bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of Deposition Parameters on the Degradation of Plasma Sprayed Polymer Coatings
Authors: Zhang T. , Gawne D.T. , Bao Y. 
Published: May 2021

Abstract
A heat transfer analysis has been undertaken to predict the influence of process parameters on the decomposition of in-flight particles and deposited layers during thermal spraying of polymer coatings. The theoretical analysis shows that polymers are unique in developing large temperature gradients, which accelerates the degradation of the surface of the particles and the coating layers. However, the analysis indicates that the degradation can be limited by the control of the plasma gas composition, the spraying distance and the torch traverse speed. The theoretical analysis has been confirmed by weight loss measurements, wear tests and microstructural observations of plasma sprayed PMMA coatings. The work shows the existence of a critical traverse speed below which satisfactory coatings cannot be produced.
RF-Plasma Technology to Enhance Spray Materials
Authors: Paskalov G. 
Published: May 2021

Abstract
This study focuses on RF-Plasma Technology (RFPT) to enhance the physical properties of powdered materials (metals, carbides, ceramics, inter-metallics, and mixtures). The efficiency and flexibility of RFPT allows for the economically viable production of powders with a high degree of densification, spheroidization and purity. RFPT is based on the used of RF inductive power used to create a plasma at atmospheric pressure. A complex model based on theoretical calculations and empirical data has been developed to describe changes in particles exposed to the plasma stream for a variety of process parameters. A specific combination of parameters is referred to as a scheme. Advanced schemes have been developed to increase the coefficient of heat transfer from the plasma stream to particles by up to 35%. RFPT is especially useful for the production of powders that have been difficult or impossible to create with traditional methods. Some of the materials processed include: ZrO2, W2C, WC and WC-Co combinations. Particle size distribution (PSD) can be tightly controlled, and can vary from 5 to 600 microns.
Characteristics of High Hardness Zirconia Coatings Formed by Gas Tunnel Type Plasma Spraying
Authors: Kobayashi A. , Kitamura T. 
Published: May 2021

Abstract
The gas tunnel type plasma spraying enables to produce high quality ceramic coatings. Moreover a high hardness coating was obtained at a short spraying distance in the case of alumina coating. A high hardness zirconia (ZrO2) coating could also be obtained at an atmospheric pressure by using the gas tunnel type plasma spraying. The Vickers hardness of the ZrO2 coating at a short spraying distance was very high: a high hardness of more than Hv = 1200 was achieved at the surface side of the coating. In this study, the characteristics of these high hardness zirconia coatings produced the gas tunnel type plasma spraying were investigated by the measurement of the Vickers hardness of the coating. The microstructure of the obtained high hardness zirconia coatings were also investigated by the microscopic method and by the X-ray diffraction method.
Independent Control of HVOF Particle Velocity and Temperature
Authors: Hackett C.M. , Settles G.S. 
Published: May 2021

Abstract
In the past, independent control of HVOF spray particle velocity and temperature has not been possible, confusing the effect of either parameter on coating properties. This study describes a method by which velocity and temperature may be varied independently. Commercial HVOF equipment fitted with a special conical supersonic nozzle having three distinct particle injection locations was used. The present results, obtained through experiments and numerical simulations, revealed several pertinent facts. First, particle velocity is principally related to combustion chamber pressure and is relatively unaffected by other design or operating conditions. Second, particle temperature is related to particle residence time within the nozzle, which can be controlled by the choice of particle injection location. In these experiments, the impact velocity and temperature of stainless steel particles were controlled within the ranges 215 to 510 m/s and 1670 to 2160 K, respectively. This range of parameters produced significant variations in splat morphology and coating microstructure. The implications of this study are not limited to the HVOF process, and may be generalized to other thermal spray techniques. From a research perspective, such particle control allows the effects of velocity and temperature on coating properties to be assessed and controlled independently. These results also have commercial application, potentially enabling the user to tailor particle impact velocity and temperature to achieve specific coating properties.
Generation of Alumina Plasma Sprayed Coatings on Alumina Substances
Authors: Bianchi L. , Denoirjean A. , Fauchais P. , Postel O. 
Published: May 2021

Abstract
The influence of alumina substrate temperature and phase structure : columnar gamma phase, columnar alpha phase and granular alpha phase on splat formation and crystal growth has been studied by SEM and Atomic Force Microscopy. X Ray Diffraction at low angle has allowed to obtain informations on phase structure of layered splats according to substrate phase structure and coating thickness. Column sizes of splats are correlated to a ID model of splat cooling showing the influence of substrate thermal properties and splat thickness on crystal growth kinetic. Finally, coatings adhesion-cohesion values function of spraying parameters are in good agreement with splat morphology and microstructural evolution.
Characterization of the Tensile Properties of Vacuum Plasma Spray Copper Deposits
Authors: Montavon G. , Robert B. , Verdy C. , Monin V. , Atcholi K.E. , Coddet C. 
Published: May 2021

Abstract
The mechanical properties (i.e., tensile and shear properties) of vacuum plasma spray copper deposits presenting different porosity levels were determined. The tensile properties of the copper plasma spray deposit appeared to strongly depend on the porosity level, but whatever was the porosity level of the sample, the fracture always exhibited a ductile character, with the failure cups expanding preferentially on the pores and secondarily on the grain boundaries of the annealed microstructures. The tests clearly shown that the material presented an isotropic ductile-plastic hardening behavior typical of copper based materials, but this behavior being significantly influenced by the porosity level of the deposit.
Thermal Spray Coating Developments for Piston Rings to be Used in Tomorrow’s Duty Engines
Authors: Delaet M. , Coddet C. 
Published: May 2021

Abstract
Plasma arc sprayed coatings are largely developed in Perfect Circle Europe because of the wide range of coating materials which ensure numerous tribological properties. Spraying parameters are of great importance in improving the coating structure and therefore the coating wear, adhesive, cohesive and corrosive resistances. The utilized plasma gas is first studied; designed experiments are then achieved to optimize the all spraying parameters. More than the spraying parameters, the powder formulation has a major influence on the coating tribological properties. Several powders are studied with the aim to reduce the ring-liner system wear. Tests on idealized samples coupled with engine tests help us to characterize the tribological behaviour of some molybdenum based coatings.
Slurry Erosion of High Velocity Oxy-fuel Thermal Sprayed Coatings
Authors: Arsenault B. , Legoux J.-G. , Hawthorne H. 
Published: May 2021

Abstract
Improvement of the high velocity oxy-fuel deposition (HVOF) process in the last decade has enhanced the microstructure of coatings in order to better perform against wear and corrosion. Indeed cermet and metal HVOF coatings are reliable and have excellent performance under slurry erosion and provide therefore an alternative to the use of high-priced material. This paper presents the results of a study undertaken within the core research program of the National Research Council of Canada technology group in surface engineering, "SURFTEC", in which the performance of ten HVOF erosion-resistant coatings was evaluated. Ten different types of HVOF coatings were studied including: six grades of WC with either Co or a Ni based matrix, one grade of Cr3C2 in a Ni-Cr matrix, and three grade of metallic alloy: Ni alloy, Co alloy and a SS 316- L. The performance of coatings was evaluated with respect to: the volume ratio and composition of metallic binder in carbide coatings, type of carbide, coating microstructure, impinging angle and the size of the erodent particles. All coatings were produced using the HVOF JP-5000 system controlled by the Hawcs-ll controller. Slurry erosion tests were conducted with a jet impingement rig with a 10 %w/w alumina particle/water slurry. The volume loss of material under various slurry erosion conditions was related to the coating properties and microstructure. Results indicate that the behavior of HVOF sprayed materials is dependent on the erodent particle size, to the erosion impinging angle to some extent and to the corrosion resistance of the cermet matrix.
Coating Protection Against Atmospheric Corrosion for Iron and Steel Structural Components: Status of Metallization in Japan
Authors: Ueno G. , Nava Y.L. 
Published: May 2021

Abstract
Low-velocity oxyfuel-spray and arc-spray coatings of Zn, Zn-Al, Al, and various Al-Si and Al-Mg alloys were tested in immersion and salt-spray conditions with artificial sea water for up to 6,000 hours. Coatings were tested as-sprayed or sealed with fluorocarbon, epoxy or silicone sealants. Comparison and overview of coatings recommended by international and Japanese standards are considered. Coatings Al 99.8 outperformed Zn 99.9 and Zn-13A1 ones while Al-(2.5~5.2)Mg and Al-(5~6)Si showed better corrosion resistance than Al 99.8 coatings. The silicone sealant offered better resistance than fluorocarbon and epoxy organic sealants.
Field Evaluation of 2CaO-SiO2-CaO-ZrO2 Thermal Barrier Coating on Gas Turbine Vanes
Authors: Mifune N. , Harada Y. , Taira H. , Mishima S. 
Published: May 2021

Abstract
Higher-temperature operation in a gas turbine has urged development of heat-resistant coatings and thermal barrier coatings. We have developed a 2CaO-SiO2-CaO-ZrO2 based thermal barrier coating. This coating should effectively prevent separation of the coating by relieving the shear stress generated due to thermal change of environment between layers with dissimilar properties. The coating was applied to stationary vanes of an actual gas turbine in a 25,000-hour test. This paper describes the results of the field test.
Highly Porous Thick Thermal Barrier Coatings Produced by Air Plasma Spraying of a Plastic-Ceramic Mixed Powder
Authors: Gualco G. , Corcoruto S. , Campora A. , Taylor R. , Schwingel D. , Oswald S. 
Published: May 2021

Abstract
In order to increase the efficiency of heavy duty gas turbines for power generation and to reduce their emissions, higher combustion chamber temperature is required; a considerable improvement of the insulation properties of the thermal barrier coatings is therefore required. 1.5 mm thick thermal barrier coatings have been deposited by air plasma spraying a mixed polyester-zirconia powder; by this process high porosity, up to 22%, has been achieved together with a good deposition efficiency (about 50%); the coating microstructure has been thoroughly examined by quantitative image analysis, determining the pores size distribution and the vertical segmentation cracks density. Thermal shock tests showed a life improvement with respect to the state-of-art by a factor &gt; 100; relationships among thermal shock life, deposition rate, segmentation cracks density and porosity were determined. Thermal expansion and thermal diffusivity were measured up to 1200 °C; failure strength, failure strain and Young's modulus were determined by a four-point bending technique.
Scaling Analysis of the Electromagnetic Powder Deposition (EPD) Gun
Authors: Uglum J.R. , Bacon J.L. , Davis D.G. , Polizzi R.J. , Sledge R.L. , Zowarka R.C. 
Published: May 2021

Abstract
The electromagnetic powder deposition (EPD) system employs high velocity gas flow to accelerate powder material to conditions required for high strength plating. The gas flow, however, is not continuous; rather it consists of bursts generated by an electromagnetic railgun and pulsed power system. Each gas burst is created by a high pressure plasma arc which fills a transverse section of the gun. This current carrying arc is driven by the railgun Lorentz force (magnetic pressure) and acts much like a piston, which via a snowplow process accelerates and compresses an ambient gas column to the flow speed required to accelerate powder particles. Analysis of the total system was carried out to provide scaling relations which give guidance in design of the system. Plating considerations define a desired powder velocity; this combined with the choice of working gas and ambient pressure determines the velocity and duration of each gas burst. Selection of gun geometry completes the definition of the pulsed power system requirements. An outline of the analysis is presented along with the physical models used.
Automated Thermal Spray Technology for Rehabilitation and Maintenance of Civil Works Infrastructure
Authors: Hock V.F. , Senary R. , Ganertz R. , Herman H. 
Published: May 2021

Abstract
Conventional corrosion protection of steel structures has usually involved the application and reapplication of lead-based paint (LBP), a material now known to be highly toxic and likely to find its way into the environment. LBP is no longer used in the field, but repair crews, nearby communities, and the environment may be exposed to unacceptably high levels of lead as the substrates of older structures are prepared for repainting during routine M&R operations. Conventional dust-containment enclosures used onsite during surface preparation (abrasive blasting) are often inadequate. The most effective containment technologies, on the other hand, tend to be expensive and cumbersome. All of these factors make surface preparation and recoating slow, technically difficult, physically demanding, and hazardous to the worker and the environment. Automated technologies have the potential to address all aspects of these interrelated infrastructure M&R problems. An example of such a technology is the Automated Thermal Spray System (ATSS). The ATSS utilizes a triaxial array of linear motion actuators to form a robot capable of performing preprogrammed sequences. The demonstration proved that the ATSS can successfully remove deteriorated lead-based paint from a steel bridge and then apply a protective coating to the exposed surface.
Comparison of Plasma-Sprayed Coatings Produced in Argon or Nitrogen Atmosphere
Authors: Leylavergne M. , Vardelle A. , Dussoubs B. , Goubot N. 
Published: May 2021

Abstract
When spraying is conducted in the ambient atmosphere, the entrainment of air cools down the plasma jet and affects its expansion. It may also cause the oxidation or the chemical decomposition of the sprayed materials. Inert Plasma Spraying (IPS), generally conducted in argon atmospheres, prevents these phenomena. However, the main drawbacks of IPS in comparison with air plasma spraying are the capital and apparating costs. To reduce the latter by 25 to 30%, nitrogen atmospheres may be used as a substitute for the conventional argon atmosphere. This paper presents a study in which titanium carbide and niobium powders were sprayed in argon and nitrogen atmospheres. Cryogenic cooling of the substrate was used during the spray process. This helps to maintain a low temperature in the chamber, produces thick coatings and allows the use of substrate materials that are sensitive to heat. The adhesion, roughness and microstructure of the coatings produced in both atmospheres are compared as well as their nitrogen content.
Analysis of Nucleation, Phase Selection and Rapid Solidification of an Alumina Splat
Authors: Vardelle A. , Robert C. , Wang G.X. , Sampath S. 
Published: May 2021

Abstract
A numerical model has been developed to study the rapid solidification of an alumina splat in thermal spray deposition. The model focuses on the melt undercooling, the selection of the various phases of Al2O3, and the subsequent non-equilibrium rapid solidification process. A thin molten layer is assumed to be brought into contact with the substrate at time t = 0. One-dimensional heat transfer is considered through splat and substrate along with a thermal contact resistance between them. The classical theory of nucleation kinetics is used to determine the nucleation temperature, assuming that nucleation takes place heterogeneously on the substrate surface. The most likely nucleated crystalline phase is investigated, based on the nucleation kinetics of various phases. Once the particular phase is identified and the nucleation temperature is calculated, the solidification starts assuming a planar interface between the solid and the liquid. Non-equilibrium kinetics of the chosen phase is applied at the moving interface to calculate the interface velocity from the interface melt undercooling. In this paper, the effect of splat variables on the solidification and cooling process of the splat are analyzed. Special attention is paid to the value of the wetting angle between the growing nucleus and the substrate, which affects greatly the nucleation temperature.
Dynamic Simulations of Multiple-Splat Spreading and Solidification
Authors: Prasad V. , Zhang H. , Sampath S. 
Published: May 2021

Abstract
A high resolution numerical model has been developed to simulate the simultaneous spreading and solidification of single and multiple-splat on a cold substrate. The model combines the level set formulation with curvilinear adaptive finite volume scheme to predict the deforming shape of the splat's free surface as well as the solidification interface shape and dynamics. An adaptive grid generation captures the solidification front and the level set formulation allows the free surface deformation caused by merging and separation. Numerical results on spreading, merging and solidification of a single splat and two splats are presented to demonstrate the capability of the scheme. It also shows that this model can be extended to predict porosity in thermal spray coatings.
Modeling and Experimental Studies of Particles Velocity and Temperature in Plasma Spraying Processes
Authors: Ilyuschenko A.Ph. , Okovity V.A. , Kundas S.P. , Kuz’menkov A.N. 
Published: May 2021

Abstract
Mathematical and computer models of movement and heating of particles in low pressure conditions are developed. The mathematical models are based on the molecular-kinetics theory of gases. A program complex for computer realization of models is developed. It contains a built-in data base of temperature dependent properties of substances, system of processing and graphic visualization of simulation results. For verification of the developed models, computer simulation and experimental measurments of Al2O3 particle temperature and velocity are conducted. These materials were sprayed in Plasma-Technik equipment at pressure 60 mBar in argon. Particle velocity was measured with a special optical device, particle temperature was defined by intensity radiation method. It was established that the developed models are adequate to real process (error of 5-8 %) and may be used for study and improvement of VPS processes.
Influence of Substrate and Coating Temperature on Columnar Growth within Plasma Sprayed Zirconia and Alumina Coatings
Authors: Haddadi A. , Nardou F. , Fauchais P. , Grimaud A. , Leger A.C. 
Published: May 2021

Abstract
The temperature within plasma-sprayed oxide coatings depends strongly on the cooling devices used during spraying as well as on coating pass thickness and powder flow rate. Two oxides, alumina and zirconia, were deposited using dc Ar-H2 plasma jets and the shape, size, and composition of the columnar structures produced were examined and found to correspond with substrate and coating surface temperatures as measured during and after spraying. The relationship between temperature and thermomechanical properties was also investigated and the results are reported in the paper.
Influence of the Torch to Substrate Velocity and Resulting Temperature on the Residual Stresses in Alumina Plasma Sprayed Coatings
Authors: Leger A.C. , Grimaud A. , Fauchais P. , Delluc G. 
Published: May 2021

Abstract
A system, developed in the laboratory, allows to record in situ the deformation of a flat beam with a displacement sensor and so to analyse stress formation during spraying and upon cooling with fixed or rotating substrates. The beam is fixed onto a pair of knife edges by springs. The knife edges are disposed on a water-cooled rotating cylindrical substrate holder and the beam substrate (2 x 15 x 100 mm3) is parallel to the holder axis. The torch is moved back and forth parallel to the holder axis and the beam temperature is recorded by a thermocouple spot welded to it and also by an IR pyrometer. The influence of beam temperature for a given torch/substrate velocity on the residual stresses is studied for alumina and zirconia coatings. With fixed substrates a sharp increase of the residual stresses related to coating microstructure exists for a transition temperature around 600°C. It seems to correspond to a columnar growth throughout the layered splats. The effect of the torch to substrate velocity and so the pass thickness is studied too.
Neutron Diffraction Residual Stress Measurement on Thermally Sprayed Coatings
Authors: Matejicek J. , Sampath S. , Brand P.C. , Prask H.J. 
Published: May 2021

Abstract
Neutron diffraction is a promising tool for the investigation of residual stresses in thermally sprayed coatings. In principle, the neutron diffraction method has several distinct advantages over other methods. 1) It is possible to perform triaxial stress analysis throughout the thickness of both the coating and the substrate without material removal. 2) The stress can be determined in all phases of a multi-phase coating. 3) Repeated measurements can be performed on mechanically or thermally fatigued specimens. 4) Stress concentrations and shape/edge effects in actual parts can be located. In this paper, these unique capabilities will be reviewed first. In the second part of the paper it will be shown how the analysis of these coatings differs from experimental analysis of bulk materials. Finally, the analysis of the stress distribution in plasma sprayed NiCrAlY and ZrO2+Y2O3 thermal barrier coatings in as-sprayed and annealed states will be presented and discussed.
Structure and Properties of HVOF Sprayed Ceramic/Polymer Nanocomposite Coatings
Authors: Petrovicova E. , Knight R. , Smith R.W. , Schadler L.S. 
Published: May 2021

Abstract
Ceramic/polymer nanocomposites promise to be a new class of materials that will have wide application either for surface protection, providing low friction and inert corrosion barriers, or where tailored electrical and magnetic properties with increased abrasion and wear resistance are required. The high velocity oxy-fuel (HVOF) combustion spray process has been used to successfully process polymer-ceramic nanocomposites at 5 - 20 volume % of reinforcement. The latest results of process-structure- property relationship studies in silica and carbon black reinforced nylon 11 coatings are presented. It was found that the improvement in mechanical properties depends on the distribution and surface chemistry of the particulates and on the increase in matrix crystallinity due to the particulates.