bluuebunny/crossref_metadata_2025_split huggingface dataset:
Production Experience of On-Line Diagnostic Systems in Plasma and Flame Spraying
Authors: Wigren J. , Nylén P. 
Published: September 2022

Abstract
In order to ensure reproducibility of thermal sprayed coating characteristics, process control by a sensor system is essential. Volvo Aero has more than 5 years experience of using different sensor systems in plasma and flame spraying. This article presents two examples where such systems have been used for quality control in production. In the first example the DPV2000 system was used in plasma spraying to control the tensile strength of an abrasive application. The study showed that the particle in-flight properties and the tensile strength were very sensitive to the carrier gas flow rate. In the second example the PlumeSpector system was used to control erosion and tensile strength in flame spraying of a composite powder composed of a core of Bentonite clay coated with a shell of NiCrAl alloy. The results show that the capability could be increased by a factor of two using on-line diagnostic control.
Fluid Dynamic Effects on Plasma Torch Anode Erosion
Authors: Sun X. , Heberlein J. 
Published: September 2022

Abstract
Anode erosion in plasma spray torches results in coating deterioration. The usable life of a torch anode is strongly dependent on the fluid dynamic behavior of the plasma inside the torch, which in turn depends on the geometric design of the anode and the operating parameters. In order to study the relative importance of these effects, cold flow investigations have been performed with a torch having a glass anode with the same geometric dimensions as a Praxair-TAFA SG 100 torch. The density differences between the arc and the cold gas were simulated by injecting heated helium from the tip of the cathode into the cold argon gas flow from the regular gas injector. Flow visualization was achieved by seeding the flow with micron-sized particles. A finite element CFD code was used to simulate the cold flow structure. The results were compared with erosion patterns observed with an actual plasma torch. The results indicate that recirculation eddies inside the torch will force a preferred anode attachment which is different for different gas injectors. Minimization of such recirculation regions by appropriate fluid dynamic design will result in more random attachment of the arc and prolonged anode life.
Microstructure and Properties of Micro-Plasma Sprayed Cu Coating
Authors: Li C.-J. , Sun B. , Wang M. , Han F. , Wu T. 
Published: September 2022

Abstract
Cu coating was deposited by microplasma spraying system under a low power of 2.8 to 4.2kW. The effects of the main processing parameters including plasma arc power, operating gas flow and spray distance on particle velocity during spraying, and the microstructure and properties of the coating were investigated. The coating microstructure was examined with optical microscopy. The coating properties were characterized by cross sectional microhardness. The particle velocity during in-flight was examined using a particle velocity/temperature measurement system based on thermal radiation. The experiment results showed that particle velocity was increased with the increase in operating gas flow, and was not influenced significantly by plasma arc power and spray distance. Moreover, the microhardness of the coating was increased with the increase in arc power and with the decrease in spray distance. The operating gas flow showed no significant influence on the microhardness of the coating. The analysis suggested that the microhardness of the coating is influenced significantly by particle temperature. The comparison showed that the microhardness of the Cu coating deposited by microplasma spray is comparable to that of the coating deposited by conventional plasma spray system at power level of 30kW.
Improvement of the Properties of Thermally Sprayed Ceramic Coating by the Infiltration of the Adhesives
Authors: Li C.-J. , Yang G.-J. , Ohmori A. 
Published: September 2022

Abstract
Thermally sprayed ceramic coating consists generally of porosity up to over ten percent. The existence of voids in the coating will degrade mechanical performance and corrosion resistance. The infiltration technique has been used to enhance the coating performance. In the present work, the adhesives of high strength are used as infiltrator for plasma sprayed alumina coatings to investigate the effect of the infiltration on the adhesive strength and erosion resistance. The adhesive strength of coating after infiltration is tested following ASTM-C-633 standard with the same adhesive. The commercial adhesives used are liquid types of adhesives. Alumina coatings are deposited by plasma spraying to a thickness about 500ìm. The adhesive strength of as-sprayed coating was tested using another epoxy resin adhesive. The test pieces are prepared without infiltration of adhesive into the coating. The results revealed that the infiltration of adhesive to alumina coating can improve significantly the adhesive strength and erosion resistance. The adhesive strength from 40 to 55 MPa can be obtained in spite of deposition conditions. The erosion resistance of the coating at 90 degrees can be improved by a factor about 3.
Optical Emission Spectroscopic Diagnostics of Atmospheric Argon Radio Frequency Inductively Coupled Plasma
Authors: Gao G. , Pershin L. , Mostaghimi J. 
Published: September 2022

Abstract
An experimental study is conducted to determine the property fields of 40 MHz argon radio frequency inductively coupled plasma using optical emission spectroscopy. The pure argon plasma was operated at the input power of 0.3 kW and under atmospheric pressure. 29 atomic argon lines with upper level energies ranging from 12.9 to 15.5 eV, continuum emission and line width are used to evaluate plasma parameters such as temperature and electron number density. Since 40 MHz plasma is in almost complete nonequilibrium, the validaty and accuracy of most usual spectroscopic methods are questioned. Analysis based on the Boltzmann diagram, line-to-continuum intensity ratio, population of continuum extrapolated level, and continuum intensity reveals the departure from thermodynamic equilibrium in the plasma. Among these methods, the Boltzmann diagram method is shown to provide reliable plasma excitation temperature as long as the Boltzmann plot is drawn based on enough spectra lines covering from infrared to ultraviolet regions. The continuum emission at wavelengths within visible region can give good estimation of the electron density by using excitation temperature in the continuum relation. The line-to-continuum is not a reliable method for the temperature measurement of nonequilibrim plasma. The electron density obtained from the Saha plot can provide rough estimation of the electron density. It is shown that the electron-atom interaction contribution to the continuum radiation is more important than being expected before for the argon plasma in our study. The non-axisymmetric distribution of the emission was found to exist within the coil zone of the plasma, which may affect the estimation of the local emission coefficient, and consequently the measured plasma fields.
Analysis of Electronic Properties of TiO2 (001) Surface Based on Band Calculations
Authors: Kellou A. , Toma F-L. , Aourag H. , Klein D. , Coddet C. 
Published: September 2022

Abstract
The electronic structure of the bulk and the surface of rutile titanium dioxide (TiO2) are analyzed from band calculation based on quantum mechanics formalism. The surface density of states and charge distributions of bulk and (001) surface are compared to better understand the mechanism of adsorption and photodegradation processes.
Influences of Substrate Roughness and Temperature on Adhesive Strength in Thermal Spray Coatings
Authors: Fukanuma H. , Ohno N. 
Published: September 2022

Abstract
It is essential to understand and clarify what causes adhesive strength between the thermally sprayed deposit and the substrate. It is known that the adhesive bond strength is strongly related to the roughness of the substrate surface, however, we are yet to know why and how the roughness affects the strength. Although the roughness works as a socalled anchor or interlocking effect, we cannot show how the effect quantitatively relates to the strength. Before we use the word “roughness”, we need to define roughness as a strict meaning in connection with the adhesive strength to avoid any ambiguity in expressing the roughness itself. Seeking the true roughness to relate to the bond strength, we have introduced a newly developed roughness indicator correlated closely with the adhesive strength. This indicator is derived by theory on the basis of the assumption that the bond strength is primarily caused by the mechanical friction between the deposit and the substrate. It was supposed that chemical and physical adhesions were secondary effects except that the molten particle, the substrate temperature or both of them are high enough to form these bonds by thermal interaction. The increase in contact area between the splat and the substrate could raise the friction force between them. The higher substrate temperature could increase the contact area when the molten particle interacts with the substrate, because the molten particle could wet better on the high temperature substrate. The substrate temperature influence on the adhesive strength was also investigated.
Structure and Magnetic Properties of Iron-Based Alloys Obtained by APS Thermal Spraying
Authors: Fenineche N.E. , Cherigui M. , Kellou A. , Aourag H. , Coddet C. 
Published: September 2022

Abstract
The development of amorphous and nanocrystalline materials took a significant part in search on materials these last years. Indeed, the magnetic, chemical and mechanic properties of materials are greatly modified when the size of crystallites becomes nanometric. The absence of crystal structure involves a macroscopic behaviour of the alloy, which is completely different from the same alloy in a polycrystalline state, particularly magnetic and mechanical properties. We have carried out coatings by APS plasma thermal spraying on a copper substrate using three types of powders, FeB (17,5% wt-B), FeSi (6,5% wt-Si) and FeNb (67,2% wt-Nb). Structure of these coatings was characterized by SEM and X-rays. We have also tested the magnetic properties of these deposits. Results obtained showed that the FeNb alloys are amagnetic with a partially amorphous structure, however FeSi and FeB alloys presented a microcrystalline structure with soft magnetic properties.
Study of Unique Microstructure in SPS Ceramic NanoCoatings
Authors: Ma X.Q. , Roth J. , Xiao T.D. , Gell M. 
Published: September 2022

Abstract
Ceramic oxide coatings were made with a unique microstructure using solution plasma spray (“SPS”), a novel variant on the conventional powder plasma spray techniques. In the SPS process, a precursor solution is fed into an air plasma torch using a liquid injector, and a nanocrystalline ceramic coating is formed directly on various substrates without post heat treatment. It was found that the microstructure of the SPS coating depended on control of process parameters for liquid feed and plasma spray to a large extent. This study deals with the formation of SPS deposited yttria stabilized zirconia coatings with a well-controlled microstructure addressing porosity, cracking and adhesion. The SPS-deposited YSZ coatings have demonstrated unique microstructural characteristics including adjustable porosity, vertical microcracks and the absence of splat boundaries. Such zirconia-base coatings show great potential for the applications of high-density electrolyte layers in solid oxide fuel cells (“SOFC”s) and high porosity/low conductivity thermal barrier coatings for industrial and gas turbines.
Thermally Grown Oxides on Electroplated Bond Coats under APS TBC
Authors: Khan Abdus , Duda Thomas , Taylor Alan , Moore Peter , Rutter Peter , Foster John 
Published: September 2022

Abstract
MCrAlY bond coats were deposited on nickel base substrate by electroplated process. The bond coats were plated using ‘CrAlY’ precursor powders suspended in an electrolytic bath containing nickel and cobalt in solution. The CrAlY powders used had size in the range generally below 10 um. The as-deposited coatings were heat-treated in a vacuum at elevated temperature. The roughness of the as-deposited coatings was on the range from 2 to 4 um (average). Yttria stabilized zirconia thermal barrier coatings, 7YSZ were deposited by air plasma spray. The thickness of the both bond coats and TBCs was varied in order to determine the effects of thickness in the stability of the thermal barrier coatings. The coated samples were tested in a static furnace and also in a thermal shock test rig where the samples could be cooled rapidly from 1000°C to 100°C at a predetermined rate. The TGO formed at temperatures in the range from 800 to 1050°C was characterized by optical, scanning electron microscope and electron beam microprobe.
Synthesis and Oxidation Behavior of Nanocrystalline MCrAlY Bond Coats
Authors: Ajdelsztajn Leonardo , Tang Feng , Schoenung Julie M. , Picas Josep , Kim Geoge E. , Provenzano Virgil 
Published: September 2022

Abstract
Thermal barrier coating (TBC) systems protect turbine blades against high-temperature corrosion and oxidation. They consist of a metal bond coat (MCrAlY, M = Ni, Co) and a ceramic top layer (ZrO2/Y2O3). In this work the oxidation behavior of conventional and nanostructured HVOF NiCrAlY coatings has been compared. Commercially available NiCrAlY powder was mechanically cryomilled and HVOF sprayed on a nickel alloy foil to form a nanocrystalline coating. Free-standing bodies of conventional and nanostructured HVOF NiCrAlY coatings were oxidized at a 1000°C for different time periods in order to form the thermally grown oxide (TGO) layer. The experiments show an improvement in oxidation resistance in the nanostructured coating when compared to that of the conventional one. This behavior is a result of the formation of a continuous Al2O3 layer on the top surface of the nanostructured HVOF NiCrAlY coating. This layer protects the coating from further oxidation and avoids the formation of mixed oxide protrusions present in the conventional coating.
Hot Corrosion Behavior of Graded Thermal Barrier Coatings Formed by Plasma Spraying Process
Authors: Mifune N. , Harada Y. , Doi T. , Yamasaki R. 
Published: September 2022

Abstract
Hot corrosion behavior of Thermal Barrier Coatings (TBCs) has been studied by comparison between double layer coatings and graded coatings. Two types of oxide ceramics, 8 mass % Y2O3-ZrO2(8YZ) and 2CaOSiO2-15mass% CaOZrO2 (C2S-15 CZ), with a bond coating of NiCrAlY were applied to metallic substrates in this study. After a hot corrosion test by V2O5-Na2SO4 corrosive ashes, hot corrosion behavior of TBC has been investigated by visual inspection, metallography, X-ray diffraction and EPMA. The C2S-15%CZ coating reacted with V2O5 only where it was in direct contact with the material. The affected area from the reaction was limited to the coating surface where V2O5 existed. The coating showed adequate hot corrosion-resistance. It was found on the 8YZ coating that Y2O3, the stabilizing component, particularly reacts with V2O5 and loses its function; this led to partial spalling of the coating. It was observed that the durability of the double layer TBC was largely influenced by the performance of a corrosion resistant NiCrAlY undercoat which provided protection against corrosive components penetrating through the ceramic topcoat. It was observed that the graded coating degraded due to oxidation of NiCrAlY particles which independently existed near the coating surface and affected the durability of TBC.
Micromechanical Analysis of Plasma Sprayed TBC: Anisotropic Elastic and Conductive Properties in Terms of Microstructure and Experimental Verification on YSZ Coatings
Authors: Sevostianov I. , Kachanov M. , Ruud J. , Lorraine P. , Dubois M. 
Published: September 2022

Abstract
Quantitative characterization of microstructures of plasma sprayed coatings, that accounts for their anisotropic and “irregular” character, is developed. An important finding is that “islands” of partial contacts along microcrack faces –even if they are very small - produce a strong effect on both elasticity and conductivity, thus reducing the “effective” microcrack density. Theoretical results are twofold: (1) conductive/elastic properties of the coatings in terms of the microstructure, and (2) conductive–elastic cross-property connections, that interrelate the anisotropic overall conductive and elastic constants. They can be utilized for “mapping” possible combinations of the two properties and, thus, for optimization of the microstructure for the combined conductive/elastic performance. Testing of the model against experimental data on YSZ coatings produces a good agreement.
Comparison of Particle In-Flight Characteristics and Coating Properties
Authors: Siegmann St. , Margadant N. , Zagorski A. , Arana-Antelo M. 
Published: September 2022

Abstract
In thermal spraying, the knowledge of process basic input parameters and their influence on the final coating properties is crucial. The optimization and reliability of atmospherically sprayed (APS) coatings, especially highly porous thermal barrier coatings (TBC), is closely linked to process understanding. This investigation aims to elucidate the correlation between the basic plasma spraying parameters (like current, plasma gas, stand-off distance, etc.) and the deduced physical dimensions like particle temperatures and velocities and the coating mechanical properties. Within this project, a large range of parameter field was chosen as long as stable plasma working conditions permitted. The influence of preparation on the microstructure analysis and data of mechanical coating measurements are shown.
Processing of Y-PSZ Thermal Barrier Coatings Implementing a High Power Laser Diode: Process Parameters
Authors: Antou G. , Hlawka F. , Cornet A. , Montavon G. , Coddet C. , Staerck J. , Fréneaux O. 
Published: September 2022

Abstract
Several studies have been undertaken recently to adapt Yttria Partially Stabilized Zirconia (Y-PSZ) thermal barrier coating (TBC) characteristics during their manufacturing process. Thermal spraying implementing laser irradiation appears as one of these possibilities to modify the coating morphology. This study aims at presenting the results concerning in situ (i.e., simultaneous treatment) and a posteriori (i.e., posttreatment) laser treatments implementing a high power laser diode. In both cases, the coatings were atmospheric plasma sprayed (APS). Laser irradiation was achieved using a 3 kW, average power, laser diode, exhibiting an 848 nm wavelength. Experiments were performed to reach two goals. First, laser post-treatments aimed at building a map of the laser processing parameter effects on the coating microstructure, in order to estimate the laser processing parameters, which seem to be suited to the change into in situ coating remelting. Second, in situ coating remelting aimed at quantifying the involved phenomena. In that case, the coating was treated layer by layer as it was manufactured. The input energy effect was studied by varying the scanning velocity (i.e., between 35 and 60 m.min-1), and consequently the irradiation time (i.e., between 1.8 and 3.1 ms, respectively).
Production of Composite Powder by Fluidized-bed Granulation Process and Evaluation of Sprayed Coating Properties
Authors: Kawase R. , Mizuma A. , Tanaka Y. 
Published: September 2022

Abstract
Ceramic / plastic composite powder (ceraplas powder) has been produced by Fluidized-bed granulation process (FG process) by varying the binder. Alumina (Al2O3) has been used as ceramics and Polyphenylene-sulfide (PPS) has been used as plastics. PPS has high heat and corrosion-resistant performance. Moreover, sprayed composite coatings have been evaluated by the observation of the coating microstructure, the thermal analysis, the corrosion test and the abrasive wear test. It has been recognized that sprayed composite coatings produced by FG powder have high corrosion-resistance and good wear resistance
Residual Stresses in Inconel 625 Coating of Organic-Based Composites Obtained by Plasma Spraying with Atmosphere and Temperature Control (ATC)
Authors: Henry B. , Borit F. , Guipont V. , Jeandin M. , Pachoutinsky D. , Lu J. , Welvaert E. 
Published: September 2022

Abstract
It is well known that residual stresses in plasma-sprayed coatings play a prominent role on coating-substrate adhesion in particular. This is all the more prominent because the coating is thick and adhesion intricate. The control and measurements of residual stresses in plasma-sprayed coatings onto organic-based substrates result in an issue of very high concern, even though very little (not to say nil) was published in this specific area. In this work, thick coating of a polyurethane resin with Inconel 625 was achieved by plasma spraying coupled with Atmosphere and Temperature Control (ATC), i.e. using cryogenic cooling to limit thermal degradation of the substrate when spraying. Residual stresses were determined by X-ray diffraction at the coating surface due to low X-ray penetration in nickel. In addition, residual stress in-depth profiles were obtained using the incremental hole drilling method. The investigation mainly focused on the measurement of residual stresses. In this paper, residual stresses were studied as a function of plasma spraying conditions. Results are discussed in the light of the coating microstructure. Residual stress measurements resulted in optimizing and controlling coating deformation and adhesion which are crucial for applications.
Optimal Substrate Preheating Model for Thermal Spray Deposition of Thermosets onto Polymer Matrix Composites
Authors: Ivosevic M. , Knight R. , Kalidindi S.R. , Palmese G.R. , Tsurikov A. , Sutter J.K. 
Published: September 2022

Abstract
High velocity oxy-fuel (HVOF) sprayed, functionally graded polyimide/WC-Co composite coatings on polymer matrix composites (PMC's) are being investigated for applications in turbine engine technologies. This requires that the polyimide, used as the matrix material, be fully crosslinked during deposition in order to maximize its engineering properties. The rapid heating and cooling nature of the HVOF spray process and the high heat flux through the coating into the substrate typically do not allow sufficient time at temperature for curing of the thermoset. It was hypothesized that external substrate preheating might enhance the deposition behavior and curing reaction during the thermal spraying of polyimide thermosets. An additional difficulty arises from the low thermal conductivity and low specific heat capacity of the PMC substrate, which prevent effective substrate preheating by the HVOF jet as in the case of metallic substrates. A simple analytical process model for the deposition of thermosetting polyimide onto polymer matrix composites by HVOF thermal spray technology has been developed. The model incorporates various heat transfer mechanisms and enables surface temperature profiles of the coating to be simulated, primarily as a function of substrate preheating temperature. Four cases were modeled: (i) no substrate preheating; (ii) substrates electrically preheated from the rear; (iii) substrates preheated by hot air from the front face; and (iv) substrates electrically preheated from the rear and by hot air from the front. Thermal properties of the polyimide needed for the simulations were determined by Differential Scanning Calorimetry (DSC) and Thermo-Gravimetric Analysis (TGA). Microstructural characterization of the coatings and the morphology of polyimide splats sprayed both with and without substrate preheating were analyzed using standard metallographic techniques. Coating temperature in cases (iii) and (iv) never dropped below the crosslinking temperature of the polyimide feedstock. This was the critical condition required for the curing reaction and successful deposition of thermosets by HVOF thermal spraying.