Functional plasma coating for sealing components

O-rings and other similar sealing components like shaft seals and retaining rings that are made of elastomers like NBR, FKM, FPM, EPDM, Viton, and silicone are used in many automotive applications.

Common uses for these parts include shock absorbers, engines, transmissions, brake systems, air conditioning units, and diesel injection pumps. For optimal performance, these elastomeric parts need to be coated to ensure they will not stick, and to make them resistant to oil and grease.

Fluorine-containing coating with low-pressure plasma

Using a low-pressure plasma process, gasses containing fluorine such as tetrafluoromethane (CF4) and sulfurhexafluoride (SF6) are used to coat components such as O-rings. Under normal conditions, these gases are exceptionally stable and do not react with other materials. However, when exposed to plasma, the fluorine bonds can be broken, creating highly reactive fluorine radicals that provide optimal surface properties. This allows the formation of barrier layers that protect the base material against permeation by fluids such as gasoline while preserving the elastic properties of the O-ring body.

Further examples are PTFE and polysiloxane coatings that reduce friction and sticking.