bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nucleation and Phase Selection in Plasma-Sprayed Alumina: Modeling and Experiment
Authors: Robert C. , Denoirjean A. , Vardelle A. , Wang G.-X. , Sampath S. 
Published: May 2021

Abstract
This paper presents a one-dimensional heat transfer model which predicts the solidification and cooling of a plasma-sprayed alumina splat after the flattening process is completed. A heterogeneous nucleation process taking place on the substrate surface was assumed. The density and average size of the formed nuclei were determined from the integration of the nucleation rate calculated from the classical kinetic theory for nucleation. This rate depends on the activation energy required for nucleation which takes into account the effect of the surface via a wetting angle between the growing nucleus and the catalytic surface. This contact angle was estimated from the comparison of the computed grain density with the density observed on splat surface using an atomic force microscope. When 67% of the splat surface in contact with the substrate are covered by grains, a planar solidification front was assumed to move through the melt. The theoretical model accounted also for the selection of the crystalline phase. Calculations were performed for various substrate materials at different initial temperatures. Results are expressed in terms of nucleation temperature, nucleation rate, density and grain size distribution.
Effects of Gun Nozzle Geometry on High Velocity Oxygen-Fuel (HVOF) Thermal Spraying Process
Authors: Sakaki K. , Shimizu Y. , Gouda Y. , Devasenapathi A. 
Published: May 2021

Abstract
Effect of nozzle geometry (such as throat diameter of a barrel nozzle, exit diameter and exit divergence angle of a divergent nozzle) on HVOF thermal spraying process (thermodynamical behavior of combustion gas and spray particles) was investigated by numerical simulation and experiments with Jet Kote II system. The process changes inside the nozzle as obtained by numerical simulation studies were related to the coating properties. A NiCrAlY alloy powder was used for the experimental studies. While the throat diameter of the barrel nozzle was found to have only a slight effect on the microstructure, hardness, oxygen content and deposition efficiency of the coatings, the change in divergent section length (rather than exit diameter and exit divergence angle) had a significant effect. With increase in divergent section length of the nozzle, the amount of oxide content of the NiCrAlY coatings decreased and the deposition efficiency increased significantly. Also, with increase in the exit diameter of the divergent nozzle, the gas temperature and the degree of melting of the particle decreased. On the other hand the calculated particle velocity showed a slight increase while the gas velocity increased significantly.
Mathematical and Computer Modeling of Particles Interaction with Plasma Jet in Low Pressure Condition
Authors: Ilyuschenko A. , Okovity V. , Kundas S. , Gurevich V. 
Published: May 2021

Abstract
On the base of gases molecular and kinetic theory a mathematical model of interaction between powder particles and plasma jet is developed. Three-dimensional description of plasma forming gas density distribution as well as particle motion in the plasma jet are a characteristic property of the model. A software for practical realization of the mathematical model is created. Said software provides the possibility to investigate an effect of low-pressure plasma spraying parameters on particle velocity and coordinates in the plasma jet. Computer simulation of particle velocity for powders from aluminium and tungsten oxides in argon plasma under 60 Mbar is conducted. A "Plasma-Technik" VPS unit is used for testing the developed model. Particle velocity measurement is made by a specially developed optical-electronic unit.
Characteristics of Residual Stress Produced by MoSi2 Plasma Spraying and Its Production Mechanism
Authors: Kim Y.C. , Chang K.H. , Horikawa K. 
Published: May 2021

Abstract
MoSi2 powder was deposited by low pressure plasma spraying on the specimen with 50%Ni-50%Cr based coat after blasted SS400 substrate. Compressive stress was generated in MoSi2 spray deposit. Tensile stress was generated in 50%Ni-50%Cr spray deposit. Large compressive stress was generated in SS400 substrate adjacent to the interface. Investigating the production mechanism of residual stress and the validity of provided residual stress, a series of the experiments were done. Blasting on the substrate, residual stress near the surface of the substrate was compressive and that of the inner part of the substrate was tensile. After the blast treatment on SS400 substrate, depositing on the substrate with 50%Ni50% Cr, residual stress of the spray deposit was tensile. This is because SS400 substrate restricts the contraction of 50%Ni-50%Cr spray deposit which has large thermal shrinkage. Depositing MoSi2 after the blast treatment, compressive stress was generated in the spray deposit. This is because the linear expansion thermal coefficient of MoSi2 is extremely small comparing with that of SS400 substrate nevertheless the temperature of the spray deposit is higher than that of the substrate. As the result, the spray deposit restricts thermal shrinkage of the substrate. The validity of estimated residual stress was shown.
Evaluation of Residual Stresses and Fatigue Life of Tungsten Carbide Thermal Spray Coated Aircraft Landing Gear Materials
Authors: Mcgrann R.T.R. , Shadley J.R. , Rybicki E.F. , Bodger B.E. , Emery W.A. , Somerville D.A. , Greying D.J. 
Published: May 2021

Abstract
Tungsten carbide thermal spray coatings have been used for more than twenty years in the commercial aircraft industry in applications such as turbine blade and flap-track wear surfaces. Additionally, the evaluation of tungsten carbide (WC) coatings to replace chrome plating in other aircraft applications has been underway for several years. For example, WC coatings applied by the high velocity, oxy-fuel (HVOF) process are being evaluated for use on aircraft landing gear parts. One factor that affects the suitability of WC coatings is the fatigue life of the coated part. This study compares the fatigue life of electrodeposited chrome plated specimens to the fatigue life of WC HVOF-sprayed specimens on aircraft landing gear alloys. Fatigue tests were run on cantilever flat beam specimens coated on one side and subjected to bending fatigue loads. Residual stress levels for the coatings were determined using the Modified Layer Removal Method on rectangular residual stress specimens processed with the flat beam specimens. Also, the Young's modulus and Poisson's ratio of the coating were determined using the Cantilever Beam Bending Method performed on beam specimens that were processed with the fatigue specimens and the residual stress specimens. Results indicate that certain levels of residual stress in the coating can enhance the fatigue life of the parts. The fatigue lives in bending tests of several WC coated specimens are compared with the fatigue life of chrome plated specimens.
Surface Morphology of Plasma Sprayed Ceramic Coatings
Authors: Oki S. , Gohda S. , Yamakawa M. 
Published: May 2021

Abstract
A novel method for characterization of microstructure of coatings is presented. Properties of plasma spray coatings are affected by their microstructure, which depends on the spraying conditions. Therefore, a detailed knowledge of microstructure is very important in order to know the coating formation mechanism and the properties of the coatings. There are many studies to characterize the microstructure of coatings. In most of those studies, the microstructures are characterized from the polished cross-section of the coatings, and the results strongly depend on the preparation methods. In this study, a new method for the characterization of coating microstructures by means of surface morphology is proposed. The distribution of shape and dimensions of splats were examined using quantitative analysis of scanning electron microscope images from the surface of the coatings. The results indicate that the surface morphology strongly depends on the spraying conditions. Keywords: characterization, coating property, splat morphology, equivalent diameter, shape factor
Characterization of Graded Ti Silicide Coating Formed by Thermal Diffusion Treatment of Low Pressure Plasma Sprayed Silicon Coating
Authors: Ohmori A. , Zhou Z. , Li C.J. 
Published: May 2021

Abstract
The silicon coating was sprayed on titanium substrate by low pressure plasma spraying and the subsequent coating was heat-treated in vacuum. It is found that a titanium silicide coating with the composition changed gradually can be formed through thermal diffusion treatment of silicon coating sprayed by low pressure plasma on titanium substrate. The formed silicide coatings are characterized by optical microscopy, scanning electron microscopy, EPMA analysis and X-ray diffraction (XRD). The forming process of the silicide coating is investigated by examining the relationship between silicide coating thickness and thermal diffusion parameters. The results show that the composition of silicide coating changes gradually from TiSi, at the silicon coating side through TiSi and Ti5Si4, to Ti5Si4, near substrate side. The thickness of such graded silicide coating is determined by temperature and holding time during heat-treatment. The diffusion of silicon into titanium substrate is mainly responsible for the formation of silicide. Moreover, the investigation of oxidation behavior of silicide coating shows that the formation of silicide coating on the titanium substrate can improve the oxidation resistance of titanium.
Microstructure Development During Plasma Spraying of Molybdenum Part 1: Splat Solidification
Authors: Robert C. , Vardelle A. , Wang G.-X. , Jiang X.Y. , Sampath S. 
Published: May 2021

Abstract
Within the framework of a scientific collaboration between the University of Limoges, France and the State University of New York, Stony Brook, USA, a joint work has been conducted on microstructure development and properties of plasma-sprayed molybdenum coatings. This first part of the work is devoted to the study of the effect of substrate nature and temperature on splat cooling, solidification and crystalline structure. They were investigated by means of a heat transfer model in the splat and the substrate, and the observation of splats by a scanning electron microscope and an atomic force microscope. The model takes into account melt undercooling, nucleation and crystal growth, as also a possible melting and re-solidification of the substrate. It has the capability to predict the grain size distribution under assumptions that the quality of contact between the splat and the underlying layer is uniform, nucleation takes place only on the substrate surface, crystal grains grow perpendicular to the substrate surface and no grain coalescence occurs during crystal growth.
Influence of Plasma Gas (Spral 22, Ar/H2) and Impurities (O2, H2O) on the Electrode Lifetime During Spraying
Authors: Gourlaouen V. , Remy F. , Leger J.M. , Sattonnet J. 
Published: May 2021

Abstract
Electrodes play an important role in the plasma-spraying process and must be frequently replaced to ensure good coating properties. The purpose of this work was to assess the effect of different plasma gases and oxygen and humidity levels on electrode lifetime. The change in arc voltage over time was recorded during spraying, and the elapsed time for a 5V drop was taken as the electrode lifetime. It was found that variations in oxygen and humidity in Ar-H2 gas mixtures have a major effect on lifetime and that the use of SPRAL22 gas could extend electrode life by a factor of three to four. These and other results are discussed in the paper.
Non-Contact Coating Thickness Measurement
Authors: Chandler P.E. , Quigley M.B.C. , Fletcher J.F. 
Published: May 2021

Abstract
There are many instances of coatings that require a nondestructive and non-contact measure of coating thickness as part of a quality control system. Specifically, this paper reports on experiments carried out on non-contact measurements of MCrAlY and TBC coatings. The system uses an infrared beam from a solid state laser to generate a thermal wave in the coating. When this wave reaches the substrate an interference effect is caused. The modulated input heating produces a modulated output infrared signal from the surface and at a different wavelength from the laser beam. The output signal has a phase difference from the input signal which is related to the coating thickness. As neither the laser nor the detector are in contact with the surface of the coating and the temperature of the coating is raised by only a few degrees this represents a non-contact NDE system. This system has been tested across a range of coating/substrate combinations. In this paper we give examples of MCrAlY and TBC coatings applied to engine components demonstrating that the accuracy of measurement is only limited by the roughness of the coating structure and substrate. The use of this system for on-line measurement during the spraying process is also discussed and results presented.
Thermo-Mechanical Characterizations of Plasma-Sprayed MCrAlY Coatings for HP Turbines
Authors: Boudot A. , Crabos F. , Monge-Cadet P. , Monceau D. , Pieraggi B. 
Published: May 2021

Abstract
Two different coatings were studied in this work : vacuum plasma-sprayed NiCoCrAlYTa and electrodeposited NiCoCrAlYTa. These coatings were deposited on AM3 single crystal alloy. The tensile and creep properties of coated single crystal test specimens were investigated. Ductile-brittle transition temperatures (DBBTs) were determined from tensile tests. Creep tests were performed on cylindrical specimens and on thin flat specimens. All the coatings were examined before and after testing. The two tested coatings induce a ductile/brittle transition. Strain rate has a great influence on the transition temperature. The comparison between the two processes of deposition illustrates the strong influence of coating microstructure. A marked decrease in creep properties was observed for thin single crystal specimens but contrary to cylindrical specimens, the coating has a quite positive influence, so that the creep life of coated thin specimens is increased.
A New Aluminium Silicon-Boron Nitride Abradable for Compressor Components
Authors: Boddenberg K. , Kock B. , Dorfman M. , Russo L. , Nestler M. 
Published: May 2021

Abstract
Air separation plants employ centrifugal compressors where air and electrical energy are the only raw materials used in the production process. In order to optimize compressor performance and efficiency, abradable coatings, originally developed for gas turbines, have been designed into turbocompressors. This paper describes the optimization and performance improvements achievable using aluminium silicon-boron nitride materials.
HVOF-Spraying vs. Hard Chrome Plating – Coating Characteristics and Aircraft Applications
Authors: Nestler M.C. , Prenzel G. , Seitz T. 
Published: May 2021

Abstract
High-velocity oxyfuel (HVOF) spraying is a viable alternative for hard chrome plating because of its excellent coating properties and substantially lower environmental pollution. Initial applications in ball valves, journals, and hydraulic cylinders on earthmoving equipment have proven successful. This paper discusses the advantages and disadvantages of HVOF spraying as an alternative to hard chrome plating for aircraft components and presents some of the early results of laboratory and in-service testing.
Influences of Metal Sprayed Coating Artificial Dental Root on the Vital Tissue
Authors: Magome M. , Hara K. , Sano K. , Ueda Y. 
Published: May 2021

Abstract
Artificial dental root materials are of great interest to medical researchers. In this study, two aluminum coating methods are investigated, atmospheric plasma and flame spraying, along with the affinity, stability, and connectivity of aluminum-based toxins. Acute toxic tests performed in vivo and in vitro show that aluminum sprayed coatings are a viable dental root material.
Nitriding of Metal Droplets in Synthesis of Intermetallic Matrix Composite Coatings by Reactive RF Plasma Spraying
Authors: Tsunekawa Y. , Hiromura M. , Okumiya M. 
Published: May 2021

Abstract
This paper presents a novel process that uses RF plasma spraying and premixed elemental powders to produce intermetallic matrix composites in situ without having to add reinforcement fibers or particles. Splats were collected on a stainless steel substrate and were analyzed to determine if nitrides had formed in metal droplets during flight and how it affected splat morphology. The typical splat morphology of impinged Ti droplets is disk-type with an outer peripheral fringe. Aluminum splats, on the other hand, are classified into two categories: a disk-type with an irregular outer periphery and a semi-massive-type. Other composites produced and examined include TiAl, AlN, and Ti2AlN.
Investigations on Thermal Spraying of Silicon Nitride-Based Powders
Authors: Berger L.-M. , Herrmann M. , Nebelung M. , Thiele S. , Heimann R.B. , Schnick T. , Wielage B. , Vuoristo P. 
Published: May 2021

Abstract
Oxide-bonded silicon nitride (OBSN) powders have been developed to address thermal spray problems associated with high temperatures. This paper examines how such powders perform when applied via detonation gun (DGS) and atmospheric plasma spraying (APS) with axial powder injection. All coatings were characterized using optical microscopy and X-ray diffraction with additional tests being performed on DGS coatings. For the first time, relatively dense Si3N4-rich coatings with an oxide binder phase were produced, and some of the DGS coatings were found to be sufficiently wear resistance for industrial use.
On The Fabrication and Properties of a Ceramic Cladded Aluminium Powder Using the Spray Drying Process
Authors: Comas B. , Mateus C. , Hansz B. , Coddet C. 
Published: May 2021

Abstract
A new family of spherical powders produced by the spray drying route has been developed. This paper describes as an example the manufacturing method of an Y2O3-coated aluminum powder. Atmospheric Plasma Spraying (APS) was used to test the corresponding coatings. Morphology and phases of powders and coatings were investigated by optical and scanning electron microscopy while the level of porosity was evaluated using image analysis. Results show that homogenous composite coatings can be obtained from cladded spray dried powders.
Thermal Stability of Nanocrystalline Inconel 718 and Ni Prepared by High Velocity Oxy-Fuel (HVOF) Thermal Spraying
Authors: Jiang H.G. , Lau M.L. , Lavernia E.J. 
Published: May 2021

Abstract
Nanocrystalline Inconel 718 and Ni powders were prepared using two approaches: methanol and cryogenic attritor milling. High velocity oxy-fuel (HVOF) spraying of milled Inconel 718 powders was then utilized to produce Inconel 718 coatings with a nanocrystalline grain size. Isothermal heat treatments were carried out to study the thermal stability of the methanol milled and cryomilled Inconel 718 powders, as well as the HVOF Inconel 718 coatings. All nanocrystalline Inconel 718 powders and coatings studied herein exhibited significant thermal stability against grain growth as evidenced by a grain size around 100 nm following annealing at 1273 K for 60 min. In the case of the cryomilled nanocrystalline Ni powders, isothermal grain growth behavior was studied, from which the parameters required for the prediction of the microstructural evolution during a non-isothermal annealing were acquired. The theoretical simulation of grain growth behavior of nanocrystalline Ni during non-isothermal annealing conditions yields results that are in good correspondence with the experimental results.
CO2 Cooling in Thermal Spraying
Authors: Gourlaouen V. , Remy F. , Hansz B. , Coddet C. 
Published: May 2021

Abstract
Thermal spraying involves high temperatures which can be a serious problem for some applications. Among different possibilities existing to cool down a specimen during spraying, the use of liquid CO2 is one of the most attractive. However, care has to be taken to obtain good results due to the specific characteristics of CO2. Moreover, there are still some remaining problems which limit the growth of such system. One of the most important is the condensation of air humidity at the exit of the atomising nozzle. Therefore, a new design of the nozzle has been developed. This design avoid ice building up and can be easily fixed on any kind of spraying set up. Examples of working conditions are presented.
Refractory Carbide Coatings Sprayed by Electrothermal Explosion of Conductive-Ceramic Powders
Authors: Soda T. , Tamura H. , Sawaoka A.B. 
Published: May 2021

Abstract
This paper examines the properties of thermal spray coatings produced by electrothermal explosion. Three refractory carbides (TaC, WC, and TiC) were sprayed onto metal substrates then analyzed using FESEM, EPMA, XRD, and microhardness testing. The new spray technique required the development of a special powder container to facilitate melting as well as the jetting process and mixing of deposit and substrate materials. Crystal structure and phase changes were also observed, which are attributed to decarburization.
Basic Research for Reactive Plasma Spraying of TiO2
Authors: Suzuki M. , Sodeoka S. , Inoue T. , Ueno K. 
Published: May 2021

Abstract
Reactive Plasma Spraying (RPS) is one of several new plasma spray processes. Although several papers have been published on this technology, they are limited in scope to metal powders, such as Ti, Cr, and Si, and coatings composed of metal and non-oxide ceramics. When oxide powders are used among starting materials to fabricate metal or nonceramic coatings, it is important to understand and account for the reduction of oxides during spraying and the chemical reaction among the powder, plasma, and atmospheric gas. The work presented in this paper focuses on the reduction of plasma-sprayed TiO2 and how it is influenced by the amount and type of plasma and chamber gas used, the addition of carbon powder, and process parameters such as chamber pressure.
Prebrazing of Ceramics by Plasma Spraying for Metal-Ceramic Joining
Authors: Kara-Slimane A. , Treheux D. 
Published: May 2021

Abstract
Traditional brazing alloys do not wet ceramics and are therefore unusable for metal-ceramic bonding. One way to overcome the problem is by depositing a metal layer onto the ceramic prior to brazing. The approach taken in this paper was to plasma spray copper onto different ceramics (Al2O3, AlN, SiAlON) and then assess the wettability of potential brazing alloys (AgCu, AgCuTi). Interface analysis showed that silver and titanium segregation occurs at the ceramic surface and that, conversely, sprayed copper diffuses into the brazed joint.
Influence of Bondcoat Surface Characteristics on the Performance of TBC Systems
Authors: Knight R. , Smith R.W. , Zhangxiong D. , Kim E.-H. , Sahoo P. , Bucci D. 
Published: May 2021

Abstract
The objective of this study was to investigate the effects of thermal spray process selection and corresponding bondcoat surface roughness on thermal barrier coating (TBC) performance. TBC's consisting of a 300 µm (12 mil) thick air plasma sprayed (APS) top coating of ZrO2-8 Wt.% Y2O3 and CoNiCrAlY bondcoats deposited by three different thermal spray processes were produced and their surface roughness characterized. The bondcoats were deposited using low pressure plasma spray (LPPS), shrouded air plasma spray (SPS) and high velocity oxy-fuel (HVOF) combustion spray. Bondcoat surface profiles were measured by profilometric and interferometric techniques and surface roughness values calculated. TBC performance was evaluated by adhesive bond strength testing, thermal shock and thermal cycling testing, and microstructural analysis. Results showed that the bondcoat deposition process used and corresponding surface roughness had significant effects on the adhesive strength, thermal shock and thermal cycling lifetime, and failure mechanisms.