bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal Stability of Microstructure and Hardness of Cold-Sprayed cBNp/NiCrAl Nanocomposite Coating
Authors: Luo X.-T. , Li C.-J. 
Published: November 2022

Abstract
cBN/NiCrAl nanocomposite coating was deposited by cold spraying using mechanically alloyed composite powders. To examine the thermal stability of coating microstructure, the nanocomposite coating was annealed at different temperatures from 750 to 1000°C. The microstructure of composite coatings was characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results showed that the nanostructure was retained in the coating when the annealing temperature was lower than 825°C which is 0.7 times of the melting point of NiCrAl matrix. The dislocation density significantly reduced when annealing temperature was higher than 750°C. The cBN particle growth became significant when the annealing temperature was higher than 825°C. The effects of crystal grain refinement and work-hardening strengthening mechanisms were quantitatively estimated as the function of annealing temperature. The effect of annealing temperature on the contribution of different strengthening mechanisms to coating hardness was discussed.
Influence of Metal Binder of WC Cermet Powder for Cold Spray and HVOF
Authors: Sato K. , Furukawa H. , Kitamura J. , Seo D. , Ogawa K. 
Published: November 2022

Abstract
From the appearance of high velocity oxygen fuel (HVOF) thermal spray system on 1980s, WC cermet coatings have been used as an anti-wear coating in many industrial manufacturing. Recently, WC cermet spray materials were applied to new thermal spray methods such as warm spray and cold spray under research phase. In HVOF spraying, WC-Co or WC-Ni series powder are used as standard contents. Ni and Co are binder metals for WC because of good wettability and suitable melting point. On the other hand, warm spray and cold spray are lower temperature process than HVOF. It is considered that any other factors of metal material such as hardness, toughness and crystal phase should be investigated in warm spray and cold spray. In this study, WC with Co or Fe alloy powders were sprayed by cold spray and HVOF to investigate the influence of binder metal for spray efficiency and coating property. It is cleared that Ni and Fe were superior to Co in spray efficiency and coating property in cold spray. The detail of above reason was under investigation, however, plastic deformability of binder metal is expected to be an important factor for WC cermet cold spraying.
Influence of Chromia Alloying on the Characteristics of APS and HVOF Sprayed Alumina Coatings
Authors: Niemi K. , Hakalahti J. , Hyvärinen L. , Laurila J. , Vuoristo P. , Berger L.-M. , Toma F.-L. , Shakhverdova I. 
Published: November 2022

Abstract
In order to improve both corrosion and wear resistance of standard plasma sprayed alumina coatings chromia alloyed feedstock powders and high velocity oxygen fuel (HVOF) spraying as an alternative process were used in this work. Alumina and alumina-chromia powders with different chromia contents (27% and 50%-mass., but with different amount of (Al,Cr)2O3 solid solution formed) were deposited by TopGun HVOF spraying and atmospheric plasma spraying (APS). The coatings were evaluated by optical microscopy, microhardness measurements, XRD and SEM. Abrasion wear resistance of the coatings was tested with the rubber-wheel abrasion test. Corrosion characteristics of the coatings were evaluated by exposure tests at 85 °C for 310 hours at low and high pH conditions. The amount of dissolved elements in solution, as analysed by ICP, was found to be a direct indication of the corrosion resistance of the coatings. Coatings deposited by TopGun HVOF spraying resulted in a denser microstructure, higher microhardness and significantly improved abrasion wear resistance as compared to corresponding coatings deposited by APS. For the tested conditions, corrosion resistance of both APS and HVOF-sprayed alumina coatings was low but significantly improved by chromia addition for both spray processes. However, the content of chromia addition alone does not allow to draw conclusions on the effectiveness of this measure.
Effect of Accelerating Gas Flow on Pore Structure and Mass Transport Property of Vacuum Cold Sprayed TiO2 Coatings Using Strengthened Nanostructured Powder
Authors: Yang G.-J. , Liao K.-X. , Li C.-J. , Fan S.-Q. , Li C.-X. , Li S. 
Published: November 2022

Abstract
The pore structure in nano-porous TiO2 coating influences the ion diffusion property and photovoltaic performance of dye-sensitized solar cells (DSC). In this paper, TiO2 coatings were deposited by vacuum cold spray (VCS) using a strengthened nanostructured powder. The pore structure, ion diffusion and dye infiltration properties were examined to understand the deposition mechanism of the coating and the suitability of cold sprayed TiO2 coating for DSC. It was interestingly found that the pores in the VCS TiO2 coating presented a bimodal size distribution with two peaks at ~15 nm and ~50 nm, which contributed to a much higher ion diffusion coefficient comparing to that of the conventional unimodal-sized nano-porous coating. The dye infiltration and loading are beneficial from the bimodal size distribution of the pores. Based on the impact behavior of the spray powder, a deposition model was proposed to explain the deposition mechanism of the strengthened nanostructured powder during vacuum cold spray.
Relationship between Particle and Plasma Properties and Coating Characteristics of Samaria-Doped Ceria Prepared by Atmospheric Plasma Spraying for Use in Solid Oxide Fuel Cells
Authors: Cuglietta M. J. , Kesler O. 
Published: November 2022

Abstract
Samaria-doped ceria (SDC) has become a promising material for the fabrication of intermediate-temperature, metal-supported solid oxide fuel cells (SOFCs). While typical SOFC materials, such as yttria-stabilized zirconia (YSZ), require high temperatures (&gt; 700°C) to exhibit suitable ionic conductivity for high cell performance, SDC displays similar ionic conductivities at lower temperatures (600°C – 650°C). The atmospheric plasma spray (APS) process is a promising technique for manufacturing metal-supported SOFCs. In this study, the in-flight characteristics, such as particle velocity and surface temperature, of spray-dried SDC agglomerates were analyzed at various plasma spray conditions using the DPV-2000 in-flight particle sensor manufactured by Tecnar Automation. Coatings of SDC were applied on stainless steel substrates using a range of spray conditions, and their resulting microstructures and deposition efficiencies were analyzed. It was found that particle temperature could be related to the specific plasma energy, and that coating porosity was related closely to the measured average particle temperature.
The Solution Precursor Plasma Spray Process for Making Zirconia based Electrolytes
Authors: Christenn C. , Ansar A. , Haug A. , Wolf S. , Arnold J. 
Published: November 2022

Abstract
Ceramic layers, such as yttria-stabilized zirconia or scandia-stabilized zirconia, used for functional layers of solid oxide fuel cells, i.e. the gas tight oxygen ion conductive electrolyte or as ceramic component in the porous cermet anode, were obtained by the Solution Precursor Plasma Spray (SPPS) process. The influence of different solvent types on microstructure was analyzed by comparison of coatings sprayed with water-based solution to ethanol-based one. Use of solvent with low surface tension and low boiling point enhances splat formation, coating microstructure and crystalline structure. Parameter adjustment to receive coatings from nitrate solutions with ethanol as solvent was carried out. Results of Raman spectroscopy indicate that an intermediate of both nitrates (zirconyl and scandium nitrate hydrate) was deposited.
Anisotropic Electrical Conductivity of Copper Coatings Deposited by HVOF
Authors: Aghaee M. , Salehi M. , Salimijazi H. R. 
Published: November 2022

Abstract
Copper coatings were deposited on ferrous substrates by utilizing high-velocity oxy-fuel spraying (HVOF). Three different coating process parameters have been used in order to optimise the required electrical characteristics. Microstructure and phase formation in the coatings were analyzed by scanning electron microscope (SEM), X-ray diffraction (XRD), and oxygen analyzer (ELTRA). Electrical resistivity of coatings was measured in-plane and through-thickness using the four-contact method. Results shown that dense coatings with high purity and low level of porosity are required to achieve high electrical conductivity. The coatings exhibited an anisotropic electrical resistivity due to the nature of the thermal spray coating microstructure. Microstructural evaluation shown that individual splats morphology and splats interfaces play important roles in the electrical conductivity.
Densification of Low Temperature HVOF Ti Coating
Authors: Liu M. , Deng C. M. , Deng G. C. , Chen J. Q. , Zhou K. S. 
Published: November 2022

Abstract
Fundamental properties of Titanium coating prepared by low temperature HVOF process aided by injection of water had been published by our research group. The results showed that low temperature HVOF process provided as a good means for the deposition of comparatively dense Ti coating, however the interconnected pores observed in Ti coating degraded corrosion resistance of Ti coating, therefore it was necessary to manufacture denser Ti coating. Two processes were respectively applied for the densification of Ti coating. One process was to perform post heat treatment for as-sprayed Ti coating with conventional Ti powder as feedstock. The other process was to modify thermal spray powder. Ti powder mixing with spherical glass powder was used to deposit denser Ti coating as a result of shot peening effect of hard glass powder. Finally the corrosion resistance for densified Ti coatings was evaluated by electrochemical characterization.
Failure in APS Porous Thick YSZ Coatings Caused by Thermal Stress
Authors: Chen Z-Y. , Feng J. , Gao Y. 
Published: November 2022

Abstract
NiCrAl/ZrO2-8Y2O3 coatings deposited on SUS304 stainless steel and 45 carbon steel substrates were prepared by APS at different preheating temperatures, of which thickness exceeded 1mm. This study analyzed the coatings’ separation from different preheated substrates in the cooling process after spraying due to residual thermal stress. The Young’s modulus of the porous YSZ coatings was calculated and also measured by Knoop indentation methods for comparison purposes. The result indicated that the failure of porous thick YSZ coatings is mainly caused by the cracks nucleation, propagation and coalescence, which is related to the thermal-expansion coefficient difference between substrate and coatings, preheating temperature, porosity of coatings and so on. Due to their increased porosity, the porous and thick YSZ coatings had much lower calculated and measured Young’s modulus values than the sintered YSZ coatings.
A Novel Plasma-Sprayed Durable Thermal Barrier Coating with the Well-Bonded YSZ Interlayer between Porous YSZ and Bond Coat
Authors: Li C.-J. , Li Y. , Yang G.-J. , Li C.-X. 
Published: November 2022

Abstract
Atmospheric plasma-sprayed YSZ thermal barrier coatings (TBCs) are widely used in industrial gas turbine engines to prevent the superalloy blades from failure. The failure of TBCs in service occurs by the spalling of YSZ coating. Crack propagation leading to the failure of plasma-sprayed thermal barrier coatings usually occurs within YSZ coating near the YSZ/Bond coat interface. In the present study, a novel durable TBCs consisting of a YSZ interlayer of the well-bonded interlamellae between the bond coat and conventional YSZ top porous coat was introduced. The YSZ interlayer was deposited at different coating surface temperatures, which resulted in the formation of YSZ with significantly improved interlamellar bonding. The result shows that thermal cyclic lifetime of the novel TBCs with the 20-30 µm thick YSZ interlayer increased by factor of 4 compared with that of the conventional one. The improved thermal cyclic lifetime was attributed to the controlled transition of cracking path from the near YSZ/bond coat interface to YSZ top layer. The effect of thickness of the YSZ interlayer on the lifetime of TBCs was also investigated.
Characterisation of Plasma Sprayed HAp Coatings on Ti Alloys
Authors: Altuncu E. , Erdogan G. , Ozturk S. , Ustel F. 
Published: November 2022

Abstract
Biocompatibility of hydroxyapatite (HAp) coatings have led to its use in a wide range of applications in both dentistry and orthopaedics. The plasma spraying method is the most commonly used method for the production of Hap (Ca5(PO4)3OH) coatings on Ti alloys. When HAp is injected into the plasma jet, several phases can coexist under the effect of a temperature gradient occurring in the bulk of the particle. The amounts of residual compounds, amorphous and recrystallized phases are related to the conditions of spraying such as gas flow rates, feed rate, spray distance, plasma current and cooling effect. Plasma-sprayed HAp coatings were analyzed by X-ray diffraction and electron microscopy.
A 3D Finite-Difference Model for the Effective Thermal Conductivity of Thermal Barrier Coatings
Authors: Qiao J. H. , Bolot R. , Liao H. L. , Bertrand P. , Coddet C. 
Published: November 2022

Abstract
Effective properties of TBCs may be quantified thanks to different measurement techniques. Image-based analysis represents an alternative method for predicting these effective properties. During the last 10 years, 2D modelling was intensively applied to estimate the thermal conductivity from coating cross-sectional images. However, real coatings present a complex 3D architecture so that the use of 2D computations based on cross-sections has to be validated. In the recent decade, 3D imaging approaches were applied for capturing 3D images of thermal spray coatings with relatively high resolution (up to 1 micrometer). Nevertheless, high resolution brings very large computational systems for which finite-element (FE) methods seem to be unsuitable due to high requirements in terms of computer memory (RAM) capacity. In the present study, a three-dimensional finite-difference-based heat transfer model was developed for analyzing the heat transfer mechanisms through a porous structure by saving RAM usage. An artificial 3D coating image, containing 300×300×300 voxels, was generated from microstructural information measured for a real coating cross-sectional image. In particular, this 3D artificial pore network was generated so that calculations performed on its cross-sections present similar results in comparison with those concerning SEM images of real coating cross-sections. Then, the results computed for the 3D image were compared with those obtained from 2D computations performed on cross-sections of the same 3D image, revealing the differences between 2D and 3D image-based analyses. Finally, the results were then compared with those computed by FE packages (OOF2 and ANSYS).
Simulation of Arc Root Fluctuation in a DC Non-Transferred Plasma Torch with Three Dimensional Modeling
Authors: Huang R. , Fukanuma H. , Uesugi Y. , Tanaka Y. 
Published: November 2022

Abstract
It has been well known that the coating quality of plasma spraying is strongly influenced by instability of jets in plasma spray due to the arc root fluctuation. A three dimensional (3D) unsteady modeling was employed in the research to analyze the arc root fluctuation in a DC non-transferred plasma torch. Numerical calculations on the distribution of gas temperature and velocity in plasma torch were carried out using argon as plasma gas. The electrical current density and potential were also discussed. The results indicate that the fluctuation of arc inside the plasma torch is mainly induced by the movement of the arc root on the anode surface. The arc root moves downstream with the flow of gas, and the arc will warp from the electromagnetic force simultaneous to the movement. While the arc warps close to the anode boundary, a new arc root is formed somewhere upstream of the original attachment. This article represents nature of fluctuation of arc root, also in this paper we will present that the voltage-drop calculated is larger than that measured experimentally based on the hypothesis of local thermodynamic equilibrium.
Properties of Nanostructured Composite Titanium Coating on Aluminium Surface
Authors: Tyurin Yu. N. , Kolisnichenko O. V. , Ivanov O. N. , Kovaleva M. G. , Maradudina O. N. , Trusova Y. V. 
Published: November 2022

Abstract
Composite coatings of titanium powder were deposited on aluminium samples by using the cumulative-detonation equipment. Consumption of fuel mixture components (propane-oxygen-air) was up to 4.3 m3 per kilo of a coating. The coatings were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM) with diffraction, X-ray phase analysis, hardness measurements, as well as plasticity and adhesion/cohesion resistance scratch tests. It is shown that the coatings are characterised by the presence of nanodispersed ceramic formations, and feature high values of plasticity, hardness and adhesion strength.
Deposition and Characteristics of Submicrometer-Structured Ceramic Coatings by Suspension Thermal Spraying
Authors: Guignard A. , Mauer G. , Vaßen R. , Stöver D. 
Published: November 2022

Abstract
The manufacture of submicrometer-structured coatings by thermal spraying is subjected nowadays to increasing research efforts in order to obtain unique and often enhanced properties compared to conventional coatings. Injecting suspensions of submicron ceramic particles into the plasma jet or the flame enables to deposit finely-structured coatings. Such fine microstructures can be advantageous for applications in the field of thermal barrier coatings (TBCs) for gas turbines. Often, suspension plasma sprayed (SPS) TBCs show unique mechanical, thermal and optical properties compared to conventional atmospheric plasma sprayed (APS) TBCs. They have thus the potential of providing increased TBC performances under severe thermo-mechanical loading. Experimental results show the capability of SPS to obtain yttria-stabilized zirconia (YSZ) coatings with high density of vertical segmentation cracks, yielding high strain tolerance and low Young’s modulus, while the porosity is still large compared to APS segmented coatings. Besides, sintering behavior of complete TBC systems under a thermal gradient exposure is of high importance. The evolution of the coating microstructure during thermal cycling test at very high temperature (1400°C) in our burner rigs as well as under isothermal annealing and its effects on the coating properties such as Young’s modulus were investigated.
Comparison of the Electrical Properties of Al2O3 Sprayed Coatings from Feedstock Powders and Aqueous Suspensions
Authors: Toma F.-L. , Scheitz S. , Langner S. , Berger L.-M. , Sauchuk V. , Kusnezoff M. 
Published: November 2022

Abstract
In this paper the characteristics (microstructure, phase compositions) and electrical insulating properties of thermally sprayed alumina coatings produced by suspension-HVOF (S-HVOF) process and conventional HVOF spray method are compared. The electrical resistance (electrical resistivity) and dielectric strength were investigated using DC-electrical resistance measurements, electrochemical impedance spectroscopy (EIS) and dielectric breakdown test. The electrical resistance was determined at room temperature at different relative air humidity (RH) levels, from 6% RH up to 97% RH. Differences in the electrical insulating properties due to the different coating characteristics are discussed. The suspension-sprayed Al2O3 coatings showed better electrical resistance stability at high humidity levels (&gt; 75% RH), which could be explained by a specific microstructure and retention of a higher content of α-Al2O3. Nonetheless, the values of dielectric breakdown voltage and dielectric strength recorded for suspension sprayed coatings were lower than those of HVOF coatings.
Properties of Coating by Plasma Spraying Ultrafine Cr3C2-25%NiCr Powders
Authors: Li Z. , Yu Y. , Zeng K. , Xianjing R. , Jianghong M. 
Published: November 2022

Abstract
Agglomerated and sintered Cr3C2-25%NiCr powders possess excellent flow ability and appearance that have been extensively applied to resist abrase and erosion in high temperature applications such as power boiler and turbine blade. Microstructure of Cr3C2-25%NiCr coatings were observed through scanning electronic microscope (SEM), and bond strength and microhardness of coatings were measured by tensile shearing test and Vickers hardness test. It is indicated that ultrafine Cr3C2-25%NiCr coatings have some outstanding properties to traditional Cr3C2- 25%NiCr coatings by plasma sprayed.
Three Anodes Compared to Three Cathodes: Evaluation of Gun Concepts for High Performance Plasma Spraying Operation
Authors: Erne M. , Kolar D. , Möhwald K. , Bach Fr.-W. 
Published: November 2022

Abstract
When plasma spraying operations require high throughput, three-cathode guns may be specified due to their stationary plasma jet and elevated power characteristics, higher feeding rates, and adequate deposition efficiencies compared to one-cathode guns. A new three-anode gun system has been introduced to the market that offers a combination of high power inputs into the plasma as well as stable process conditions. These new guns feature a narrower nozzle outlet diameter compared to multi-cathode designs and they can be used with hydrogen as secondary plasma gas. Both of these characteristics result in higher plasma velocities and net powers. The conceptional designs for two such guns are discussed as well as their suitability for suspension and shrouded plasma spraying.
Theory and Experiment on Hollow Spherical Powders Production
Authors: Solonenko O. P. , Gulyaev I. P. , Smirnov A. V. 
Published: November 2022

Abstract
Hollow spherical (HOSP) powders of metals, metal alloys and oxide ceramics are of great interest for thermal spraying, powder metallurgy and material science. For the last decade due to constant rise of interest in HOSP powders and expansion of areas of their application, the efforts of researchers, including authors of present paper, are focused on developing methods of producing the hollow microspheres, based on processing of agglomerated powders in thermal plasma. Exists a range of methods of producing the agglomerated powders with size of dozens of microns, which particles consist of several uniformly mixed nano- submicron- and micron sized powder components: 1) spray drying, 2) processing of atomized suspensions; 3) mechanical treatment of powder mixtures in high-energy planetary mills, etc. A brief overview the results of R&D directed to production of various HOSP oxide and metallic powders (α-alumina, zirconia stabilized by yttria, quartz, nickel allow) by the use of DC torches with interelectrode inserts (cascade torches) and twin torch is presented. In particular, the theoretical approach providing the requirements to plasma flow in criterion view have been developed. A physical and mathematical model of hollow particle behavior in plasma flow is developed and discussed.