Investigations On Non-Current And Current-Carrying Tribological Behaviors Of Ti₃SiC₂ And Ti₃AlC₂ Ceramics

According to the background of the conductive Ti₃SiC₂-class ceramics applying in the current collector material sliding against the contact wire of high sliding-speed railway, the material Ti₃SiC₂ and Ti₃AlC₂ were basically investigated on their non-current and current-carrying tribological behaviors. The research work in this thesis mainly involved the following aspects: Friction and wear behaviors of the Ti₃SiC₂ and Ti₃AlC₂ materials sliding against low-carbon steels under the situations of non-current and current-carrying conditions were analysed by means of a series of friction tests, the effect factors such as normal pressure and sliding speed were discussed on the friction coefficient and wear rate, then the form of the oxide layer and its self-lubrication were probed into consequently, and last, it gave a scientific description to the effect of current intensity on the friction and wear rate.The research showed that, the material Ti₃SiC₂ and Ti₃AlC₂ exhibited good friction and wear characteristics. The friction coefficient decreased with the increase of the normal pressure and sliding speed irrespective of the current exist or not.To the wear rate,it increased with the increase of sliding speed, but it revealed different tendency with the increase of normal pressure under the circumstance of with and without current. The self-generating oxide layer in the friction surface of Ti₃SiC₂ and Ti₃AlC₂ were in a fused state in the process of the friction behavior, it revealed a good lubricating function, and it was the main factor that the two materials exhibited the low friction and small wear rate. With electric current, the friction coefficient and wear rate were larger than that of without electric current; the effect was more notable with the increase of current density. The result from the observation and analysis showed, the micro-electric-arc and electric heat effect generated between the two sliding surfaces were the main reasons why the friction coefficient and wear rate became larger.