Numerical simulation of nucleation, solidification, and microstructure formation in thermal spraying

Zhang, H.; Wang, X.Y.; Zheng, Lili; Sampath, Sanjay

doi:10.1016/j.ijheatmasstransfer.2003.11.030

Cited by 46 publications

(18 citation statements)

References 14 publications

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“…It is well known that in plasma spraying process, the powder particles are quickly melt in the plasma stream and accelerated to the substrate where they spread upon impact and rapidly solidify (Ref [26][27][28][29][30]. Thus during the rapid solidification, two-phase mixture of equilibrium phases in a eutectic alloy could be replaced by an extended solid solution like noncrystalline phase (i.e., metallic glass), nonstable phases, or a new crystalline phase simply by quenching with enough rapidity from the liquid state (Ref [31][32][33][34][35].…”

Section: Influence Of Particle Size On the Nitriding Reactionmentioning

confidence: 99%

Reactive Atmospheric Plasma Spraying of AlN Coatings: Influence of Aluminum Feedstock Particle Size

et al. 2010

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Feedstock powder characteristics (size distribution, morphology, shape, specific mass, and injection rate) are considered to be one of the key factors in controlling plasma-sprayed coatings microstructure and properties. The influence of feedstock powder characteristics to control the reaction and coatings microstructure in reactive plasma spraying process (RPS) is still unclear. This study, investigated the influence of feedstock particle size in RPS of aluminum nitride (AlN) coatings, through plasma nitriding of aluminum (Al) feedstock powders. It was possible to fabricate AlN-based coatings through plasma nitriding of all kinds of Al powders in atmospheric plasma spray (APS) process. The nitriding ratio was improved with decreasing the particle size of feedstock powder, due to improving the nitriding reaction during flight. However, decreasing the particle size of feedstock powder suppressed the coatings thickness. Due to the loss of the powder during the injection, the excessive vaporization of fine Al particles and the completing nitriding reaction of some fine Al particles during flight. The feedstock particle size directly affects on the nitriding, melting, flowability, and the vaporization behaviors of Al powders during spraying. It concluded that using smaller particle size powders is useful for improving the nitriding ratio and not suitable for fabrication thick AlN coatings in reactive plasma spray process. To fabricate thick AlN coatings through RPS, enhancing the nitriding reaction of Al powders with large particle size during spraying is required.

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Section: Influence Of Particle Size On the Nitriding Reactionmentioning

confidence: 99%

Reactive Atmospheric Plasma Spraying of AlN Coatings: Influence of Aluminum Feedstock Particle Size

et al. 2010

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“…(13) is only true when the substrate temperature remains constant or thermal conductivity of the substrate is much higher than that of the impact particle. To improve the accuracy, Zhang et al [26] modified Eq. (13) to include temperature distribution in the substrate by redefining the Jakob number based on the temperature difference between the equilibrium freezing temperature, T m , and the bottom temperature of the droplet, T B , e.g.,…”

Section: Splat Formation and Flattening Ratiomentioning

confidence: 99%

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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“…Studies investigated microstructure development in alloy splats [JM150] and effect of droplet sizes on nucleation processes [JM151]. Other studies involve droplets , spraying [JM155] and splat cooling [JM156,JM157].…”

Section: Droplets Spray and Splat Coolingmentioning

confidence: 99%

Heat transfer—A review of 2004 literature

Goldstein

Ibele

Patankar

et al. 2010

International Journal of Heat and Mass Transfer

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Numerical simulation of nucleation, solidification, and microstructure formation in thermal spraying

Cited by 46 publications

References 14 publications

Reactive Atmospheric Plasma Spraying of AlN Coatings: Influence of Aluminum Feedstock Particle Size

Reactive Atmospheric Plasma Spraying of AlN Coatings: Influence of Aluminum Feedstock Particle Size

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

Heat transfer—A review of 2004 literature

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