Low Friction and Wear of Elastomers by DLC Coating

Sealing rubber components suffer from high friction and wear causing leakage of lubricants. Leakages by formation of flaws lead to loss of energy and pollution. Amorphous carbon (diamond-like carbon, DLC) coatings combine their higher hardness with the high flexibility of the elastomeric substrate, also called rubber, to achieve low friction and low wear. Different coating properties were regarded by varying the deposition parameters in the PECVD process. The hardness and thickness were measured in order to carve out the best match to the preassigned requirements for a durable coating. Eleven elastomers from three rubber types (EPDM, FKM and NBR), exhibiting the same value of hardness (75 Shore A), were coated. Dry friction tests with the uncoated and coated elastomers were execut ed in order to determine the coefficient of friction (COF) and examine the wear resistance of the material. The investigations prove a considerably low coefficient of friction of all three rubber types by using DLC coatings compared to the uncoated variants (µuncoated = 1.2 to µDLC = 0.2). The promising results drive the development of customized coatings for various materials used as seals and need to be protected against frictional damages.