bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Tensile and Shear Strength of Thermally Sprayed Coatings
Authors: Kašparová M. , Zahálka F. , Houdková Š. , Volák J. 
Published: November 2022

Abstract
The work deals with the evaluation of strength characteristics of thermally sprayed coatings. The main aim was concentrated on the tensile and shear loading of HVOF (Stellite Alloy 6, Tribaloy 400) and arc sprayed (13%Cr, CuAl8) coatings. The investigation of the coatings behaviour on the coating-substrate interface is important for the evaluation of one of significant coating mechanical properties that influence properties of the whole coating-substrate system. The magnitude of the coating bond strength during tensile and shear stresses predicates the coating stability, reliability, impact resistance, resistance against failure and mostly operating lifetime. The determination adhesive-cohesive strength was performed according to EN 582 and EN 15340 Standards.
Thermal Shock Resistance of Plasma-Sprayed Thermal Barrier Coatings
Authors: Takahashi S. , Hirano N. , Kojima Y. , Harada Y. , Kawasaki A. , Ono F. 
Published: November 2022

Abstract
The thermal shock resistance of plasma-sprayed thermal barrier coatings (TBCs) with different top coats was investigated according to the Japanese Industrial Standard "Testing methods for thermal cycle and thermal shock resistance of thermal barrier coatings" (JIS H 8451:2008). Three types of ceramics powders, namely, Al2O3, 8 mass % Y2O3-stabilized ZrO2 (YSZ) and La2Zr2O7 (LZ) were used in the top-coat spray. After the specimens were subjected to a thermal shock, the tensile adhesive strength of the TBCs was measured and the thermal shock resistance as defined in JIS H8451 was determined. The thermal shock properties of the TBCs were found to depend strongly on the chemical composition of the top-coat material. For TBCs with Al2O3 and LZ, the adhesive strength decreased with increasing thermal shock temperature difference (ΔT). On the other hand, little change in the adhesive strength was observed with increasing ΔT for YSZ TBC. From these results, the thermal shock resistance, ΔTc, was determined to be 480 °C for Al2O3, 680 °C for LZ and more than 880 °C for YSZ TBC. Furthermore, the influence of thermal shock on the adhesive strength of TBCs was investigated in detail through observations of cross-sectional microstructures and fracture surfaces after adhesive testing.
Electrical Resistivity of Thermally Sprayed Cr2O3-TiO2 Coatings
Authors: Trache R. , Berger L.-M. , Toma F.-L. , Stahr S. , Lima R. S. , Marple B. R. 
Published: November 2022

Abstract
In this study, the influence of spray parameters on the electrical resistivity of thermally sprayed ceramic coatings from the system Cr2O3-TiO2 was investigated. Fused and crushed feedstock powders with contents of 10 wt. % and 20 wt. % chromium oxide were deposited by APS and HVOF. Temperature and velocity of the particles in the spray jet as well as the coating surface temperature were analyzed during the deposition process. Impedance spectroscopy was used to investigate the electrical resistivity of the coatings and the results were correlated to coating microstructure and phase composition. It was found that phase transformations occur during the spray process. In the coatings a high temperature phase (n-phase) and rutile were observed. Though, the ratio of rutile depends on the spray methods employed for coating deposition. The electrical resistivity of coatings obtained by HVOF can be correlated to the content of chromium oxide. Furthermore, the surface temperature of the coating during deposition also shows some influence. Concerning the coatings resulting from APS, the different mixtures of the plasma gases (Ar-H2 and Ar-N2) are supposed to have the most important influence on the electric resistivity.
Solidification of Plasma Transferred Arc Coatings
Authors: Bond D. , D’Oliveira A. S. C. M. 
Published: November 2022

Abstract
Plasma Transferred Arc is the only thermal spray process that results in a metallurgical bond with the substrate. When compared with other welded coatings finer microstructures are observed after PTA processing, which have been associated with the faster solidification rate imposed by this technique. However, the powdered/atomized material used that forms the thermal spray, can play an important role in the solidification of coatings depending on their chemical composition and their grain size. This study analyzed the solidification of PTA coatings processed with an atomized cobalt based alloy (Stellite 6) with different average grain sizes. Typically, solidification of a welded coating follows solidification principles regarding the nucleation and growth of their microstructure determined mainly by the solidification rate. The role of the powdered feedstock in the solidification of coatings is analyzed based on the assumption that solidification is influenced by the initial interface energy of the atomized grains that melt in the plasma arc before reaching the melt pool. A commercial atomized Stellite 6 alloy was divided in two groups according to their grain size, below and over 125 microns, and deposited with the same processing parameters. Coatings were characterized by laser confocal microscopy and Vickers microhardness. Differences in coatings hardness and microstructure of coatings were associated with the grain size of the deposited alloy and subsequent solidification.
Numerical Study on the Role of Substrate Size in Supersonic Jet Flow and Substrate Preheating Process in Cold Spraying
Authors: Yin S. , Wang X.-F. , Li W.-Y. , Xie R. 
Published: November 2022

Abstract
This study investigates the effect of substrate conditions on supersonic jet flow pattern, particle acceleration and substrate preheating process in cold spraying. Computational fluid dynamic (CFD) approach is employed in the present work to achieve this objective. The simulated results show that substrate diameter has some effects on gas flow regime and thus particle acceleration. When the substrate diameter is smaller than the nozzle exit diameter, the size of the bow shock formed in front of the substrate is rather small, which contributes to increase the particle impact velocity. With increasing the substrate diameter gradually, the flow regime becomes more and more insensitive to the substrate diameter and the pattern becomes uniform. Moreover, the current numerical work also reveals that substrate preheating process can be significantly influenced by substrate thickness. With the increment in substrate thickness, the preheating effect becomes increasingly undesirable and the substrate surface temperature presents a downward trend.
Effects of Spray Nozzle Design on Cold Sprayed Magnesium Alloy Coating and its Composite
Authors: Suo X. K. , Guo X. P. , Li W. Y. , Planche M. P. , Bolot R. , Liao H. L. , Coddet C. 
Published: November 2022

Abstract
In this paper, a commercial AZ91D magnesium alloy powder and its mixture with 30 vol.% SiC powder were used to deposit coatings by cold spraying. Two types of converging-diverging nozzles with different cross-sectional shapes were employed. The velocity and temperature of in-flight particles under different operating conditions were simulated using the FLUENT software. The simulated results show that the particle velocity through the rectangular cross-section nozzle is the same with that through the circular one. However, the coating observation shows that the AZ91D coating and its composite could only be deposited using the rectangular cross-section nozzle. The increase of gas temperature has little effect on the coating microstructure, porosity and microhardness. Furthermore, the observation of the composite coating produced under the gas temperature of 600°C shows that the SiC content in the composite is about 23 vol.%. The microhardness of the composite is improved to about 140 HV0.3 due to the enhancement of SiC particles, compared to that of about 100 HV0.3 for the AZ91D coating.
Iron Boride Coatings Produced by Cold Spray Processes
Authors: Ozdemir I. , Ogawa K. , Sato K. , Seo D. 
Published: November 2022

Abstract
Iron based coatings have recently gained much attention as they have favorable mechanical, frictional, and corrosion properties. The coatings possessed a high content of iron borides are particularly valuable for satisfying engineering needs. Boron and iron form two major boride phases, FeB and Fe2B, with different mechanical and thermal properties. Orthorhombic boride FeB is considered to be viable candidate to enhance the surface hardness and wear resistance of components, since it has high hardness. Producing of such coating by cold spray method is considered to be an alternative for boronizing method which is a conventional thermochemical surface hardening process. In this work, the crushed ferroboron (FeB) powders of Fe-17.9B-0.4C-1.6Si-0.3Al (wt. %) were deposited onto low carbon steel substrate by cold spraying. However, low and high pressure cold spraying allowed depositing very thin and single layer on the substrate, due to the intrinsic brittleness of the powder. Therefore, several contents of Al, Ni and Fe metallic powder and their combinations were added to FeB powder to obtain thick coating via cold spray processes. Post heat treated coatings at a temperature of 700 °C resulted in increase of the hardness, possibly the formation of hard phases such as intermetallic compound.
Microstructural Changes During Heat Treatment of Cold Sprayed Pure Titanium Coatings
Authors: Wong W. , Irissou E. , Legoux J.-G. , Yue S. 
Published: November 2022

Abstract
This research systematically examines the effect of heat treatment on the microstructural properties of cold sprayed titanium coatings. Heat treatments were performed on as-sprayed coatings at 200, 400, 600, and 800°C for four hours under argon atmosphere. Vickers microhardness, microstructural investigation using FEG-SEM, structural characterization using XRD, and porosity evaluation using SEM image analysis were performed on as-sprayed and heat treated coatings. Results demonstrated that static recovery and static recrystallization may have occurred for heat treated coatings at 600 and 800°C. In addition, for the heat treated coating at 800°C, significant oxidation occurred and a slight decrease in porosity took place. Furthermore, a thin metallic layer characteristic of a solid solution or an intermetallic compound, was found at the coating/substrate interface.
Corrosion Resistance of Thermally Sprayed Coatings and Welded Overlays in Waste Incineration Environments
Authors: Pokhmurska H. , Wielage B. , Durham R. N. , Schütze M. , Franik D. , Gebert A. 
Published: November 2022

Abstract
Several model Fe- and Ni-based alloys with increased content (up to 30 at.-%) of protecting scale forming elements were developed. High temperature corrosion resistance of bulk alloys as well as thermally sprayed coatings and welded overlays were investigated under the waste power plants simulated atmosphere (500 °C, 100 hours, 75N2-20O2-4.9Ar-0.1Cl2). Arc and HVOF spraying as well as PTA overlay welding were used to produce the coatings. After an exposure the samples were examined with electron probe micro-analysis (EPMA). It was shown that the protection behaviour of overlay welds depends on the content of alloying elements, although the last is limited because of weldability decrease by high alloying level. High temperature corrosion resistance of thermally sprayed coatings is determined by their porosity, which can be varied over a very broad range depending on the applied spray method. The arc sprayed coatings need an additional post-treatment to close a porosity. Two methods were applied, pre-oxidation treatment in the air and sealing with the commercial sealant. Newly developed iron-based coatings with increased aluminium content (&lt; 20 wt- %) sprayed with HVOF-spraying with powders obtained by means of high energy ball milling demonstrate high corrosion resistance. Selected coatings were evaluated for 1000 h exposure under chlorine-containing salt deposits at the higher temperature (600 °C).
Suspension Plasma Spraying (SPS) of Manganese-Cobalt Spinel Coatings
Authors: Puranen J. , Hyvärinen L. , Lagerbom J. , Kylmälahti M. , Koivuluoto H. , Vuoristo P. 
Published: November 2022

Abstract
Suspension plasma spraying (SPS) is regarded as a promising way to produce new coating structures with improved properties. In this study, SPS was studied as a possible manufacturing process for producing thin MnCo2O4 spinel coatings for used as protective coatings in metallic interconnector plates of SOFC’s. Suspension of nanosized MnCo2O4 powder and ethanol was thermally sprayed by using an F4-MB plasma gun with radial suspension feeding. The influence of spraying parameters, such as plasma gas composition, total gas flow, current and spraying distance for coating architecture was studied by using field-emission scanning electron microscopy (FESEM) and X-ray diffraction method (XRD). Spraying parameters had a strong influence on the coating structure and composition. Coating with the most homogenous structure were formed when sprayed with the low energy spraying parameters whereas high energy parameters resulted in formation of a columnar microstructure containing larger cobalt rich areas.
Correlation between Process Parameters and Thermal Cycling Lifetime for Thermal Barrier Coatings
Authors: Altuncu E. , Ustel F. 
Published: November 2022

Abstract
With the modification of plasma spray parameters, porosity ratio of top coat can control along the cross-section. This improves the thermal cycle resistance and decrease the thermal conductivity. Plasma sprayed ZrO2/8 wt.–% Y2O3–NiCrAlY TBC systems which have different porosity (%8-12) and range of 250-350µm thicknesses of top coats, during thermal cycling tests with different hold times at 1350 °C have been performed. The main failure modes: delamination cracking, TGO growth rate and phase transformation are strongly dependent on the hold temperature and time. The correlation between TBC thermal cycle lifetimes and duration of high temperature hold time per cycle is shown and discussed with depending on thickness and porosity ratio.
Isothermal Oxidation Behavior of NiCoCrAlTaY Coating Deposited by High Velocity Air-Fuel Spraying
Authors: Yang G.-J. , Xiang X.-D. , Xing L.-K. , Li D.-J. , Li C.-J. , Li C.-X. 
Published: November 2022

Abstract
The performance of a thermal barrier coating is influenced by the high temperature oxidation behavior of bond coat. In this paper, NiCoCrAlTaY bond coat was deposited by high velocity air-fuel (HVAF) spraying, and the microstructure and surface morphology of the bond coat before and after oxidation were examined. Results show that the HVAF sprayed NiCoCrAlTaY coating presented a dense microstructure and some partially melted particles in a near spherical morphology were deposited on the coating surface. A uniform α-Al2O3 oxide was formed on the HVAF sprayed MCrAlY coating surface after the pre-oxidation treatment in an argon atmosphere. A small fraction of nodular-shaped mixed oxides was formed when the MCrAlY coating was oxidized at 1000°C for 100 h. The amount of the mixed oxides did not significantly increase after 200 h oxidation. The large particles on the bond coat surface maintained homogeneous α-Al2O3 oxide scale in 200 h oxidation at 1000°C in air. A model is proposed to explain the formation of nodular-shaped mixed oxides.
Durability of Low Pressure Plasma Sprayed MoB/CoCr Coating in Molten Al-12.07wt%Si Alloy
Authors: Chen X. 
Published: November 2022

Abstract
MoB/CoCr, a novel material for thermal spraying, with high durability is used to resist erosion by molten Al-12.07wt%Si alloy. The durability of the MoB/CoCr coating prepared by low pressure plasma spraying (LPPS) has been investigated using a molten-metal immersion tester. The test revealed that the MoB/CoCr coating has much higher durability without dissolution in the molten Al-12.07wt%Si alloy. Little change of crystal structure, mainly composed of ternary borides of Co2MoB2 and CoMoB, is observed after the immersion test, suggesting that the ternary borides have much higher durability.
Using of CFD Simulations for Increasing Speed and Temperature of Flame Spray Technology
Authors: Zabransky T. 
Published: November 2022

Abstract
This paper describes computational fluid dynamics (CFD) simulations for state-of-the-art flame-spray processes and experimental validation of these simulations. Alternative nozzle designs are presented along with analysis of their impact on flow-field and flame parameters. Validated CFD models are used for performance prediction of these nozzles. Several variants are compared and the possibility of improvement of technology parameters is analyzed.
Basic Physics and Engineering Program System SPLAT – SPRAY DEPOSIT for Computer-Aided Design of Coatings Formation
Authors: Solonenko O. P. , Blednov V. A. , Iordan V. I. 
Published: November 2022

Abstract
In our previous publications the preference was given to develop the theoretical fundamentals which could be used for rapid and sufficiently accurate prediction of thickness and diameter of splat vrs the key physical parameters (KPPs), i.e. temperature, velocity and size of droplet, and substrate temperature. Theoretical solutions derived have permitted to obtain the number of practically useful consequences are of interest for thermal spray technology in context of sensitivity analysis and establishing the inverse link between the splat characteristics and KPPs. For constructive solution of the feedback problem, there are formulated the essence of this notion. The natural basis is the requirements imposed on splats as elements of the mesostructure, from which the coating is formed in the course of spraying. This approach, realized as subsystem “SPLAT”, allows one at the first stage of designing a coating to concentrate the attention on the space-time characteristics of splat formation. After comprehensive evaluation of the operation room of KPPs, providing the formation of splats required, subsystem “SPRAY DEPOSIT” allows one at the second stage of designing a coating to predict its lamellar structure and functional characteristics (porosity, adhesion, cohesion etc.) taking into account a variable surface topology at splat by splat deposition.
Atomization of Water Droplets in Atmospheric Plasma Jets
Authors: Soysal D. , Ansar A. 
Published: November 2022

Abstract
Liquid injection plasma spraying is of growing interest for thermal spray applications like thermal barrier coatings and solid oxide fuel cells, since finely structured coatings offer improved properties over conventionally spray ones, for example lower thermal diffusivity and higher catalytic activity. One challenge is the optimization and understanding of the injection process. With a new high speed shadowgraphy setup, the injection and atomization of individual drops was observed and described in detail in this work which is, to our best knowledge, not reported before. A drop atomization cone model is derived from observations. A new modelling approach is developed which allows the prediction of the drop atomization cones by analytical calculations. The simulations are compared to measurements and deviations are explained by neglected effects which will be included in further developments of this model.
Adhesion of Ceramic Coating on Thin and Smooth Metal Substrate: A Novel Approach with a Nanostructured Ceramic Interlayer
Authors: Vert R. , Carles P. , Laborde E. , Mariaux G. , Meillot E. , Vardelle A. 
Published: November 2022

Abstract
The adhesion of plasma-sprayed coating is to a large extent controlled by the cleanness and roughness of the surface on which the coating is deposited. So, most of the plasma spray procedures involve surface pretreatment by grit-blasting to adapt the roughness of the surface to the size of the impacting particles. This preparation process brings about compressive stresses that make it inappropriate for thin substrates. The present works aims to elaborate a ceramic coating on a thin metal substrate with a smooth surface. The coating system is intended for use in a generation–IV nuclear energy system. It must exhibit a good adhesion between the ceramic topcoat (about 0.5-mm thick) and the smooth metal substrate (1-mm thick) to meet the specifications of the application. Our approach has consisted in depositing the ceramic layer on a few micrometers thick ceramic layer made by suspension spraying. We have observed the interface between both ceramic layers by transmission electronic microscope and studied the adhesion of the nanostructured layer by the Vickers Indentation Cracking technique and that of the coating system by tensile test.
Effect of Dispersed TiC Content on the Microstructure and Thermal Property of Shrouded-Plasma-Sprayed FeAl/TiC Composite Coatings
Authors: Tian L.-H. , Li C.-X. , Li C.-J. , Yang G.-J. 
Published: November 2022

Abstract
FeAl intermetallics matrix composites reinforced by ceramics particles such as titanium carbide have attracted much attention in recent years. In this study, shrouded plasma spraying with nitrogen as a protective gas was employed to deposit TiC particles dispersed FeAl/TiC composite coatings. Fe-35Al powder and Fe-35Al/TiC composite powders containing 35 vol.% and 45 vol.% TiC prepared by mechanical alloying were used as feedstock powders. The microstructure of the ball-milled powders and the as-sprayed coatings was characterized by scanning electron microscopy and X-ray diffraction. The mean coefficient of thermal expansion (CTE) of FeAl and FeAl/TiC was measured. The results showed that dense FeAl and FeAl/TiC coatings with low oxide inclusions were deposited by shrouded plasma spraying. The mean CTEs calculated based on the Reuss formula are reasonably consistent with those measured in the present study. As a result, the CTE of FeAl-based composite coating can be properly controlled by adjusting TiC content in the composite coating to match with that of the substrate.
Spraying of Metallic Powders by Hybrid Gas/Water Torch and the Effects of Inert Gas Shrouding
Authors: Kavka T. , Matějíček J. , Ctibor P. , Hrabovský M. 
Published: November 2022

Abstract
A hybrid DC arc plasma torch, combining water and gas stabilization, offers a high flexibility in plasma characteristics. These can be controlled in a wide range by the torch operational parameters, such as arc current and secondary gas flow rate. In this study, their influence on plasma spraying of tungsten and copper was investigated. To suppress the in-flight oxidation of the metals, inert gas shrouding was applied. In-flight particle diagnostics, analysis of free-flight particles and coatings was performed for spraying experiments in the open atmosphere and with argon shrouding. Both in-flight particle behavior and coating properties were found to be sensitive to the torch parameters. The application of shrouding was found to affect particle in-flight parameters, reduce the oxide content in the coatings and generally improve their properties, such as thermal conductivity. However, different degree of these effects was observed for copper and tungsten.
Development of Optical Monitoring of the Thermal Spraying
Authors: Chivel Yu. , Smurov I. 
Published: November 2022

Abstract
A new approach has been made in monitoring of the thermal spraying. Monitoring of the process is based on visualization of particles movement using both high speed video camera and wide-band high intensive illumination and measurements of particles temperature velocity and size and their distribution. Synchronously with the registration of the particles parameters surface temperature of the coating has been measured with 2-channel pyrometer with a high spatial and a temporal resolution. The results of investigations of the Cold spraying and D-gun spraying are presented.