The “weak” friction-induced vibration can help to monitor the change in friction and wear state of friction pairs and detect the failure of surface damage. However, they are typically submerged in complex interference components during friction. Therefore, detecting accurate “weak” friction-induced vibration is key to using it entirely. A method based on the correlation between friction-induced vibration and sound signals was proposed to achieve this goal. The ball–disk wear experiments were conducted under oil lubrication using a wear tester. Vibration and sound pressure signals generated during the experiments were recorded. By the spectrum analysis of the cross-correlation function calculated from the two types of signals, the “weak” FIV components submerged in the original signals were detected. The experimental results showed that the root mean square change of the “weak” friction-induced vibration detected in the vibration and sound pressure signals was highly consistent with the friction coefficient change. It could effectively characterize the transition of the wear stage from running-in to stable wear of the friction pairs. Therefore, the cross-correlation analysis of vibration and sound signals could be a reliable tool for detecting the “weak” friction-induced vibration.

The triboelectrification phenomenon can occur during the friction process of metal contact pairs. An in-depth understanding of triboelectrification behaviour is incredibly beneficial to controlling friction and wear. However, due to the complexity of the driving mechanism, it is still challenging to gain a thorough understanding of the triboelectrification behaviour of metal–metal contact pairs. To further reveal the triboelectrification behaviour during the friction process of metal pairs, wear experiments of GCr15 steel–cast iron were carried out on a CFT-I tribometer under oil-free and oil lubrication conditions. The triboelectric current signal was collected during the investigation, and its variation was discussed. The result shows that the varying trend of the triboelectric current was consistent with that of the friction coefficient in the friction process. The triboelectrification of similar metal contact pairs primarily driven by material transfer was closely related to friction and wear conditions.