Benefits of Hydrogen in a Segmented-Anode Plasma Torch in Suspension Plasma Spraying

Dolmaire, Alice; Hartikainen, Enni; Goutier, Simon; Béchade, Emilie; Vardelle, Michel; Geffroy, Pierre-Marie; Joulia, Aurélien

doi:10.1007/s11666-020-01134-2

Cited by 10 publications

(5 citation statements)

References 33 publications

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“…An increase in the total plasma gas volume or hydrogen content lead to an increase in the process power. The higher thermal conductivity of hydrogen gas enables a higher heat transfer to the feed material 20 . To analyze the effect of plasma gas parameters on coating development, column density, coating porosity, process efficiency, and coating thickness per coating cycle of the samples are investigated for each experimental parameter and presented in Figure 3.…”

Section: Resultsmentioning

confidence: 99%

“…The higher thermal conductivity of hydrogen gas enables a higher heat transfer to the feed material. 20 To analyze the effect of plasma gas parameters on coating development, column density, coating porosity, process efficiency, and coating thickness per coating cycle of the samples are investigated for each experimental parameter and presented in Figure 3. An examination of the microstructure shows that a microstructural differentiation of the coatings is difficult to recognize.…”

Section: Plasma Gas Propertiesmentioning

confidence: 99%

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Evaluation of major factors influencing the TBC topcoat formation in axial suspension plasma spraying (SPS)

Joeris

Tiwari

Brinckmann

et al. 2022

Int J Applied Ceramic Tech

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Suspension plasma spraying (SPS) is ideally suited to produce porous or dense columnar, strain-tolerant thermal barrier coatings (TBCs) and also offers the possibility of producing other microstructures such as feathery and dense vertically cracked coatings. The specific properties of the TBC are significantly influenced by the formed microstructure, that is, affected by feedstock material and process parameters. In this work, the effects of various process parameters in the SPS process are investigated. It was found that the suspension feed rate has a significant effect on the microstructure, especially on the column density of the coating, whereas the suspension solids content mainly affects the coating porosity. Additionally, the surface roughness and topography of the bond coat are crucial for the formation of columnar coatings and were therefore investigated. Despite comparable roughness values for as-sprayed bond coats for high velocity oxy fuel and vacuum plasma spray produced coatings, the surface structures differ significantly from each other and affect the microstructure of the deposited topcoat.Characterization of mechanical properties by means of micro-indenter can be suitable for columnar coatings to determine Young's modulus within a column. However, due to the heterogeneity of the coating, the method is not suitable to describe the mechanical properties of the topcoat.

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Section: Resultsmentioning

confidence: 99%

Section: Plasma Gas Propertiesmentioning

confidence: 99%

Evaluation of major factors influencing the TBC topcoat formation in axial suspension plasma spraying (SPS)

Joeris

Tiwari

Brinckmann

et al. 2022

Int J Applied Ceramic Tech

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show abstract

“…Particles follow the deviated plasma streamlines and give rise to wider column and smaller inter-columnar voids. Dense coatings can be achieved by increasing the plasma enthalpy and speed by favoring the increase of v ⊥ but also by improving the liquid fragmentation and evaporation [22,57].…”

Section: Coating Growthmentioning

confidence: 99%

“…Figure 2: a) Current/voltage characteristics of main DC plasma torches families used in plasma spraying of liquid feedstocks, Conventional Torch (CT), Segmented Torch (ST), Multielectrode Torch (MT), Axial Multi-electrode Torch (AMT). b) Specific enthalpy dependence on electrical power(20,(22)(23)(24).…”

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confidence: 99%

Relationships between arc plasma jet properties and plasma/liquid interaction mechanisms for the deposition of nanostructured ceramic coatings

Rat¹,

Bienia²,

Dhamale³

et al. 2022

Plasma Phys. Control. Fusion

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Ceramic nanostructured coatings with intermediate thicknesses between 10 and 100 µm exhibit improved thermal and mechanical properties for thermal barrier coatings or wear resistant coatings. Such coatings comply with the technical requirements of aeronautical and automotive applications. This implies to develop deposition processes with high throughput and deposition rates promoting the formation of nanostructured coatings. The use of a liquid phase as a carrier medium of nanoparticles or of solution precursors has been shown to be of major interest when being injected within a thermal plasma jet. The as-sprayed materials can form ceramic nanostructured coatings provided the liquid injection encompassing the physicochemical properties of liquid and its injection method copes with the plasma properties. Especially the repeatability of the interaction phenomena between the liquid phase and the arc jet has a key role in the efficiency deposition so that some research efforts are devoted to stabilize the arc while a liquid jet is continuously injected within the plasma. Alternatively a pulsed arc plasma jet can be generated and associated with a time-phased injection of droplets. This paper presents the different issues related to the arc plasma properties produced by direct plasma torches including the arc instabilities and their influence on plasma/liquid interaction mechanisms leading to the formation of nanomaterials. A focus is made on pulsed plasma spraying associated with a synchronized injection of microsized droplets by means of an inkjet printing method.

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“…The plasma reaches temperatures of about 23,500, 20,000 and 17,000 K in the torch, about 14,200, 13,600 and 12,800 K at the nozzle exit and about 8700, 8500 and 8000 K at the substrate location (0.45 m) from the nozzle exit, for a torch power of 40, 50 and 60 kW, respectively. The high temperature in the plasma torch are explained by the presence of the arc that converts the electric current to heat [36] and also by the high specific enthalpy of the Ar-H 2 gas mixture due to the addition of hydrogen that increases the enthalpy and decreases the gas mass flow rate. The lower temperatures after the nozzle exit can be explained by the energy consumed by the dissociation of the hydrogen molecules.…”

Section: The Temperature and Velocity Distribution Of Ar-he Plasma Jetmentioning

confidence: 99%

Numerical Analysis of the Interactions between Plasma Jet and Powder Particles in PS-PVD Conditions

et al. 2021

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Plasma spray-physical vapor deposition (PS-PVD) refers to a very low-pressure (~100 Pa) deposition process in which a powder is injected in a high-enthalpy plasma jet, and mostly vaporized and recondensed onto a substrate to form a coating with a specific microstructure (e.g., columnar). A key issue is the selection of the powder particle size that could be evaporated under specific spray conditions. Powder evaporation takes place, first, in the plasma torch between the injection location and nozzle exit and, then, in the deposition chamber from the nozzle exit to the substrate location. This work aims to calculate the size of the particles that can be evaporated in both stages of the process. It deals with an yttria-stabilized zirconia powder and two commercial plasma torches operated at different arc powers with gas mixtures of argon and helium or argon and hydrogen. First, it used computational fluid dynamics simulations to calculate the velocity and temperature fields of the plasma jets under very low-pressure plasma conditions. Then, it estimated the evaporation of the particles injected in both plasma jets assuming an isothermal evaporation process coupled with momentum and heat transfer plasma-particle models in a rarefied plasma. The calculations showed that, for different powers of the Ar–H2 and the Ar–He operating conditions of this study, the heat flux from the plasma jet to particles inside the torch is much higher than that transferred in the deposition chamber while the specific enthalpy transferred to particles is comparable. The argon-helium mixture is more efficient than the argon-hydrogen mixture to evaporate the particles. Particles less than 2 μm in diameter could be fully evaporated in the Ar–He plasma jet while they should be less than 1 µm in diameter in the Ar–H2 plasma jet.

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Benefits of Hydrogen in a Segmented-Anode Plasma Torch in Suspension Plasma Spraying

Cited by 10 publications

References 33 publications

Evaluation of major factors influencing the TBC topcoat formation in axial suspension plasma spraying (SPS)

Evaluation of major factors influencing the TBC topcoat formation in axial suspension plasma spraying (SPS)

Relationships between arc plasma jet properties and plasma/liquid interaction mechanisms for the deposition of nanostructured ceramic coatings

Numerical Analysis of the Interactions between Plasma Jet and Powder Particles in PS-PVD Conditions

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