Silicone grease

Silicone grease is a waterproof grease made by combining a silicone oil with a thickener. Most commonly, the silicone oil is polydimethylsiloxane and the thickener is amorphous fumed silica. Using this formulation, silicone grease is a translucent white viscous paste, with exact properties dependent on the type and proportion of the components.

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Use in industry

Silicone grease is commonly used for lubricating and preserving rubber parts, such as O-rings. Additionally, silicone grease does not swell or soften the rubber, which can be a problem with hydrocarbon based greases. It functions well as a corrosion-inhibitor and lubricant for purposes that require a thicker lubricant, such as the operating mechanism of the M1 Garand rifle.

The most common use of it is an elastic heat transfer coupling material between semiconductor circuit elements and attached cooling metal parts. This way thermal resistance of touching surfaces is typically lowered by 50 percent.^{[citation needed]} The high thermal stability is the key property that allows these greases to operate on hot, cold and wet surfaces of peltier elements.

Silicone grease is also used widely by the plumbing industry in faucets and seals, as well as dental equipment. Electrical utilities use silicone grease to lube separable elbows on lines which must endure high temperatures. Silicone greases generally have a temperature range of -40 to 400 °C.

Use in the chemical laboratory

Silicone grease is widely used as a temporary sealant and a lubricant for interconnecting ground glass joints, as is typically used in the chemical laboratory. Although silocones are normally assumed to be chemically inert, several historically significant compounds have been prepared by unintended reactions. For example, the first salt of the crown ether (OSi(CH₃)₂)_n (n = 6, 7) were prepared by reactions resulting from contacting organolithium and organopotassium compounds with silicone greases.^[1]

References

1. ^ Jamie S. Ritch and Tristram Chivers (2007). "Silicon Analogues of Crown Ethers and Cryptands: A New Chapter in Host–Guest Chemistry?". Angewandte Chemie International Edition 46: 4610 – 4613. doi:10.1002/anie.200701822.