Influence of Silicon on the Wear Properties of Amorphous Carbon Under Dry and Lubricated Conditions

Diamond-like carbon (DLC) coatings have drawn much attention as potential surface coatings for engineering contacts because of their excellent friction and wear resistance properties. However, much less is known about their friction and wear mechanisms, especially at higher contact pressures. In this study, two amorphous carbon DLCs, with (a-C:Si) and without Si (a-C), have been investigated to understand the influence of Si on friction and wear under dry, base oil- and fully formulated oil-lubricated conditions. Si does not affect friction but significantly affects wear. a-C:Si shows lower wear than a-C but imparts higher wear on the steel counterpart. The steel counterpart that forms a hybrid tribolayer (transferred carbon from DLC + additive-derived tribofilm products) exhibits superior wear resistance properties.