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Cohesion, along with adhesion (attraction between unlike molecules), helps explain phenomena such as meniscus, surface tension and capillary action. Mercury in a glass flask is a good example of the effects of the ratio between cohesive and adhesive forces.
The contact angle of the three-phase system is a function not only of dispersive adhesion (interaction between the molecules in the liquid and the molecules in the solid) but also cohesion (interaction between the liquid molecules themselves). Strong adhesion and weak cohesion results in a high degree of wetting, a lyophilic condition with low ...
The balance between the cohesion of the liquid and its adhesion to the material of the container determines the degree of wetting, the contact angle, and the shape of meniscus. When cohesion dominates (specifically, adhesion energy is less than half of cohesion energy) the wetting is low and the meniscus is convex at a vertical wall (as for ...
The van der Waals force of adhesion is also dependent on the surface topography. If there are surface asperities, or protuberances, that result in a greater total area of contact between two particles or between a particle and a wall, this increases the van der Waals force of attraction as well as the tendency for mechanical interlocking.
Liquid oxygen has a clear cyan color and is strongly paramagnetic: it can be suspended between the poles of a powerful horseshoe magnet. [2] Liquid oxygen has a density of 1.141 kg/L (1.141 g/ml), slightly denser than liquid water, and is cryogenic with a freezing point of 54.36 K (−218.79 °C; −361.82 °F) and a boiling point of 90.19 K (−182.96 °C; −297.33 °F) at 1 bar (14.5 psi).
The contact angle (θ), as seen in Figure 1, is the angle at which the liquid–vapor interface meets the solid–liquid interface, and is determined by the balance between adhesive and cohesive forces. As the tendency of a drop to spread out over a flat, solid surface increases, the contact angle decreases.
The advancing contact angle can be described as a measure of the liquid-solid cohesion while the receding contact angle is a measure of liquid-solid adhesion. The advancing and receding contact angles can be measured directly using different methods and can also be calculated from other wetting measurements such as force tensiometry (aka ...
Many mechanics theories exist on this topic. The majority of them attribute the increase in adhesion strength to the greater thermodynamic stability of the impurity element bonded with oxygen than the metal bonded to the oxygen. [2] [8] Inserting yttrium into nickel alloys to strengthen the oxide adhesion is an example of the reactive element ...