Spreading and Arrest of a Molten Liquid on Cold Substrates

Tavakoli, Faryar; Davis, Stephen H.; Kavehpour, H. Pirouz

doi:10.1021/la5017998

Cited by 37 publications

(49 citation statements)

References 30 publications

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“…For freezing-induced pinning, the literature offers various hypotheses for the criterion for contact line arrest [5][6][7][11][12][13]. For example, the delay in the arrest was argued to be caused by the requirement for a critical nucleus to form near the contact line [11,12]. However, a detailed description of growth of the nucleus in the presence of flow is lacking.…”

Section: A Mechanism Of Solidification-induced Pinningmentioning

confidence: 99%

“…Arrest of the drop can be due to temperature-dependent viscosity (generally diverging when approaching the melting point), or more dramatically due to solidification near the liquid/solid interface. Such cases were investigated for droplet impact [5][6][7][8]10], as well as for spontaneous spreading after gentle deposition on solid substrates [11][12][13]. Inkjet printing and applications such as spray coating indeed involve droplet impact.…”

Section: Introductionmentioning

confidence: 99%

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Drop spreading and gelation of thermoresponsive polymers

et al. 2018

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Spreading and solidification of liquid droplets are elementary processes of relevance for additive manufacturing. Here we investigate the effect of heat transfer on spreading of a thermoresponsive solution (Pluronic F127) that undergoes a sol-gel transition above a critical temperature Tm. By controlling the concentration of Pluronic F127 we systematically vary Tm, while also imposing a broad range of temperatures of the solid and the liquid. We subsequently monitor the spreading dynamics over several orders of magnitude in time and determine when solidification stops the spreading. It is found that the main parameter is the difference between the substrate temperature and Tm, pointing to a local mechanism for arrest near the contact line. Unexpectedly, the spreading is also found to stop below the gelation temperature, which we attribute to a local enhancement in polymer concentration due to evaporation near the contact line.

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Section: A Mechanism Of Solidification-induced Pinningmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Drop spreading and gelation of thermoresponsive polymers

et al. 2018

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“…Sketches of the different hypotheses for contact line arrest. Arrest occurs when (a) the contact angle of the spreading drop equals the angle of the freezing front at the contact line [14,15], (b) a critical volume at the contact line is solidified [26], and (c) the liquid at the contact line reaches a critical temperature (present work).…”

Section: Introductionmentioning

confidence: 99%

Contact line arrest in solidifying spreading drops

et al. 2017

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When does a drop, deposited on a cold substrate, stop spreading? Despite the practical relevance of this question, for example, in airplane icing and three-dimensional metal printing, the detailed mechanism of arrest in solidifying spreading drops has remained debated. Here we consider the spreading and arrest of hexadecane drops of constant volume on two smooth wettable substrates: copper with a high thermal conductivity and glass with a low thermal conductivity. We record the spreading radius and contact angle in time for a range of substrate temperatures. The experiments are complemented by a detailed analysis of the temperature field near the rapidly moving contact line, by means of similarity solutions of the thermohydrodynamic problem. Our combined experimental and theoretical results provide strong evidence that the spreading of solidifying drops is arrested when the liquid at the contact line reaches a critical temperature, which is determined by the effect of kinetic undercooling.

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“…Further understanding of the recalescence stage for undercooled liquid, in terms of dynamics and structure, could possibly unveil a strong influence of this stage on solidification of static or spreading drops. Furthermore, in many fluids-mechanical research and experimental studies on freezing supercooled drops, whether static 17 or dynamic drops, 18,19 the recalescence stage has not been considered.…”

Section: Introductionmentioning

confidence: 99%

Freezing of supercooled water drops on cold solid substrates: initiation and mechanism

Tavakoli¹,

Davis

Kavehpour³

2015

J Coat Technol Res

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Drops of liquid are placed on substrates having temperatures below the melting point of the liquids (supercooling). All well-known stages of cooling and freezing (supercooling-recalescence-main solidification-ice cooling) of water drops on both hydrophilic and hydrophobic surfaces were observed using a k-type thermocouple and an IR camera. Duration of the main solidification and the ice cooling stages were found to be dependent on the drop size. However, no conclusive relationship can be made regarding the duration of the supercooling stage with the drop size and the surface hydrophobicity. Using an IR camera, we observed that the solidification initiation of the main drop, which corresponds to the supercooling stage duration, is triggered by the erratic wave-like recalescence front of the surrounding condensed microdrops. The nucleation always initiates from the trijunction and propagates into the drop volume with different structural morphologies determined by temperatures and surface hydrophobicity of the substrate. The recalescence front speed of the main drop varies from 50 to 150 mm/s with supercooling temperatures.

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Spreading and Arrest of a Molten Liquid on Cold Substrates

Cited by 37 publications

References 30 publications

Drop spreading and gelation of thermoresponsive polymers

Drop spreading and gelation of thermoresponsive polymers

Contact line arrest in solidifying spreading drops

Freezing of supercooled water drops on cold solid substrates: initiation and mechanism

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