bluuebunny/crossref_metadata_2025_split huggingface dataset:
Innovation of Ultra-Fine Structured Alloy Coatings Having Superior Mechanical Properties and High Temperature Corrosion Resistance
Authors: Ma X.Q. , Gandy D.W. , Frederick G.J. 
Published: September 2022

Abstract
High temperature protection requires full coating density, high adhesion, minor oxide inclusions, and preferably fine grains, which is not achievable in most thermal spray processes. High velocity oxygen-fuel (HVOF) thermal spray process has been applied extensively for making such coatings with the highest density and adhesion strength, but the existence of not or partially melted particles are usually observed in HVOF-formed coatings because of relative low flame temperature and short particle resident time in the process. This work has investigated the development of an innovative HVOF process using a liquid-state suspension/slurry containing small alloy powders. The advantages of using small particles in a HVOF process include uniform coating, less defective microstructure, higher cohesion and adhesion, full density, lower internal stress and higher deposition efficiency. Process investigations have proven the benefits for making alloy coatings with full density and high bond strength attributing to increased melting of the small particles and the very high kinetic energy of particles striking on the substrate. High temperature oxidation and hot corrosion tests at 800°C have demonstrated that the alloy coatings made by the novel process have superior properties to conventional counterpart coatings in terms of oxidation rates and corrosion penetration depths.
Detonation Flame Sprayed Diamond-Bronze Coatings for Grinding Applications
Authors: Tillmann W. , Vogli E. , Nebel J. 
Published: September 2022

Abstract
Grinding applications for the machining of stone and concrete require composite tools where large diamonds are perfectly embedded into a metallic matrix. With the detonation flame spraying process it is possible to manufacture these superabrasive composites. Excellent embedment of the voluminous superabrasive particles into the matrix coating material can be realized in order to produce high quality composite layers for grinding applications of stone and concrete. In this paper different diamond sizes as well as different volume contents of diamond in matrix are compared. Especially, the influence of particle size on its implantation efficiency is investigated and the influence of process and substrate temperature is analyzed. The thermal sprayed grinding tools are evaluated in the sense of their morphology as well as their grinding abilities. Compared to sintered diamond-bronze samples the results of an adaptively designed grinding test for the machining of concrete are presented and analyzed.
Hot Corrosion and High Temperature Oxidation Performance of WC-Co Coatings by Detonation-Gun Spray on a Boiler Steel
Authors: Kaur M. , Singh H. , Prakash S. 
Published: September 2022

Abstract
Detonation-gun spray technology is a novel coating deposition process which is capable of achieving very high gas and particle velocities approaching 4-5 times the speed of sound. This process provides the possibility of producing high hardness coatings with significant adherence strength. In the present study, this technique has been used to deposit WC-Co coatings on T22 boiler steel. Investigations on the oxidation performance of detonation-sprayed WC-Co coatings in air and in molten salt Na2SO4-82Fe2(SO4)3 at 700°C under cyclic conditions have been carried out. The thermogravimetric technique was used to establish the kinetics of corrosion. The uncoated boiler steel suffered a catastrophic corrosion in the form of intense spalling of its oxide scale during air, as well as, molten salt induced oxidation. The WC-Co coated specimens showed lesser overall weight gains in comparison to their uncoated counterparts in both the environments. The oxidation kinetics for the coated specimens followed nearly the parabolic rate law. The overall weight gain has been found to be higher in the case of air oxidation as compared to that in salt environment for all the cases. Scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS) techniques were used to analyse the corrosion products, which indicated the formation of W and O as main elements in the oxide scales of the coated steel in both the environments.
Characterisation of Ceramic Nanostructured Coatings Prepared by Thermal Spraying of Suspensions
Authors: Toma F.-L. , Berger L.-M. , Naumann T. , Langner S. 
Published: September 2022

Abstract
Functional characteristics of materials including the mechanical, electrical, environmental and tribological performance can be significantly improved using nanostructured feedstock. Over the last few years much research has been dedicated to the development of thermal spraying techniques with liquid precursors to prepare fine nanostructured coatings. In this work nanostructured ceramic coatings were prepared using the technique of suspension spraying. Titania and alumina powders with sizes in the nanometre to submicrometre range were used to prepare aqueous and alcoholic suspensions. Atmospheric plasma and high-velocity flame were employed as enthalpy sources. The morphologies and crystalline structures of the sprayed ceramics were mainly characterised by SEM and XRD. The aim of this work was to carry out a comparative study and to discuss the nanostructured ceramic coating microstructures as a function of the physicochemical properties of the feedstock suspensions and spraying parameters.
Microstructural and Tribological Aspects of Thermally Sprayed Ti-Cr-Si Coatings
Authors: Bandyopadhyay P.P. , Siegmann S. , Hadad M. , Jaeggi C. 
Published: September 2022

Abstract
This paper is a first report of thermally sprayed Ti 60 Cr 32 Si 8 (at-%) alloy coating. It has been reported previously that such an alloy assumes quasicrystallinity in presence of oxygen, when made to undergo rapid quenching. In these cases, either TiO or SiO2 is used as an ingredient in the alloy so that it can act as a source of oxygen. This paper describes an attempt to produce a quasicrystal by thermally spraying the alloy in air, i.e. in presence of oxygen, either by flame or atmospheric plasma spraying. The spray parameters for both the processes have been varied in the experiment in a wide range. A vacuum plasma sprayed coating served as the reference. This investigation includes a detailed study of the microstructure and phases by optical microscopy, Scanning Electron Microscopy (SEM), X–Ray diffractometry (XRD), microhardness and porosity. An estimate of the composition of the coating has been done using Glow Discharge Optical Emission Spectroscopy (GDOES). The parametric variations have been correlated with the coating microstructure. It has been found in the study that there is a likelihood of obtaining quasicrystalline phase by atmospheric plasma spraying of this alloy under favourable parametric conditions. The tribological properties of these coatings were studied using a ball on disc reciprocating tribometer.
Improving the Properties of HVOF- Sprayed Cr2O3 by Nanocomposite Powders
Authors: Varis T. , Knuuttila J. , Suhonen T. , Kanerva U. , Silvonen J. , Leivo J. , Turunen E. 
Published: September 2022

Abstract
Superior wear performance combined with excellent friction properties against metals makes chromium oxide (Cr2O3) an interesting coating material for many industrial applications. However, Cr2O3 is a challenging material for HVOF spraying due to its high melting temperature. Fracture toughness and lamella cohesion of a coating is limited and may be improved by using ceramic-ceramic –nanocomposite powders, which forms phases with improved properties. In this study Cr2O3-TiO2 systems were selected aiming to improve the toughness and lamella cohesion of coating without reducing the excellent wear properties.
The Effect of Undercooling on Solidification of YSZ Splats
Authors: Liu H. , Bussmann M. , Mostaghimi J. 
Published: September 2022

Abstract
The impact and solidification history of individual YSZ particles has been the subject of many experimental and theoretical studies. Yet it is customary to assume that solidification occurs at the equilibrium temperature. Furthermore, the diffusion of the solute (yttria) in the liquid phase during solidification of a splat has not been considered. Using our model, we study non-equilibrium effects during the rapid solidification of a molten YSZ particle, by solving the so-called hyperbolic equations for heat and mass transfer. The hyperbolic model predicts the interface undercooling (due to thermal and solutal effects) and velocity as a function of time, as well as the yttria redistribution within the solid phase. Results are then compared to corresponding ones that we obtained from a parabolic model, in order to assess the extent to which YSZ solidification is influenced by non-equilibrium effects. Results indicate that these effects are limited to the early part of the solidification process when undercooling is most significant. At this stage, the interface velocity is unsteady, and solute redistribution is most evident. As solidification decelerates, the non-equilibrium effects wane and solidification can then be properly modeled as an equilibrium process.
KINETIKS 4000—New Perspective with Cold Spraying
Authors: Hoell H. , Richter P. 
Published: September 2022

Abstract
Seven years after its introduction, the KINETIKS cold spray system from Cold Spray Technology GmbH is proving its reliability in various industrial applications. As pressure and temperature of the process gas are the primary parameters generating high particle velocities, the improvement respective development of the system family was focused on those. A further step of improving coating properties was the development of a powder preheating feature. Applications using this technology are now starting in a wide field from automotive up to aerospace products.
The LARGE Plasma Torch for Surface Chemistry Applications and CVD Processes: A Status Report
Authors: Zimmermann S. , Theophile E. , Landes K. , Schein J. 
Published: September 2022

Abstract
The LARGE is a new generation DC-plasma torch featuring an extended arc which is operated with a perpendicular gas flow to create a wide (up to 45 cm) plasma jet well suited for large area plasma processing. Using plasma diagnostic systems like high speed imaging, enthalpy probe, emission spectroscopy and tomography the LARGE produced plasma jet characteristics have been measured and sources of instability have been identified. With a simple model/simulation of the system LARGE III-150 and numerous experimental results, a new nozzle configuration and geometry (LARGE IV-150) has been designed, which produces a more homogenous plasma jet. These improvements enable the standard applications of the LARGE plasma torch (CVD coating process and surface activation process) to operate with higher efficiency.
Standard HVOF Process Compared to the HVOF Process for Internal Coating with Fine Powders
Authors: Matthaeus G. , Brandl W. , Secosan I.-F. , Marginean G. , Chirila V. , Ackermann D. 
Published: September 2022

Abstract
The main argument against the use of the internal HVOF process is the high thermal stress to which the substrates are subjected during the coating process. Traditional HVOF guns operate with a flame-stream energy level of 100–200 kW. Rendering HVOF technology usable for the application of internal coatings requires the reduction of the energy level of the flame stream to 20 kW, while safeguarding high particle velocity and sufficient temperature despite the reduced energy level. This requires an integrated process consisting of the HVOF gun, powder feeder, fuel control, and fine powder; the particle sizes of the powder are -25+5 µm, -15+5 µm, and -10+3 µm. Thermico’s ID CoolFlow M HVOF internal spraying gun comes equipped with a 5 mm acceleration nozzle and radial powder feed. It is suitable for internal diameters of 80 mm and above and eliminates the typical overheating problem. The ID CoolFlow M HVOF gun is suitable for internal coatings with Thermico 776 WC-CoCr powder, which comes in grain sizes of -15+5 µm and -30+15 µm. A comparison of both processes requires a number of specimen coatings with different parameters, which have to be compared to reference coatings. These reference coatings are produced using a Thermico CJS K4.2-776/G gun in combination with WC-CoCr 86 10 4 powder with a grain size of -30+15 µm, and a CJS K5.2-776 gun, using a finer powder with a grain size of -15+5 µm. The base material consists of heat-treated steel rings with a hardness of 45 HRC, an internal diameter of 130 mm and a wall thickness of 10 mm. Subsequently, the density, porosity, and structure of the specimen is assessed, and they are checked metallographically and with a scanning electron microscope, including EDX analysis. The specimen wear is monitored using the prototype of an internal coating test stand, developed by the Institute of Materials Science at the University of Applied Sciences Gelsenkirchen. It is essentially based on the same principle as the pin-on-disc tribometer for relative movements.
Effects of SO2 on Decay Durability of the 8YZ Coating Having Cermet Under Coat
Authors: Hamashima K. , Ishikawa Y. 
Published: September 2022

Abstract
In the production line of glass sheets, the 8%Y2O3-ZrO2 thermal spray coatings have put into practical uses. These coatings have under layers of metal Cr3C2-Ni/Cr cermets, to improve their bonding strength. In forming process of glass, non-oxygenated atmosphere containing sulfur dioxide is selected continually to improve the surface condition of glass sheets. Degradation and pealing of these coating have been observed frequently due to increasing of SO2 concentration. In this study, effects of SO2 on decay durability of the 8YZ coating having meta cermet under coat are examined. Interactions between the atmosphere and the top-layer or the under layer are clarified individually by some basic examinations and analysis. It is clarified that peeling of the bi-layer coating was occurred at the boundary region between top coat and under coat. By exposure test of the coated sample and some powders for N2-SO2 at 113K, following results obtained, 1) Some cracks and fine streaks are observed also, in the bottom region of the ZrO2 top layer after the exposure test of coated sample.. 2) Main components of these streaks are Cr and S. 3) Sulfur contents of Cr3C2 cermet and Cr3C2 are increased remarkably by the exposure test. 4) By the exposure, Cr3C2 can be converted into a Cr2O3 or a CrSx. due to reaction with SO2. As peeling of the coating on carrying roll is induced by oxidation and sulfurization of Cr3C2, the under layer of Cr3C2 cermet is not suitable especially as its under coat.
New Approach to the Problem of Cathode Wear in DC Arc Plasma Torches
Authors: Kavka T. , Arnold J. , Syed A. , Kupke T. , Schneider G. 
Published: September 2022

Abstract
High heat load on the surface of electrodes in DC arc plasma torches results in strong wear of electrodes. This takes place during the start up and shutting down procedure as well as during long-term running of the torch and results in arc voltage reduction. Such changes in voltage lead to a modification of the plasma jet properties and effect adversely reproducibility of deposits, which are undesirable for industrial applications. The present work offers a new approach to compensate cathode wear in DC arc gas stabilized plasma torches by using moveable anode. With this design of torch, the distance between the cathode tip and anode can be varied. Voltage fluctuation analysis show the possibility of a reasonable arc modification by approaching the nozzle to the cathode caused by a change of the flow field inside the arc chamber and the arc dynamics. Smaller cathode tip-nozzle distances result in higher arc voltage with reduced fluctuations accompanied by a positive effect on the plasma jet properties. Thus, the negative influence of cathode wear on generated plasma properties can be suppressed and the lifetime of the cathode can be extended by simple approaching the nozzle.
Microplasma Spraying of ZrO2 Coatings
Authors: Borisov Y. , Vojnarovich S. , Kislitsa A. , Borisova A. , Karpets M. , Tunik A. 
Published: September 2022

Abstract
Experiments for estimation of influence of microplasma parameters in ZrO2 – coating properties were performed with using of fractional-factorial design of the experiments. Regression equations for determination of the parameters significance and a selection of conditions for a deposition of coatings with specified properties were obtained. Possibility of deposition of ZrO2 - Y2O3 coating with tetragonal phase content 90 wt.% and more without cubic phase content by microplasma spraying was shown. Conditions of microplasma ZrO2-coating spraying with high content of tetragonal phase (93-95%) and porosity (1,3-1,8%) were established. Measurement of microplasma sprayed ZrO2-coating spots has established that the spots have an elliptical shape. Size of major and lateral axis (and also sprayed hill altitude) depends on spray parameters, mainly on amperage and spray distance. Microplasma sprayed ZrO2-coating can be applied for repair of small local defects on thermo barrier coatings and a deposition of zirconia electrolyte layer in solid oxide fuel cell.
Thin and Dense Yttria-Partially Stabilized Zirconia Electrolytes for IT-SOFC Manufactured by Suspension Plasma Spraying
Authors: Brousse E. , Montavon G. , Fauchais P. , Denoirjean A. , Rat V. , Coudert J.-F. , Ageorges H. , Wittman-Teneze K. , Caron N. 
Published: September 2022

Abstract
Intermediate temperature - solid oxy-fuel cells (IT-SOFCs) include in their design a solid electrolyte layer made of yttria-partially stabilized zirconia (Y-PSZ), an ionic conductor, through which oxygen ions diffuse. This layer needs to fulfill several characteristics among which a low leakage rate corresponding to a non-connected pore network and a low level of stacking defects such as microcracks or globular pores. Moreover, the thickness of this layer needs to be as low as possible (about 20 µm) in order to limit ohmic losses. Suspension plasma spraying (SPS) appears as a potential technological route to manufacture such layers structured at micrometric or sub-micrometric scales. In SPS, a stabilized suspension, made of a liquid, solid particles and a dispersant, is injected within the plasma flow. The liquid is very quickly fragmented and then vaporized and the individual particles, or the particle agglomerates, depending on the average size and morphology of the solid feedstock, are heated and simultaneously accelerated towards the substrate surface where they impact, spread and solidify, analogously in a first approximation to larger particles, to form a layer. The architecture of the layer is very closely related to plasma operating parameters (from which derive plasma flow stability), from the suspension characteristics, in particular the feedstock particle size distribution and from the suspension injection parameters. This work aims at presenting recent developments made to optimize some of these operating parameters to maximize the electrolyte layer characteristics.
Simulation of PYSZ-Particles Impact and Solidification in Atmospheric Plasma Spraying Coating Process
Authors: Bobzin K. , Bagcivan N. , Parkot D. , Petkovic I. 
Published: September 2022

Abstract
In this work numerical simulation results of the impact and solidification of molten PYSZ-particles on flat and rough substrate surfaces are presented. This investigation deals with the effect of the particle state prior impact, particle diameter and substrate roughness, on splats spreading behaviour and final morphology. The particles have a diameter range between 20 – 60 µm. Particle initial conditions prior to impact: speed, temperature and melting state, are taken from previous simulation modelling approaches of particle accelerating and heating. Simulations of fluid dynamics, heat transfer and solidification during the particle impact were performed using computational fluid dynamics. Tracing of free surfaces determinates volume of fluid method. Heat flux at the particle-substrate interface and temperature dependent liquid phase viscosity of PYSZ are studied and discussed. Simulated splat morphologies are compared with experimentally obtained splats.
How Long is the Way to Manufacture Solid Oxide Fuel Cells with Suspension Plasma Spraying?
Authors: Marchand O. , Rampon R. , Bertrand G. , Filiatre C. 
Published: September 2022

Abstract
In order to achieve SOFC at reduced costs, atmospheric plasma spraying (APS) could be an attractive technique. However, it is difficult to elaborate plasma sprayed coatings with the appropriate porosity for the electrodes and full density for the electrolyte. The spray process has been adapted by providing a suspension as feedstock material. SPS shows important advantages over APS, since it is now possible to spray finer powders to obtain either a thin (10 µm) dense layer as electrolyte or thick and finely structured porous layers for the electrodes. Nevertheless some questions still remain before considering manufacturing SOFC by SPS. The major one is to understand the influence of the suspension and the injection parameters on the drops formation and transformation in plasma before impinging upon the substrate as well as of the suspension characteristics (formulation, particle size and amount, viscosity, surface tension,...). To answer these questions, suspensions based on nickel oxide (NiO) and YSZ (yttria stabilized particles) have been prepared and functional layers have been produced by SPS. This work is compared with previous studies of YSZ sprayed suspensions.
HVOF-Sprayed TiC-Strengthened Fe-Coatings as Alternative to Conventional Carbide Materials
Authors: Bobzin K. , Ernst F. , Richardt K. , Warda T. , Reisel G. 
Published: September 2022

Abstract
HVOF-sprayed carbide based coatings such as WC/Co or Cr3C2/NiCr are industrially well established for wear and corrosion protection applications. Due to their high carbide content of typically 75 wt.-% and more, they are providing a very high hardness and excellent wear resistance. Unfortunately costs for matrix materials like Ni or Co underlie strong fluctuations and are significant higher compared to iron. Therefore an alternative concept to the conventional carbides is based on TiC-strengthened low cost Fe-base materials, which are already in use for sintering processes. Depending on the carbon content the Fe-base material can additionally offer a temperable matrix for enhanced wear behaviour. Within this study the sprayability of TiC-strengthened Fe-powders with a gaseous and a liquid fuel driven HVOF-system has been investigated. The resulting coatings have been analysed with respect to microstructure, hardness and phase composition and compared to galvanic hard chrome, HVOF-sprayed and remelted NiCrBSi and HVOF-sprayed Cr3C2/NiCr (80/20) coatings as well as sintered Fe/TiC reference materials. Furthermore the Fe/TiC coatings have been heat treated to proof the retained temperability of the Fe-matrix after thermal spray processing. For determination of wear properties tribometer tests have been conducted. Currently the corrosion resistance of the sprayed Fe/TiC coatings is investigated as well the wear behaviour in a practical hydraulic test bench.