Time-frequency analysis of the tribological behaviors of Ti6Al4V alloy under a dry sliding condition

Application of titanium and its alloys in the aerospace, biomedical and chemical industry has renewed researchers' interests in their tribological properties. This paper presents a new method for evaluating the kinetic friction and wear performances of Ti6Al4V alloy using a time-frequency approach. The short-time Fourier transform (STFT) was selected to analyze the time-frequency properties of the friction force signals collected in the tribological tests of Ti6Al4V alloy sliding against three different materials. The obtained results showed that the amplitudes of friction force signals were closely related to the differences in wear rates of the tribo-pairs. Furthermore, the frequency amplitudes of the friction force where high energy appeared increased with the sliding time during adhesive wear process and fluctuated significantly during abrasive wear. Meanwhile, the high amplitude at the fundamental frequency of the friction force in STFT indicate the formation of transfer films. To confirm the STFT-based tribological behaviors of Ti6Al4V against different counterbodies in a dry sliding condition, the wear rates and worn surfaces were examined using conventional methods. This study demonstrates that the wear rates and wear mechanisms of the tested samples as well as their changes with time can be identified from the amplitude, distribution and fluctuation of the frequency peaks of the friction force signals. Furthermore, the time-frequency analysis of the friction force is an effective way to study the time-dependent wear process of materials, in particular, changes in the dominant wear mechanism and wear rate.