- published: 18 Aug 2016
- views: 1376
In fluid mechanics, dewetting is one of the processes that can occur at a solid–liquid or liquid–liquid interface. Generally, dewetting describes the rupture of a thin liquid film on the substrate (either a liquid itself, or a solid) and the formation of droplets. The opposite process—spreading of a liquid on a substrate—is called wetting. The factor determining the spontaneous spreading and dewetting for a drop of oil placed on a liquid substrate (water here) with ambient gas, is the so-called spreading coefficient :
where is the gas-water surface tension,
is the gas-oil surface tension and
is the oil water surface tension (measured on the fluids before they are brought in contact with each other)
When , the spontaneous spreading occurs, and if
, dewetting occurs.
Spreading and dewetting are important processes for many applications, including adhesion, lubrication, painting, printing, and protective coating. For most applications, dewetting is an unwanted process, because it destroys the applied thin film.
Watch as Dr. Aiwen Wu, Senior Applications Engineer, demonstrates the hydrophobic nature of a native PTFE membrane and a surface modified PTFE (non-dewetted) membrane when exposed to DI water and IPA. He also explains what prewetting accomplishes and the benefit of surface modified membranes for use in applications with strong acids, bases, high-temperature water, and surfactants. Runtime: 03:19 mins. Watch Part I: https://youtu.be/OkFDy3m69-w
Tom Witelski (Duke University) presents at the UW Applied PDE Seminar Title: Multiscale Dynamics Of Dewetting Fluid Films Abstract: Instabilities of thin liquid films spreading on solid surfaces are of great concern for many applications involving coating flows. Generally called dewetting instabilities, several stages of dynamics yield rupture, growth of dry spots, and ultimately break-up of the film into sets of droplets. These instabilities can be captured by a lubrication model consisting of a fourth-order nonlinear parabolic PDE for the film height. The long-time behavior can be reduced to a finite-dimensional system for the dynamics of the remaining droplets as interacting quasi-steady localized structures. The final stage, coarsening, is the successive re-arrangement and merging of...
New study shows that liquid droplets form in unexpected ways. Read more: http://bit.ly/2d4Psgn JOIN AAAS: http://scim.ag/2bxrxnH
Can solids wet a surface? How to control the self-assembly of complex nano-architectures of crystalline silicon.
Instability and Patterning of Thin Polymer Films by Dr. R. Mukherjee, Department of Chemical Engineering, IIT Kharagpur. For more details on NPTEL visit http://nptel.iitm.ac.in
Ethanol liquid dewetting process (in UMass-Amherst)
Bob Willis Defect of the Month explains reasons for de-wetting which can be more difficult with coatings. The video is just one of the Defect of the Month videos featured by IPC, SMTA and Circuits Assembly to help provide better understanding of process issues and help support training of younger engineers If you need more defect images to download from our extensive photo library, videos or inspection standards wall charts the links are provided below Photo Library https://www.bobwillis.co.uk/soldering-standards/ Inspection Charts https://www.bobwillis.co.uk/product-category/quality-control-wall-charts/ Video Library https://www.bobwillis.co.uk/product-category/video-library/ More Defect of the Month Videos coming soon Past Defect of the Month magazine pages are available online...
PVA is excited to announce our newest series, PVA Pro Tip! A member of the PVA team will be dropping by twice a month to fill you in on their favorite tips and tricks for a seamless conformal coating process. This week, Frank Hart shows us how to combat dewetting on your printed circuit board. Contact PVA: http://ow.ly/f2am50AE2g4
In fluid mechanics, dewetting is one of the processes that can occur at a solid–liquid or liquid–liquid interface. Generally, dewetting describes the rupture of a thin liquid film on the substrate (either a liquid itself, or a solid) and the formation of droplets. The opposite process—spreading of a liquid on a substrate—is called wetting. The factor determining the spontaneous spreading and dewetting for a drop of oil placed on a liquid substrate (water here) with ambient gas, is the so-called spreading coefficient :
where is the gas-water surface tension,
is the gas-oil surface tension and
is the oil water surface tension (measured on the fluids before they are brought in contact with each other)
When , the spontaneous spreading occurs, and if
, dewetting occurs.
Spreading and dewetting are important processes for many applications, including adhesion, lubrication, painting, printing, and protective coating. For most applications, dewetting is an unwanted process, because it destroys the applied thin film.
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