Detection of Solid Lubricant Film Failure During Sliding by Vibration Monitoring

摘要

Pin-on-disk friction tests were carried out to examined the feasibility ofacceleration vibration monitoring for detection of solid lubricant film failure during sliding. MoS2 sputtered film on a steel disk and on a Si3N4 disk, and MoS2 bonded film on a steel disk were rubbed against a 440C steel ball. From the measured acceleration vibration signal, kurtosis of amplitude distribution and rms were calculated, and frequency analysis was made. A partial failure of sputtered MoS2 film can be clearly detected by the increase in kurtosis. A high value of kurtosis is due to an impulse-like shock imposed by a pin/substrate contact. At the same time, the rms, the component of natural frequency of pin bending mode and the component of disk rotating frequency of envelope detected signal also increased. The changes were small, indicating that these parameters were not relevant to detection of partial film failure. However, a marked increase of these parameters was observed as film failure progressed. These parameters are effective for detection of complete film failure. For MoS2 bonded film, many small metal contacts were observed from the initial stage of the test. The wear process seems to be different with bonded MoS2 film. The appearance of a vibration wave was also different from that of a sputtered film; more continuous shocks seem to excite the arm. This leads to a lower value of kurtosis, thus resulting in effectiveness of kurtosis. However, the film failure can be detected by monitoring the rms value.