Hysteresis in porosimetry

On a smooth surface of SiO₂ in air, hysteresis of the wetting angel of mercury was found. In an evacuated system of controlled pore glass this hysteresis is even greater and is the cause of volume hysteresis in mercury intrusion porosimetry. Pores with diverging radius along their length also cause volume hysteresis. In this case the slope of the walls in the conical parts of the pore is of great importance. This is illustrated for selected models. The procedure for the evaluation of the volume of ink-bottle pores, previously suggested in the literature, cannot be considered a correct, therefore. The values of the surface tension of mercury, λ_L, of the advancing wetting angle θ_A, and of the receding angle, θ_R, depend on the radii of the pores. Their values have been evaluated. Under the condition of mercury extrusion the line tension τ plays a role: its value, τ = 236 × 10^?9 mN, has been determined.