bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Shock Waves on Impact Velocity of Cold Spray Particles
Authors: Jodoin B. 
Published: June 2022

Abstract
The modeling of the cold gas dynamics spray process is conducted. The Navier-Stokes equations are solved for the gas flow, including turbulence model equations. The model is validated with experimental measurements for flows with and without shock waves. It predicts accurately the gas flow for both cases. A one-dimensional model is used to track the particles injected in the flow. It is shown that the effects of the shock wave present in front of the substrate are not negligible for small diameter particles and have a direct influence on their impact velocity. The spray stand-off distance is shown to have a direct effect on the flow structure and on the impact velocity of the particles. It is shown that the one-dimensional approach is not sufficient for the particle analysis.
Improvement in Wire Arc Spray by Super Sonic Cold Gas Jet
Authors: Sakaki K. , Shimizu Y. 
Published: June 2022

Abstract
In wire arc spray, atomizing gas is one of the most important parameters. The atomizing gas in wire arc spray is improved by using super sonic cold gas (non combustion gas) jet for better coating characteristics. To generate the super sonic cold gas jet, one is an optimization of nozzle shape with conventional compressed gas and another is that the pressed gas heated at 500-800K is supply to converging-diverging nozzle. Namely, coating deposition mechanism of cold spray, which is high particle impact velocity to substrate, is applied to wire arc spray. In this study, gas dynamics investigated the effect of pressure and temperature of supplied nitrogen gas, nozzle geometry on wire arc spray process (thermodynamical behavior of atomizing gas and coating properties).
HVOF Wire (HIJET) Sprayed Coatings of 0.8% C Steel—Its Structure & Applications
Authors: Modi S.C. , Calla E. 
Published: June 2022

Abstract
The high velocity combustion wire (HVCW) sprayed coatings have unique structures and properties which are different from the conventional wire / powder HVOF coatings. This paper studies the coatings of 0.8% C Steel formed by the HVCW system. 0.8% C Steel coatings formed by the HVCW system were studied for their wear resistance (pin on desk wear test) and phase composition. Methods like SEM with Wavelength Dispersion Spectroscopy (WDS) attachment were utilized for determining the composition of the coatings. Microhardness and tensile bond strength of the coatings were also ascertained. A set of conventional oxy-acetylene wire flame spray coatings of 0.8% C Steel were also prepared and these coatings were then compared with the HVCW coatings. Possible applications of the HVCW coatings are discussed based upon the properties of the coatings.
High Velocity Combustion Wire Spraying—Systems and Coatings
Authors: Kreye H. , Kirsten A. , Gärtner F. , Qi X. , Krõmmer W. 
Published: June 2022

Abstract
Thermal spray processes using wires as feedstock are widely used to produce wear and corrosion protective coatings of nickel, cobalt or iron based alloys. In general, these coatings are processed by flame or arc spraying. In view of using massive wires as spraying material, the hardness and wear resistance of layers is limited by the possibility to produce the corresponding wires of such materials. In addition, the performance of wire sprayed coatings can be restrained by the amount of defects in the microstructure, like pores, oxides and cracks, which are particularly evident in the cases of flame and arc spraying. New High Velocity Combustion Wire (HVCW) systems open the opportunity to reduce the amount and size of the defects by an increased particle velocity. Also, improvements on wear resistance may be achieved by using cored wires. The paper gives an overview on recent developments in HVCW spraying using massive and cored wires.
Process-Microstructure-Property Relationships in Controlled Atmosphere Plasma Spraying (CAPS) of Ceramics
Authors: Beauvais S. , Guipont V. , Borit F. , Jeandin M. , Español Pons M. , Khor K.A. , Robisson A. , Saenger R. 
Published: June 2022

Abstract
Thermal plasma spray processes with their various operating parameters can be considered as flexible technique to carry out appropriate ceramics coatings. This work deals with plasma spraying of several ceramics powders (hydroxyapatite (HA), Al2O3-TiO2, Al2O3, ZrO2-Y2O3 (YSZ) and Cr2O3) with suitable parameters using a CAPS system ("Controlled Atmosphere Plasma Spraying"). The HPPS (High Pressure Plasma Spraying), APS (Air Plasma Spraying) and IPS (Inert Plasma Spraying) modes were applied in order to obtain the suitable microstructure. The microstructures and phase compositions allowed to establish that surrounding high-pressure in the CAPS chamber is leading to a good heating of the powder and a good quality for the coatings.
Impact of Self Propagating High Temperature Synthesis of Spraying Materials on Coatings Based on Aluminium and Metal-Oxides
Authors: Bach Fr.-W. , Babiak Z. , Duda T. , Rothgardt T. , Tegeder G. 
Published: June 2022

Abstract
The properties of thermal sprayed coatings depend mainly on the thermal and kinetic energy of the spray particles. Increase of thermal energy of sprayed particles can be realized using exothermic reactions between components in sprayed particles. Self propagating high temperature synthesis (SHS) is especially suitable to benefit from released energy in the spraying process. At present most commonly used spray material with exothermal reaction is Ni+Al. However, the highest amount of heat is produced in the reactions of aluminium and metal oxides. Of special interest are Cr2O3, NiO, CuO and V2O5 because they obtain high reaction energies. Furthermore products of the reaction are of special, functional interest like NiAl as bonding agent or alumina as a wear resistant coating. To assure good contact between reacting substances (Al/Oxides) powders for plasma spraying were prepared by mechanical alloying. Calorimetric investigations of plasma sprayed coatings prove that during spraying Al reacts exothermically with oxides. Increase of oxide contents improves coating adhesion/ cohesion properties, hardness, and reduction of porosity. Results are discussed on the base of light microscopy, scanning electron microscopy (SEM) and X-ray structure analysis (XRD).
Reactive HVOF Thermal Spraying of Nanocrystalline Ni Powders
Authors: Lee J. , Ajdelsztajn L. , Lavernia E.J. , Kim N.J. 
Published: June 2022

Abstract
Ni powders prepared by mechanical milling under liquid nitrogen for 15 hr were sprayed using two stoichiometric ratios of the oxygen-fuel mixture in an effort to promote the formation of fine oxide phases. The oxide phases were introduced in an effort to improve mechanical properties and thermal stability of the coatings, via chemical reaction between oxygen and milled powders during flight and after impingement. The microstructure and properties of the milled powders and as-sprayed coatings were characterized by scanning electron microscopy, transmission electron microscopy and nanoindentation. The average grain size of the milled powders was 15.7 ± 5.1 run and ultrafine NiO and Ni3N particles with a size less than 5 run were distributed in the milled powders. These fine oxide and particles distributed in the powders were formed as a result of interaction between Ni, N from the milling slurry, and O from the surrounding environment under the energetic milling conditions. The coating microstructure was composed of nanocrystalline grains with an average grain size of 92.5 + 41.6 nm and extremely fine NiO particles of ~5 nm distributed homogeneously inside the grains. Ni3N phase was not found in the coating as it appears to have decomposed during HVOF thermal spraying. The coating sprayed with higher oxygen fraction in a hydrogen-oxygen mixture showed no significant increase in hardness and elastic modulus when compared to those of the coating sprayed with lower oxygen fraction in hydrogen-oxygen mixture. This was attributed to the small difference in the volume fraction of NiO particles between the coatings. These results indicate that new techniques of ultrafine dispersoid introduction in nanocrystalline coatings are potentially attractive as a means to improve the mechanical properties of the coating through reactive HVOF spraying.
Cryogenic Cooling in High Power Plasma Spraying
Authors: Dhers J. , Goubot N. , David T. , Baudoin J. 
Published: June 2022

Abstract
Thermal spray usually involves high temperatures in short times. This phenomenon is enhanced with the use of an HPPS system (Plazjet from Tafa). To spray a Zirconia coating, high powers are necessary such as 200 kW providing for the substrate an important increase in the surface temperature. Furthermore, the good quality of a thermal spray coating results in the low surface roughness, a satisfactory microstructure cohesion, a minimal distortion of the part when spraying on large sheets with a thick thermal barrier coating. Cooling with compressed air is widely used but other solutions are studied concurrently; CO2, nitrogen, and air; these gas are tested in different conditions of pressure and flow. Some improvements in terms of temperature in the coating and roughness have been found.
On the Adhesion Mechanisms of Thermal Spray Deposits Manufactured While Implementing the PROTAL Process
Authors: Verdier M. , Montavon G. , Costil S. , Coddet C. 
Published: June 2022

Abstract
Excepted in a few cases where metallurgical bonding occurs between deposit and substrate, thermal spray deposit adhesion generally results from a mechanical anchoring. In this case, the very first impinging particles forming the first deposited layer spread and solidify into and around the cavities of the grit-blasted surface. A palliative process to degreasing and grit-blasting prior to thermal spraying is simultaneous laser ablation; i.e., the PROTAL process. In such a case, little topographic change results from the laser-matter interaction: deposit adhesion does not derive anymore mainly from mechanical anchoring but from other types of bonding such as chemical bonding. This paper aims to clarify the bonding mechanisms of thermal spray coatings manufactured implementing the PROTAL process. The case of metallic coatings deposited on metallic substrates is especially discussed. At first, laser ablation effects on various metallic substrates are presented, from the topographic and energetic points of view. Then, the induced effects on impinged particle morphologies are discussed. The results are correlated to thick deposit adhesion.
Influence of Laser Glazing on the Characteristics and Tribological Performance of Plasma and Detonation Sprayed WC-Co Coatings
Authors: Joshi S.V. , Thawari G. , Kumar L.S. , Sen D. , Sundararajan G. 
Published: June 2022

Abstract
This paper deals with a comprehensive evaluation of the laser glazing or re-melting route as a possible means of specifically enhancing the performance of thermal sprayed WC-Co coatings. In the present study, a high-power continuous-wave 9kW CO2 laser was utilized for laser treatment of plasma sprayed as well as detonation sprayed WC-Co coatings. The influence of the two most important laser-related variables, namely laser power and scan speed, on the properties of the laser-treated layers was investigated. Both mere surface densification by melting a thin top layer of the coating as well as melting of the entire portion of the coated layer were targeted during laser treatment. In each case, the laser treated coatings were fully characterized by optical microscopy, scanning electron microscopy, and microhardness measurements. In addition, the influence of laser processing on the elemental distribution, phase constitution and extent of defects in the treated layers was investigated. The tribological performance of the laser-glazed coatings was also evaluated and compared against the performance of their as-sprayed counterparts. The study has revealed significant differences between the response of plasma and detonation sprayed WC-Co layers when subjected to laser treatment. The potential of plasma-sprayed coatings to match the performance of the inherently superior detonation sprayed coatings by adopting laser glazing as a post-processing step has also been assessed.
Preparation of Bioactive and Porous Titanium Coating by Vacuum Plasma Spraying and Chemical Treatment
Authors: Shi J.M. , Ding C.X. , Wu X.Q. 
Published: June 2022

Abstract
This article describes a method of preparing bioactive and porous titanium coatings on titanium-based substrate using vacuum plasma spraying and chemical treatment in alkali solution. The porous titanium coating was fabricated in two-layer structure. The bond strength, average porosity and roughness (Ra) of the porous titanium coating are 55MPa, 30% and 21µm, respectively. The chemical treatment of as-sprayed titanium coatings was carried out in 5.0M NaOH solutions at 40 °C for 24h. The surface morphology and structure of the porous titanium coating before and after chemical treatment were examined by SEM and laser Raman spectroscopy. The treated titanium coating was immersed into SBF to evaluate its bioactivity by examining apatite formation on its surfaces. It was observed by SEM and TF-XRD that apatite was formed on the surface of the treated titanium coating after immersion in SBF. The spherical aggregates gradually grew large by consuming calcium and phosphate ions in SBF and covered the surface with increase in soaking time. Incorporation of CO32- ions into apatite crystal lattice was revealed by FT-IR. The results obtained indicated that net-like sodium titanate formed due to NaOH attack was responsible for apatite nucleation and growth. It is concluded that vacuum plasma spraying and subsequent chemical treatment is an effective way to produce bioactive and porous titanium coatings.
Evaluation of Sealants on Al-Zn Alloy Sprayed Coating by Galvanostatic Technique
Authors: Tanaka M. , Takatani Y. 
Published: June 2022

Abstract
The sealing effect of various sealants applied to sprayed coatings in sodium chloride aqueous solution was investigated with the galvanostatic technique in which the same quantity of electricity is fed to each test material coated with sealant film cut crossly. The amount of dissolved sprayed coating sealed with sealant can be obtained as the difference between the dissolved material volume at the crosscut part and that in the solution. From the result it was found that the higher the sealing effect of sealant the more aluminum is dissolved from the sprayed coating at the crosscut part, which is considered to mean in case of the sealant poor in sealability, sprayed coating is dissolved even where it is coated with sealant and electrolytic current is dispersed. This proves that the galvanostatic technique is effective in evaluating the sealing effect of sealants.
On the Microstructure of Vacuum Plasma Sprayed Cu-3%Ag Alloy
Authors: Dembinski L. , Grosdidier T. , Coddet C. 
Published: June 2022

Abstract
This study was undertaken to investigate the influence of the initial powder particle size on the microstructure development in a Cu-3wt% Ag alloy obtained by vacuum plasma spraying of a mixture of copper and silver powders. Various mixtures of powder particles were used where the copper powder particle size was kept as –80/+40 μm, while the silver powder particle size fraction was varied. Vacuum plasma spraying (VPS) in inert gas atmosphere was used to elaborate thick coatings (2 mm) with limited oxygen contamination. Significant variations in microstructure were obtained depending on the Ag powder size fraction that was used. These differences in behavior are discussed taking into account differences in the solid state precipitation mechanisms in the alloy.
The Effect of Off-Angle Spraying on the Structure and Properties of HVOF WC/CoCr Coatings
Authors: Ruggiero P.F. , Strock E. , Reynolds D. 
Published: June 2022

Abstract
The aerospace industry currently applies high velocity oxy-fuel (HVOF) coatings to turbine engine, structural, and landing gear components. An increasing demand for HVOF wear resistant coatings to replace electrolytic hard chrome (EHC) on landing gear components has renewed focus on the spray limitations of HVOF WC/CoCr. One such limitation resulting from the line-of-sight HVOF process is the spray angle. In this study, HVOF WC/CoCr coatings were sprayed at several angles while maintaining consistent combustion characterisitics and standoff distance. The measured responses included tensile bond strength, microhardness, residual stress, coating surface roughness, and dry fretting wear resistance. Fatigue response was also of interest, but no results were available at the time this paper was written. The microstructure of each coating was examined, both normal to the surface and in cross section. Coatings sprayed at 90° exhibited the highest microhardness and most compressive residual stress, both considered favorable for good wear response. But these coatings also exhibited the highest as-sprayed roughness, least homogeneous microstructure normal to the surface, and lower wear resistance compared to the off-angle coatings; however, the off-angle coatings apear to cause greater wear of the contacting surface. The microstructural differences among the coatings are related to the measured responses.
Effect of Spraying Distance on Plasma Deposit’s Behavior
Authors: Ctibor P. , Rohan P. , Chráska P. 
Published: June 2022

Abstract
Spraying distance (SD) is one of the main parameters that can affect the spraying process - its efficiency as well as deposit's character. The reason lies in a different thermal history of particles corresponding to different spraying distances. Variation in the structure, preferred orientation, variation of the phase contents and/or in the chemical composition of deposits can be then found for different SDs. Consequently, properties of coatings can greatly vary, not only in the resistance state but also on deposit's annealing. Some materials are, however, more and some less sensitive to that effect. The goal of this work is to compare CaTiO3 samples produced by plasma spraying with WSP at SD = 350 and 450mm with sintered samples. The following properties were compared: microhardness, thermal expansion coefficient, permittivity and reflectivity. Porosity and the differential thermal analysis of resistance and annealed deposits were also compared. Perovskite CaTiO3 belongs among materials very stable during spraying - neither chemical nor phase differences were found between the feedstock powder, free-flight particles, as-sprayed deposit and annealed deposit. Despite that there are significant differences in behavior of deposits and freestanding parts sprayed from different SDs. All the recorded differences for CaTiO3 plasma sprayed deposits with varying SDs must be therefore accounted to the deposit's structural differences, such as pore and splat sizes and shapes and preferred orientation. Additional differences on annealing can be probably attributed to the different amount of "stored" thermal energy in deposits due to the varying SD. However, there is a lower limit for SD assuring a quality deposit on spraying.
Atmospheric Plasma Spraying of Ti Particles — In-Flight Particle Reactivity — Coating Properties
Authors: Ponticaud C. , Grimaud A. , Denoirjean A. , Lefort P. , Fauchais P. 
Published: June 2022

Abstract
Titanium powder has been sprayed with nitrogen or Ar/H2 d.c. plasma jets flowing in air. Particles have been collected at several distances downstream of the nozzle exit. In the first 40- 60 mm, convective movements created within the liquid droplets entrain homogeneously nitrogen and oxygen in the particle cores. Farther downstream, convection is less important and absorption of nitrogen and oxygen is controlled by diffusion from the particles surface. After solidification induced by high quenching rates (in the order of 10 K/s) due to different cooling means, particles are composed by a superficial layer which is an oxi-nitride of titanium and in their core by a solid solution α-Ti containing both nitrogen and oxygen.
Ensemble In-Flight Particle Diagnostics Under Thermal Spray Conditions
Authors: Bisson J.F. , Lamontagne M. , Moreau C. , Pouliot L. , Blain J. , Nadeau F. 
Published: June 2022

Abstract
The Accuraspray is a new in-flight particle sensor that provides information on the average in-flight particle temperature, using two-color pyrometry, and velocity, using a cross-correlation calculation. Various aspects influencing the reliability of the sensor estimates are studied. First, the sensitivity of the temperature and velocity estimates to the positioning of the sensor with respect to the particle jet, such as the angular orientation of the fibers and the working distance to the spray plume, is evaluated. Then, the influence of the plasma radiation on the temperature measurement is estimated. This influence can be reduced significantly by filtering out the low frequency components of the pyrometric signals, which contain most of the plasma fluctuations. Finally, a lower limit in the signal-to-noise ratio (SNR), for which an acceptable temperature estimate is obtained, is evaluated. A valid velocity estimate can still be obtained with a lower SNR. All these studies were performed under various spraying conditions, including plasma spraying and HVOF, using various feedstock materials (YSZ, Al-Si, cermets).
Control of Plasma Sprayed Particles Temperature and Velocity by Chamber Pressure
Authors: Sodeoka S. , Suzuki M. , Inoue T. 
Published: June 2022

Abstract
The effect of chamber pressure on the temperature and the velocity of the plasma sprayed particles was measured quantitatively through the chamber window. As the chamber pressure increases, the plasma flame shortens. At the same time, the particle slows down and the particle temperature increases. The multivariate analysis among the spray parameters and the measured values reveal that the particle temperature and the particle velocity can be controlled individually as a function of the chamber pressure and the spray distance. The zirconia coatings were fabricated by controlling the particle temperature and velocity at the impinging upon the substrate individually. Increase of the particle temperature increased the deposition efficiency, the density and the hardness of the coating. On the other hand, increase of the particle velocity up to a certain value also increased them, but the excessive velocity decreased them. Because the shortened dwelling time prevented the powder core from melting, even if the surface was sufficiently heated.