Friction of undulated surfaces coated with MoS2 by pulsed laser deposition

Solid lubricants such as molybdenum disulfide can provide very low friction , but their effectiveness especially in the geometrically constrained slidi ng pairs is limited by plowing of coated surfaces by wear particles. Even i n the presence of solid lubricants wear particles cause higher friction by plowing the interface. To minimize plowing undulated surfaces with microgro oves perpendicular to the sliding direction can be used to trap wear partic les. Smooth and undulated stainless steel surfaces were coated with molybde num disulfide by pulsed laser deposition (PLD) and friction tested. Under i dentical test conditions, the friction coefficient of coated undulated surf aces is between 20-40 percent lower than that of coated smooth surfaces. Th e friction coefficient of undulated uncoated surfaces is about 100-350 perc ent less than that of smooth uncoated surfaces. Moreover the entrapment of wear particles at the interfaces of geometrically constrained bearings may lend to seizure even when bearing surfaces are coated with solid lubricants . The use of undulated surfaces on these sliding systems has shown improved operating time and a reduced maintenance cycle.