bluuebunny/crossref_metadata_2025_split huggingface dataset:
Expansion of the Applicable Range of HVOF Process Conditions
Authors: Wank A. , Schwenk A. , Liu M. , Zhou K.S. , Deng C.M. , Deng C.G. 
Published: September 2022

Abstract
A conventional GTV K2 kerosene fuel HVOF spraying system has been modified with the aim to expand the applicable range of process conditions in order to also cover the presently existing gap between conventional HVOF and cold gas spraying. Different measures have been applied in order to reduce heat transfer and increase momentum transfer to spray particles. Increase of momentum transfer results both in reduced particle temperature as a consequence of reduced dwell time in the hot flame area and high particle velocities. In detail expansion nozzles with conical shape that provide improved expansion of combustion gases, combustion chambers with reduced critical diameters that provide increased combustion chamber pressures and the injection of coolant media water and / or nitrogen into the combustion chamber are applied. The effect of modified spraying conditions on the process characteristics and coating properties have been studied for a variety of materials. Besides copper, titanium alloys and MCrAlYs also WC/Co(Cr) and Cr3C2/Ni20Cr have been sprayed and respective coatings have been analysed concerning their microstructure, gas content, microhardness and wear resistance. In particular a moderate increase of oxygen content in dense titanium alloy coatings compared to the powder feedstock from 0.41 to 0.59 wt.-% proves the high potential of the undertaken measures to expand the application field of HVOF spraying. Thereby existing systems only need relatively small modifications to achieve this expansion.
Evaluation of Boron Carbide Based Thermal Sprayed Coatings for Tribological Applications
Authors: Lima C.R.C. , Rosales M.J. , Camargo F. 
Published: September 2022

Abstract
The superior mechanical properties of Boron Carbide make it very attractive for use as a wear resistant coating in tribological applications. Boron carbide is the hardest non-oxide ceramic produced in large quantities. It offers a high erosion and abrasion resistance, high chemical and outstanding heat resistance. B4C can be formed on a suitable substrate by thermal spray process as an alternative to high wear carbide coatings. The objective of this work was to investigate and to characterize the mechanical properties of a boron carbide based coating applied by HVOF spraying using a non commercial powder for corrosion and abrasion applications. The produced coatings were evaluated by metallographic procedure, microhardness, porosity and roughness measurements as well as adhesion and wear tests. The results are promising and signal good applications for such coatings.
Effects of Nanosize Particles on the Intermetallic Compound Formations of Cold Sprayed Coatings
Authors: Lee H. , Choi J.O. , Ko K.H. 
Published: September 2022

Abstract
Comparative studies on the intermetallic compound (IMC) formations of nano- and micro-size Sn with Ni and Cu in cold gas dynamic sprayed (CGDS, or Cold Spray) coatings were carried out. High purity pure nano (average 150 nm) and micro (under 45 μm) Sn were selected and prepared as raw materials mixture in order to be sprayed onto Ni and Cu plate-shape substrates. Nano particles of Sn were successfully coated under conventional coating parameters when they are mixed with microsize materials. And thermodynamic predictions regards to compound formation similarly worked out for both nano and micro Sn mixture. However, the kinetics of formation reaction were turned out to be different. In all case, nano particle showed more sluggish behavior. After post-annealing, microsize Sn formed larger amount of IMC with Ni than nanosize Sn although, owing to larger interfacial area, more intensive reactivities were expected. Also, there were significant differences in the size and distribution of eutectic pores as well.
Characterisation of Corrosion Resistant Deposits by Cold Gas Dynamic Spray
Authors: Marrocco T. , Harvey D. , Hussain T. 
Published: September 2022

Abstract
Despite much research effort and many application development studies, corrosion resistant alloy (CRA) coatings, prepared by thermal spraying still provide greatly inferior corrosion resistance when compared to parent material of the same composition, due to a network of oxides and pores in the coatings. However, the recent development of Cold Gas Dynamic Spray (CGDS) technology has made possible the deposition of low porosity and oxide-free CRA coatings. This paper describes the corrosion performance of Ni-based Alloy 625 following cold spraying onto steel substrates both as-sprayed and following heat treatment. Microstructures and oxygen content of powders and coatings were investigated, and coating microhardness and strength were determined in both as-sprayed and post treated conditions. Mercury intrusion was used to measure the interconnected porosity in the as-deposited and post-treated coatings. Finally, the corrosion behaviour of the sprayed and post-treated coatings was measured using a standard test (ASTM B117-07a).
Improving Powder Injection in Plasma Spraying by Optical Diagnostics of the Plasma and Particle Characterization
Authors: Mauer G. , Vaßen R. , Stöver D. , Kirner S. , Marqués J.-L. , Zimmermann S. , Forster G. , Schein J. 
Published: September 2022

Abstract
Powder injection parameters like gas flow, injection angle and injector position strongly influence the particle beam and thus coating properties. The interaction of the injection conditions on particle properties based on DPV-2000 measurements using the single-cathode F4 torch is presented. Furthermore, the investigation of the plasma plume by emission computer tomography is described when operating the three-cathode TriplexPro torch. By this imaging technology, the three-dimensional shape of the radiating plasma jet is reproduced based on images achieved from three CCD cameras rotating around the plume axis It is shown how the formation of the plasma jet changes with plasma parameters and how this knowledge can be used to optimize particle injection.
Microstructural Modelling and Performance Simulation of Engineered Bio-Composites
Authors: Tietz U. , Berndt C.C. , Schmitz K.-P. 
Published: September 2022

Abstract
A primary goal in modern orthopaedics is increasing the rate and long-lasting anchoring of implants in the human body. Hydroxyapatite, having a chemical structure and chemistry that is identical to bone, significantly enhances the on growth and subsequent ingrowth of natural bone material. Nevertheless some aspects of the performance of hydroxyapatite coatings have not been investigated sufficiently; for example the in vivo, long-term behaviour of the material, including the time-dependent dissolution accompanied by changes of mechanical properties have been poorly documented. The current study creates an idealized, virtual microstructural coating model that examines the time-dependent behaviour and properties of hydroxyapatite coatings. The analyses examine time vs. dissolution dependencies that reflect in vivo behaviour.
Effect of Ambient Pressure and Substrate Temperature on Heat Transfer at Interface Between Molten Droplet and Substrate Surface
Authors: Fukumoto M. , Tanaka K. , Yang K. , Usami T. , Yasui T. , Yamada M. 
Published: September 2022

Abstract
Effect of substrate temperature and ambient pressure of deposition chamber on contact condition between free falling droplet and substrate surface were investigated. Cu droplet and SUS304 substrate were used for the experiment. To estimate the contact condition, temperature history of molten droplet was measured at splat-substrate interface by thermocouples embedded in the substrate and high frequency data logging system. Quantitative porosity on splat bottom surface and degree of circularity of splat shape was evaluated. Splat adhesion strength experiment was conducted and dynamic wetting behavior of substrate by molten droplet was captured by ultra-high speed video. Heating substrate and vacuuming chamber pressure enhanced the heat transfer from splat to substrate, which can be attributed to the good contact at splat bottom surface. Adhesion strength of the splat to the substrate corresponded well with degree of circularity. Consequently, substrate temperature and ambient pressure of deposition chamber have an equivalent effect to contact condition at interface between droplet and substrate surface.
Homogenization of Coating Properties in Atmospheric Plasma Spraying – Current Results of a DFG (German Research Foundation)-Funded Research Group
Authors: Bobzin K. , Bagcivan N. , Petković I. , Schein J. , Landes K. , Forster G. , Hartz-Behrend K. , Kirner S. , Marqués J.-L. , Zimmermann S. , Bach Fr.-W. , Möhwald K. , Prehm J. , Xin L. 
Published: September 2022

Abstract
In the area of atmospheric plasma spraying, newly-developed triple-cathode technologies offer the potential to homogenize the coating properties with respect to porosity and residual stresses. Focused on numerical simulation, combined with advanced diagnostics, the goal of this research group is to adjust these properties systematically. A numerical model that couples fluid dynamic, electro-magnetic and thermal phenomena for a three-cathode torch was developed to investigate the plasma and the electric arc behaviour inside the torch. With help of self-developed computer tomography equipment, which is based on emission spectroscopy, combined with the solution of the Saha equation in thermodynamical equilibrium, it is now possible to reconstruct the 3- dimensional temperature distribution close to the torch outlet. This measurement allows us to confirm the torch numerical modelling. Coating formation is simulated by coupled computational fluid dynamics (CFD) and FEM simulation, so that fluid structure interaction is taken into account. This innovative approach has the advantage to predict residual stresses which occur during cooling and moreover the shrinking effects can be considered. By simulation of the individual regions, in combination with experimental results, which also include the particle velocity, diameter and surface temperature, the corresponding process parameters can be obtained for the desired coating properties.
Arc Spraying of WC-FeCSiMn Cored Wires – Part 1: Bending, Compression and Tension Behavior
Authors: Nebel J. , Vogli E. , Tillmann W. 
Published: September 2022

Abstract
This is the first of two papers concerning the intrinsic mechanical properties of arc-sprayed WC-FeCSiMn coatings. In part 1 the elastic and plastic forming behavior of the layers are investigated by indentation, bending and tensile tests. They were performed on coated mild steel substrates as well as freestanding as-sprayed samples with different geometries. Considering the coatings microstructure, element and pore distribution, as well as the local microhardness the results of the indentation, bending, and tensile tests were evaluated. The critical role of pores and inhomogeneities within the sprayed coating was examined in detail. Micro- and macrocracking were investigated by SEM after the indentation and tensile tests. In-situ surface observation by optical 3D-microscopy was used to study the onset of cracking during the 3-point bending test.
A Comparative Study of the Splat Morphology and the Splat-Substrate Interaction for NiCr Sprayed Onto Stainless Steel by Both Plasma and HVOF Spraying
Authors: Brossard S. , Munroe P. R. 
Published: September 2022

Abstract
The various thermal spraying methods available include the plasma process, which uses a plasma flame to melt a fine powder before it is sprayed onto a substrate, and the High Velocity Oxy-Fuel (HVOF) spray process, in which the flame is made from the combustion of oxygen. These methods differ both in the temperature and velocity with which the molten particles impact the substrate, leading to different coating characteristics. This includes differences in splat morphology and the nature of microstructural interactions at the splat-substrate interface. That is, features such as local melting of the substrate, the existence of porosity and the presence of oxides. For this study a nickel-chromium powder was sprayed onto mirror-polished stainless steel substrates using both plasma spray and HVOF to form single splats. These splats, and their interface with the substrate, were characterized using a range of microstructural characterization techniques and the observed differences were correlated to the spray conditions used.
Functionally Graded Coatings Produced by Means of Twin Wire Arc Spraying
Authors: Tillmann W. , Vogli E. , Abdulgader M. 
Published: September 2022

Abstract
Functionally graded coatings (FGC), in which the composition and properties vary gradually from the bond layer to the top layer, are introduced in this study. Using a mixing nozzle, a graded coating was generated employing twin wire spraying (TWAS) process. The deposition started with a base layer of massive metallic wires for better adhesion to the substrate. At following top layers hard material, in form of powders, was injected to the massive wires to enhance the wear protection. The results show that microstructure, porosity, and compositions are gradually varied in the coatings. This is a clear indication for the better performance in as-sprayed FGC than coatings sprayed by means of cored wires. The approach was to grade the coating composition from pure metallic to composite with higher content of hard material particles. The goal of the study is to articulate the needed coating performances by customizing the layers deposited regarding to their position.
Effects of Fluid/Solid Couplings on the Plasma Flow Inside a Direct Current Plasma Gun
Authors: Bolot R. , Coddet C. , Allimant A. , Billières D. 
Published: September 2022

Abstract
The present study is devoted to the modelling of the arc formation in a direct current plasma gun newly commercialized by Saint-Gobain Coating Solutions (Avignon, France). The CFD computations were performed using the FLUENT code and the electromagnetic coupling was taken into account on the basis of a three dimensional model. The main advances compared to previous works performed on the same subject are numerous. First of all, whereas most of earlier models include the arc region only, the CFD domain was here extended to the gas injection region (i.e. upstream part of the gun, including the gas injection sleeve), thus allowing a better description of the effect of the gas injection on the plasma flow. Second, whereas earlier works include the fluid domain only, the present model includes a fluid/solid coupling in the anode. In particular, the thermal and electromagnetic equations are solved not only in the fluid parts but also in the tungsten and copper parts of the anode. This change was found to be important because the internal surface of the anode is no more a boundary of the domain. Thus, its temperature (and electric potential) becomes variable and is thus not necessarily imposed. Finally, the implemented model provides interesting results describing the arc behaviour inside the plasma gun.
Effect of Using Liquid Feedstock in a High Pressure Cold Spray Nozzle
Authors: Farvardin E. , Stier O. , Luthen V. , Dolatabadi A. 
Published: September 2022

Abstract
This study investigates the effect of water injection in the high pressure chamber of a cold spray nozzle. A de Laval nozzle geometry with constant back pressure and temperature is modeled numerically using Reynolds Stress Model coupled equations. Water spray with a droplet size of 10 – 100 μm is modeled using both uniform and Rosin-Rammler size distributions. The two-phase flow of gas-liquid is modeled using an unsteady discrete phase mass source with two-way coupling with the main gas flow. Upon injection, the droplets in the water spray evaporate while travelling through the nozzle due to momentum and energy exchange with the gas flow. The evaporation behavior in presence of water content is modeled and a correlation between the initial diameter and the diameter just before the throat is obtained. As a result, the proper droplet size distribution with a fully evaporative spray can be used as a carrier of nano-particles in cold spray nozzles. Having the results, guide us to substitute the un-evaporated part of the droplet with an equal diameter agglomerate of nano particles and find a minimum fraction of nano particles suspended in the liquid which guarantees fully evaporative liquid spray injection.
Assessment of Flame-Sprayed Glaze Layers as Diffusion Barriers on Refractory Materials
Authors: Preziosa O. , Denoirjean A. , Montavon G. , Denoirjean P. , Fauchais P. , Chartier T. , Barthhelemy C. , Laurent V. , Lombard D. 
Published: September 2022

Abstract
Large (3 x 3 x 0.05 m3) refractory pieces (as the ones used for examples in smelters or incinerators) do not sustain regular glazing in a kiln, mostly due to high associated costs. Still, glass coatings could find use on such pieces due to their physical properties (durability, chemical inertia, tightness, etc.). Thermal spraying, using oxyacetylenic flame in particular, appears as a cost-effective solution permitting to circumvent the aforementioned disadvantages. This study aims at evaluating the quality of two types of coatings in terms of permeability. The first type considered coatings (resulting from a previous optimization of the spray operating parameters) sprayed directly on the substrates whereas the second one considered an additional brass underlayer manufactured by twin-wire electric arc spraying. The wettability of the glaze on the refractory substrate and on the brass underlayer was studied to comprehend the coating structural attributes (thickness, porosity, crazing, etc.) as well as their effects on the permeability. A specific measuring device was developed to assess permeability.
Corrosion Behavior of NiCrBSi Alloy Coatings Manufactured Via in Situ Plasma Spray – Laser Re-Melting Process
Authors: Serres N. , Hlawka F. , Costil S. , Langlade C. , Machi F. 
Published: September 2022

Abstract
Pressure to identify alternatives to hard chromium electroplating has increased these few last years, related to environmental requirements, because of the use of hexavalent chromium, a highly toxic substance. The plasma spray technique allows the formation of thick coatings which present moderate adhesion to the substrate and show porosity and formation of oxide interlayers, which impairs to obtain full benefits of the coatings properties. In this sense, a treatment can be necessary to improve the properties of these coatings. In this paper, the effect of an in situ laser melting treatment of NiCrBSi coatings, deposited by plasma spraying was investigated. It is demonstrated by a Life Cycle Assessment (LCA) that this process is clean. Moreover, the corrosion resistance of as-sprayed and in situ remelted layers was evaluated by potentiodynamic polarization curves. The corrosion resistance was increased because of the finer structure and higher densities of the coatings, nevertheless, corrosion mechanisms occurring in all cases are different.
Cyclic Oxidation Behavior of HVOF-Sprayed Ni-20Cr Coating on ASTM-SA213-T22 Boiler Steel at 900 °C
Authors: Kaushal G. , Singh H. , Prakash S. 
Published: September 2022

Abstract
In this study, HVOF thermal spray technique was used to deposit Ni-20Cr coating on a commonly used boiler steel ASTM-SA213-T22.The specimens with and without coating were subjected to cyclic oxidation testing at an elevated temperature of 900°C to ascertain usefulness of the coating for 50 cycles. Each cycle consisted of 1 hour heating in a silicon carbide tube furnace followed by 20 min cooling in air. Mass change technique was used to approximate the kinetics of oxidation. The uncoated sample suffered intensive spallation along with a significant overall mass gain. The oxidation rate was found to reduce appreciably after the deposition of the coating by 91%. The exposed specimens were characterized by X-ray diffraction [XRD] and scanning electron microscopy/energy dispersive spectroscopy [SEM/EDS]. It was observed that HVOF-sprayed Ni-20Cr coating was suitable to provide oxidation resistance to the given steel in the air environment.
Tribological Analysis of WC Cermet Coatings with Friction Test Under Tensile Stress Condition
Authors: Nomakuchi K. , Itoigawa F. , Kitamura J. , Sato K. 
Published: September 2022

Abstract
This paper describes tribological properties of WC cermet coating layers which are thermally sprayed with HVOF. On the assumption of the severe sliding condition in which large compress and tensile stress are applied to a surface layer simultaneously, relatively hard material is chosen as counter parts and additional tensile stress is applied. WC/12%Co, WC/10%Co/4%Cr and WC/20%CrC/7%Ni are employed as coating material. From the experimental results, it is found that the WC cermet spray coatings by the HVOF are inferior to sintered WC/Co with regard to fracture toughness near the surface and pseudo plastic deformation which are main wear behavior in severe sliding condition. It is also found that a heat treatment has certain effect to eliminate the wear caused by the surface fracture, while, for the pseudo plastic deformation, it does not exhibit much effect.
Next Generation Thermal Barrier Coatings for the Gas Turbine Industry
Authors: Curry N. , Markocsan N. , Li X.-H. , Tricoire A. , Dorfman M. 
Published: September 2022

Abstract
The aim of the study presented in this paper was to develop the next generation of production ready air plasma sprayed thermal barrier coating with a low conductivity and long lifetime. In order to achieve these goals; a number of coating architectures were produced using commercially available plasma spray guns. Modifications were made to powder chemistry including; high purity powders for sintering resistance, Dysprosia stabilised Zirconia powders and powders containing porosity formers. Agglomerated & Sintered (A&S) and Hollow Oven Spherical Powder (HOSP) morphologies were used to attain beneficial microstructures. Finally, dual layer coatings were produced using the different powder morphologies. Evaluation of the thermal conductivity of the coating systems from room temperature to 1200°C was conducted using laser flash technique. Tests were done on as-sprayed samples and samples heat treated for 100 hours at 1150°C in order to evaluate the first stage sintering resistance of the coating systems. Thermal conductivity results were correlated to coating microstructure using image analysis of porosity and crack content. The results show the influence of beneficial porosity on reducing the thermal conductivity of the produced coatings.
Feasibility of Polycarbonate Coatings by Cold Spray Process
Authors: Seo D. , Mahiou N. , Ogawa K. , Shoji T. , Ito K. , Tirtom I. 
Published: September 2022

Abstract
Cold spray deposition of polycarbonate on the various substrates has been investigated. The polycarbonate particles are sieved and accelerated at elevated temperature in air through a DeLaval type nozzle, and are deposited on the metallic and ceramic substrates. The influences of the particle size, the gas temperature, the thermal conductivity and surface roughness of substrate on the deposition process are studied. As a result, the continuous deposits are formed on the metallic substrate. The powder sieved below 300 μm shows better deposition efficiency. Thin film of melted polycarbonate has been formed on the surface of substrate to act as a bonding layer, and its crystalline structure is changed to be amorphous, which is the more stable state for the polycarbonate. The coating seems to be better when the thermal conductivity of metallic substrate is low. For the ceramic substrates, there is no deposition whatever was the thermal conductivity.