Introduction of Silicone Fluids: Stable, Inert Media

Silicone fluids have unique properties because they are not products of petroleum or organic chemistry. They were the first, and are still the only, major class of polymers that are products of inorganic chemistry. Silicone fluids consist of a broad range of different materials with the following characteristics:

• Wide service temperature range
• Low viscosity changes vs. temperature
• Thermal stability
• Low flammability
• Shear stability
• Dielectric stability
• High compressibility
• Chemical inertness
• Low surface tension
• Low toxicity

These features have facilitated the adoption of silicones as dielectric, hydraulic, heat transfer, power transmission, and damping fluids. They have found applications when incorporated as additives into plastics and rubbers as process and release aids, into coatings for flow and level control, and into process streams as antifoams. Other unique properties have led to their introduction in acoustical applications such as ultrasonic sensors and sonar buoys. Light refractive and index matching properties have allowed the use of silicones in fiber optics and optoelectronics. This proliferation of applications has engendered many improvements and refinements of silicone fluids.

Silicone fluids can be divided into six general classes:

• Conventional fluids
• Thermal fluids
• Organic compatible fluids
• Fluorosilicone fluids
• Hydrophilic fluids
• Low temperature fluids

The conventional fluids, also referred to as polydimethylsiloxanes, exhibit all the properties of the silicone family. The other classes of fluids can be considered modifications of the conventional fluids in which one set of properties has been enhanced, but generally other properties are altered or sacrificed.