Wear life mechanism of journal bearings with bonded MoS2 film lubricants in air and vacuum

Friction and wear life tests on the oscillation motion of journal bearings with bonded MoS2 film lubricants on both the shafts and bearing bushes were carried out in air and in vacuum. The film partially debonded from the near substrate rather than wore out when the lives of the bearings ended. The wear lives in vacuum were several tens of times longer than those in air, and the friction coefficient in vacuum was about a quarter of that in air. By calculating shear stresses at the interfaces of the films and substrates, considering friction, wear lives in air and in vacuum could be plotted on a unified S–N curve. This means that the fatigue debonding of the film is a predominant mechanism, irrespective of the atmosphere, and the difference in the wear lives with respect to the atmosphere is attributed to the difference in the friction magnitude.