bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polyamide-11 Powder Coatings by Flame Spraying
Authors: McAndrew T.P. , Céré F. 
Published: September 2022

Abstract
Thermoplastic Polyamide-11 powder coatings serve many industries – such as water handling, automotive, and appliances. This utility is based on the ability to simultaneously provide exceptional resistance to: corrosion, impact/abrasion, and numerous chemicals. Typically application is by traditional methods – electrostatic spray or fluidized bed dipping. The present work demonstrates for the first time that the flame spray method can produce Polyamide- 11 powder coatings very close in performance to those produced by traditional methods. The keys are proper substrate pre-heating, and flame conditions that minimize polymer degradation. Coatings performance, impact resistance, and molecular weight data are presented.
Effect of Substrate Surface Topography and Temperature on Millimeter and Micrometer Sized Splat Formation and on Thermal Contact Resistance
Authors: Zhang G. , Liao H. , Cherigui M. , Coddet C. 
Published: September 2022

Abstract
Flame sprayed PEEK (poly-ether-ether-ketone) coatings, with an amorphous structure, were subjected to isothermal treatments with annealing temperatures from 180 to 300 °C and holding time from 1 to 30 min. The coating structures were studied by means of DSC (Differential Scanning Calorimetry) and XRD (X-Ray Diffraction) analyses. All annealed coatings exhibit semi-crystalline structures. Coexistence of thick and thin lamellae in the spherulites of annealed coatings can be deduced from the analysis results. The Knoop hardness and the interfacial adhesion of the coatings were examined. The annealed coatings exhibit higher hardness than the amorphous ones. The formation of the thick lamellae is the determinant factor for improving the coating hardness. However, the annealed coatings exhibit a weak adherence to the substrate. Some fissures or spherical porosities could be observed, in certain zones, on the coating/substrate interface. The formation of these fissures and porosities could be ascribed to the coating residual stress and the big volume contraction during the crystallisation that occurred under the annealing condition.
Wetting and Spreading of PEEK Single Splats on Aluminium
Authors: Withy B.P. , Hyland M.M. , James B.J. 
Published: September 2022

Abstract
PEEK was sprayed with a Browning Aerospray HVAF thermal spray gun to enable the study of the wetting and interaction of single splats with an aluminium 5005 substrate. Single splats were obtained by exposing the substrate to the spray flame for 0.02 s by dropping a steel shutter with a 25 mm aperture milled in the centre. The single splats were then analysed through SEM (scanning electron microscopy) and FIB microscopy (focussed ion beam). Splat shape was found to be dependant on nozzle length, with a 100 mm nozzle resulting in more splashing, and a 450 mm spray distance providing more disc splats. PEEK splats do not wet the aluminium oxide surface well. Porosity occurs independently of nozzle length, in the form of cracks and pores in the splats, some cracks completely segmenting a splat.
Effect of Substrate Roughness on Splatting Behavior of HVOF Sprayed Polymer Particles: Modeling and Experiments
Authors: Ivosevic M. , Gupta V. , Cairncross R.A. , Twardowski T.E. , Knight R. , Baldoni J.A. 
Published: September 2022

Abstract
A three-dimensional model of particle impact and deformation on rough surfaces has been developed for HVOF sprayed polymer particles. Fluid flow and particle deformation was predicted by the Volume of Fluid (VoF) method using Flow-3D® software. The effect of roughness on the mechanics of splatting and final splat shapes was explored through the use of several prototypical rough surfaces, e.g. steps and grooves. In addition, a numerical representation of a more realistic rough surface, generated by optical interferometry of an actual grit blasted steel surface, was also incorporated into the model. Predicted splat shapes were compared with SEM images of Nylon 11 splats deposited onto grit blasted steel substrates. Rough substrates led to the generation of fingers and other asymmetric three-dimensional instabilities that are seldom observed in simulations of splatting on smooth substrates.
On the Reproducibility of Air Plasma Spray Process and Control of Particle State
Authors: Srinivasan V. , Vaidya A. , Streibl T. , Friis M. , Sampath S. 
Published: September 2022

Abstract
Controlling particle state is important to not only achieve the required microstructure and properties in coatings but also to clearly isolate and understand the role of other clusters of variables (such as the various substrate and deposition conditions) on the aforementioned attributes. This is important to design coatings for high performance applications and in the ongoing efforts towards achieving prime reliance. This study examines the variabilities in particle state and explores a few strategies to control them for improved reproducibility with the aid of in-flight particle and plume sensors. The particle state can be controlled by controlling the torch parameters or by directly controlling the particle state itself via feedback from particle and plume sensors such as DPV2000 & TDS. There exist at least a few control protocols to control the particle state (predominantly temperature and velocity) with judicious choice of critical parameters. In the present case the particle state has been controlled by varying the critical torch parameters in a narrow range using 8% YSZ of angular morphology (fused and crushed) with 10-75 microns size distributions in conjunction with a N2-H2 laminar (non-swirl) plasma. Two important results emerge. (1) The particle state resulting from averaged individual particle measurements (DPV 2000) is surprisingly stable with variabilities in T &lt; 1% and variability in V of &lt; 4%. Ensemble approaches yield a somewhat higher variability (5%). In spite of this the variability in basic coating attributes such as a thickness and weight is surprisingly large. (2) Applying a much simpler control strategy to only control the particle injection and hence the particle trajectory results in reduced variabilities in coating attributes.
Sensing, Control, and Insitu Extraction of Coating Properties: An Integrated Approach towards Establishing Process Maps
Authors: Sampath S. , Srinivasan V. , Vaidya A. , Gouldstone A. , Liu Y. , Nakamura T. 
Published: September 2022

Abstract
Over the last decade there has been an explosion in terms of available tools for sensing the particle spray stream during thermal spray processes. This has led to considerable enhancement in our understanding of process reproducibility and process reliability. However, in spite of these advances, the linkage to coating properties has continued to be an enigma. This is partially due to the complex nature of the build-up process and the associated issues with measuring properties of these complex coatings. In this paper, we present an integrated strategy, one that combines process sensing, with process modeling and extracting coating properties in situ through the development of robust and advanced curvature based techniques. These techniques allow estimation of coating modulus, residual stress and non-linear response of thermal sprayed ceramic coatings all within minutes of the deposition process. Finally, the integrated strategy examines the role of process maps for control of the spray stream as well as design of thermal spray coatings. Examples of such studies for both MCrAlY and YSZ coatings will be presented.
Investigation of Time-Dependent Instabilities of Plasma Spraying Process Using Online Diagnostic Systems
Authors: Weckmann H. , Fiebig S. , Syed A. , Arnold J. 
Published: September 2022

Abstract
Reproducibility of plasma spraying process and resulting deposits is one of the most essential requirements for its application in industrial environment. In most cases, only controlling process input parameters does not suffice for achieving stability and reproducibility of the process. Besides short time plasma instabilities such as arc root fluctuation, process deviations in longer time operations may arise due to electrodes wear and need to be identified by online diagnostics of the plasma spraying process. In this study two online diagnostic systems were employed to investigate the long-term behaviour of a F4-type plasma gun with a convergent and divergent Laval-nozzle. A Plasma Instability Analysis (PISA) system was applied to identify electrode wear and plasma fluctuation phenomena within the gun whereas Particle Flux Imaging (PFI) was used to correlate the electrode wear with the plasma jet characteristics at the nozzle exit. The long-term performance of electrodes was investigated under continuous operation and under periodic reignition of the torch. A good correlation between aberrations in the plasma process observed with PFI and changes in the frequency spectra detected by PISA was found.
Effective Spectral Emissivity Measurement of Thermally Sprayed YSZ Thermal Barrier Coating at High Temperature Using a Wide-Band Single Wavelength Pyrometer
Authors: Moulla L. , Planche M.P. , Coddet C. 
Published: September 2022

Abstract
Single-wavelength pyrometers are widely used as a noncontact temperature measurement tool in material processing, petrochemical and laser-machining industries. In addition, these intensity-based IR sensors are used extensively as a diagnostic and health monitoring in the development and research of advanced high-temperature military and commercial gas turbine engines. In contrast to thermocouples, optical pyrometers have several advantages. First, they are easy to install and second they do not bring any disturbance to the measured system. However, they suffer from some problems, in particular the variation of the material emissivity and perturbations introduced by extraneous radiations. Yttria stabilised Zirconia (YSZ) thermal barriers are known to be more emissive and opaque in the 8-14 µm spectral band, therefore we can take advantage using this spectral band in temperature measurement. Spectral emissivities of an YSZ sample were measured using two commercial pyrometers. And a method for adapting commercial wide-band pyrometers (generally used for low temperature measurements) for high temperature measurements of thermal barrier coatings was tested.
Ultrasonic Testing of the Splat-Substrate Interface
Authors: Ducos M. , Bossuat B. , Walaszek H. , Barradas S. , Jeandin M. 
Published: September 2022

Abstract
The studying of splats in thermal spray is prominent to improve coating properties due to better understanding of coating build-up mechanisms. Most of studies, however, devoted to splats rest on physical aspects of the build-up, which feature the behaviour of a single particle impinging on a substrate. These studies involve the nature, velocity and intrinsic characteristics of the particle. The present work deals with the study of the splat-substrate interface using an ultra-sonic (U.S.) technique. This technique is based on the determining of splat-substrate adhesion (for an elementary splat or a group of splats) to help in the optimising of spraying conditions. APS copper splats were studied for Al-based substrates. This U.S. technique was already tested successfully for adhesion control of thermally-sprayed coatings in Basel, Switzerland. Further development then related to the specific experimental set-up for splat analysis using several transducers. This involved the use of various frequencies, various sizes for the focal spot and various scan velocities. In this study, results from this U.S. technique were discussed in the light of the observation of cross-sections of U.S.- controlled splats. U.S. C-Scan images were shown to fit well with cross-sectional images. In a general conclusion, the work showed the feasibility and efficiency of advanced U.S. control of splats to promote thermally-sprayed coatings whatever the process, i.e. plasma spray, flame spray, HVOF or cold spray.
Deposition of Nickel-Aluminide Coatings by Gaseous Detonation Spraying
Authors: Kharlamov Y.A. , Kharlamov M.Y. 
Published: September 2022

Abstract
The influence of the particle velocity on the formation intermetallic of coatings is discussed. The primary phases of detonation sprayed NiAl coatings are NiAl and Ni3Al, and also a solid solution of Ni in NiAl. The lamellar and homogeneous distribution of Al may be due to the oxidation of the powder particles during their flight in the pulsating high temperature, high velocity jet of the gas detonation process. During heating and melting of the powder particles, an aluminum oxide film is formed. This film takes part in the coating formation and affects the Al distribution. Another important observation is the presence of NiAl and Ni3Al phases in the coating structure. The transition zone between the coating and substrate has a thickness of 10-15 µm. The character of the distribution curves of Al and Ni confirms the lamellar distribution of NiAl and Ni3Al phases in the coating.
Microstructure and Properties of New Abradable Seal Coatings for Compressor Applications
Authors: Bobzin K. , Lugscheider E. , Zwick J. , Ernst F. , Sporer D. , Hopkins N. , Hertter M. , Matejicek J. 
Published: September 2022

Abstract
In modern jet engines, the efficiency of the compressor stages is highly dependent upon the clearance between housing and rotating compressor blades. To control the over-tip leakage, abradable coating systems are applied on the housing. In the high pressure compressor they typically consist of a thermal sprayed multiphase material, comprising a metal matrix combined with a dislocator and/or a solid lubricant as well as a defined level of porosity. In this study, novel material systems have been sprayed via the plasma and flame spray process and compared to reference materials. Resulting microstructures have been analyzed as well as important coating characteristics evaluated, including coating hardness and erosion resistance. Furthermore rig tests were performed to analyse the coatings abradability behaviour under different operation conditions of the compressor.
Characterization of AlCuFeB Quasicrystalline Coatings Sprayed by APS
Authors: Stihle A. , Liao H. , Bertrand P. , Allain N. , Coddet C. , Kenzari S. 
Published: September 2022

Abstract
Plasma sprayed composite coatings were prepared with a mixed powder of AlCuFeB + aluminium. One focus of this study has been the effect of air plasma spraying processing parameters on the characteristics of quasicrystalline composite coating. In this study, Taguchi L9 design of experiments was employed to study the investigated process parameters. Significant effects on the microstructure were observed. For the composite coating (quasicrystal + aluminium) parameters were optimized, considering phase retention and porosity level. Tribological tests were performed with a ball on disk device at room temperature for this composite coating. Results show that quasicrystal phase can be kept in the coating after spraying.
Exploring Thermal Spray Grey Alumina Coating Pore Network Architecture by Combining Stereological Protocols and Impedance Electrochemical Spectroscopy
Authors: Antou G. , Montavon G. , Hlawka F. , Cornet A. , Coddet C. 
Published: September 2022

Abstract
Complex multi-scale pore network architecture characterized by a multi-modal pore size distribution and connectivity develops during the manufacturing of ceramic thermal spray coatings from intralamellar and interlamellar cracks generated when each lamella spreads and solidifies to globular pores resulting from lamella stacking defects. This network significantly affects the coating properties and their in-service behaviors. The De Hoff’s stereological analysis permits the quantification of the 3-D distribution of spheroids (i.e., pores) from the determination of their 2-D distribution estimated by image analysis when analyzing the coating structure from a polished plane. Electrochemical impedance spectroscopy aims at electrochemically oscillating a material surface by frequency variable current and potential and at analyzing the complex impedance. When a coating covers the material surface, the electrolyte percolates through the more or less connected pore network to locally corrode the substrate. The resistive and capacitive characteristics of the equivalent electrical circuit will depend upon the connected pore network architecture. Al2O3-13TiO2 coatings were atmospherically plasma sprayed using several sets of power parameters, the arc current intensity, the plasma gas total flow rate and the plasma gas composition, namely to scan their effects on the pore network architecture. In parallel, particle characteristics upon impact, especially their related dimensionless numbers such as Reynolds, Weber and Sommerfeld criterion, were determined. Analyses permitted the identification of (i) the major effects of power parameters on the pore architecture and (ii) the related formation mechanisms.
Advanced Particle Characterization for Improved Understanding of Spray Coating Quality
Authors: Pirard E. , Campana F. , Janssen J.P. 
Published: September 2022

Abstract
The size and shape of individual particles are essential characteristics to control their behavior during spraying. Thanks to recently available technology in powder image analysis, this paper investigates the correlation between the geometric properties of several thousands of particles and their flowability (Hall flowmeter) and apparent density (Scott volumeter). Four different chromium carbide Cr3C2-NiCr 75/25 powders used for HVOF wear / oxidation resistant coatings are studied. The coating quality obtained for each powder by the HVOF spraying process is further investigated using metallographic image analysis.
Vanadium-Rich Iron-Based Thermal Spray Coatings for Combined Wear and Corrosion Protection
Authors: Wielage B. , Pokhmurska H. , Grund T. , Ahrens S. , Wank A. , Reisel G. , Schnick T.M. , Deppe E. 
Published: September 2022

Abstract
Newly developed iron based hard alloy powders with high chromium and vanadium contents are used for coating production by means of HVOF and LPPS. Crack free and dense coatings with fairly homogeneous microstructure are possible for both spraying methods. XRD analyses of sprayed coatings prove phase compositions similar to those of the powder feedstock when using HVOF systems. In contrast LPPS coatings contain a large share of amorphous phase. Microhardness of LPPS and HVOF coatings is about 1,200 HV0.3 and 800 - 950 HV0.3 respectively. The higher microhardness of LPPS coatings is attributed to the presence of the amorphous phase. However, LPPS coatings are brittle and tend to crack under mechanical load. Wear resistance of coatings is determined by means of corundum grinding disk and ASTM G65 wear test. Corrosion behavior is characterized by means of salt fog test and electrochemical measurements. Cermet and stainless steel 316L coatings are used for comparative purposes in the investigations.
Design and Characterization of a Simulated Environment Erosion Test Bed
Authors: Kosikowski D. , Stanisic J. , Ostrom T. , Mohanty P.S. 
Published: September 2022

Abstract
A simulated environment erosion test platform consisting of a control chamber, a modified HVOF gun, and a programmable logic control module is presented. This robust equipment can vary angles of impingement from 0-90 degrees, erodent velocities up to 300 m/s, and temperatures exceeding 2000°C. The erodent velocity, flow rates and temperatures are directly measured employing a high speed camera, and a DPV/CPS 2000 particle flight diagnostic sensor in contrast to estimates typically reported in the literature. It is demonstrated that, although the gas jet type erosion test apparatuses are frequently used in laboratories, quantitative parameter characterization is essential for setting up a test protocol. Both room and high temperature tests have been performed on this test bed. It is believed that the quantitative characterization of test parameters would greatly assist the designer in choosing and developing the appropriate erosion resistant coatings for their application.
Evaluation of Thermal Stresses in Thermo-abrasive Blasting Nozzles
Authors: Gorlach I.A. 
Published: September 2022

Abstract
Thermo-abrasive blasting is a technique, which combines conventional abrasive blasting and HVAF processes to prepare surfaces prior coating. Thermo-abrasive blasting has a number of advantages over conventional abrasive blasting as the result of a higher nozzle pressure and heat, which helps to remove impurities from the surface. However, practice showed that the short life of blasting nozzles due to thermal stresses and excessive wear is the biggest drawback of this method. Therefore, the correct nozzle geometry and suitable materials are critical for an efficient operation of thermo-abrasive blasting systems. In this study, computational fluid dynamics and finite element analyses were used to obtain the temperature distribution and to evaluate thermal stresses in nozzle materials. The materials investigated include tungsten carbide-cobalt (WC-6wt.% Co), hot pressed dense silicon carbide (SiC) and SiALON (Si3N4-Al2O3-AlN). The analysis and experiments showed that WC-CO nozzles produce the best overall results of thermal shock resistance and wear in thermo-abrasive blasting.
Formation of Pores in Thermal Spray Coatings due to Incomplete Filling of Voids under Solid Particles
Authors: Xue M. , Mostaghimi J. , Chandra S. 
Published: September 2022

Abstract
A three-dimensional, time-dependent numerical model of free-surface flows and heat transfer including phase change has been used to simulate the impact of a liquid droplet on a solid particle and to predict the size of the void under the solid particle caused by incomplete filling by liquid landing on top of it. The solid particle was considered to be a protrusion on the substrate. Fluid flow in the impacting liquid droplet was modeled using a finite difference solution of the Navier-Stokes equations in a 3D Cartesian coordinates assuming laminar, incompressible flow. Heat transfer in the liquid droplet was modeled by solving the energy equation, assuming densities of liquid and solid to be constant and equal to each other. The free surface of the liquid droplet was assumed to be adiabatic. The porosity in this simulation was defined as the volume of the incompletely filled void under the solid particle to the volume of the solid particle. The simulation was repeated with different process parameters, and the results showed that process parameters play significant roles in determining the amount of porosity. A correlation is found to express the porosity as a function of the process parameters.
Nanomechanical Properties of Zirconia- Alumina Plasma Sprayed Nanocomposite Coatings
Authors: Zhao W.M. , Wang J. , Zhai C.S. , Sun B.D. 
Published: September 2022

Abstract
Mechanical properties of micro/nanoscale structures are necessary to design reliable ceramic coatings. Micro/nanomechanical characterizations of novel nanocomposite coatings (NCCs) and micron composite coatings (MCCs) have been studied. Hardness, elastic modulus and creep resistance of these materials were measured by means of nanoindentation. It is found that the nanocomposite coatings exhibit higher hardness, elastic modulus and creep resistance as compared to the micron composite coatings. The nanoindentation tests used in this study can be satisfied to evaluate the mechanical properties of micro/nanoscale structures of ceramic coatings