A study of the bonding mechanism of sprayed coatings

Kitahara, Shigeru; Hasui, Atsushi

doi:10.1116/1.1312746

Cited by 66 publications

(21 citation statements)

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“…Li et al [4] have recently shown that the substrate melted and interacted with the spreading droplet. These experimental results confirmed that better bonding between the sprayed coating and the substrate could be achieved through the formation of intermetallic compounds as a result of substrate melting during droplet-substrate interaction [1,2,[4][5][6].…”

Section: Introductionsupporting

confidence: 84%

“…Hence, substrate melting has extensively been investigated. Kitahara et al [1] reported that substrate melting occurred when nickel, chromium, molybdenum and tungsten were plasma-sprayed onto aluminium and mild steel substrates. As a result, a layer of an intermetallic compound was formed at the substrate-coating interface [1].…”

Section: Introductionmentioning

confidence: 99%

“…Kitahara et al [1] reported that substrate melting occurred when nickel, chromium, molybdenum and tungsten were plasma-sprayed onto aluminium and mild steel substrates. As a result, a layer of an intermetallic compound was formed at the substrate-coating interface [1]. Subsequently, Steffens et al [2] indicated that substrate melting strongly depended on the droplet thermo physical properties, contact temperature and solidification time.…”

Section: Introductionmentioning

confidence: 99%

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Evidence of Substrate Melting of NiCr Particles on Stainless Steel Substrate by Experimental Observation and Simulations

Tran

Brossard

Hyland

et al. 2009

Plasma Chem Plasma Process

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Single NiCr splats were plasma-sprayed onto a polished stainless steel substrate held at room temperature. The splat-substrate interface was characterized by focused ion beam and transmission electron microscopy. The frequent observation of NiO particles, particularly in pores within the splat, and at the periphery of splat, suggests that the principal oxidation process occurs at the substrate surface, where the splats are exposed to a water vapor-rich environment. It was also observed that the splat adhered well in some locations where elemental-diffusion and jetting of the substrate occurred, suggestive of substrate melting. A three-dimensional numerical model was developed to simulate the impact of a splat onto a substrate. The simulation shows that the observation of the central pore in the splat and the phenomenon of substrate melting may occur. Based on these results, the effect of water release on oxide formation and splat morphology can be explained.

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Section: Introductionsupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evidence of Substrate Melting of NiCr Particles on Stainless Steel Substrate by Experimental Observation and Simulations

Tran

Brossard

Hyland

et al. 2009

Plasma Chem Plasma Process

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“…The inset image shows a SEM image of the splat prior to cross-sectioning. In the central pore of the splat (1) can be found a porous oxide phase, which will be shown later by TEM to be mainly NiO, along with some metallic NiCr particles (2). A thin layer of NiCr can be found at the bottom of the pore (3), while the shape of the splat around the central hole shows a distinct rim (4): the NiCr seems to have been ''pushed'' upward on solidification, probably due to the instability of the gas released by the specimen upon impact (4).…”

Section: Stainless Steel Specimenmentioning

confidence: 98%

Study of the Splat-Substrate Interface for a NiCr Coating Plasma Sprayed onto Polished Aluminum and Stainless Steel Substrates

et al. 2009

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In the plasma spraying process, the mechanisms by which molten particles impact on and bond with the substrate are not fully understood. For this study a nickel-chromium powder was sprayed onto mirror polished aluminum 5052 and stainless steel 304 substrates to form single splats. The splats and their interface with the substrate were studied using detailed microstructural characterization with emphasis on the shape of the splats, the nature of the splat-substrate interface, including the degree of contact and the extent of melting of the substrate and mixing with the splat material, and the presence, either on or within the splats of phases such as oxides. It was shown that melting of the substrate, along with intermixing and diffusion between substrate and splat materials, occurred for the steel substrate, but not for the aluminum substrate. Oxides including nickel oxide, chromium oxide, and aluminum oxide were also observed, the type and distribution of these phases depended on the substrate type.

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“…Kitahara et al [11] reported substrate melting phenomena in thermal spraying. In their experiments, various metals, e.g., Ni, Cr, Mo, Ta, W, were plasma sprayed on aluminum and mild steel substrates.…”

mentioning

confidence: 98%

Toward the Achievement of Substrate Melting and Controlled Solidification in Thermal Spraying

Zhang

Wei

Zhang

et al. 2007

Plasma Chem Plasma Process

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The substrate is usually kept at a distant location in traditional thermal spraying, and substrate melting, which can improve splat adhesion usually does not happen. By moving the substrate close to the plasma flame and attaching a temperature control device to the backside of the substrate, as well as by additional heating from the molten droplets, substrate melting may occur and directional splat solidification becomes possible. In this proposed design, the substrate temperature is controlled by spray distance, flame temperature and initial substrate temperature. The variations of particle in-flight characteristics and contact interface temperature on spray distance are investigated. Optimal operating conditions are determined.heat transfer coefficient, W m -2 K -1 h i h fus Latent heat of fusion, J kg -1 Ja Jakob number, Ja = c ps (T f -T sub )/h fus k Thermal conductivity, W m -1 K -1 L v Latent heat of vaporization, J kg -1 L m Latent heat of melting, J kg -1 _ m v Mass melting rate, kg s -1 P Pressure, Pa Pr Prandtl number, Pr = m/a _ Q Energy input due to particles, W m -3 r, R Radial coordinate, m Re Reynolds number, Re = qVd/l St Stefan number, St = c pl (T p -T f )/h f t Time, s T Temperature, K T B Splat bottom temperature, K T m Melting temperature, K e u ! Favre average velocity vector, m s -1 u 0 ! Velocity fluctuation, m s -1 V Particle speed, m s -1 V p ! Particle velocity vector, m s -1WeWeber number, We = qV 2 d/r x,y,z Coordinate, m Y i Mass fraction of the i th speciesGreek Symbols a Thermal diffusivity, m 2 s -1 h Coordinate in the circumferential direction D Temperature factor e Emissivity U Viscous dissipation, kg m -3 s -1 l Viscosity, kg m -1 s -1 l t Turbulent viscosity, kg m -1 s -1 m Kinetic viscosity, m 2 s -1 n Flattening ratio q Density, kg m -3 r Surface tension, N m -1 r s Stefan-Boltzmann constant, W m -2 K -4

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A study of the bonding mechanism of sprayed coatings

Cited by 66 publications

References 0 publications

Evidence of Substrate Melting of NiCr Particles on Stainless Steel Substrate by Experimental Observation and Simulations

Evidence of Substrate Melting of NiCr Particles on Stainless Steel Substrate by Experimental Observation and Simulations

Study of the Splat-Substrate Interface for a NiCr Coating Plasma Sprayed onto Polished Aluminum and Stainless Steel Substrates

Toward the Achievement of Substrate Melting and Controlled Solidification in Thermal Spraying

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