Effect of surface wettability of TiO2 particles on evaporation enhancement of silicone oil in the bulk of electrorheological suspensions

Hydrophilic, oleophilic and raw TiO2 particles are dispered respectively in silicone oil to form electrorheological suspensions and the effect of surface wettability of TiO2 particles on evaporation enhancement of silicone oil is studied. The results show that the evaporation rate of silicone oil increases with the decrease of surface wettability of the particle and the increase of the depth of suspension which indicates that the evaporation mainly occurs in the bulk. The observed phenomena have been explained mainly on the basis of heterogeneous nucleation theory of bubbles. In the bulk of suspensions, the less wettable surface of nanoparticles, the less critical activation energy needed for bubble nucleation, the easier it is to form bubbles which is the origin of the evaporation.