A mathematical model for cooling and rapid solidification of molten metal droplets

Bergmann, Dirk; Fritsching, Udo; Bauckhage, Klaus

doi:10.1016/s1290-0729(00)00195-1

Cited by 77 publications

(15 citation statements)

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“…Even in the restricted number of cases where attempts have been made to capture the two phase interaction, these have generally used particles of fixed size (i.e. droplet breakup is ignored) [25,26], a very small number of particles [4], or have been restricted to very small times after the second fluid is introduced due to the computationally intensive nature of the calculation [27]. Consequently, we believe that numerical atomization models may have significantly overestimated cooling rates.…”

Section: Figmentioning

confidence: 99%

Estimation of Cooling Rates During Close-Coupled Gas Atomization Using Secondary Dendrite Arm Spacing Measurement

Farrell

Mullis

Adkins

2013

Metall Mater Trans B

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Al-4 wt.%Cu alloy has been gas atomized using a commercial close-coupled gas atomization system. The resulting metal powders have been sieved into six size fractions and the secondary dendrite arm spacing has been determined using electron microscopy. Cooling rates for the powders have been estimated using a range of published conversion factors for Al-Cu alloy, with reasonable agreement being found between sources. We find that cooling rates are very low compared to those often quoted for gas atomized powders, of the order of 10 4 K s -1 for sub-38 μm powders. We believe that a number of numerical studies of gas atomization have overestimated the cooling rate during solidification, probably as a consequence of overestimating the differential velocity between the gas and the particles. From the cooling rates measure here we estimate that such velocities are unlikely to exceed 20 m s -1 .

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Section: Figmentioning

confidence: 99%

Estimation of Cooling Rates During Close-Coupled Gas Atomization Using Secondary Dendrite Arm Spacing Measurement

Farrell

Mullis

Adkins

2013

Metall Mater Trans B

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“…Before applying the heat balance equation, it is necessary to check the condition that there is no internal temperature gradient present within the droplet (N Bi (Biot number) 1) (Bergmann et al, 2000). For calculations, the properties reported elsewhere for PEG 6000 have been used (Kukova, 2003).…”

Section: Solidificationmentioning

confidence: 99%

Batch production of micron size particles from poly(ethylene glycol) using supercritical CO2 as a processing solvent

Nalawade

Picchioni

Janssen

2007

Chemical Engineering Science

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The major advantage of using supercritical carbon dioxide (CO 2 ) as a solvent in polymer processing is an enhancement in the free volume of a polymer due to dissolved CO 2 , which causes a considerable reduction in the viscosity. This allows spraying the polymer melt at low temperatures to produce micron size particles. We have used supercritical CO 2 as a solvent for the generation of particles from poly(ethylene glycol) (PEG) of different molecular weights. Since PEG is a hydrophilic compound, it is a most commonly used polymer for encapsulating a drug. PEG particles with different properties may allow keeping a good control over the release of the drug. It has been possible to produce particles with different size, size distribution, porosity and shape by varying various process parameters such as molecular weight, temperature, pressure and nozzle diameter. A flow and a solidification model have been applied in order to have a theoretical insight into the role of different parameters. ᭧

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“…Droplet collision effects are ignored. The droplet dynamics and cooling/solidification have been calculated based on the models described in Bergmann [9]. The time step size used was ∆t = 10 µs and 2500 iterations were calculated.…”

Section: Atomization Modelmentioning

confidence: 99%

A Unified Computer Model of the Spray Forming Process of Inconel 718 Rings

Garmendia¹,

Landaberea²,

Vicario³

et al. 2005

Superalloys 718, 625, 706 and Various Derivatives (2005)

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A unified computer model of the process of spray forming Inconel 718 rings has been developed. The target of the model is to optimize the process input parameters to achieve the correct shape, microstructure and minimum porosity. The model is divided in three main parts that correspond to the atomization phase of the material, the flight behaviour of the droplets and the solidification and growth of the ring. Different modelling techniques have been used for each part of the model. For the atomization step, stability analysis for the primary atomization and a tracking model for secondary atomization were used. Computational fluid dynamics calculations for the thermal and mechanical behaviour of the droplets in their travel to the substrate were used for the in-flight behaviour step. Shape and growth models, as well as thermal models, based on finite element calculations were used to predict the final shape and temperature history of the as sprayed ring. Various computer programs have been written to link results between different submodels and to transform the format of intermediate computer files.

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A mathematical model for cooling and rapid solidification of molten metal droplets

Cited by 77 publications

References 0 publications

Estimation of Cooling Rates During Close-Coupled Gas Atomization Using Secondary Dendrite Arm Spacing Measurement

Estimation of Cooling Rates During Close-Coupled Gas Atomization Using Secondary Dendrite Arm Spacing Measurement

Batch production of micron size particles from poly(ethylene glycol) using supercritical CO2 as a processing solvent

A Unified Computer Model of the Spray Forming Process of Inconel 718 Rings

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