity are needed for abradable coatings. Polymers are used to create and control porosity in plasma sprayed coatings, a critical design requirement in adjusting abradability and erosion properties of thermal spray coatings. Combustion spray coatings generate porosity through the lower deposition velocities and temperatures compared to plasma and typically do not need polymer phases. Solid lubricants are added to help weaken the structure of thermal spray coatings and reduce frictional heating and material transfer to the blade.
Towards Highly Sintering-Resistant Nanostructured ZrO2-7wt% Y2O3 Coatings for TBC Applications by Employing Differential Sintering
Authors: Lima R.S. , Marple B.R. 
Published: September 2022

Abstract
Envisioning the use of nanostructured YSZ coatings at high temperatures cause concerns in the scientific community. Questions have been raised about the possibility of accelerated sintering of these ultra-fine materials and the associated changes in properties that could accompany this sintering. In this work, nanostructured YSZ coatings were engineered to counteract sintering effects by tailoring the coatings to exhibit a bimodal microstructure formed by (i) a matrix of dense YSZ zones (produced from molten YSZ particles) and (ii) large porous nanostructured YSZ zones (produced from semi-molten nanostructured YSZ particles) that were embedded in the coating microstructure during thermal spraying. These coatings were subjected to heat treatment in air at 1400°C for 1, 5 and 20 h. The superior driving force for sintering exhibited by the porous nanozones, when compared to that of the dense zones, caused the nanozones to shrink at much faster rates than those exhibited by the denser matrix zones (i.e., differential sintering), thereby creating a significant network of voids in the coating microstructure. Due to these effects, after 20 h exposure at 1400°C, the thermal conductivity and elastic modulus values of the conventional coatings were approximately two times higher than those of the nanostructured ones.
Application of HVAF for Thermal Spraying of Zn-Al
Authors: Gorlach I. 
Published: September 2022

Abstract
Traditional metal spraying techniques, which have been used in industry for decades, such as Wire Flame and Twin-Wire Arc are classified as low velocity processes because the sprayed material is conveyed by compressed air having subsonic velocity. In order to improve the bond strength, HVAF was applied for thermal spraying for anticorrosion protection. In this paper, zinc-aluminium (Zn-Al) coatings thermal sprayed using the HVAF method are analysed. The thermal sprayed coatings were characterized by the standard techniques, such as light microscopy, scanning electron microscopy with energy-dispersive spectroscopy, X-ray diffraction, salt spray and bond strength tests. The results show that thermal sprayed coatings have a dense structure, a high bonding strength, low presence of oxides and high resistance to corrosion. This is attributed to high flow/particle velocities and relatively low combustion temperatures of HVAF in comparison with other thermal spraying technologies. High spray rate and good coating quality make the HVAF thermal spray method a viable alternative to the conventional Wire Flame and Twin-Wire Arc methods for thermal spraying of Zn-Al coatings.
Gas-Tight Coatings Produced by Very Low Pressure Plasma Spraying
Authors: Verdy C. , Zhang C. , Sokolov D. , Liao H. , Klein D. , Coddet C. 
Published: September 2022

Abstract
A certain level of porosity is always presented in thermal spray ceramic coatings. LPPS or some specific APS processes can allow to reduce it but it is difficult to obtain coatings with a low thickness (less than 100 m) which are fully gas-tight because of cracks or interconnected pores. This gas-tight property is for example very suitable for the ceramic electrolyte of solid oxide fuel cells (SOFC). Some ZrO2-Y2O3 coatings were obtained by the VLPPS process, a LPPS system operating at a pressure of about 100 Pa. The specific structure of these coatings is a mixture of condensed vapors and splats. The results are very satisfying because ZrO2-Y2O3 coatings with a thickness of about 70 micrometers are tight under a hydrogen pressure of 2x105 Pa. This paper presents some ZrO2-Y2O3 coatings obtained by different processes (APS, LPPS and VLPPS) and their properties.
Study on Gas Permeation Behaviour Through Atmospheric Plasma-Sprayed Yttria Stabilized Zirconia Coating
Authors: Zhang C. , Liao H. , Planche M. , Coddet C. , Li C.-X. , Yang G.-J. , Li C.-J. 
Published: September 2022

Abstract
Gas permeation behaviour through atmospheric plasma-sprayed 8 mol% yttria stabilized zirconia (YSZ) electrolyte coating was studied experimentally. YSZ coatings were fabricated using different powder feedstock. The temperature and velocity of in-flight particles during spraying were measured with a diagnostic system. The results showed that particle temperature and velocity were significantly influenced by the size of powders. The gas permeability of these coatings was estimated by a specific instrument with pure O2, N2 and H2. It was found that the gas permeability was reduced by decreasing the size of powder. Gas permeation behaviour through plasma-sprayed YSZ coating was studied. Transition flow was compatible to gas permeation behaviour for all three plasma-sprayed YSZ coatings. The relationship between gas permeation behaviour and coating microstructure is discussed in this article.
Detailed Analysis of the Plasma Jet of F4 and Delta Torches by Means of Tomography
Authors: Dschung F. , Forster G. , Zierhut J. , Marqués J.-L. , Schein J. , Haberbosch R. , Guide B. 
Published: September 2022

Abstract
One important aspect concerning the coating of surfaces using thermal spray is the improvement of the injection of material particles into the gas jet and thus the deposition efficiency. Therefore a better knowledge of the temperature distribution within the jet is relevant in order to optimize spraying conditions. Particularly interesting is the existence of a well-defined threefold finger structure in the plasma jet produced by triple electrode torches, which allows an efficient injection of coating material due to the existence of zones with higher and lower viscosity. The jet structure, however, lacks rotational symmetry and can therefore not be analyzed by systems relying on the validity of the Abel inversion, thus new systems have to be developed. In this work an innovative tomography device is described that has been designed for this purpose. By circling half around the plasma jet and taking simultaneously intensity images under different view orientations, a three-dimensional intensity distribution of the jet is generated, which can be used to determine the temperature distribution.
Thermoelectric Properties of Plasma Sprayed (Sr, Y)TiOx Thick Film
Authors: Sodeoka S. , Suzuki M. , Inoue T. , Obara H. 
Published: September 2022

Abstract
SrTiOx is an expected oxide thermoelectric material, which performance can be improved by doping Y3+ in place of Sr2+. However, the maximum content of Y3+ is limited to about 10% because of the phase transformation in the equilibrium sintered material. By contrast, plasma sprayed (Sr, Y)TiOx, which was essentially rapidly quenched, could solve Y up to 20% of Sr-site without the second phase, and produce the increase in the electric conductivity and the decrease in the thermal conductivity. But the absolute value of Seebeck coefficient decreased with an increase of Y content. As the result, the ZT value, which showed the performance for thermoelectric power generation, was reached only 0.1 in the Y content range 10% to 25% of Sr site.
Plasma Sprayed Coatings of High Purity Ceramics for Semiconductor and Flat-Panel Display Production Equipment
Authors: Kitamura J. , Ibe H. , Mizuno H. , Aoki I. 
Published: September 2022

Abstract
High purity oxide ceramic powders of alumina (Al2O3) and yttria (Y2O3) for plasma spraying have been developed to apply to semiconductor and flat-panel-display (FPD) production equipments. The ceramic coatings onto inside chamber wall of the equipments are required to have highly erosion resistance against CF containing plasma, widely used in dry etching process for micro-fabrications of the devices. Yttria is increasingly used in this application due to the high resistance compared to alumina. It is found that the yttria coating formed from agglomerated-and- sintered powder consisting of large primary particle has smoother eroded surface. Considering that particle deposition onto the devices, this coating will be effective to decrease generation of large sized particle, which is easily deposit onto the devices. Electric insulating properties of the coatings are also investigated to apply to electrostatic chuck. Electric breakdown voltage of yttria coatings is almost comparable to that of alumina coatings. However, yttria is difficult to apply due to its lower mechanical strength. Using smaller powder as feedstock is effective to improve the electric properties and influence of coating purity is lower than the powder size.
Parameters Controlling Properties of Coatings Sprayed by Suspension Plasma Spraying
Authors: Etchart-Salas R. , Rat V. , Coudert J.F. , Fauchais P. 
Published: September 2022

Abstract
Recent works have been devoted to achieve dense and thin (&lt;15 µm) zirconia coatings using a relatively new process, Suspension Plasma Spraying (SPS). Nevertheless, the parameters controlling the microstructure of the deposit are not yet clearly identified, particularly for the injection of suspension. Hence, the liquid penetration into the plasma has been observed with a fast shutter (10-5 s) camera coupled with a laser flash and triggered by a defined instantaneous voltage level of the plasma torch. This paper is focused on the treatment of the suspension jet or drops according to the suspension properties (with the viscosity, particles load, injection velocity…) and depending on the different spray parameters such as the plasma forming gas mixture composition and the plasma torch design (either PTF4 or home made torch). These works have permitted the obtention of zirconia coatings with low thicknesses (~10 µm) and dense structure (~4% of porosity).
Liquid Precursor Plasma Spraying: Observation of Liquid Feedstock Break-Up
Authors: Marchand C. , Chazelas C. , Mariaux G. , Vardelle A. 
Published: September 2022

Abstract
The use of liquid precursors in plasma spraying makes it possible to produce coatings with more refined microstructures than in conventional plasma spraying. Depending on the injection device, the liquid feedstock is injected into the plasma jet in the form of liquid jet or droplets. The instabilities on the liquid-gas interface cause the mechanical break-up of liquids into drops that are subjected to further break-up until the droplets reach a stable state or evaporate. The process break-up may strongly influence the size, trajectories and, therefore, treatment of the droplets in the plasma medium. This study deals with the experimental observation of liquid break-up under plasma spray conditions when using a conventional DC plasma torch with radial injection by means of a pneumatic injection system that can deliver either liquid stream or blobs.
Tribological Comparison between FeCrSiMnB and FeCrSiMnC+WSC Arc Sprayed Coatings
Authors: Tillmann W. , Vogli E. , Ferreira da Cunha A. 
Published: September 2022

Abstract
Thermal spraying technologies take part in the current worldwide scene as serviceable and profitable technologies for a wide range of intents. The growing adoption of those techniques has driven companies to progressive investments in efforts to reach innovative designs and market needs. Wear resistance is among the desired features which certain components must be able to provide while performing. In this context tribology has an outstanding importance, where the adoption of suitable materials and operational parameters jointly contribute for a longer lifetime of parts. This contribution presents a comparison of AISI 1045 (DIN C45) steel surfaces coated by means of arc spray process, employing cored wires as feedstock. Corresponding light microscopy, SEM-EDX, 3Dprofilometry, hardness and ball-on-disk analyses were conducted to understand the tribological behaviour of two unlubricated iron-based layers with and without carbides reinforcement. The results point out equivalent thickness, porosity and as-sprayed roughness for both coatings. Higher hardness and lower friction coefficients for the carbide free coating as well as a downward trend considering the coefficients of friction for coated and uncoated surfaces under heavier loads.
Numerical Simulation of an Electromagnetically Controlled Plasma Jet During Atmospheric Plasma Spraying
Authors: Brußies E. , Stiller J. , Grundmann R. 
Published: September 2022

Abstract
We present the results of an investigation of the effects of a travelling magnetic field (TMF) on the plasma flow using a commercial program package. The argon plasma generation in the electric arc and the Lorentz force induced by the TMF are simulated with specific equations, which are derived from the magnetofluiddynamic equations using appropriate simplifications. First calculations confirm the predicted effects.
Preparation and Mechanical Properties of Cold Sprayed Nanocrystalline Aluminum
Authors: Hall A. , Yang P. , Brewer L. , Buchheit T. , Roemer T. 
Published: September 2022

Abstract
Nanostructured materials are of widespread interest because of the unique properties they offer. We have demonstrated that nanocrystalline 6061 and 5083 aluminum powders, prepared using liquid nitrogen (LN2) ball milling, can be consolidated using the cold spray process. TEM analysis of the cold spray coatings reveals that the cold spray process caused significant grain refinement. Gas atomized 6061 and 5083 aluminum powders were ball milled in liquid nitrogen resulting in a powder microstructure containing 250-400 nm grains. Cold spray coatings prepared using these feed stock materials exhibited homogenous microstructures with grain sizes of 30-50 nm. TEM analysis of the as-received powders, ball milled powders, and coatings are shown. Mechanical property measurements made using nano-indentation techniques show that the hardness of the coatings prepared using the LN2 ball milled 6061 is approximately double the hardness of the coatings prepared using the same powder in its as-received condition.
Comparison between APS, HVOF and High-Velocity Suspension Flame Spraying (HVSFS)-Deposited Al2O3 Coatings
Authors: Bolelli G. , Cannillo V. , Lusvarghi L. , Rauch J. , Killinger A. , Gadow R. 
Published: September 2022

Abstract
The High-Velocity Suspension Flame Spraying (HVSFS) technique, a recently-developed modification to the standard HVOF process enabling the use of suspension feedstock, was employed in order to deposit Al2O3 coatings from a nanopowder suspension. These coatings were compared to conventional APS and HVOF-sprayed ones. HVSFS coatings possess lower overall porosity and lower pore interconnectivity degree. Indeed, most of the nanoparticles were fully melted by the gas jet, thus forming very thin, well-flattened lamellae, having smaller columnar crystals than conventional coatings. Accordingly, HVSFS coatings possess higher hardness and elastic modulus, as determined from nanoindentation tests. Ball-on-disk tribological tests also indicate that HVSFS coatings possess much better sliding wear resistance than conventional ones, because they are capable of forming denser and more protective surface tribofilms during dry sliding.
Plasma Spraying of Tungsten Carbide-Cobalt Coatings by the Water-Stabilized System (WSP)
Authors: Ctibor P. , Kasparova M. , Bellin J. , Le Guen E. 
Published: September 2022

Abstract
Tungsten carbide – cobalt powders (WC-17wt.%Co) were plasma sprayed by a water-stabilized system WSP. A matrix of experiments with variable feeding distances and spray distances was carried out. Thinner coatings were carried out on carbon steel substrates and thicker coatings on stainless steel substrates to compare fast cooling conditions – the former with slower cooling conditions. Basic characterization of coatings was done by XRD, SEM and light microscopy plus image analysis. Microhardness was measured on polished cross sections. The main focus of investigation was on resistances against wear in dry as well as wet conditions. The appropriate tests were performed with set-ups based on ASTM G65 and G75, respectively. The influence of spray parameters onto coating wear performance was observed. The results of mechanical tests are discussed in connection with changes of phase composition and with the character of the coating’s microstructure. The results show that for obtaining of the best possible WC-17Co coating with WSP process, from the viewpoint of wear resistance, the desired parameters combination is long feeding distance combined with short spray distance.
Evaluation of Shear Test Results for Determination of Shear Load Resistance of Thermally Sprayed Coatings
Authors: Hartmann S. , Deuerler F. , Winkler R. 
Published: September 2022

Abstract
The shear test in accordance with EN 15340 is a new test method for testing the bond between substrate and thermally sprayed coatings. It has been developed in order to enable a test method without the disadvantages of the method currently in use, the adhesion test. In the adhesion test the adhesives influence the test results; therefore in the shear test no adhesives are used. The adhesives are among others the reason for a large deviation of the test results using the pull-off test. Using the shear test the mode of the test results depend on the ratio between adhesion and cohesion; this ratio causes three different fracture modes. In order to investigate the deviation depending on the fracture mode samples have been coated by wire flame spraying, arc, plasma and HVOF spraying. Different ceramics, carbides and metals have been used as thermal spraying materials. For each material-process combination between 30 and 120 samples have been coated. This report describes the interpretation of the results of the shear test depending on the fracture mode and the coating materials applied by different thermal spraying processes. The deviation of the results depending on the fracture mode has been investigated using a shear test device by which the shear force is recorded over the displacement of the coating. The knowledge of the deviation and the distribution of the results is necessary to decide on the required number of samples to reach a result with a defined reliability.
Microstructures and Oxidation Behavior of Cr39Ni7C Cermet Coatings Oeposited by Diamond Jet Spray Process
Authors: Ye F.-X. , Wu S.-H. , Ohmori A. 
Published: September 2022

Abstract
For the promising erosion and oxidation resistance of carbide cermet coating, Cr39Ni7C cermet coatings were deposited by Diamond Jet spray process using a commercial Sulzer Metco 5241 powder in this study. The microstructure, phase composition and high temperature oxidation behavior of the deposited coatings were investigated. The speed and temperature of in-flight particles were measured by DPV-2000. The results revealed that the speed of in-flight particles decreased from 229 m/s to 150 m/s with the increasing of spraying distance from 100 mm to 300 mm, whereas the average temperature of in-flight particles increased from 1926 to 2245 K. The decarburization of Cr3C2 increased with the increasing of fuel gas flow from 30 FMR to 40 FMR for higher heat enthalpy of flame. Due to the formation of Cr2O3 on/in the coatings at high temperature, the sprayed coatings had good oxidation resistance at 1073 K in air atmosphere. For the lower porosity of the coating deposited under the spraying distance of 150 mm, its oxidation resistance was better than that sprayed under the spraying distance of 200 mm.
Effect of the Blasting Time on the Amount of the Residual Grit on a Blasted Steel Substrate
Authors: Maruyama T. , Miyazaki T. , Kobayashi T. 
Published: September 2022

Abstract
The substrate surface roughening and cleaning are very important process for pre-treatment of a substrate for thermal spraying. There are some methods for the pre-treatment. Especially, the grit blasting process is the most general process. However, some grits embed into the blasted substrate, and the embedded grits remain on it. The girt embedment is affected by various conditions of the blasting process. It is important to make known the effect of the blasting time on the residual grit amount. A carbon steel substrate was blasted by white alumina grit. The blasting time was changed. The surface roughness of the blasted substrate increased monotonically with increasing blasting time. During very short time at the starting of blasting, the residual grit amount increased with increasing blasting time. Then the amount of the residual grit decreased with increasing blasting time. The penetration depth of the residual grit on the blasted substrate denoted the same tendency of the residual grit amount. There may be a critical time that the residual girt amount becomes the local minimum value.