Date of this Version
C.Huang. Condensation and subsequent freezing delays as a result of using a femtosecond laser functionalized surface, MS thesis, University of Nebraska-Lincoln, 2017.
Femtosecond laser surface processing (FLSP) enhances the anti-icing properties of a commonly used aircraft alloy, Al 7075-O Clad. The wettability of Al 7075-O Clad was altered by changing the surface morphology through FLSP and the surface chemistry through siloxane vapor deposition. Tall mound and short mound FLSP functionalized surfaces were created through two sets of laser parameters. Atmospheric condensation and subsequent freezing of condensates on FLSP Al 7075-O Clad was studied. Results indicate that both structure height and surface wettability play a role in the delay of freezing. Freezing occurred on the FLSP superhydrophilic surface faster than on a unprocessed Al 7075-O Clad surface; however, freezing was delayed for all superhydrophobic FLSP surfaces. Tall structure FLSP functionalized surfaces delayed freezing time longer than short structure FLSP functionalized surfaces, although all were superhydrophobic. FLSP functionalized surfaces were able to delay freezing by up to 530 seconds compared to unprocessed Al 7075-O Clad surfaces. Self-propelled condensate jumping on FLSP functionalized superhydrophobic surfaces occurred during the condensing process. The self-propelled jumping phenomena provides a means to promote anti-icing materials, especially where jumping drops can be swept away in the flowing airstream.
Advisor: Dennis R. Alexander