Ultra fast laser machined hydrophobic stainless steel surface for drag reduction in laminar flows

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Hydrophobic surfaces have attracted much attention due to their potential in microfluidics, lab on chip devices and as functional surfaces for the automotive and aerospace industry. The combination of a dual scale roughness with an inherent low-surface-energy coating material is the pre-requisite factor for the development of an artificial superhydrophobic surfaces. Ultra short pulse laser (USPL) machining/structuring is a promising technique to obtain the dual scale roughness. Moreover, ultra short laser pulses allow machining without or with limited thermal effects. Flat stainless steel (AISI 304L) were laser machined with ultraviolet laser pulses of 6.7ps, at different laser processing parameters. Next, the samples were coated with a monolayer of perfluorinated octyltrichlorosilane (FOTS) to get a superhydrophobic surface. The degree of hydrophobicity was accessed by static contact angle measurement. Laser patterned surface has longitudinal micro channels. Drag reduction in liquid flow can be obtained due to the shear free boundary condition at air-liquid menisci. The geometry of the patterns was analyzed with optical and scanning electron microscopy. Micro-Particle Image Velocimetry (μPIV) has been employed to measure and visualize the flow over such patterns
Original languageUndefined
Title of host publicationProceedings of the 11th International Symposium on Laser Precision Microfabrication
Place of PublicationStuttgart, Germany
PublisherJPLS Japan Laser Processing Society
Publication statusPublished - 8 Jun 2010
Event11th International Symposium on Laser Precision Microfabrication, LPM 2010 - Stuttgart, Germany
Duration: 7 Jun 201010 Jun 2010
Conference number: 11


Conference11th International Symposium on Laser Precision Microfabrication, LPM 2010
Abbreviated titleLPM


  • drag reduction
  • contact angle
  • laser patterning
  • METIS-267226
  • IR-79814
  • Hydrophobic
  • Micro-structure

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