bluuebunny/crossref_metadata_2025_split huggingface dataset:
Composition Effects of La2Ce2O7 Thermal Barrier Coatings against Calcium-Magnesium-Aluminum-Silicate (CMAS) at 1250°C
Authors: Wang Li-Shuang , Li Guang-Rong , Li Cheng-Xin , Liu Tao , Yang Guan-Jun , Li Chang-Jiu 
Published: August 2022

Abstract
The evaporation of both CeO2 and La2O3 in high temperature plasma arc leads to deviation of plasma sprayed La2Ce2O7 coating composition from the starting powder particle. Such change results in significantly inhomogeneity of compositions within a coating which influences the performance of calcium-magnesium-alumina-silicate (CMAS) corrosion. In this study, the pellets with different Ce / La ratio were interacted with molten CMAS glass. The penetration of molten CMAS on different pellets was characterized by scanning electron microscopy and energy dispersive spectrum (EDS) and the phase of different powder mixtures treated at 1250 °C was characterized by X-ray diffraction ( XRD ). The effects of pellets with different Ce / La ratio on the CMAS corrosion after thermal exposure at 1250 °C for 50 h were investigated. The result demonstrated that pellets with ratio of Ce / La greater than or equal to 1.0 were completely dissolved into the molten CMAS, at the same time the others were also damaged, forming diffusion layer and reacted layer, respectively. The difference of the ratio of Ce / La indeed affected their performance against CMAS attack.
High Thermal Conductivity Plasma Sprayed AlN Coating
Authors: Shahien Mohammed , Yamada Motohiro , Fukumoto Masahiro , Egota Kazumi , Okamoto Kenji 
Published: August 2022

Abstract
Aluminum nitride (AlN) ceramics is characterized with its high thermal conductivity and chemical stability. However, it was impossible to fabricate AlN coatings by conventional thermal spray processes directly from AlN feedstock powder due to thermal decomposition of AlN during spraying. In the last decade we were apple to fabricate the AlN coatings through the reactive plasma spraying process (RPS) in the atmospheric ambient. This study describes the way to fabricate high thermal conductivity plasma sprayed AlN coatings. The thermal conductivity of the AlN coatings was investigated by laser flash method. The as sprayed coating had very low thermal conductivity (2.43 W/m.K), compared to the AlN value. It is attributed to presences of high oxide content (Al5O6N, γ-Al2O3 and α-Al2O3 phases), low density (2.32 g/cm3) and high porosity in the plasma sprayed coating (about 22%). Besides that, although the N2 gas flow improved the nitride content, the thermal conductivity decreased gradually. It is related to the further increase of the coating porosity and decreasing its density with the N2 gas. The influence of the process parameters on the thermal conductivity was investigated and to fabricate high thermal conductivity AlN coating adjusting the oxide content, the coating porosity and microstructure are the main factors. Very high thermal conductivity (about 95 W/m.K) atmospheric plasma sprayed AlN coating was fabricated. The coating consists of mainly AlN phase (more than 95% AlN), very small amount of oxide phases, low porosity (about 3%) with a sintered microstructure (nicked-shape sintered particles).
Influence of Elemental Evaporation on the Composition of La2Ce2O7 Splats Deposited by Plasma Spraying
Authors: Wang Li-Shuang , Liu Tao , Li Guang-Rong , Yang Guan-Jun , Li Chang-Jiu , Li Cheng-Xin 
Published: August 2022

Abstract
La2Ce2O7 (LCO) is one of the promising candidates of high temperature thermal barrier coating materials. However, during plasma spraying, the evaporation of both CeO2 and La2O3 in high temperature plasma jet leads to deviation of coating composition from the starting powder particle. Such change results in significant inhomogeneity of compositions within a coating which influences the performance of resultant coating. In this study, an agglomerated La2Ce2O7 powder with Ce / La ratio of 1.5 and in a size range of 5-60 μm was used to deposit the splats and coatings under different plasma spray conditions. The compositions of La2Ce2O7 splats in different sizes were characterized by scanning electron microscopy and energy dispersive spectrum (EDS), and splat dimensions were characterized by 3D laser microscopy. The relationship between droplet size and splat composition was examined. Results showed that the Ce / La ratio in splats changes significantly with the splats diameter in a range from 1.5 to 0.7. There is a big difference in the composition of APS coatings deposited by coarse and fine powders. The mechanism causing splat composition change was examined based on the selective elemental loss during plasma heating of LCO particles in APS, aiming to control LCO coating composition.
Microstructure and Properties of Equiaxed 316L Stainless Steel Coating Deposited by LPPS
Authors: Yang Deming , Gao Yang , Sun Chengqi 
Published: August 2022

Abstract
The equiaxed microstructure of 316L stainless steel coating was successfully deposited by low pressure plasma spraying (LPPS), which was different from the lamellar microstructure prepared by other thermal spraying technologies. In this article, the effect of substrate temperature during deposition process and post annealing treatment on the lamellar – equiaxed microstructural transition were investigated. The results indicated that the homogeneous equiaxed grains without lamellar boundaries coatings were observed when the deposition temperature was about 900 °C. Completely lamellar microstructural coatings were deposited at the substrate temperature of about 300 °C, and the lamellar microstructure can transform to equiaxed microstructure after annealing treatment. The hardness of equiaxed coating was lower than lamellar coating.
Numerical Study of the Arc Fluctuations in DC Plasma Torch
Authors: Ardakani Esmaeil Safaei , Mostaghimi Javad 
Published: August 2022

Abstract
Plasma spray technology is widely employed by industry to apply coatings on different components to protect them from corrosion, wear and high temperature environments. The gases introduced into the DC plasma torch are heated by the arc and a plasma jet exits the torch. Powders are injected into the plasma jet where they are then accelerated, heated, and melted before impacting the substrate, which is placed at some distance from the outlet of plasma spray torch. Plasma arc exhibits strong voltage fluctuations which correspond to the movement of the anode arc root attachment. Understanding the arc movement within the torch and how it affects the flow and temperature fields of the plasma jet exiting the torch is of great importance. Understanding the flow, temperature and electromagnetic fields within the DC plasma torch is extremely challenging and there is a limited number of investigations in the literature. In order to provide unique sets of surface characteristics, e.g., thermal barriers, wear and corrosion resistance, a high quality coating with appropriate combination of powder and base materials must be produced. To produce a high quality coating, powder particles should be uniformly heated and accelerated, and then deposited onto the substrate. In this paper, an unsteady 3-dimensional model of the arc movement within the plasma torch is reported. The proposed model is employed to solve electric potential and magnetic vector potential equations in addition to continuity, momentum and energy equations. The k-ε turbulence model was used to model the turbulence of the flow field inside a non-transferred DC argon plasma torch. The geometry of the torch was that of SG-100 torch (Praxair). TO study the effect of the arc length on the voltage, first a steady-state model was considered for a range of arc lengths and arc-root radii. The results of this model provided the relation between arc length and arc voltage for a set of arc root radii and given argon flow rate. Then, given voltage fluctuation profile, the unsteady, arc root attachment movement was simulated from the estimation which found from steady models. Results show that the effects of velocity and temperature fluctuations at the outlet of the torch (where the particles are injected) are not negligible and such fluctuations exceed 15% of their average values. These will in turn affect the particle heating history and will negatively impact the microstructure of the coating.
Residual Stresses Analysis of Cold Sprayed Coatings by Numerical Simulation
Authors: Li Wenya , Yang Kang , Zhang Dongdong 
Published: August 2022

Abstract
In this paper, a preliminary analysis on the residual stress evolution of cold-sprayed coatings taking copper coating as an example was performed. An integrated frame of calculation was proposed based on the simulation results obtained from the developed thermo-mechanically coupled Eulerian model. In a single Cu splat, the residual stress appears to be large tensile stress near the surrounding area of the interface and be small tensile stress at the bottom. In single pass Cu coating, the residual stress is variable and there exists not only compressive stress but also tensile stress. When the impacting velocity changes, the resultant residual stresses also vary in both cases. The present simulated results were related to the reported experiments by others, while there is much difference.
Scuffing Resistance of HVOF Sprayed Nanostructured Carbide Coatings
Authors: Żórawski Wojciech , Makrenek Merard 
Published: August 2022

Abstract
This paper discusses results of research concerning the microstructure and scuffing resistance of HVOF sprayed WC- 12Co nanostructured and conventional coatings under dry friction conditions. The observations were carried out by means of a Falex type tester. It was found that HVOF sprayed nanostructured WC-12Co coatings showed the most homogeneous structure, the greatest scuffing resistance and the highest hardness.
Shot Peening Effect on the Morphology and Roughness of HVOF Coatings
Authors: Sucharski Gustavo Bavaresco , Paredes Ramón Sigifredo Cortés , Pukasiewicz Anderson Geraldo Marenda , Vaz Rodolpho Fernando 
Published: August 2022

Abstract
The HVOF process is characterized by the deposition of a low porosity and oxide content coating and the particles projected by this process have high kinetic energy, resulting in a high density coating. However, the presence of non-melted particles can affect the porosity, tensile adhesion, hardness and surface finishing. In this article, the influence of the shot peening treatment on morphology, porosity, tensile adhesion and roughness of some FeMnCrSi(Ni/B) HVOF coatings have been studied. High carbon steel particles with spherical geometry were used for shot peening. The results show that the shot peening reduces the porosity, mainly in the coatings with higher porosity level, and generates an increase of hardness with no phase transformations. The increase in adherence is also a benefit generated by the treatment. The surface quality analyses show a significant roughness reduction. With shot peening a compressive residual stress state was achieved in the coating, improving mechanical properties.
Solution Precursor Plasma Spraying of Bismuth Titanate by Means of Inductively-Coupled Thermal Plasma
Authors: Le Roux B. , Veilleux J. 
Published: August 2022

Abstract
Lead-free piezoelectric materials are nowadays drawing considerable attention as lead titanium zirconium oxide (PZT) is considered “as a substance of very high concern” by the European Chemicals Agency because of its toxicity. An interesting PZT replacement material for high temperature capable ultrasonic transducers is bismuth titanate (Bi4Ti3O12), which could be used for pipe thickness and corrosion monitoring in the oil & gas and nuclear industries. In this study, solution precursor plasma spraying (SPPS) is used to deposit Bi4Ti3O12 coatings onto stainless steel substrates by means of inductively-coupled thermal plasma. The crystal structure and the morphology of the deposited coatings is studied as a function of the SPPS operating parameters such as plasma gases, electrical power, chamber pressure and spraying distance. SPPS of piezoelectric materials is an interesting one step process alternative to the time consuming layered-based chemical spray pyrolysis/calcination of sol-gel precursors.
TGO Formation and Failure Mode of TBC Systems Comprising PVD-Al Interlayers
Authors: Ali I. , Grund T. , Lampke T. , Wett D. , Nestler D. , Wagner G. 
Published: August 2022

Abstract
The physical characteristics and volume growth of TGOs in TBC systems lead to TBC failure. It is proved that enriching the BC/TC interface with α-Al2O3 is beneficial to an extended operational time by prolonging the steady-state growth stage of the TGO. The corresponding phase reactions in TBC systems with heightened Al activity, however, are not studied yet. In this work, the stage formation of TGO layers of TBC systems with PVD-Al interlayers is described. The study uses thermal cyclic loading with dwell time at maximum high temperature of 1,150 °C. The crack formation in the ceramic top coat and the TGOs thickness at the interface are investigated by SEM/EDS after 1, 6, 12, 24, 40 and 80 thermal cycles. The results plot the interface change and crack formation as a function of the thermal cycle number. The corresponding failure mode is discussed.
Breaking Behavior of Oxide Scale on the LPPS Bond Coat Surface during Pretreatment in Vacuum
Authors: Zhang Bang-Yan , Yang Guan-Jun , Li Cheng-Xin , Li Chang-Jiu 
Published: August 2022

Abstract
Pre-diffusion treatment (high temperature vacuum treatment) plays an important role in the growth of the thermally grown oxide (TGO) on the low pressure plasma spray (LPPS) bond coat surface. Results show that the initial thin oxide scale, formed during deposition process, on the as-sprayed bond coating surface has broken and shrunk to discontinuous oxide particles through the elements diffusion during the pre-diffusion. Two kinds of pre-diffused bond coats deposited in different oxygen partial pressure atmosphere show different results of the average distance between the individual oxide particles on the pre-diffused bond coating surface. In this study, a three dimensional model with thermal grooving theory was developed to explore the essential condition for the scale breaking and explain the differences of these results. This research can provide reference for the preparation optimization and pre-treatment optimization of bond coat towards high performance TBCs.
Characterisation and In Vitro Corrosion Resistance of Plasma-Sprayed Hydroxyapatite and Hydroxyapatite–Silicon Oxide Coatings on 316L SS
Authors: Singh Gurpreet , Singh Hazoor , Sidhu Buta Singh 
Published: August 2022

Abstract
In the current investigation plasma spray technique was used for depositing hydroxyapatite (HA) and hydroxyapatite – silicon oxide (SiO2) coatings on 316L SS substrate. In HA-SiO2 coating, 20 wt% SiO2 was mixed with HA. The feedstock and coatings were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) / energy-dispersive X-ray spectroscopy (EDX) analyses. The corrosion resistance of the uncoated, HA coated and HA + 20 wt% SiO2 coated 316L SS was investigated by electrochemical corrosion testing in simulated human body fluid (Ringer’s solution). After the corrosion testing, the samples were analyzed by XRD and SEM / EDX analyses. The addition of SiO2 reduces the crystallinity of the coating. The corrosion resistance of the 316L SS was found to increase after the deposition of the HA + 20 wt% SiO2 and HA coatings.
Coaxial Introductions of Resin Rods with Ceramics Nanoparticles into Gas Flame Spraying
Authors: Takai Kazuto , Kirihara Soshu 
Published: August 2022

Abstract
Solid resin rods including ceramics nanoparticles were fed successfully into a Rokide flame gun to create dense coated layers without micro cracks and pores applying for electric, magnetic and dielectric components. In this investigation, alumina particles of 170 nm in average diameter were dispersed into acrylic liquid resin at 40 % in volume fraction. The paste material was injected into an brass mold of φ4 ~ 200 mm in inner dimension and thermally cured through heating at 120 °C for 60 min. Formed solid rods were fed coaxially into an oxyacetylene gas flame by using the Rokide spraying system. Sprayed particles were collected in a water bath for microstructure observations by a scanning electron microscope and crystal phase analyses by an X-ray diffraction spectroscopy. Fine ceramics layer formations will be discussed systematically by the feeding speed of solid rods and gas flame condition of air pressure and oxygen pressure.
Comparative Study of the Erosive Wear of Thermally Sprayed Coatings Using Powder and Flexi-Cord Feedstock Materials
Authors: Lima C.R.C. , Libardi R. , Mojena M.A.R. , Fals H.C. , Leal C.V. , Camargo F. 
Published: August 2022

Abstract
Sprayed deposits using conventional wire and powder materials open a wide range of possibilities to solve wear problems in engineering equipment. The option for new different spray technologies and consumables like nanostructured powder materials and nanocomposite cored wires has expanded the engineering possibilities. Cored wire technology allows the use of compositions that cannot be drawn into wire form like carbides in metallic matrix and high-temperature materials, thus intensifying the use of low operating cost welding and spraying processes to demanding wear applications. The objective of this work was to compare the mechanical characteristics and erosive wear performance of coatings obtained by Flame Spray and High Velocity Oxygen Fuel Spray using some selected powder and flexi-cord wire materials. The wear resistance of the coatings was determinate by slurry erosion wear test.
Enhancing Plasma-Sprayed LSCF Cathode Performance by Infiltration Method
Authors: Li Ying , Li Cheng-Xin , Zhang Shan-Lin , Yang Guan-Jun , Li Chang-Jiu 
Published: August 2022

Abstract
LSCF(La0.6Sr0.4Co0.2Fe0.8O3) with a perovskite structure has been widely studied as cathode materials for intermediate solid oxide fuel cell(SOFC). It has well-known excellent electrode performance due to its high ionic and electronic conductivity. However, application of LSCF cathode is likely to be limited by the surface catalytic properties and long term stability. Sr and Co may segregate from LSCF under cathode polarization, leading to increased resistance of the cathode. Oxygen hyper-stoichiometric La2NiO4+δ with a K2NiF4 structure possesses a higher catalytic properties, ionic conductivity and stability compared to LSCF cathode. However, the electrical conductivity of the La2NiO4+δ (76 S cm–1 at 800 °C ) in the IT range are lower than 100 S/cm, which is regarded as the minimum requirement in electrical conductivity for an SOFC cathode. Taking account of both the advantages and disadvantages of the two different cathode materials, and good chemical compatibility of those two cathode materials, it is possible to prepare a composite cathode by infiltrating a thin film of La2NiO4+ä on the porous LSCF to enhance the LSCF cathode performance. Therefore, in this study, the LSCF cathode was deposited by atmospheric plasma spray. The porous LSCF cathode was infiltrated by La2NiO4+δ. The microstructure was characterized by SEM and TEM. The effect of infiltration on the polarization of LSCF cathode was investigated.
High Velocity Oxygen Fuel Sprayed Insulation Coatings for Applications in High Power Electronics
Authors: Luth J. , Cichosz M. , Lehmann M. , Hartmann S. , Trenkle F. 
Published: August 2022

Abstract
Electrically insulating coatings featuring high dielectric strength, high electrical resistance and high thermal conductivity are essential for applications in high power electronics. The capability of HVOF-sprayed coatings for high power electronic components based on 20 different powders was investigated in this study. The powders used are aluminum oxide ceramics containing additives of chromium oxide, titanium oxide and magnesium oxide. Key result of this study is that both, pure alumina (Al2O3) and one class of spinel (Al2O3 - 28MgO) meet the requirements for electrical insulation. In order to reach high resistivity, the insulation coatings should be sealed subsequently. The amount of impurities, such as Na2O or Fe2O3 must be less than 0.1%.
Influence of Metal Bond Coat Thickness on Adhesion Strength of APS Ceramic Coatings
Authors: Barr John , Estrada Christopher , Victoria Nelson , White Bob , Harrison Jerome 
Published: August 2022

Abstract
This paper investigates the influence of metal bond coat (MBC) thickness on the adhesion strength of air plasma spray (APS) ceramic coatings for extreme service ball valve applications. The study was conducted using three different ceramic coatings (Cr2O3, Cr2O3-Al2O3, and TiO2) applied on three different substrates (Titanium G12, Inconel 625, and 2507 Duplex stainless steel) with varying thicknesses of MBC. Tests were performed for adhesion strength (ASTM C633), metallography (ASTM E1920), and percent porosity (ASTM E2109 Method B). The results showed that the adhesion strength of the ceramic coatings was not reduced until the MBC thickness exceeded 0.060 in. The failures observed were either cohesive in the ceramic, cohesive in the adhesive, or a combination of both. It was concluded that a recommended MBC thickness limit of 0.030 in. can be established based on the experimental data.
In-Situ Sensors Deposited by Laser Cladding
Authors: Zhang Yanli , Mack Daniel Emil , Mauer Georg , Vaßen Robert , Guillon Olivier 
Published: August 2022

Abstract
A new method for fabricating microsensors which can provide accurate real-time temperature monitoring of thermal barrier coatings on gas turbine engines was developed. A high temperature K-type thermocouple sensor for hostile environments was deposited using a coaxial pulsed laser cladding process with optimized process parameters giving minimal intrusive features to the substrate and afterwards embedded in typical ceramic layers. The dimensions of the cladded thermocouple were about one hundred microns in thickness and width. The thermal and electrical response of the cladded thermocouple was tested before and after embedding over temperatures ranging from ambient up to approximately 500 °C in a furnace with flowing argon as protective gas. The results were compared to that of a commercial standard K-type thermocouple, which indicate that laser cladding is a promising technology for manufacturing microsensors for in-situ monitoring in harsh operation environments.