Ultraphobic surface for high pressure liquids

A process of making an ultraphobic surface adapted for repelling a liquid at a pressure of at least one atmosphere in contact with the surface, the process comprising:

• providing a substrate having an outer surface;
• and
• forming a multiplicity of substantially uniformly shaped asperities on the outer surface of the substrate, each asperity having a common asperity rise angle relative to the substrate portion, the asperities positioned so that the surface has a contact line density measured in meters of contact line per square meter of surface area equal to or greater than a contact line density value “ΛL” determined according to the formula:
• Λ
• L
• =
• -
• 10
• ⁢
• ,
• ⁢
• 330
• γcos
• ⁡
• (
• θ
• a
• ,
• 0
• +
• ω
• -
• 90
• ⁢
• °
• )
• where γ is the surface tension of the liquid in Newtons per meter, is the experimentally measured true advancing contact angle of the liquid on the asperity material in degrees, and ω is the asperity rise angle in degrees.

A process for producing a surface having ultraphobic properties at liquid pressures up to a predetermined pressure value, the process comprising:

• selecting an asperity rise angle;
• determining a critical contact line density “ΛL” value according to the formula:
• Λ
• L
• =
• -
• P
• γcos
• ⁡
• (
• θ
• a
• ,
• 0
• +
• ω
• -
• 90
• ⁢
• °
• )
• where P is the predetermined pressure value, γ is the surface tension of the liquid, θa,0 is the experimentally measured true advancing contact angle of the liquid on the asperity material in degrees, and ω is the asperity rise angle;
• providing a substrate member;
• and
• forming a multiplicity of projecting asperities on the substrate so that the surface has an actual contact line density equal to or greater than the critical contact line density.