‘Herringbone’ defect formation in planar-flow melt spinning

•HB scaled as fλ=0.08We/τ whereas CW scaled as fλ=2.0/τ.•The appropriate characteristic velocity u was the wheel speed, u=U.•The HB and CW defects correlated with a pinned and unpinned meniscus, respectively.•HB could be avoided by forcing meniscus unpinning at the nozzle corner. A short-wavelength,...

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Bibliographic Details
Published in:Journal of materials processing technology 2013-10, Vol.213 (10), p.1743-1752
Main Authors: Cox, B.L., Steen, P.H.
Format: Article
Language:English
Subjects:
Casting
Crosswave defect
Defect formation
Herringbone defect
Planar-flow melt spinning
Planar-flow spin casting
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Summary:•HB scaled as fλ=0.08We/τ whereas CW scaled as fλ=2.0/τ.•The appropriate characteristic velocity u was the wheel speed, u=U.•The HB and CW defects correlated with a pinned and unpinned meniscus, respectively.•HB could be avoided by forcing meniscus unpinning at the nozzle corner. A short-wavelength, periodic feature (≈1mm) similar in appearance to a herringbone pattern appeared on ribbon produced at high rates (≈10m/s) by the planar-flow process. These marks corresponded to a high-frequency (≈10kHz) disturbance to the process stream. Observations of herringbone formation came from ribbon profilometry, customized nozzle tests and high-speed meniscus imaging. These observations were compared against observations of the ‘crosswave’ feature formation which were subject to prior study. It is demonstrated here that herringbone marks, in contrast to the crosswave marks, were mainly influenced by the substrate motion of translation. Herringbone formation is also reported to have correlated with the pinning of the liquid puddle at the nozzle edge.
ISSN:0924-0136
DOI:10.1016/j.jmatprotec.2013.04.009