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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

NANOSCALE VIEW OF THE EVAPORATING CONTACT LINE PROFILE OF A SESSILE WATER DROPLET ON A SILICON SURFACE

Get access (open in a dialog) DOI: 10.1615/IHTC16.nmt.023083
pages 7003-7010

摘要

Dynamics of the volatile liquid near the contact line due to evaporation is of importance for both heat transfer science and industry. Different modeling approaches have used different assumptions for the microscopic contact angle boundary condition. The experimental evidence for their assumptions has been rare and the contact line movement mechanism remains vague. In this study, we focused on the microscopic contact angle and the contact line profile during the water droplet evaporation in a saturated environment. The evaporation was induced by substrate heating. An atomic force microscopy has been applied to measure the contact line profile in nano scale. The contact line was receding due to the weak evaporation and the speed was less than 45 nm/s. The main results indicated that the film profile follows the macroscopic droplet wedge profile till several nanometers from the apparent contact line. The local contact angle was not constant and changed with the contact line speed. A nano thin film was detected beyond the apparent contact line.