Friction behaviours of molybdenum-based coatings under fretting condition

This paper investigates friction coefficient behaviour of molybdenum-based coatings under fretting conditions. Fretting wear tests are performed under experimental conditions similar to those found at dovetail connections of an aero-engine. One specimen and two flat-and-rounded pads are used for each fretting wear test. Specimens are coated with Mo-MoS2 or Mo-N coatings, while fretting pads are coated with MoS2 particles. Friction coefficient values are measured during fretting wear tests and are directly compared with each other. It is identified that Mo-N coatings maintain better anti-fretting performance than Mo-MoS2 coatings. Results also show that a notable difference exists between friction coefficient evolutions of coatings. The friction coefficient value of Mo-MoS2 coating increases almost linearly, while that of Mo-N coating increases rapidly after short decrease following an initial running-in period. Finally, friction coefficient evolutions are expressed as a linear or an exponential form.