The thermal conductivity of silica is 0.27W/cm · K
Fumed silica is a nanoscale white powder produced by the high-temperature hydrolysis of silicon halides in a hydrogen oxygen flame, commonly known as gas phase silica. It is an amorphous silica product with a primary particle size between 7-40nm and an aggregate particle size of approximately 200-500 nanometers. The specific surface area is 100-400m2/g, and the purity is high. The SiO2 content is not less than 99.8%. The untreated gas-phase silica aggregates on the surface contain various silicon hydroxyl groups.
One is isolated and undisturbed free hydroxyl groups; The second is the bonding of silicon hydroxyl groups that are connected and form hydrogen bonds with each other. The untreated gas-phase white carbon black aggregates on the surface are aggregates containing multiple - OH groups, which easily form a uniform three-dimensional network structure (hydrogen bonding) in liquid systems. This three-dimensional network structure (hydrogen bond) will be broken when subjected to external forces (such as shear force, electric field force, etc.), causing the medium to become thinner and viscosity to decrease. Once the external force disappears, the three-dimensional structure (hydrogen bond) will recover on its own and viscosity will increase, indicating that this thixotropy is reversible.