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Rare-earth Oxides:
Harnessing their Hydrophobic Potential to
Provide Infrastructural Upgrades in
Hydropower Plants
Sami Khan | Advisor: Kripa K. Varanasi
Ph.D. Candidate in Mechanical Engineering ‘16
Massachusetts Institute of Technology
Wettability overview
Most previous research has focused on developing more complex surface
textures; only few have address the key challenge of robust hydrophobic
materials.
1
Hydrophobicity applications
Steam turbines:
reducing moisture-
induced efficiency
losses
Condensers:
increasing heat transfer by
promoting dropwise
condensation
Aircrafts & wind turbines:
preventing ice formation
and degradation due to
erosion
Minimizing Food Waste Resisting drop impact
2
Lack of robust hydrophobic materials
Although durable materials such as metals and ceramics, which are generally
hydrophilic, can be rendered hydrophobic by polymeric modifiers, these
deteriorate in harsh environments.
1 mm
3
Can we find a material that is both robust
and intrinsically hydrophobic and derive
viable applications for hydropower?
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Hydrophobic Rare Earth Oxides
5
Adhesion Layer for Improving Longevity
6
With Adhesion LayerWithout Adhesion Layer
Problem with Typical Coatings
7
Longevity of Rare-earth Oxide Coatings
8
Applications to Hydropower
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Anti-Biofouling
Anti-Corrosion/ErosionScale Resistance
Drag Reduction
Conclusions and Recommendations
• Hydrophobic rare-earth oxide coatings present an attractive
multi-dimensional array of enhancements for the hydropower
industry
• These benefits include: bio-fouling resistance, drag reduction,
corrosion and erosion resistance, and overall, a reliable, long-
term form of protection
• Further research to evaluate the long-term capital and
operating costs and justify benefits for a typical plant, as well
as prove longevity and versatility of applications
• These coatings can be retrofitted in existing systems or
applied in new plants, and should be considered by
hydropower facilities in the overall scheme of infrastructure
modernization.
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Robustness: Abrasive Wear Resistance
5 mm
Sustained hydrophobicity after abrasive wear
Robustness: Thermal Stability
2 mm
2 mm
Sustained hydrophobicity after high temperature exposure
Hydrophobicity applications
Steam turbines:
reducing moisture-
induced efficiency
losses
Condensers:
increasing heat transfer by
promoting dropwise
condensation
Aircrafts & wind turbines:
preventing ice formation
and degradation due to
erosion
Minimizing Food Waste Resisting drop impact
15
