bluuebunny/crossref_metadata_2025_split huggingface dataset:
New Thermal Spray Coating Technology for Corrosion/Erosion Protection
Authors: Ferree Bill 
Published: September 2022

Abstract
A laminated coating, using the thermal spray and other processes, protects a metal substrate in a highly corrosive and highly erosive environment. The combination of noble metals and ceramics offer highly bonded, pore free coatings for demanding industrial applications. This paper offers case examples to exemplify some success stories.
Plasma Spraying with Low Power Consumption and High Efficiency
Authors: Gao Yang 
Published: September 2022

Abstract
An innovative plasma spraying technology has been developed with low power consumption and high deposition efficiency. The plasma torch was operated at arc currents from 50 to 150A and voltages from 50 to 80V. The powder particles were injected into the arc region from the inside of nozzle entry by the carrier gas that then transferring through the plasma flame. The ceramic coatings of Cr2O3 and ZrO2- Y2O3 were created at power consumption less than 10kW and powder feed rate of 30-50g/min. The deposition efficiency could reach 70%, higher than that of 40kW APS with an external powder feed. In addition, the enthalpy, temperature and velocity of low power plasma jet were also measured by an enthalpy probe.
High-Pressure, Non-Pulsing Powder Feeder for Cold Spray and Thermal Spray Processes
Authors: Roemer Timothy J. , Beatty D.E. , Mayer A.J. , Papyrin A.N. , Blose R.E. , Nichols R.T. 
Published: September 2022

Abstract
The rapid emergence of cold spray technology provides numerous applications that require spraying fine (&lt;10 microns) powders, providing more uniform deposition, improved measurement of deposition efficiency and quick turn around time. The performance of high-pressure commercial powder feeders, currently available, lacks one or more of these desired performance characteristics. Further, researchers are interested in spraying many powders of different materials or particle size distributions where the powder feeder can be quickly and easily cleaned without replacing expensive consumables. The Ktech laboratory powder feeder has been designed to operate under a wide variety of carrier gas pressures (0 – 500 psig). This laboratory feeder delivers a continuous flow of powder, has a variable canister volume and is quick and easy to clean. This unique design facilitates short run research applications or higher volume extended run time dispensing. The feeder is designed to operate in either a locally or remotely through a PC based Ethernet connection. The laboratory powder feeder represents an excellent tool for high-pressure cold spray or low-pressure thermal spray processes requiring the delivery of fine powders.
Preparation of TiO2 Photocatalyst by Thermal Spraying with Liquid Feedstock
Authors: Yang G.-J. , Li C.-J. , Han F. , Mao S.-F. 
Published: September 2022

Abstract
TiO2 is the most promising photocatalyst to decompose industrial pollutants in water and air. Compared with TiO2 powder, the immobilized form is more suitable for application. In the present paper, the nanostructured TiO2 photocatalyst is formed by thermal spraying with liquid feedstock. The microstructure of the nanostructured TiO2 is characterized by infrared spectrum, X-ray diffraction, scanning electron microscope, and transmission electron microscope. The photocatalytic performance is characterized with photodegradation of phenol in aqueous solution. The effects of annealing treatment on the crystalline structure of the TiO2 deposit and the photocatalytic performance are investigated. The results showed that TiO2 photocatalyst deposited by thermal spraying with liquid feedstock presents nanostructure and anatase crystalline structure mainly. The crystalline structure of TiO2 deposit can be controlled by post annealing treatment. The as-sprayed TiO2 coating can decompose phenol in water with the presence of H2O2 and UV light. Phenol can be destroyed easily while the complete mineralization takes a little more time. Annealing treatment can improve the photocatalytic performance of TiO2 coating. The present results revealed that the TiO2 coating in rutile structure presents a better photocatalytic performance compared with as-sprayed TiO2 coating in anatase structure.
Study on Alumina-based Nano Composite Coating Prepared by Plasma Spray
Authors: Suzuki M. , Sodeoka S. , Inoue T. 
Published: September 2022

Abstract
In order to obtain nano-structured ceramics composite coating for high temperature application, pre-mixed Al2O3/Y2O3 powders were plasma-sprayed in this study. Plasma spraying of spray-dried Al2O3/Y2O3 powder resulted in the formation of amorphous coating of metastable Al2O3-Y2O3 solid solution. After the heat treatment, α-Al2O3/YAG nano-structured composite coating was successfully obtained via eutectic reaction between Al2O3 and Y2O3. It was possible to control the sizes of Al2O3 and YAG particles widely by heat treatment with proper condition. Hardness of the coatings showed close relationship with their microstructure.
Peculiarities of Structure of Quasicrystalline Al-Cu-Fe System Coatings Produced By Thermal Spraying Methods
Authors: Borisova A. , Borisov Y. , Panko M. , Adeeva L. , Kolomytsev M. , Shakhraj A. , Sladkova V. 
Published: September 2022

Abstract
The effect of methods and conditions of thermal spraying on structure and phase composition of coatings of the Al-Cu-Fe system alloy powders has been investigated. It is shown that the maximum ø-phase content of the coatings can be produced by the method of air-gas plasma spraying. In this case the thermal spray coatings inherit the multi-phase nature of initial powders. Preheating of the substrate prior to spraying allows the ø-phase content of the coatings to be increased.
Influence of Powder Size and Strength on HVOF Spraying – Mapping the Onset of Spitting
Authors: Itsukaichi T. , Osawa S. , Ahmed R. 
Published: September 2022

Abstract
In the case of thermal spraying of cermet powders using HVOF with longer barrel, such as a JP-5000 and a Diamond Jet 2700, spitting and clogging troubles tend to be brought about on the inner wall of the barrel. This phenomenon comes from the existence of fine particles (in spray powders) which tend to fully melt through barrel. This investigation has been carried out to realize the influence of powder particle strength and particle size distribution of agglomerated and sintered Cr3C2-25%NiCr powders during HVOF spraying. It is found that the finer and weaker the powder particles, the higher the deposit efficiency. However, the finer and weaker the powder particles, the easier is the onset of spitting and clogging phenomena. On the contrary, it is found that the coarser and stronger the powder particles, the lower the deposit efficiency with less spitting and clogging phenomena. Finally optimum powder particle strength and particle size distribution of Cr3C2-25%NiCr powders have been found in this study using a JP-5000 system.
Structure and Property of WC-17Co Coatings Sprayed by HVO/AF
Authors: Zha Bailin , Wang Hangong , Su Xunjia 
Published: September 2022

Abstract
The paper analyzed microstructure and property of WC-17Co coatings sprayed by High Velocity Oxygen/Air Fuel Spray under three kinds of spray conditions, which are HVOF, HVO-AF and HVAF. Coatings bond well with the substrate. The average bonding strength exceeds 70Mpa. Coatings are dense and hard, and the average porosity is about 1%. Microhardness of coatings is between HV10000.2 and HV12000.2. Coatings are mainly composed of WC with little W2C and Co3W3C. With the increasing of Nitrogen, decarburization of WC was reduced.
Modeling of the Substrate Temperature Evolution during the APS Thermal Spray Process
Authors: Bolot R. , Li J. , Bonnet R. , Mateus C. , Coddet C. 
Published: September 2022

Abstract
A numerical model is presented for the computation of heat transfers during the APS thermal spray process. This model includes the contributions of both the impinging plasma jet and that of the particle flux on the substrate heating. The contribution of the impinging plasma jet is taken into account using a computational fluid dynamic model describing the impact of the plasma jet on the substrate. For this part of the work, a two-layer extension to the Chen-Kim k-s model was used allowing the description of both the turbulent plasma jet and that of the flow in the viscous sub-layer formed on the substrate surface. The contribution of the sprayed particles is taken into account considering their distribution in the spray jet. Since this is an important parameter that could affect the model accuracy, measurements of the deposit thickness profiles were first performed using the non-destructive acoustic microscopy method and the corresponding particle flux distribution was then deduced. Heat transfers inside the substrate were then computed using a three dimensional in-house code based on a finite volume approach. In the case studied, the results show that the contribution of the sprayed particles forming the coating is much more focalized than that of the plasma flow itself whereas the substrate nature has a strong influence on the thermal flux dissipation (not presented in the following). These elements are expected to provide useful information concerning the coating adhesion mechanisms and the formation of residual stresses during the coating elaboration.
Application of CFD for Wire-Arc Nozzle Geometry Improvement
Authors: Gedzevicius I. , Bolot R. , Liao H. , Coddet C. , Valiulis A.V. 
Published: September 2022

Abstract
The present study was devoted to the optimization of the nozzle exit geometry of a TAFA 9000 wire-arc spray gun. Computational Fluid Dynamic was first used in order to examine the effect of different nozzle configurations, considering small changes operated on the original design. Finally, one of the modified geometries tested numerically was retained in view of the CFD results and the corresponding new nozzle was machined. In a second step, experiments were performed in order to observe the effect of the new design on in-flight droplet characteristics. For this part, a comparison was made between the original design and the modified one for two different type wires (a steel wire and a stainless steel cored wire). These experiments were performed using the well known DPV 2000 device for different operating conditions. The results indicate that the modified design provides a significant increase in the droplet velocity (about 20% higher for the new design) with unchanged thermal spray parameters, indicating that the gun exit design may have a strong influence on inflight characteristics of the droplets. Moreover, droplets were collected in water and the size distribution was analyzed.
Primary Breakup of Metal in the Wire Arc Spray Process
Authors: Hussary N.A. , Heberlein J.V.R. 
Published: September 2022

Abstract
The significance of metal atomization in the wire arc spray process is directly related to the final coating quality produced. Since the early observations of the melting behavior of the wire tips by Steffens, relatively little has been done to further the understanding of the mechanisms involved. The primary atomization of the molten wire tips show existence of sheets and extrusions on both electrodes which are strongly dependent on the system operating parameters. High-speed imaging has been used in this study, for classification of sheet, membrane and extrusion formations as a function of atomizing gas pressure, voltage and current settings. The breakup of metal structures formed on the electrodes is further classified in a manner consistent with established classifications for the break-up of other liquids, e.g. water or fuel. Quantitative descriptions of metal sheet lengths and breakup times are presented. The improved understanding of the metal breakup mechanisms in the wire arc spray process may provide a basis for (a) modification of existing computational codes for prediction of particle sizes and trajectories, and (b) for modifications to torch designs for providing more uniform particle fluxes.
Oxidation of Ni-Based Alloys Sprayed by a Water-Stabilized Plasma Gun (WSP)
Authors: Voleník K. , Chráska P. , Dubský J. , Had J. , Leitner J. , Schneeweiss O. 
Published: September 2022

Abstract
During air plasma spraying, molten metal particles flying in the plasma jet are oxidized. As a result, a part of the metal melt is converted into oxide melt. After the particle impact and solidification, oxidation continues as a gas – solid reaction. The present paper deals with oxidation of two binary Ni-based alloys. One of them, Ni-20%Cr, is frequently used in thermal spray applications. Another one was a Ni-Fe alloy with an approximate proportion of both components 1:1. The feedstock powders were plasma sprayed by a water-stabilized gun WSP. PAL 160. To analyze the reaction products of the in-flight oxidation stage, the flying particles were trapped and quenched in liquid nitrogen. Oxides resulting from both oxidation stages were studied in the as-sprayed deposits after their cooling down to room temperature. The oxide amounts in the samples were determined indirectly by oxygen level measurement using "extractive fusion" (LECO-method). Structure of the oxides, separated by dissolution of the metallic phase, was investigated by X-ray diffraction. Iron-containing oxides were also characterized by Mössbauer spectroscopy. From the point of view of reaction kinetics, both alloys behaved in a similar way. The particles quenched in liquid nitrogen contained less than 2% of oxygen, whereas in the deposits these values were higher, up to 4.5 %. Two oxide phases were found in all plasma sprayed Ni-Cr samples: a rhombohedral phase similar to (Ni,Cr)2O3 and a tetragonally distorted spinel phase (Ni,Cr)3O4, both of them very rich in chromium. Another oxide, NiO, was present mainly in the deposits. In the oxidation products of Ni-Fe alloy, the dominant phase was similar to nonstoichiometric wüstite FeO. The results of thermodynamic calculations are in sound agreement with the experiments except for the presence of the tetragonal phase, the composition of which is near to Cr3O4, in oxidation products of Ni-Cr alloy.
Dependence of Thermal Sprayed Particle/Substrate Interface Microstructure on Substrate Temperature
Authors: Fukumoto M. , Hamada K. , Shiiba M. 
Published: September 2022

Abstract
Ni, Ni-Al and Ni-Cr powder particles were plasma sprayed onto the mirror polished metallic substrate surface and the effect of substrate temperature on the particle/substrate interface microstructure was investigated. Sprayed particles were fully melted, sphere in a shape and oxidized on their surfaces during spraying in an air atmosphere. The surface oxide layers were detected as Al or Cr rich thin layer, respectively by electron probe micro analysis (EPMA). After spraying of the particles onto the substrate, cross section microstructures at particle/substrate interfaces were investigated. As a result, almost no oxide layer was detected at the particle/substrate interface when the substrate was kept at room temperature. On the other hand, the oxide layer was apparently recognized at the interface when the substrate was kept at a certain elevated temperature, such as at 673K. The difference in the existence of the oxide layer at interface seems to relate the wettability of the substrate by the liquid particles. The transition temperature, Tt, for each powder material was measured. The meaning of elemental addition to the base metal was considered from the changing tendency in Tt value of each powder material. Through the investigation results obtained, dominating factor on the flattening of the thermal sprayed particles onto the flat substrate surface was estimated.
A Numerical Study of the Sources of Variation in In-Flight Particle Characteristics in Atmospheric Plasma Spraying
Authors: Friis M. , Nylén P. 
Published: September 2022

Abstract
The resulting thermal and mechanical properties of atmospheric plasma sprayed coatings, are strongly dependent on the particle in-flight characteristics, which in turn depend on the spray gun variables. In industrial production the spray gun variables are set to constant values and closed loop controlled. However, calibrations of the variable levels are regularly performed and variations within specified tolerance limits allowed, which cause variations in the particle in-flight characteristics. The objective of this work was to investigate how these calibration variations affect the particle in-flight characteristics and the final coating properties. The investigation was performed using three-dimensional computational fluid dynamics simulations. The process model correspond to the SM-F-100 Connex gun, spraying ZrO2 for thermal barrier coating applications. Particle in-flight characteristics were calculated using a stochastic discrete particle model. Validation of the model was performed using the optical DPV2000 system, and fair agreement was found. Voltage, arc current, primary, secondary and carrier gas flow rates were systematically varied one factor at a time and their separate effects on the particle in-flight characteristics evaluated. The most important variables influencing the particle characteristics were current and voltage. Final simulations considering extreme cases enabled determination of the particle characteristics limiting conditions due to tolerance variations. Coating microstructure evaluations of two of these extreme cases revealed that the total porosity could vary up to 4% due to tolerance variations.
Particle Temperature and Velocity Characterization in Spray Tooling Process by Thermal Imaging Technique
Authors: Mohanty P.S. , Allor R. , Lechowicz P. , Parker R. , Craig J. 
Published: September 2022

Abstract
A two-color imaging pyrometer system is employed to examine twin wire arc spray gun used in Spray Tooling Process. Key aspects analyzed in this study include particle temperature, particle velocity, and particle distribution. The influence of process parameters such as gas flow rate, type of gas (N2, and air), voltage and current, as well as, spray cap design has been studied. Influence of a super atomizer called the arc jet has also been investigated. The measurements were taken at 80 mm, 160 mm and 200 mm from the gun tip. Finally, the influence of the material on the spray characteristics has been examined. The material list includes 0.8% carbon steel, 0.8% Carbon steel with B, stainless steel, Molybdenum, Ni, Ni-Al and Copper. The type of gas used for atomization significantly influences the particle temperature and velocity. Lowest temperature is observed with nitrogen gas and the highest temperature with the arc jet. Arc jet also produced particles with significantly higher velocity. The flow rate did influence the particle velocity where as temperature wasn’t affected noticeably. The wire material has considerable impact on the particle temperature and velocity. Lower melting point alloys showed higher temperature whereas the velocity has complex dependence on the density and viscosity of the material. Cap type affects the temperature and velocity of the particle. As cap opening increases the temperature and velocity decrease.
Particle Properties Tailor Coating Microstructure, Porosity and Phase Composition
Authors: Döring J.-E. , Vaßen R. , Stöver D. , Castro R.G. 
Published: September 2022

Abstract
During plasma spraying in-flight particle characteristics are influenced by the many operating parameters associated with the deposition process. The distinctive temperature and velocity signals given by particles as they exit the plasma torch can be used to develop processing maps for defining the optimal operating envelope. Knowing the temperature and velocity history of the particles, the evolution of the microstructure, the amount of porosity and the phase composition can potentially be predicted. In this paper, the relationship of system parameters (stand-off distance, torch power, plasma gas composition and process gas flow) was correlated to in-flight particle characteristics of yttria stabilized zirconia and compared to the resulting coating features such as thickness, microstructure, porosity and phase composition. The appearance of the coating (i.e., color) was also compared after the deposition process. Yttria stabilized zirconia was deposited on grit blasted samples using an F4 (Sulzer Metco) plasma torch. Before depositing each sample on the substrate, the particle properties were measured at the desired stand off distance perpendicular to the particle jet covering an area of 18x18 mm2 using the Tecnar DPV2000 inflight particle analyzer. The coatings were cross-sectioned for microstructure analysis, thickness measurements and deposition efficiency. Free standing films were used for mercury intrusion porosimetry. Grey levels of the coatings were obtained by optical microscopy and subsequent digital image recording. X-ray-diffraction analysis was also used to obtain the phase composition. Results showed that different particle temperature and velocity conditions lead to specific porosity and varying colors of the deposit. The color of the deposit was correlated directly to the amount of monoclinic phase in the as-deposit material.
Residual Stress Analysis in Thermally Sprayed Layer Composites, Using the Microhole Milling and Drilling Method
Authors: Escribano M. , Gadow R. , Buchmann M. 
Published: September 2022

Abstract
Mechanical and tribological properties of layer composites like hardness, bonding strength, friction and wear coefficients as well as operation performance, component reliability and finally the system lifetime are mainly influenced by residual stresses after the thermal spraying and machining process. The residual stress situation in thermally spray coated composites is superimposed by different stress mechanisms occurring during the manufacturing process based on heat and mass transfer during the coating deposition. Using the microhole milling and drilling method, residual stress fields can be measured in a quasi non destructive way over the drilling depth with appropriate resolution. In several drilling and micromilling operations a circular, cylindrically shaped microhole is brought step by step into the component surface. The residual stresses are locally relieved due to material removal, deform the surface around the drilled microhole and are measured by high resolution measurement tools, e.g. strain gauges (DMS), for every drilling step in form of relaxed surface strains. Using calibration curves and material data (E, μ) the measured surface strains are converted into nominal strains at the bottom of the drilled hole for every drilling step. Out of the differentiated strains, in-plane stress fields can be incrementally determined by Hooke's law. This study describes residual stress measurement features, the FEM-calculation and idealization of calibration curves as well as results of exemplary stress measurements.
Photocatalytic Properties of TiO2 Coatings as a Function of Coating and Substrate Characteristics
Authors: Toma F.L. , Berger-Keller N. , Bertrand G. , Klein D. , Coddet C. 
Published: September 2022

Abstract
Titanium dioxide (TiO2) is an attractive material for numerous technological applications such as photocatalytic applications. The photocatalysts allow the environmental purification of air and water by the decomposition of toxic organic compounds and removal of harmful gases. This work was focused on the production and evaluation of the environmental properties of titanium dioxide coatings obtained by the plasma spray technique. To carry out the step of validation of the TiO2 coatings for their environmental functionalities, a control test of the photocatalytic effectiveness was performed with respect to nitrogen oxides. A custom-designed test chamber has been developed. The photocatalytic properties of different coatings were studied as a function of various parameters (porosity, anatase/rutile ratio, nature of the substrate).