Date of Award

2023

Publication Type

Thesis

Degree Name

M.A.Sc.

Department

Mechanical, Automotive, and Materials Engineering

Keywords

Hydrophobic, Oleophobic, PolyMUMPs, Surface patterning, Double-undercut

Supervisor

V.Stoilov

Supervisor

R.Riahi

Rights

info:eu-repo/semantics/openAccess

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Abstract

Surface patterning is an overwhelming approach to mechanically modifying metal surfaces and improving their tribological properties, such as repellency, lower friction, and more excellent corrosion resistance. Patterned surfaces can be applied to various industrial uses, such as cutting tools, submarines, and self-cleaning surfaces. In this paper, the novel nature-inspired flat-top-pillar "double-undercut" designs were proposed to achieve an apparent angle that satisfies super-hydrophobicity and endure higher pressure on which external forces are exerted. The main objective is to enlarge the change in Gibbs free energy for the system to exhibit a heterogeneous wetting to a homogeneous one by excavation on the surface needed to be patterned to obtain an additional 30% of the atmospheric pressure while maintaining an apparent contact angle of greater than 150°.

The analytical approach yielded decent results showing an extra pressure of more than 3 atm averaged from three different scales of two distinct double-undercut designs calculated by the stability equation derived by the Gibbs free energy. Numerical, finite element analysis was also performed in COMSOL-Multiphysics and demonstrated a Canthotaxis wetting transition phenomenon. An average of 800 pascals of additional pressure was achieved for designs of three distinct permutations of double-undercut angles (50°-40°, 50°-36°, and 40°-36°). Specimens were fabricated on silicon wafers by PolyMUMPs method for proof-of-concept and were ready for the future experiment on apparent contact angle and cross-sectional SEM at post breaching the Cassie-Baxter state.

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