bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modified Supersonic Nozzles for the Vacuum Plasma Spraying
Authors: Schwenk A. , Mihm S. , Nutsch G. , Wank A. , Gruner H. 
Published: August 2022

Abstract
Two new inner contours of de Laval nozzles (V70, V21) for F4 torch, which have already successfully been established for the Atmospheric Plasma Spraying (APS) are investigated for application under Vacuum Plasma Spraying conditions (VPS). Studies have been performed with regard to power efficiency, sound level and arc voltage fluctuations as well as coating quality and deposition efficiency for use of CoNiCrAlY powder as feedstock material. The results are compared to the commonly used standard VPS nozzle. CFD calculations and enthalpy probe measurements of plasma gas velocity and temperature distribution in the centreline of the supersonic plasma jets are carried out in order to get insight in the basic dependencies.
Constructive Aspects for the Application of Hard-Metal Coatings Using High Velocity Oxygen Fuel Flame Spraying (HVOF); Experience and Examples
Authors: Steinke T. , Bäker M. , Döring J.-E. 
Published: August 2022

Abstract
For 20 years now, the HVOF-method has been an industrially-established process for the application of hard-metal coatings to prevent wear phenomena from happening. A successful application combines the typical process parameters, conditions of materials and, above all, constructive frame conditions. In the following, we will present investigations for coating uneven outlines/contours such as edges, cavities or uneven surfaces. Furthermore, constructive frame conditions will be deduced from these and compared to our practical experience. The distribution of the layer thickness and its accessibility with the spray jet will be discussed as well. Here, we will have a closer look on which mechanical properties the basic substance has regarding hardness
Surface Preparation of Steel Substrates Using Grit-Blasting
Authors: Varacalle D.J. , Rhodaberger W. , Sampson E. , Guillen D. 
Published: August 2022

Abstract
The primary purpose of grit blasting for thermal spray applications is to ensure a strong mechanical bond between the substrate and the coating by the enhanced roughening of the substrate material. This study presents statistically designed experiments that were accomplished to investigate the effect of abrasives on roughness for A36/1020 steel. The experiments were conducted using a Box statistical design of experiment (SDE) approach. Three grit blasting parameters and their effect on the resultant substrate roughness were investigated. These include blast media, blast pressure, and working distance. The substrates were characterized for roughness using surface profilometry. These attributes were correlated with the changes in operating parameters. Twin-Wire Electric Arc (TWEA) coatings of aluminum and zinc/aluminum were deposited on the grit-blasted substrates. These coatings were then tested for bond strength. Bond strength studies were conducted utilizing a portable adhesion tester following ASTM standard D4541.
High Quality Coatings by VPS with Combined IC/DC-Spraying Technology
Authors: Gruner H. , Moens J. , Gruner Ph. 
Published: August 2022

Abstract
Direct current (DC) plasma spraying, in atmosphere (APS) or under vacuum condition (VPS), is a standard spraying technology to produce high performance coatings for important applications. Although inductive coupled (IC) plasma torches have been known since the early sixties, its use for industrial coating production remained limited due to the static gun requirement. An adequate substrate manipulation opens up the IC-spraying for its practical use. A VPS system was realized which combines IC- with DC-spraying. The potential of this new facility is highlighted by coatings of W and Yb2O3. The key parameters to achieve an optimized coating structure are explained.
Continuous Coating of Technical Textiles from “Coil to Coil”
Authors: Gadow R. , von Niessen K. 
Published: August 2022

Abstract
A pilot plant equipment for continuous coating of technical textiles is implemented to establish thermal spraying as a new and promising coating technique in the textile industry. In order to apply thermal spraying to temperature sensitive and flexible fiber structures two main difficulties have to be taken into account. First, the flexible structure of a textile fabric has to be fixed and stretched to achieve a sufficient mechanical support. Second, the kinetic and thermal energy of the molten particles and the hot gas jet may damage the fibers and their woven structure both mechanically and chemically. Special winding equipment is designed to allow various fabrics to be fixed and stretched in a way that enables the coating of wound fabrics from “coil to coil”. With this equipment even temperature sensitive fabrics, like cotton or polyester, but also aramide, carbon and oxide ceramic fabrics are coated by atmospheric plasma spraying or electric arc wire spraying in the case that higher deposition rates are required. Fabric coils up to a web width of 1500 mm can be coated continuously with a well-defined pre-stress in one single procedure.
Plasma Plume Condition Forming of Cascaded Type Plasma Guns
Authors: Hawley D. , Refke A. , Landes K.D. 
Published: August 2022

Abstract
In the thermal spray industry there remains a constant demand for more stable, controllable and economical processing devices. Most thermal spray applicators apply a wide range of materials especially those who are allied with the turbine markets. Each material coating specification requires a relatively specific range of velocity and temperature transferred to the powder particle to achieve the required material properties on the part. The plasma gun has become a dominant process tool in the turbine industry due to the wide range of parameters that are achievable with the basic tool. In addition, there are today a large number of individual plasma guns that are each known to provide excellent results with some, but not all coating requirements. In many cases the optimum gun running condition can never be achieved due to the interdependence of arc behavior and gas conditions. The turbine industry is currently largely populated with guns that are based on the technology as it was developed in the 1960’s. These guns are characterized by poor voltage stability with a large quasi periodic oscillation in the 3-5 kHz range as described by Bisson [1], with poor performance and life under more extreme operating conditions. A key element of any plasma gun is the nozzle geometry. The cascaded gun types as typified by the Triplex offer a unique opportunity to study and document a wide range of operational parameters, especially at extreme operating conditions.
Robotic Trajectory Autogeneration in Thermal Spraying
Authors: Deng S. , Liao H. , Zeng C. , Charles P. , Coddet C. 
Published: August 2022

Abstract
The quality of thermal spray coatings depends not only on the spray parameters but also on the gun trajectory. When using a robot, trajectory generation represents an important part of the work. Different workpieces require different spraying trajectories and even a same workpiece will require different spraying trajectories versus different spraying techniques. The purpose of this study was to develop a software toolkit to auto generate the spraying trajectory. Thermal Spray Toolkit is an add-in software of Robot Studio® which is a simulation and off-line programming software of ABB Company. This toolkit provides several projects of trajectory generation: spraying on a quadrilateral piece; spraying on a circular piece; spraying on a curved surface; etc. Furthermore, all the parameters of the trajectory are adjustable, such as traverse step; distance of overstep; etc. The results show that this development is reliable and applicable.
Calcium Phosphate Coatings Produced by Solution Precursor Plasma Spray
Authors: Garcia E. , Gan L. , Pilliar R. , Coyle T. 
Published: August 2022

Abstract
Calcium phosphate (Ca-P) coatings have been used as surface coatings on porous metallic implants in dentistry and orthopaedics for the last twenty years. These Ca-P coatings, nominally hydroxyapatite (HA), have been shown to promote bone fixation and osteconductivity on Ti and Ti alloy substrates used for those purposes. Such coatings can be formed by different methods including plasma spray. In addition to the well known advantages of the plasma spray technique to deposit coatings, a new version of this technique, i.e. solution precursor plasma spray (SPPS), has been reported to produce submicron/nanocrystalline structured coatings. Nanocrystalline HA coatings may improve the resorption of the coating in the body, avoiding the irritant effect of large particles which may be seen in current thermal sprayed HA coatings. The main purpose of this work was to study the suitability of a sol-gel Ca-P solution precursor (calcium nitrate tetrahydrate and ammonium dihydrogen phosphate) as feedstock for the air plasma spray (APS) coating technique. We report on the formation and the characteristics of the coatings so formed on Ti6Al4V substrates. The presence of different Ca-P crystalline and amorphous phases was assessed by X-ray diffraction analysis. The X-ray photoelectron spectroscopy technique was used to characterize the surface chemical composition of the Ca-P coatings. The microstructural features of the coatings were characterized by scanning/transmission electron microscopy combined with image analysis in order to evidence the presence of submicron/nanocrystalline Ca-P features. Final results are discussed in terms of the spraying parameters. Abstract only; no full-text paper available.
Cold Spray Deposition of Nanocrystalline Materials
Authors: Ajdelsztajn L. , Jodoin B. , Schoenung J.M. 
Published: August 2022

Abstract
This work describes recent progress in cold spray deposition of nanocrystalline metals and alloy. Gas-atomized powders (Ni and Aluminum alloys powder) were mechanically milled under liquid nitrogen to achieve a nanocrystalline grain size of the order of 10-30 nm. The powders were subsequently sprayed using a nozzle designed with a validated numerical model for cold spray technology. The resulting coatings were evaluated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), micro- and nanoindentation. TEM analysis shows that the nanocrystalline grain structure of the cryomilled feedstock powder was retained after the cold spray process. A significant increase in hardness was observed for all the cryomilled material when comparing with the conventional gas-atomized powder. The ability to use cold spray to produce nanocrystalline large deposits with low porosity (&lt;1%) was also demonstrated in this work. Abstract only; no full-text paper available.
Thermal Shock Resistance of Thick Graded Nanostructured Zirconia-NiCoCrAlY Composite Coatings by Plasma Spraying
Authors: Yang H. , Wang H.G. , Cao X.P. 
Published: August 2022

Abstract
Thick Nanostructured PSZ- NiCoCrAlY graded TBCs were got by air plasma spraying. The results reveal the morphology and phase transformation of TBCs by means of SEM and XRD. The plasma spray process results in a characteristic layered structure consisting of lamellae, unmelted nano-particles and an inter-lamellar porosity. The test results of thermal shock show that the graded coatings have different failure behavior, which caused by thermal stress, radial cracks penetrating and substrate oxidation. The failure mode was the spallation of top coat due to thermal stress. The improved strain tolerance of the top coat was benefited from the high coating porosity, the segmentation cracking, the fine-splat size and the unmelted nanoparticles. It has been found that the lamella consists of nanoscale columnar grains parallel to the spraying direction.
Nanostructured and Conventional Titania Coatings for Abrasion and Slurry-Erosion Resistance Sprayed via APS, VPS and HVOF
Authors: Lima R.S. , Marple B.R. , Leblanc L. 
Published: August 2022

Abstract
In order to characterize the performance of nanostructured coatings during wear, nanostructured and conventional titania (TiO2) coatings were sprayed via three different thermal spray processes: APS, VPS and HVOF. Three distinct types of wear resistance were evaluated: dry-abrasion and slurry-erosion at 30° and 90°. The ranking of the wear performance of the different coatings varied for the three wear tests, except for the HVOF-sprayed nanostructured titania. The HVOF-sprayed nanostructured coating exhibited the highest wear resistance in all three types of wear. The different angles of erosion (30° and 90°) did not cause a change in the wear performance (ranking) of the HVOF-sprayed nanostructured coating, as was observed for the other coatings tested. The superior mechanical performance of the HVOF-sprayed nanostructured titania can be explained by observing the microstructure of the coating via high magnification SEM. These observations show that the nanostructured zones in the coating microstructure act as crack arresters, thereby increasing the coating toughness. The wear scars for the different coatings were also analyzed via SEM and used to help understand the wear performance of the different materials.
Magnetic Properties of HVOF Thermally Sprayed Coatings Obtained from Nanostructured Powders
Authors: Cherigui M. , Fenineche N.E. , Coddet C. , Gang J. , Grosdidier T. 
Published: August 2022

Abstract
Ultra fine grain Fe-Si based coatings were synthesised by HVOF thermal spraying of nanostructured powders obtained from mechanical milling. Magnetic measurements revealed a soft magnetic character for all the coatings. Additions of boron, niobium and copper were investigated. The thermal stability and the evolution of the coercivity with temperature were observed to be remarkable.
Phase Formation Mechanisms in Plasma Sprayed Hydroxyapatite Coatings
Authors: Sun L. , Berndt C.C. , Gross K.A. 
Published: August 2022

Abstract
Phase composition control is a prime concern for plasma sprayed hydroxyapatite [Ca10(PO4)6(OH)2; i.e., HA] coatings due to the complexity of both HA structure and plasma spray process. The present study aims to better understand the phase formation mechanism in the HA coating through compositional, structural and microstructural studies of HA coatings obtained from various spraying processes. A process model was established by considering both a single HA splat formation and coating buildup processes. Three HA recrystallization mechanisms were proposed on the basis of the temperature-time experiences of particles, their cooling rates, and the heat and hydroxyl accumulation during coating formation. The model explained very well the experimental results. It was concluded that crystallinity alone was not capable of reflecting the coating composition due to the existence of various portions of crystalline HA; i.e., unmelted, recrystallized and dehydroxylated HA, as well as the gradient compositional structure from the coating interface to the surface. Some newly formed nanocrystalline regions were also revealed in the coating microstructure.
Fluid Dynamic Stability of Plasma Spray Jets
Authors: Heberlein J. , Outcalt D. , Hallberg M. , Yang G. , Strykowski P. , Pfender E. 
Published: August 2022

Abstract
Instabilities of plasma spray jets have been a source of inconsistencies in coating properties. These instabilities can be minimized through the use of central injection torches or torches with fixed anode attachment. However, any low density ( &lt; ~0.7) jet is globally unstable to small disturbances. Globally unstable jets are characterized by a short potential core, rapid spreading, and high entrainment, all of which are present in a plasma jet. Plasma jets have ratios of jet density to density of the surrounding gas on the order of 0.01, as well as rather low Reynolds numbers and thick boundary layers. In the present work, the instabilities are investigated through analysis of the disturbance growth in the shear layer between the plasma and the cold surrounding gas. These investigations are using two types of experiments, one consisting of a SG 100 spray torch with several optical diagnostic methods being applied to the shear layer analysis. The other experiment simulates the plasma jet at low temperatures by using a helium core jet exhausting into a sulfur hexafluoride (SF6) environment. The simulated plasma jet (SPJ) has a density ratio of 0.03. The simulated plasma jet (SPJ) allows controlled variation of the boundary layer through different fluid dynamic arrangements. It further allows use of diagnostics such as hot wire anemometry and PIV to clearly characterize the shear layer. Some of the characteristics of the shear layer are presented and comparisons between the plasma jet and the simulated plasma jet, and initial results on controlling the jet instability, are discussed. Abstract only; no full-text paper available.
Development and Properties of Tungsten-Based Coatings Sprayed by WSP(R)
Authors: Matejicek J. , Neufuss K. , Kolman D. , Chumak O. , Brozek V. 
Published: August 2022

Abstract
Plasma sprayed tungsten and tungsten-copper coatings are being developed for potential application as plasma facing materials for fusion reactors. Initial spray tests indicated difficulties in tungsten melting and in-flight oxidation. Numerical modeling was performed to help explain these issues. A complex study of the process and its products was performed, including: in-flight diagnostics, characterization of isolated splats, and structure, composition, thermal and mechanical properties of the coatings. Based on these results, the process was optimized, with respect to powder size and various spraying parameters, to improve melting of the particles, reduce oxidation and increase the deposition efficiency.
Plasma Sprayed Ultra High Temperature Ceramic Materials Tested in Simulated Operative Conditions
Authors: Tului M. , Valente T. , Marino G. 
Published: August 2022

Abstract
Thermal protection systems represent the key issue for the successful re-entry of a space vehicle. Future concepts for space launchers foresee sharp aerodynamic profiles as conventional aircrafts, which offers several advantages with respect to current blunt shapes. As a drawback, aerodynamic heat flux increases dramatically and state of art hot structures materials cannot withstand them. UHTC (Ultra High Temperature Ceramics) materials are very promising candidate materials for such applications. An innovative, proprietary methodology was developed to produce, by plasma spraying deposition, a ceramic composite containing SiC particles (25 wt %) dispersed in a ZrB2 matrix. With such a technique both coatings and self standing parts were fabricated. The present paper reports the results of a development activity aiming at testing plasma sprayed real scale components in simulated operative conditions by means of a Plasma Wind Tunnel. The results of the tests showed that plasma sprayed UHTC materials can withstand very high heat flux conditions in an oxidizing environment. Abstract only; no full-text paper available.
In Flight Particles Analysis for the Characterization of the Arc Spray Process
Authors: Planche M.P. , Liao H. , Coddet C. 
Published: August 2022

Abstract
The aim of this study was to point out the role of each electrode in the droplets formation in twin arc spraying. This way, two consumable wires of different properties, namely steel and copper, were sprayed simultaneously. The DPV 2000 diagnostic system was used to determine the size, temperature and velocity of in-flight particles, detected at the same locations than those previously tested on particles collection. Then, a model based on the particle temperature was developed to separate particles from the anode and the cathode wires. Results showed significant modifications in term of size, velocity, temperature and repartition when changing material electrodes. To validate the proposed model, modelling results were first compared to results found on properties of collected particles, i.e. sizes and percentages. Then, important differences of in-flight particles characteristics, velocity and temperature, were pointed out depending on the electrode nature and on radial locations in the spray jet. Finally, some coatings were sprayed at the same locations and analyzed in term of thickness. Results showed that the thickness distribution was largely dependent on the anode nature, which was in close agreements with in-flight particles analysis.
Correlation of Inflight Particle Parameters and Properties of HVOF Sprayed Cermet Coatings
Authors: Wielage B. , Wank A. , Rupprecht C. , Wank A.C. 
Published: August 2022

Abstract
HVOF sprayed cermet coatings are used for wear protection in numerous application fields. Most feedstock powders can be processed successfully with different spraying guns but optimized parameters for high quality coating production cannot be transferred directly. Besides substrate temperature only particle velocity and temperature inflight and at impact on the substrate determine the resultant coating properties. Two typical HVOF powders, WC/Co 88/12 and Cr3C2/Ni20Cr 75/25, are sprayed using the kerosene fuel system GTV K2 and particle parameters are recorded just prior to impact on the substrate with the passive diagnostic tool Spray Watch. Detailed correlation of particle parameters and the coating properties porosity and micro hardness as well as deposition efficiency is worked out in order to deduce particle parameter ranges providing coatings with defined optimum properties. The transferability to another kerosene fuel HVOF spraying gun, Tafa JP5000, is tested. It is also shown that effects like wear of the nozzle can be detected by use of the Spray Watch. Secondary correlation of particle parameters and machine settings is carried out to build a base for straight forward closed-loop control of the HVOF spraying process applying process diagnostics
Dense Titanium Coatings by Modified HVOF Spraying
Authors: Kawakita J. , Fukushima T. , Kuroda S. , Katanoda H. , Matsuo K. , Fukanuma H. 
Published: August 2022

Abstract
Titanium has an excellent corrosion property in chloride containing environments such as seawater. A modified HVOF spray process was developed by introducing a mixing chamber between the combustion chamber and the powder feed port. Nitrogen gas was fed into the mixing chamber to control the temperature of the combustion gas generated in the combustion chamber. By controlling the flow rate of nitrogen, various Ti coatings with different degree of oxidation and porosity could be fabricated. The densest coating produced by this process with surface polishing treatment maintained excellent corrosion protection over a steel substrate in artificial seawater in a laboratory test over 1 month.
Effect of Angle of Impingement on Erosion-Corrosion Behaviour of a WC-Co-Cr HVOF Sprayed Coating
Authors: Hodgkiess T. , Perry J.M. , Neville A. 
Published: August 2022

Abstract
This paper describes an investigation of the influence of impingement angle of a solid/liquid jet upon the erosion corrosion behaviour of a tungsten carbide-cobalt-chromium thermal sprayed coating. The coating type investigated was a nominal WC-10%Co-4%Cr material, HVOF-sprayed onto a stainless steel substrate. This coating was subjected to a submerged impinging jet at 12 m/s of 3.5% NaCl solution containing various concentrations of suspended sand particles at 18°C. The angles of impingement employed were 30, 45, 60, 75 and 90 degrees and the measured total weight losses exhibited a significant influence of impingement angle with reduced material losses at more oblique angles of jet impact. The implementation of cathodic protection to the specimens enabled the pure mechanical component of the overall erosion-corrosion damage to be determined and this was also found to be dependent upon the angle of impingement of the liquid/solid stream. In contrast, the pure corrosion component (determined from in-situ electrochemical monitoring) exhibited no systematic trends with impingement angle. The findings are discussed in terms of the detailed erosion-corrosion mechanisms and implications for operational durability of cermet coatings