Vapor phase silica can adsorb and fix the base oil in the framework to form grease with stable structure.
As a kind of inorganic thickener, vapor silica does not melt itself, and the grease prepared has high drop point, good lubrication performance and oxidation stability at high temperature. Because of its large specific surface area and strong thickening ability, it is an ideal thickener for producing high temperature greases.
Gaseous silica exhibits excellent rheological behavior. When dispersed in a non-polar liquid, silanol groups on the surface of different particles interact with each other to form Bridges through hydrogen bonds. This three-dimensional structure structure produces a thickening effect.
When a system is subjected to a mechanical force, such as agitation or shaking, the structure is damaged. The type and duration of the mechanical force acting determine the extent of the damage. The result is that the thickened system becomes liquid again. If left in a static state, the vapor phase silica particles will reconnect to restore their original viscosity.
This phenomenon is called pseudoplasticity.
The experimental results show that the gas phase silica thickened with methyl silicone oil has good water resistance, while the grease prepared with its thickened mineral oil has poor water resistance.
Silica is used directly as a lubricant additive
Because of its large specific surface area, high diffusivity, difficulty in sintering, and low melting point, the vapor phase silica can not only form a shear film on the friction surface and reduce the friction coefficient, but also fill and repair the friction surface to a certain extent and play an anti-wear role as a direct additive.
The experimental results show that the water resistance of grease prepared by thickening of surface modified nano silica is improved.