The effect of heat-treatment of silica gel at high temperature

Electrorheological Response and Structure Growth of Colloidal Silica Suspensions

“…Water content in the particles was adjusted to 4.5 wt% by means of a vacuum drying treatment and measured by thermogravimetric analysis (21)(22)(23). Silicone oil (TSF451-200) with a Newtonian viscosity of 0.149 Pa · s and a density of 969 kg/m 3 was obtained from Toshiba Silicone Company, Ltd. and used as received.…”

“…It is believed that aggregation of particles between electrodes plays an important role in electrorheological behavior (15)(16)(17)(18)(19)(20). Since electric properties of suspensions depend on aggregative structures of particles (21)(22)(23), it is desirable for quantitative understanding to perform in situ measurements of the shear stress and the electric properties.…”

Microstructure and transmittance of silica gels for application as transparent heat insulation materials

“…In this context, the neck formation is amplified between particles, thus increasing the average pore size, decreasing the BET surface, and increasing the matrix strength [32]. Kondo et al [33] pointed out that temperatures higher than 700°C lead to intense decreased surface areas of silica gels. By these facts it can be assumed that densification processes, ripening at high temperatures, and coarsening are promoted extensively in the case of a treatment at 900°C, which led to the lowest porosity.…”

Correlation between Generated Shear Stress and Generated Permittivity for the Electrorheological Response of Colloidal Silica Suspensions

“…The water content of the particles was measured by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The weight loss of silica particles in the range of ambient temperature up to 200°C is primarily attributed to the desorption of adsorbed water, while the weight loss in the range 200 -1000°C is attributed to the dehydroxylation of silanol groups (27)(28)(29). The water content in Table 1 presents the weight loss in the temperature range up to 200°C.…”

“…Supermicrometer-sized particles with an average diameter of 75 m were obtained from Kanto Chemical Co., Inc. (Silicagel 60N). Since it has been reported (27)(28)(29) that adsorbed water in silica particles affects electrorheology, the amount of adsorbed water was regulated by means of a vacuum drying treatment (130 -200°C, 1-20 h). The water content of the particles was measured by thermogravimetric analysis (TGA) and differential thermal analysis (DTA).…”