Silicone fluid is a kind of polyorganosiloxane with chain structure with different degree of polymerization. It is made from: dimethyl dichlorosilane is hydrolyzed to produce the primary polycondensation ring which is cracked and rectification to produce the low ring body. Then the ring body, the head sealing agent and the catalyst are put together to polymerize to get all kinds of different degree of polymerization of the mixture, through vacuum distillation to remove the low boiling matter can produce silicone fluid.

Silicone fluid has the following characteristics: excellent heat resistance, electrical insulation, weather resistance, hydrophobic, physiological inertia and small surface tension. In addition, it is of low viscosity-temperature coefficient and high compressibility. Some varieties also have the characteristics of radiation resistance, non-corrosiveness to metal, nontoxicity and so on.

The function of silicone fluid: commonly used as senior lubricants, shock oil, insulation oil, defoaming agent, demoulding agent, polishing agent and vacuum diffusion pump oil. Among all kinds of silicone fluids, methyl silicone fluid is the most widely used and the most important one. The second is methylphenyl silicone fluid. In addition, there are ethyl silicone fluid, methyl phenyl silicone fluid, silicone fluid containing nitrile, etc. Various functional silicone fluids and modified silicone fluids are mainly used for special purposes.

Disadvantages of silicone fluid:

1. Small surface tension (easy to leak from the machine).
2. High gas solubility (it is difficult to design gas seal device).
3. High thermal expansion coefficient of silicone fluid (possible overpressure problem).
4. Poor lubricity of silicon oil, especially poor lubricity of steel friction pair.
5. Certain hygroscopicity (when the water content is higher than 100 10-6, the electrical performance drops sharply)