Phenomena Involved in Suspension Plasma Spraying Part 1: Suspension Injection and Behavior

Fazilleau, J.; Delbos, C.; Rat, Vincent; Coudert, Jean-François; Fauchais, Pierre; Pateyron, Bernard

doi:10.1007/s11090-006-9019-1

Cited by 154 publications

(110 citation statements)

References 23 publications

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“…SPS is a far more complicated process, as the particle size on coating deposition is not pre-determined, as it is with powder processes. When injecting a suspension as a solid stream into a DC arc plasma gun jet, the fragmentation of the suspension stream occurs roughly two orders of magnitude faster than the vaporization of the solvent [20]. It is therefore important to consider first the influence of the various conditions on the fragmentation of the suspension and the resulting droplet size.…”

Section: Theory Of Suspension Fragmentation and Depositionmentioning

confidence: 99%

Thermal Conductivity Analysis and Lifetime Testing of Suspension Plasma-Sprayed Thermal Barrier Coatings

Curry

VanEvery²,

Snyder³

et al. 2014

Coatings

117

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Suspension plasma spraying (SPS) has become an interesting method for the production of thermal barrier coatings for gas turbine components. The development of the SPS process has led to structures with segmented vertical cracks or column-like structures that can imitate strain-tolerant air plasma spraying (APS) or electron beam physical vapor deposition (EB-PVD) coatings. Additionally, SPS coatings can have lower thermal conductivity than EB-PVD coatings, while also being easier to produce. The combination of similar or improved properties with a potential for lower production costs makes SPS of great interest to the gas turbine industry. This study compares a number of SPS thermal barrier coatings (TBCs) with vertical cracks or column-like structures with the reference of segmented APS coatings. The primary focus has been on lifetime testing of these new coating systems. Samples were tested in thermo-cyclic fatigue at temperatures of 1100 °C for 1 h cycles. Additional testing was performed to assess thermal shock performance and erosion resistance. Thermal conductivity was also assessed for samples in their as-sprayed state, and the microstructures were investigated using SEM.

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Section: Theory Of Suspension Fragmentation and Depositionmentioning

confidence: 99%

Thermal Conductivity Analysis and Lifetime Testing of Suspension Plasma-Sprayed Thermal Barrier Coatings

Curry

VanEvery²,

Snyder³

et al. 2014

Coatings

117

View full text Add to dashboard Cite

show abstract

“…To produce finely structured ceramic or cermet (WCCo) coatings of sub-micrometer-sized or nanometer-sized particles a suspension of these particles is thermally sprayed (Ref 79,(163)(164)(165)(166). Spray conditions are somewhat more complex than those of conventional spraying because the suspension penetration within the hot gases jet, its fragmentation and resulting droplets penetration within the hot gases jet, the cooling of the hot gases and the very low inertia of sub-micrometer-sized or nanometersized particles, both implying very short spray distances (between 30 and 50 mm against 100-120 mm in conventional spraying), see the review of Fauchais et al (Ref 79).…”

Section: Coatings From Nanometer-sized Sprayedmentioning

confidence: 99%

From Powders to Thermally Sprayed Coatings

2009

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Since the early stages of thermal spray, it has been recognized that the powder composition, size distribution, shape, mass density, mechanical resistance, components distribution for composite particles play a key role in coating microstructure and thermo mechanical properties. The principal characteristics of particles are strongly linked to the manufacturing process. Coatings also depend on the process used to spray particles and spray parameters. Many papers have been devoted to the relationships existing between coating properties and structures at different scales and manufacturing processes. In many conventional spray conditions resulting in micrometric structures, among the different parameters, good powder flow ability, and dense particles are important features. Thermal plasma treatment, especially by RF plasma, of particles, prepared by different manufacturing processes, allows achieving such properties and it is now developed at an industrial scale. Advantages and drawbacks of this process will be discussed. Another point, which will be approached, is the self-propagating high-temperature synthesis, depending very strongly upon the starting composite particle manufacturing. However, as everybody knows, ''small is beautiful'' and nano-or finely structured coatings are now extensively studied with spraying of: (i) very complex alloys containing multiple elements which exhibit a glass forming capability when cooled-down, their under-cooling temperature being below the glass transition temperature; (ii) conventional micrometer-sized particles (in the 30-90 lm range) made of agglomerated nanometersized particles; (iii) sub-micrometer-or nanometer-sized particles via a suspension in which also, instead of particles, stable sol of nanometer-sized particles can be introduced; and (iv) spray solutions of final material precursor. These different processes using plasma, HVOF or sometimes flame and also cold-gas spray will be discussed together with the production of nanometer-sized particles via the chemical reaction method or by a special type of milling: the cryogenic milling process often referred to as ''cryomilling.''

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“…Control of columnar microstructures is therefore dependent on the size of the droplet generated during the atomization of the suspension as this decides the size of the impacting particle that will form the coating. Atomization may be considered discretely from solvent vaporization as the former has been shown to occur an order of magnitude faster than the latter [7]. A number of factors influence the atomization of the suspension and size of droplets in the plasma stream.…”

Section: Introductionmentioning

confidence: 99%

Performance Testing of Suspension Plasma Sprayed Thermal Barrier Coatings Produced with Varied Suspension Parameters

Curry

VanEvery²,

Snyder³

et al. 2015

Coatings

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Suspension plasma spraying has become an emerging technology for the production of thermal barrier coatings for the gas turbine industry. Presently, though commercial systems for coating production are available, coatings remain in the development stage. Suitable suspension parameters for coating production remain an outstanding question and the influence of suspension properties on the final coatings is not well known. For this study, a number of suspensions were produced with varied solid loadings, powder size distributions and solvents. Suspensions were sprayed onto superalloy substrates coated with high velocity air fuel (HVAF) -sprayed bond coats. Plasma spray parameters were selected to generate columnar structures based on previous experiments and were maintained at constant to discover the influence of the suspension behavior on coating microstructures. Testing of the produced thermal barrier coating (TBC) systems has included thermal cyclic fatigue testing and thermal conductivity analysis. Pore size distribution has been characterized by mercury infiltration porosimetry. Results show a strong influence of suspension viscosity and surface tension on the microstructure of the produced coatings.

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Phenomena Involved in Suspension Plasma Spraying Part 1: Suspension Injection and Behavior

Cited by 154 publications

References 23 publications

Thermal Conductivity Analysis and Lifetime Testing of Suspension Plasma-Sprayed Thermal Barrier Coatings

Thermal Conductivity Analysis and Lifetime Testing of Suspension Plasma-Sprayed Thermal Barrier Coatings

From Powders to Thermally Sprayed Coatings

Performance Testing of Suspension Plasma Sprayed Thermal Barrier Coatings Produced with Varied Suspension Parameters

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