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This is often the case for water on bare metallic or ceramic surfaces, [15] although the presence of an oxide layer or contaminants on the solid surface can significantly increase the contact angle. Generally, if the water contact angle is smaller than 90°, the solid surface is considered hydrophilic [16] and if the water contact angle is ...
γ ls is the liquid–solid surface tension, γ la is the liquid–air surface tension, γ sa is the solid–air surface tension, θ is the contact angle, where a concave meniscus has contact angle less than 90° and a convex meniscus has contact angle of greater than 90°. [8]
The solid angle of a sphere measured from any point in its interior is 4 π sr. The solid angle subtended at the center of a cube by one of its faces is one-sixth of that, or 2 π /3 sr. The solid angle subtended at the corner of a cube (an octant) or spanned by a spherical octant is π /2 sr, one-eight of the solid angle of a sphere. [1]
Figure 1: Contact angle for a liquid droplet on a solid surface. In other words, only one thermodynamically stable contact angle exists. When a drop of liquid is placed on such a surface, the characteristic contact angle is formed as depicted in Fig. 1. Furthermore, on an ideal surface, the drop will return to its original shape if it is ...
If water has a contact angle between < <, then the surface is classed as hydrophilic, whereas a surface producing a contact angle between < < is hydrophobic. In the special cases where the Contact angle is 150 ∘ < θ {\displaystyle 150^{\circ }<\theta } , then it is known as superhydrophobic.
Surface tension prevents the clip from submerging and the water from overflowing the glass edges. Temperature dependence of the surface tension of pure water. Water has an unusually high surface tension of 71.99 mN/m at 25 °C [64] which is caused by the strength of the hydrogen bonding between water molecules. [65] This allows insects to walk ...
In 1805, Thomas Young defined the contact angle θ by analyzing the forces acting on a fluid droplet resting on a solid surface surrounded by a gas. [8] A liquid droplet rests on a solid surface and is surrounded by gas. The contact angle, θ C, is the angle formed by a liquid at the three-phase boundary where the liquid, gas, and solid intersect.
To determine how well a liquid wets a solid surface is proportional to the contact angle from the liquid while on the solid. This is determined by the respective surface tensions of the solid and liquid. William Zisman's contribution to adhesives in the way of his Zisman Plot, which has a variation today that graphs 1-cos(θ SL) vs γ L. In ...