Identification and evaluation of wear phenomena under electric current by using an acoustic emission technique

The use of acoustic emissions to evaluate the tribological characteristics of the collector friction system of an electric railway was investigated. Both mechanical wear and wear by arc discharge and melting occur at the sliding interface. When friction and wear experiments were performed with a pin-on-disk-type sliding-friction tester with an electric current flowing between the specimens, an analysis of the frequency of the resulting AE signal showed that each phenomenon produced a distinct AE frequency spectrum. The tribological characteristics of the materials in the presence of an electric current can therefore be evaluated from features of the AE frequency spectrum. •Electrical damage can be detected by acoustic emission monitoring.•Acoustic emission signals at 0.5–1.5 MHz correspond to arc discharge.•Acoustic emission signals at 0–0.5 MHz correspond to melting.•Electrical wear modes can be determined from the frequency spectra of AE signals.•Tribological characteristics of working electric conductors can be evaluated.