bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measured and Simulated Particle Flow Field Parameters in a High Power Plasma Spray
Authors: Swank W.D. , Chang C.H. , Fincke J.R. , Haggard D.C. 
Published: May 2021

Abstract
High power supersonic plasma guns operating in excess of 200 kW can produce molten particles with 3 to 4 times the impact velocity of conventional plasma sprays. With this increased range of particle velocity it is important to understand the relationship between the torch input parameters and the sprayed particle velocity, temperature, pattern and size. Stainless steel particle velocity, temperature, size and relative number are measured for a high power plasma spray system operating at 110 kW. At the same torch operating conditions the plasma and particle flow fields are simulated with a newly developed computational model. It was found that the injection geometry plays an important role in the particle entrainment, heating and acceleration. In spite of the complexity of the system, i.e. supersonic plasma velocity with a high swirl component, the simulation produced reasonalble particle trajectories resulting in good agreement between the calculated and measured particle velocity, temperature and size distributions.
Vaporization of Metal Powders in Plasma Sprays
Authors: Li K.-I. , Vardelle M. , Vardelle A. , Fauchais P. , Trassy C. 
Published: May 2021

Abstract
In plasma spraying, deposition efficiency depends, to a great extent, on powder losses at the injection point, vaporization phenomena and particle rebound at impact. This paper discusses an attempt to determine the mass balance in metal spraying by studying the injection and vaporization of a metal powder in a plasma jet and correlating the results to the mass deposition efficiency of the process. The study of particle vaporization consisted of measuring the metal atoms concentration by absorption spectroscopy while injection was examined by a 2-D imaging technique.
Mathematical Model for Process Thermal Spraying Coating Formation
Authors: Ilyuchenko A. , Vityaz P. , Okovity V. , Abrashin V. , Gromyko G. , Veremeinko T. , Zajac G. 
Published: May 2021

Abstract
This paper presents a mathematical model of the plasma-spray coating formation process that allows one to estimate bond strength energy, a parameter related to coating quality. Bond strength energy is defined on the basis of particle-substrate or system balance. Unknown quantities in the energy equation are obtained from nonstationary Navier-Stokes equations for velocity field and pressure and from thermoelasticity equations for temperature and stress. Complexities associated with particle spreading and nonlinear hydrodynamics have made it necessary to develop a stable numerical technique.
On-Line Diagnostics of Traditional Flame Spraying as a Tool to Increase Reproducibility
Authors: Wigren J. , Hansson M.-O. , Gougeon P. , Moreau C. 
Published: May 2021

Abstract
Although very frequently used, traditional (low velocity) flame spraying is a much forgotten process. No major research has been performed during the last decade. This paper focuses on the problem of reproducibility of a typical flame gun used with modern automated process equipment. An on-line diagnostic process control tool measuring the temperature, velocity, size and position of the powder in the flame was applied during spraying of abradable coatings of NiCrAl/Bentonite, coatings which are commonly applied to fan and compressor housings of gas turbines. An automated closed loop flame spray unit with mass flowmeters for the oxygen and acetylene gases was used. Influence of different process parameters on the sprayed particles, such as nozzle design, gas flows, and powder feed rate is discussed. Coating properties, such as erosivity, porosity, microstructure and tensile strength, are evaluated. It is demonstrated that even fairly small process changes influence the flame sprayed particles as well as the properties of the resultant coating.
Parametric Study of Suspension Plasma Sprayed Hydroxyapatite
Authors: Boyer E. , Gitzhofer F. , Boulos M. 
Published: May 2021

Abstract
Thermal plasma spraying is a suitable technique for hydroxyapatite [HA, Ca10(P04)6(OH)2] coating preparation. Suspension Plasma Spraying (SPS) is a newly developed process based on a suspension of fine (&lt;10 μm) or even ultrafine (&lt;100 μm) powders, axially fed into the RF plasma through an atomization probe. The atomization of the suspension results in microdroplets (20 μm in size). They are flash dried, melted and finally impacted onto the substrate to solidify and build the coating. The aqueous suspension of HA is chemically synthesized. Our experiments included variations of the plasma gas composition (Ar/O2, Ar/H2), the plasma deposition reactor pressure. Characterizations techniques (e.g. X-ray diffraction, scanning electron microscope and transmission electron microscope) were applied to resultant SPS HA coatings which possessed good crystallinity and about 3% weight α-TCP and lime. The texture examination has shown that preferential crystal orientation followed the (001) Miller's plane family. SPS by RF induction plasma has proved to be a reliable process for the production of thick (200 μm) HA coatings with high deposition rate (&gt;150 μm/min).
Experimental/Analytical Investigations of Air Plasma Spray Tungsten Carbide-Cobalt Coatings at Kelly Air Force Base
Authors: Varacalle D.J. , Acosta E. , Figert J. , Syma M. , Worthington J. , Carrillo D. 
Published: May 2021

Abstract
Air plasma sprayed tungsten carbide-cobalt coatings are being used at Kelly Air Force Base for a fretting application for convergent seals in aircraft engines. Experimental and analytical studies were conducted to investigate the plasma spraying of two powders for this application. Statistical processing schemes were accomplished in conjunction with analytical modeling of the air plasma spray (APS) process. Classical and statistically designed experiments (SDE) chosen to be conducted were determined by analytical modeling. The coatings were characterized for composition, hardness, porosity, surface roughness, deposition efficiency, and microstructure. Attributes of the coatings are correlated with the changes in operating parameters. Wear screening of the coatings from the experiments was conducted using an abrasion tester based on ASTM Standard Test B611-85.
An Experimental Study of Twin-Wire Electric Arc Sprayed Zinc and Aluminum Coatings
Authors: Varacalle D.J. , Hagrman D.L. , Fincke J.R. , Swank W.D. , Zanchuck V. , Sampson E. 
Published: May 2021

Abstract
An experimental study of twin-wire electric arc spraying of zinc and aluminum coatings demonstrates the suitability of the process for anticorrosion applications. Experiments were conducted using Box-type full-factorial designs. Operating parameters were varied around the following process parameters: nozzle diameter, nozzle geometry, and system pressure. A systematic design of experiments displayed the range of processing conditions and their effect on the resultant coatings. The coatings were characterized with hardness and deposition efficiency tests, and optical metallography. Coating properties are quantified with respect to roughness, hardness, porosity, thickness, bond strength, and microstructure. The features of the coatings are correlated with the process changes. Selected analytical calculations and process diagnostics of the meltpool dynamics are presented.
Mechanical Properties of Water Stabilized Plasma Spray-Formed Alumina-13wt% Titania
Authors: Leigh S.H. , Berndt C.C. , Sampath S. , Herman H. 
Published: May 2021

Abstract
Mechanical properties of water stabilized plasma spray-formed Al2O3-13wt%TiO2 have been investigated by using indentation techniques and a four-point bend test. Young's modulus was determined by four point bend, nano- and Knoop indentation tests. Modulus of rupture was measured by the four-point bend test. The anisotropic behavior as well as the reduced Young's modulus and strength of thermal spray deposits are extensively investigated and can be related to the unique microstructure; i.e., the spheroidal shape of pores, cracks and splats as well as inter-lamellar boundaries. The heat treatment substantially enhanced the mechanical properties and the microstructure becomes more homogeneous and isotropic; that is, the deposits lose their unique nature and become more similar to bulk materials.
Residual Stress Calculation by Finite Element Methods
Authors: Gruhn H. , Fischer W. , Funke C. , Malléner W. , Stöver D. 
Published: May 2021

Abstract
For simulating residual stresses in plasma sprayed multilayer systems a finite element and an analytic model are compared with measured results. The measured stresses which depend on substrate temperature of the plasma spray process are produced exactly by the finite element model. Mesh deformation and simulated stress distribution of the sample are studied.
Analysis of the Stress State in Thermal Barrier Coatings during a Thermal Cycle
Authors: Jönsson G. , Persson C. 
Published: May 2021

Abstract
Thermal barriers made up by a ceramic top coating and a metallic bond coating are subjected to thermal cycles in service. The thermal stresses vary during the cycles and the residual stresses change as a result of plastic flow and creep. The stress state in thermal barrier coatings during a thermal cycle has been examined with a finite element method using temperature dependent material data. The calculated results were verified by measurements of the residual stresses with the layer removal technique before and after cycling of specimens heated in furnace with air environment. According to the simulation of a thermal cycle to 700 ° C, using a finite element method, the bond coat is approximately stress free after 1 hour dwell time. Thus, the residual stresses after a thermal cycle is a result of thermal expansion mismatch and temperature drop.
Characterization of Thermally Sprayed Coatings Using Manual vs. Automated Microhardness Testing
Authors: Blann G.A. , Hoffmann M. 
Published: May 2021

Abstract
Thermally sprayed coatings are applied to various substrates for the purpose of providing a wear-resistant, corrosion-resistant, or heat barrier surface. The materials used to coat a substrate will vary in hardness with respect to each other and with respect to the substrate. Denser coatings produce more reliable hardness data than less dense coatings due to the absence of pores and other inconsistencies in the coating. Variations in coatings will cause preparation problems such as pullout, edge rounding, or coating-to-substrate relief which effects the reliability of hardness determinations. The repeatability of hardness data is directly related to the density of the coating. This paper deals with the effect of coating characteristics (density) on the reliability of manual and automated hardness measurements.
A Potential NDT Method for Rapid Quality Control of Thermal Sprayed Coatings
Authors: Lugscheider E. , Remer P. , Herbst C. , Barbezat G. 
Published: May 2021

Abstract
An overview on potential non-destructive testing (NDT) methods for the inspection of thermally sprayed coatings in production lines is given. The suitability of several NDT techniques has been investigated with view on their sensitivity for the detection of defect sizes possibly being critical for Thermal Spray coatings. Eventually, a method is presented that shows qualification for detection of subsurface flaws in coatings such as delaminations and cracks and offers flaw distinction by image analysis procedures. A storage and archiving of test results is possible thus completing full quality control and meeting possible warranty claims. The major advantage of the NDT process is its very high detection speed which guarantees high productivity even for high volume production systems. Thus a full-area detection of large coated components becomes possible. The process is not restricted to plain components, but is usable for the detection of internally coated cylinders as well.
Modeling of the Laser Engraving at Plasma Sprayed AI2O3, TiO2 and AI2TiO5 Coatings for Anilox Rolls
Authors: Groc M. , Pawlowski L. , Smurov I. 
Published: May 2021

Abstract
Paper presents a study of modeling and numerical simulation of laser engraving process. The 1-D simulation concerned CO2 c.w. pulsed laser engraving of plasma sprayed alumina, titania and aluminum titanate coatings. These coatings will possibly replace the Cr2O3 ones used currently in manufacturing of anilox rolls. The model was refined in comparison to the previous one (1) by taking into account the speed of the roll at the engraving. The actual thermophysical coefficients of plasma sprayed alumina, titania and aluminum titanate were input to the computations. The model enabled calculation of the engraving's depth in function of the principal laser treatment parameters viz. pulse length and laser power density. Finally, the overflow effect at the laser treatment of new ceramics was discussed and compared to that occurring at Cr2O3 engraving.
Erosion Resistance of Arc Sprayed Coatings to Iron Ore at 25°C and 330°C
Authors: Dallaire S. , Levert H. 
Published: May 2021

Abstract
Iron ore pellets are sintered and reduced in continuous large industrial oil-fired furnaces. From the furnace, large volumes of hot gas are sucked by powerful fans. Being exposed to gas-borne iron particles and temperatures ranging between 125°C and 328°C fan components are rapidly deteriorated. Extensive part repair or replacement are required for maintaining a profitable operation. The arc spraying technique has been suggested for repair provided it could produce erosion resistant coatings. Commercial wires were arc sprayed using various spray parameters to produce thick coatings. Arc-sprayed coatings and reference specimens were erosion tested at 25°C and 330°C and impact angles of 25° and 90° in a laboratory gas-blast erosion rig. This device was designed to impact materials with coarse (32 -300 μm) iron ore particles at a speed of 100 m/s. The volume loss was accurately measured with a laser profilometer. Few arc sprayed coatings exhibited erosion resistance comparable with structural steel at low impact angles. Erosion of arc sprayed coatings and reference specimens dramatically increases at 330°C for both 25° and 90° impact angles. Erosion-enhanced oxidation was found responsible for the increase in wastage above room temperature. Though arc spraying can be appropriate for on-site repair, the development of erosion resistant coatings is required for intermediate temperatures.
Abrasive Wear Characteristics of Ni-base Self-fluxing Alloy Spraywelding Overlays
Authors: Ding Z. , Knight R. , Smith R.W. 
Published: May 2021

Abstract
The results of low stress, pin-on-disc and high stress grinding abrasive wear tests on coatings produced by plasma and oxy-acetylene flame spraywelding are presented. FNil5A and FNiWC35 Ni-based self-fluxing alloys were selected as typical spraywelding materials for abrasive wear resistance. The abrasive wear resistance mechanisms of welded overlays produced by various materials and processes were also characterized by hardness tests, microstructural and compositional analyses, and through analysis of the effect of different kinds of abrasive on the wear resistant of Ni-base self-fluxing spraywelding overlays. Results showed that FNiWC35 overlays exhibited improved resistance under low stress abrasion, but the relative wear resistances of FNiWC35 and FNil5A still depended primarily on the type and hardness of the abrasive medium used. For the same material, the abrasive wear resistance of oxyacetylene flame sprayed overlays was higher than that produced by plasma spraywelding. The wear resistance of the plasma spraywelding overlays depended not only on the material, but also strongly on the spraywelding process parameters.
Corrosion Resistance of Thermal Sprayed Titanium Coating with Resin Seal in Chloride Solution
Authors: Ishikawa K. , Suzuki T. , Kitamura Y. , Tobe S. 
Published: May 2021

Abstract
Corrosion behavior of a flame sprayed titanium coating sealed by some resins was investigated in 3.5% NaCl solution by an electrochemical polarization measurement and an immersion test. The composition and structure of the sprayed film was also analyzed by SEM and EPMA. Although an as-sprayed titanium had no resistance to the corrosion because of its porosity, the sprayed titanium sealed with epoxy or silicon resin showed an excellent resistivity against the chloride corrosion. In spite that almost half amount of the titanium changed to oxide, nitride and carbide through the gas flame spraying, the conversion of the metal to the compounds had little effect to decrease the corrosion resistivity. The sprayed and sealed titanium coating obtained by a conventional onsite thermal spraying is expected as an economical material for chloride containing environments.
Production of Recycled Polyethylene Terephthalate Coatings by HVOF and Plasma Spray
Authors: Lima R.S. , Takimi A.S. , Lima M.D. , Bergmann C.P. 
Published: May 2021

Abstract
The polyethylene terephtalate (PET) is a polymer with a high melting (265°C) and glass transition (67°C) temperatures, insensitive to moisture and common solvents. Also it has an wide range of mechanical properties attainable by variations of molecular weight, orientation and crystallinity. Due to these characteristics allied with the glass-like transparency, light weight and unbreakable character, PET is used to form high performance bottles for carbonated soft drinks, wines, beers and food packing. The world annual consumption of PET for these purposes is increasing, with impressive prospects for the future. This characteristic leads to other situation. The consumption of energy and natural resources together with the environmental problems caused by disposable plastics, make the engineering and materials scientists try to find for different ways to recycled plastics. The characteristics of PET mentioned above seen to be very proper to use as a material for coating.
DC Plasma Polymer Composite Coatings for Abrasion Resistant Protective Surfaces
Authors: Tufa K.Y. , Gitzhofer F. 
Published: May 2021

Abstract
A new concept of high energy recovery of dc plasma torch has been developed and applied to the deposition of polymer composites. The heat transferred to low cost fillers, such as alumina or silica injected into the high temperature zone of the plasma, is recovered in the applied polymer coating, which is injected downstream in a much cooler zone of the plasma. The result is a polymer/ceramic composite spraying process having the following benefits: Shrinkage phenomena due to polymer recrystallisation is eliminated, providing a good coating adhesion, a high spray material throughput rate is achieved and die risk of coating polymer combustion is greatly reduced. The polymer composite form decreases the overall costs of coatings and the type of filler employed influences the properties of the composite. Abrasion resistant composites have been produced with alumina and silica fillers (50 wt.%). Medium density polyethylene (MDPE), sprayed with 50 wt.% reinforcement, have shown abrasion resistance as high as UHMWPE. Polymer degradation, abrasion mechanisms and microstructures of these composite coatings are explained.
Influence of a Filler Composition and Conditions of Flame Spraying on a Structure and Mechanical Properties of Composite Polymer Coatings
Authors: Borisov Yu. , Korzhik V. , Sviridova I. , Skorokhod A. 
Published: May 2021

Abstract
In thermal spraying of metal-polymer coatings, the processes of polymers oxidation and destruction can have special features, as the temperature of heating of the filler particles can significantly exceed the temperature of destruction of the polymer binder. Hence, the need to study the features of the process of formation of thermal sprayed coatings from filled polymers and their physico-chemical, mechanical and service properties. This paper describes the influence of a filler composition and conditions of flame spraying on a structure and mechanical properties of composite polymer coatings. It is observed that addition of 5-10 vol. % of Fe-Ni-B alloy powder to low-pressure polyethylene polymer matrices, improves the wear resistance of thermal sprayed coatings 1.2-1.3 times under the conditions of gas-abrasive wear, compared to purely polymer coating, owing to the combination of the higher hardness of the coating with the high damping properties of the polymer matrix.
The Effects of Silica Content and Thermal Cycles on Young’s Modulus and Residual Stresses in Yttria Stabilized Zirconia Thermal Barrier Coatings
Authors: McGrann R.T.R. , Rybicki E.F. , Shadley J.R. , Sanchez R.E. , Brindley W.J. 
Published: May 2021

Abstract
The Young's modulus of the ceramic top coat of a plasma sprayed thermal barrier coating (TBC) has been reported to vary by as much as a factor of three with changes in processing parameters and by as much as a factor of four due to prolonged thermal exposure. Since the residual stress is expected to vary directly with the modulus of the ceramic layer, it follows that a change in modulus will change the residual stresses in the ceramic layer. The objective of this study was to evaluate the modulus of plasma sprayed coatings as a function of thermal cycle exposure and silica content of the ceramic. The study employed the Cantilever Beam Bending Method to examine Young's modulus for an yttria stabilized zirconia TBC applied by plasma spraying, for zero and ten thermal cycles and for silica contents of 0.1% and 1.0%. Results are discussed in terms of mechanisms that may affect modulus and the effect of modulus variations on residual stresses.
Thermal Spraying of Nanostructured Coatings by Hypersonic Plasma Particle Deposition
Authors: Heberlein J. , Rao N.P. , Neuman A. , Blum J. , Tymiak N. , McMurry P.H. , Girshick S.L. 
Published: May 2021

Abstract
A novel plasma spray process for producing nanostructured coatings, hypersonic plasma particle deposition (HPPD), has been experimentally investigated. In HPPD, vapor phase precursors are injected into a plasma stream generated by a DC arc. The plasma is quenched by supersonic expansion through a nozzle into a vacuum (~ 2 torr) deposition chamber. Ultrafine particles nucleated in the nozzle are accelerated in the hypersonic free jet downstream of the nozzle and inertially deposited onto a substrate. The short transit times between the nozzle and the substrate (&lt; 50 μs) prevent inflight agglomeration, while the high particle deposition velocities result in the formation of a consolidated coating. We have investigated the production of silicon and silicon carbide coatings using SiCl4 and CH4 precursors. Silicon deposits analyzed by transmission electron microscopy were found to have nanostructured regions with grain sizes varying from 5-20 nm. Corresponding particle size distributions measured before deposition using an extractive aerosol probe peaked around 15 nm, suggesting negligible grain growth occurred in the samples studied. Silicon carbide particle size distributions measured at various deposition chamber pressures verify that the low residence time characteristic of the HPPD process minimizes in-flight agglomeration.