bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plasma Sprayed Coatings from Powders of Alloyed Cast Iron Mill Debris
Authors: Kharlamov Y.A. , Budagyanch N.A. , Shevchenko A.V. 
Published: July 2022

Abstract
Manufacturing of alloyed cast iron forming rolls is accompanied by generation of valuable solid waste as cutting and grinding swarf. The objective of this investigation was to evaluate the potential for mill debris to be used as a new source of inexpensive powders for thermal spraying of wear resistant coatings. More than 25 high-carbon iron alloy compositions are used in roll production. The structure of these cast irons usually includes from 2 to 4 phases (such as troostite, bainite, needled martensite, austenite, and graphite). The properties of powders obtained from mill debris were characterized in terms of particle size and shape, composition, structure, technological fluidity, and bulk density. The obtained powders were used for plasma spraying of wear resistant coatings. The results indicate that cutting and grinding swarf may be a feasible raw material source for economical alloyed powders, granules, and other materials for coatings. The composite plasma sprayed coatings obtained from powder mixtures of alloyed cast iron and nickel-base alloy have better tribological performance in comparison to coatings from any single powder alloy.
A Comparative Diagnostic Analysis of Morphologically Different YSZ powders
Authors: Vaidya A. , Streibl T. , Sampath S. , Zhang H. 
Published: July 2022

Abstract
A wide range of manufacturing processes are used to supply yttria stabilized zirconia powders for plasma sprayed TBC applications. From previous studies it is known that the difference in coating properties can potentially result from variations in powder feedstock as a consequence of particle inflight behavior and particle impact. An additional strong contribution to splat variation results from changes in the particle in flight behavior. In order to understand the variation in particle condition as a consequence of different powder morphologies, a detailed diagnostic analysis was carried out for plasma densified (PD), fused and crushed (FC) and agglomerated & sintered (A&S) powders. In this study a “3D multiple sensors” based integrated approach was used to evaluate these differences. Direct feed back sensors were used for optimization and combined with sophisticated diagnostics for in-depth studies. To obtain comparable results, three batches of commercial powders were sized to the same specification. For a given set of spraying parameters the recorded spray stream characteristics such as plume position, particle temperature, size and velocity deviated strongly for the given morphologies. By optimizing injection, the different powders can be made to follow nominally similar trajectories. This study reveals the sensitivity of each powder to process parameters and the variability in particle state that can result from it. Some techniques are suggested to optimally inject the different powders and to achieve similar particle states for these morphologies
Vibrational Corrosion Potential of HastelloyC Coatings by GS-HVOF Spraying
Authors: Kawakita J. , Kuroda S. , Fukushima T. , Kodama T. 
Published: July 2022

Abstract
Coatings of HastelloyC fabricated by HVOF spraying with a gas shroud (GS) have shown the superior barrier characteristic and corrosion resistance in seawater environment. During immersion of these coatings in artificial seawater, however, vibrational behaviour of the corrosion potential was observed. Some types of surface modification of the sprayed coatings and changing of the spray condition were carried out and their effect on the corrosion potential was investigated. It was revealed that the vibration is related to surface oxides formed during the spray process. Surface modification of the sprayed coatings and changing of the spray condition could reduce the vibration effectively.
Corrosion Protection of a Metal Spray Coating by Using an Inorganic Sealing Agent for Its Micropores
Authors: Kanematsu Hideyuki , Barry Dana M. , McGrath Paul , Ohmori Akira 
Published: July 2022

Abstract
An investigation has been carried out to determine the corrosion protection that an inorganic sealing agent provides for micropores of spray coating films. The sealing agent used is composed of silicate compounds and easily penetrates the micropores of spray coating films. Generally speaking, its stability under ultraviolet light is much higher than any organic sealing agents available. In this study, the sealing capability of the inorganic agent was tested using several kinds of spray-coated specimens. In addition, observations were made about the anticorrosion characteristics of these sealed specimens. The samples used for this study were Zn/Al spray coated steel and pure aluminum spray coated steel. The inorganic silicate-sealing agent was applied to all of the specimens. However, some of them were ground until the sealing agent was completely removed from the surface of the specimens. For the latter case, the silicate-sealing agent remained only in the micropores of the spray-coated films. These specimens were observed by SEM-EDX to observe the sealing condition. Their corrosion characteristics were also observed by performing a CASS test. Using these results, we were able to evaluate the sealing agent’s protective capability for spray coatings.
Oxidation Behaviour of Molybdenum Disilicide Coatings at 1500 °C
Authors: Wielage B. , Reisel G. , Wank A. , Fritsche G. 
Published: July 2022

Abstract
Molybdenum disilicide (MoSi2) is a suitable material for high temperature applications especially because of its excellent high temperature oxidation resistance. For several high temperature applications MoSi2 shows high potential to be used as a protective coating. The oxidation behaviour of HVOF sprayed MoSi2 coatings is studied at 1500 °C. The oxidation tests are carried out in a simultaneous thermogravimetric device and the mass change is measured in dependence on the oxidation time. The microstructure of the coatings before and after oxidation is examined by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDXS). The mass of the coating increases according to a parabolic function. During the oxidation test the microstructure changes significantly from a typical thermal spray coating microstructure with lamellae, pores and a phase mixture of MoSi2 and Mo5Si3 to a two phase system with sharply separated grain boundaries. On the surface of the coating a silicon dioxide layer with a thickness of less than 10 µm is formed.
Restricted Oxidation of HVOF Sprayed Deposits by Composition Control of Combustion Gas
Authors: Kawakita J. , Kuroda S. 
Published: July 2022

Abstract
Improved HVOF spraying with a gas shroud has been developed to fabricate environmental barrier coatings of corrosion resistant alloys such as HastelloyC. For such coatings, control of oxidation of the powder material during spraying is very important and the gas shroud has been effective to lower oxygen content to 0.19mass%. In the present study, further reduction of oxygen content to 0.063mass% was achieved by changing the composition of combustion gas by introducing nitrogen into the combustion chamber. This value is almost comparable to the oxygen content 0.042mass% of the feedstock powder but the porosity of the coating increased. Introduction of nitrogen to the combustion chamber lowered the temperature of the spray particles in flight while maintaining their high velocity. Another coating with 0.14mass% was obtained with open porosity below 0.1vol% by changing the mixing ratio of nitrogen, which exhibited improved environmental barrier property in artificial seawater.
Influence of Substrate Properties on the Impact Resistance of WC Cermet Coatings
Authors: Osawa S. , Itsukaichi T. , Ahmed R. 
Published: July 2022

Abstract
This research delivers an integrated performance of generic coating-substrate systems under impact loading, and comprehends the understanding of underpinning failure mechanisms. This investigation thus benchmarks the coating design process for high impact stress applications. Repeated severe impacts to the coatings often result in poor performance by cracking and delamination from the coating-substrate interface. The durability and delamination resistance of coatings depend on the choice of coating and substrate materials, coating deposition process and service conditions. The design of overlay thermal spray coatings thus requires an optimization of these parameters. A thorough understanding of the underpinning failure mechanisms is thus critical for future coating developments. This investigation thus provides an insight to the role coating and substrate properties on the impact resistance of coated materials, and maps the relationship between the impact resistance of WC-Co and WC-CrC-Ni coatings on a variety of substrates. Results indicate that coating’s delamination resistance during impact loading not only depends upon the hardness and roughness of the substrate material, but more importantly, substrates with higher work-hardening coefficient indicate a higher delamination resistance during impact loading.
Solid Particle Erosion Resistance of Thermally Sprayed Functionally Graded Polymer/Ceramic Coatings
Authors: Ivosevic M. , Knight R. , Kalidindi S.R. , Palmese G.R. , Sutter J.K. 
Published: July 2022

Abstract
The use of polymer matrix composites [PMC's] in the gas flow path of advanced turbine engines offers significant benefits for aircraft engine performance, but their useful lifetime is limited by their poor erosion resistance. HVOF and flame sprayed polymer/cermet functionally graded coatings based on a polyimide matrix filled with varying volume fractions of WC-Co are being investigated to improve the erosion and oxidation resistance of polymer matrix composites. A study of the coating's effectiveness as erosion barriers was accomplished through a statistical analysis of the results of solid particle erosion testing of coated and uncoated PMC samples using a design of experiments [DoE] approach. Three coating systems and a control were evaluated in a randomized test matrix. The coatings were tested at room temperature and 250 °C, using an alumina erodent impacting the coatings at a speed of 100 m/s at angles of 20° and 90°. Erosion volume loss at 250 °C was approximately twice than at room temperature, but the maximum erosion volume loss did not exceed 0.30 mm3 at the elevated temperature. In general, as the angle of incidence of the eroding material increased from 20 degrees to 90 degrees the volume loss increased.
A Study of Gas and Particle Flow Characteristics in HVOF Thermal Spraying Process
Authors: Katanoda H. , Kuroda S. , Kawakita J. , Fukanuma H. , Matsuo K. 
Published: July 2022

Abstract
This paper analyzes the behavior of coating particles as well as the gas flow in a High-Velocity Oxy-Fuel (HVOF) gun by using numerical simulation. Special attention is paid to the particle behavior in turbulent boundary-layer inside the barrel.
Chemical Composition Optimization of Perovskite Coatings by Suspension Plasma Spraying for SOFC Cathodes
Authors: Monterrubio-Badillo C. , Ageorges H. , Chartier T. , Coudert J.F. , Fauchais P. 
Published: July 2022

Abstract
The purpose of this work is to optimise the chemical composition of perovskite coatings prepared by injecting a suspension of submicrometric LaMnO3 perovskite particles (d50 =~ 1 µm) in a direct current (d.c.) plasma jet. The perovskite powder composition, the particle size and the plasma parameters were modified in order to diminish the manganese evaporation. The process consists in mechanically injecting a well dispersed stable suspension of submicrometric perovskite particles in a dc plasma jet. In the process, large suspension droplets (~300 µm) are sheared into tiny ones (a few µm) by the plasma jet flow. Then the solvent is evaporated and the particles melt resulting in perovskite droplets of about 1 µm impacting on the substrate, the coating resulting from their layering. Such coatings are to be used as cathodes for the SOFCs (Solid Oxide Fuel Cells). Best results were obtained by injecting a stable suspension containing a 10 mol% MnO2 doped perovskite powder with 3 µm particle size in an Ar plasma forming gas and 300 A of current intensity.
Denser Ceramic Coatings Obtained by the Optimization of the Suspension Plasma Spraying Technique
Authors: Siegert R. , Döring J.-E. , Marqués J.-L. , Vaßen R. , Sebold D. , Stöver D. 
Published: July 2022

Abstract
The innovative suspension plasma spraying (SPS) technique, in which the carrier gas used to inject particles (10…100 µm) into the plasma jet is replaced by a liquid feedstock, is currently under development procuring denser ceramic coatings due to the use of submicron particles. The suspension properties, as well as the most relevant injection parameters - injection angle and liquid velocity - are adjusted to improve the coating quality at acceptable deposition rates. In addition, the plasma jet instabilities are studied and correlated to the coating properties. In the present work, a feasibility study is conducted addressing the key factors influencing the coating morphological properties such as the porosity, cracks, molten-fraction and amount of over-spray. The experimental setup is adapted to different DC plasma torch architectures (Sulzer-Metco F4 and Triplex) operating under atmospheric conditions with the aim of correlating the plasma jet qualities to the properties of the feedstock under consideration. The metallographic probes and fractured surfaces of the resulting yttria stabilized zirconia (YSZ, 5 wt. % Y2O3) coatings are analyzed by means of light microscopy and scanning electron microscopy (SEM).
Design of a Nozzle Extension for Thermal Spray Under Very Low Pressure Conditions
Authors: Bolot R. , Klein D. , Coddet C. 
Published: July 2022

Abstract
Conventional equipments used for low pressure plasma spraying are designed for a chamber pressure of a few tens of mbar. During the past three years, an increasing interest for thermal spray under very low pressure conditions (as low as 1 mbar) was encountered but no significant advances concerning the spray gun design was proposed. However, it is clear that actual tools do not allow providing uniform plasma jets and that the produced jets present successive expansions and constrictions due to a poor adaptation of the nozzle exit pressure regarding to the chamber one. In the present paper, the use of a nozzle extension is proposed. The holding nozzle is a lengthened F4 type one and the diverging part of the nozzle is formed by a fastened external extension. The design of the nozzle extension is a bell-contoured Laval type one and its dimensions (exit diameter and length) are much higher than for conventional diverging nozzles. An improvement in the jet homogeneity and uniformity is expected.
Development of High Quality Thermal Sprayed Metal Coating Process by Shielding Control
Authors: Sakakibara N. , Manabe Y. , Hiromoto Y. , Kobayashi Y. 
Published: July 2022

Abstract
The shielding controlled plasma spraying process is investigated to improve corrosion resistance of the metal surface. In this process, a shielding nozzle that covers just the spraying area is attached in front of the tip of a commercial plasma spray gun nozzle, and the environment surrounding the plasma jet is controlled by nitrogen flow. As the oxygen concentration in the shielding nozzle is maintained as low as 0.5%, the metal oxide contents in volume of CoNiCrAlY coating and the porosity of the coating reduced to 0.2% and 0.3% respectively under optimal spray particle size. The corrosion potential of CoNiCrAlY coating sprayed by this process in an acid solution including chloride ions is staying about -150 mV for 1000 hours, and no rust is observed during this test. On the other hand, that of the coating sprayed by atmospheric plasma spraying process changes from about -300 mV to about -500mV for 1000 hours, and the rust comes to the surface of the coating after 10 hours. Therefore the developed shielding controlled plasma spraying process is concluded to improve the corrosion of the metal.
Improved Design of de-Laval-type Nozzles for Atmospheric Plasma Spraying
Authors: Schwenk A. , Gruner H. , Zimmermann S. , Landes K. , Nutsch G. 
Published: July 2022

Abstract
An optimised de-Laval-type-contour for the Atmospheric Plasma Spraying (APS) with respect to the thermal and deposition efficiency as well as to the arc voltage fluctuations and the sound level of the plasma torch is presented. Investigations of the plasma gas dynamics and two different feedstock materials (Al2O3 (fused and crashed) and Cr2O3 (agglomerated and sintered)) have been done to promote the industrial utilization of convergent-divergent nozzles for the APS.
Arc Spraying with Dynamic Current Generators
Authors: Wilden J. , Bergmann J.P. , Jahn S. 
Published: July 2022

Abstract
Low running costs, high spray rates and efficiency make electric arc spraying a good tool for coating large areas with high production rates. The main applications are in the field of corrosion and wear protection of large structures, e. g. parts for bridges or offshore industry. New applications are expected for high quality coatings produced by cored wires. Disadvantages of the arc spraying process are that only electrically conductive wires can be processed and the lower particle velocity in comparison to other thermal spray processes like HVOF or APS. Depending on the process parameters the oxidation of particles has a negative effect on the mechanical and the electrochemical properties of the coating, too. In this paper some investigations with new and flexible power supply systems for arc spraying are presented. The particle size and the morphology of the coating can be optimised, due to the possibility of changing the current generator characteristic and modulating the power by pulsing up to 500 Hz. The oxidation of particles can be reduced by a lower heat input based on lower spray voltage. For a higher quality of the coating microstructure investigations with dynamic generators were performed for Zn, Al, ZnAl, 110MnCrTi8 and Al. An enhancement of the process stability was achieved, too.
Microstructure and Properties of Molybdenum Coatings Deposited by Microplasma Spraying Torch with a Novel Hollow Cathode
Authors: Li Chang-Jiu , Sun Bo 
Published: July 2022

Abstract
A microplasma spraying torch with a hollow cathode electrode is designed to melt completely the refractory materials and deposit coatings at plasma power level up to several kilowatts. The designed torch permits spray material to be fed into plasma arc jet through axial powder injection. In the present study, molybdenum is used as a typical refractory spray material. The effects of the main processing parameters including plasma arc power, plasma gas flow and spray distance on the particle velocity during spraying, and the microstructure and properties of the coatings are investigated. The microstructure of coating is characterized with optical microscopy and scanning electron microscopy. The properties of the coating are characterized by microhardness and abrasive wear tests. The particle velocity during in-flight is carried out using a particle velocity/temperature measurement system based on thermal radiation. The comparison of the microstructure and property of micro-plasma sprayed Mo coatings with those of the coating deposited by the conventional plasma spraying operated at a power of 42 kW is performed. The results show that the abrasive wear loss of the Mo coatings deposited by the micro-plasma spray torch is comparable to that of the coating deposited by the conventional plasma spraying disregarding the one order difference in the plasma operating power.
Interactions Between Molten Metal Splats Landing on a Substrate during Coating Formation
Authors: Dhiman Rajeev , Chandra Sanjeev 
Published: July 2022

Abstract
Interactions between multiple splats landing on a substrate was studied experimentally by photographing deformations of droplets as they land and freeze on the substrate, or previously solidified splats. Uniform-size molten tin droplets (550 µm diameter) were produced using a drop-on-demand generator. To achieve high impact velocities the stainless steel coupons used as substrates were mounted on the rim of a rotating flywheel and heated using cartridge heaters to vary substrate temperature. To hit a falling droplet with the substrate and photograph its impact, a timing circuit was used to synchronize the ejection of a droplet, triggering of the camera and a flash to provide illumination. The substrate temperature and substrate roughness significantly affected splat impact dynamics. Droplets hitting a smooth cold substrate splashed extensively whereas those hitting a hot substrate spread in the form of a smooth disc. The final splat shapes were dependent on the offset distance between the impacting droplet and the previously solidified splat. The size of fingers around the splat edge increased with the offset distance. Large pieces of metal detached from the droplet rim when the droplet hit a rough substrate whereas droplets hitting previously solidified splats splashed in a star-like shape with extremely long fingers.
High Powered Axial Injection Plasma Torch for Internal Surfaces
Authors: Young N. , Celler Z. , Dolomont D. , Burgess A. 
Published: July 2022

Abstract
Northwest Mettech Corporation has recently developed a new high power torch for spraying internal surfaces, the Axial III ID. The Axial III ID has been successfully operating at 135 kW while spraying inside a drum with an inner diameter of 34 cm. The three-electrode axial injection configuration of the new torch is based on the current Axial III torch. Various coatings were sprayed inside a drum while monitoring the torch temperature. The results of these experiments are presented in this paper.
Microplasma Wire Spraying
Authors: Borisov Yuri , Kislitsa Alesandr , Voynarovich Sergey 
Published: July 2022

Abstract
The method of microplasma spraying provides a small size of the spraying spot (a few millimeters), is characterized by small dimensions of relevant equipment and a low level of noise. A plasmatron with a device for feeding a wire has been designed to use wire as a material for coating spraying. Experiments on microplasma spraying of coatings were conducted using molybdenum, tungsten, titanium, nichrome, copper, brass, tin, aluminum, steel and stainless steel wires. The use has been made of wires with a diameter of 0.2-0.4 mm. Relationship between the wire material and diameter at a wire feed speed ensuring optimal conditions of the spraying process has been established. Structure and properties of coatings produced by the microplasma wire spraying method have been studied. Results of the studies are indicative of the possibility of thus producing the dense coatings at a spraying spot size of 3-8 mm.
Some Trials to Improve Uniformity of Film Thickness by Manual Thermal Spraying
Authors: Imai Norihiro , Seki Masao 
Published: July 2022

Abstract
In this article, three methods are studied to improve the uniformity of film thickness by manual thermal spraying. These methods are projection of personal computer graphics by the liquid crystal projector, irradiation of the laser ray, and on-line measurement of metal wire length for the thermal spraying.