Читать книгу The Rheology Handbook - Thomas Mezger - Страница 106

1 for τ0 = 200 Pa and ρ = 2.0 g/cm3 = 2000 kg/m3, results: a = 10 mmfor τ0 = 3 Pa and ρ = 1.0 g/cm3 = 1000 kg/m3, results: a = 0.3 mm

Comment: The obtained values should only be seen as a rough estimation since other factors, such as roughness of the wall, more or less (in-)homogeneous sagging behavior, and surface tension of the coating additionally may have a crucial effect on the result. If the value of the yield point is determined according to Chapter 3.3.4.1, the restrictions should also be taken into consideration as discussed in that section. However, the thickness of the wet layer also depends strongly on its time-dependent behavior during structural regeneration directly after the shear-intensive application (thixotropic behavior). In order to obtain useful results for R & D it is recommended to evaluate leveling and sagging behavior as explained in Chapter 3.4.2.2 (and Table 3.3), or even better as shown in Chapter 8.5.2.2 (and Table 8.4).

End of the Cleverly section

Figure 3.23: Volume element of a coating layer on a wall, with weight FG , wet layer thickness a, layer width b and layer length c