Contact angle Young

Then, the Young contact angle is calculated combining equation (3.21) and the equation of Wenzel, yielding ... 

When the optimal conditions are satisfied, i.e., a well-controlled atmosphere, a pure, homogeneous and smooth solid surface and an accurate measurement system, the Young contact angle and the liquid surface energy can be derived with an accuracy of 3 deg and 2% respectively allowing the work of adhesion (Wa = [Pg.144]

In principle, the Young contact angle can be measured only for a metal presaturated with C. In practice, two major difficulties exist first, the high roughness and porosity of polycrystalline graphite, second, the difficulty of performing standard sessile drop experiments with metals fully presaturated in C (Hara et al. 1995). This second difficulty arises because substantial dissolution of... 

From the Young contact angle the surface tension is assessed, using Eq. (1) and a correlation for interfacial tensions, such as given by Eq. (2) some correlations require repetition of the process with a few different liquids in order to be able to assess the surface tension. 

The Young contact angle is the starting point for any design. 

If surface roughness is the primary cause of hysteresis, it may be impossible to obtain Young contact angles. In such cases, the advancing contact angle is influenced more by the microscopic geometry than it is by interfacial energetics. 

The other major application of contact angles is the characterization of real surfaces as they are received or manufactured. These may not be Young contact angles and may therefore not be thermodynamically significant. Nevertheless, they can serve to assess solid surfaces qualitatively and detect relatively gross changes in surface energy. 

R. Tadmor, Line Energy and the Relation between Advancing, Receding, and Young Contact Angles, Langmuir, 2004, 20, 7659-7664. 

Presenting the data in a cosine-cosine plot facilitates comparison with the Wenzel predictions (area E), a Unear function of surface energy (cosine of Young contact angle) with the roughness factor as slope and axis intercept of zero. 

A liquid is not completely wetting the solid that was equilibrated with the liquid vapor, and a dynamic contact angle 9, which is not the Young contact angle on a flat solid [132], appears at the liquid penetration front and AG = yiv cos 9. 

R. Tadmor, "Line energy and the relation between advancing, receding, and Young contact angles," Langmuir, vol. 20, pp. 7659-7664, 2004. 

---