Tribological Characteristics Of Ti₃SiC₂-Class Material

The tribological characteristics of Ti₃SiC₂-class ceramic and its composite material have been researched in this thesis. The stability of friction and its effect to current-carrying friction and wear have also been investigated. We have investigated the friction and wear characteristics of Ti₃AlC₂ ceramic bulk preliminary in the case of low speed and lubricated. The following are some results of research.1) The friction coefficient and wear rate of Ti₃SiC₂ and Ti₃AlC₂ ceramic increase in the case of current-carrying compared with non-current carrying , and the stronger the current intensity is , the more notable the amplitude is. On one hand, the friction coefficient and the wear rate decrease as the normal pressure increases. On the other hand, the friction coefficient increases as sliding speed increases, and the wear rate has the opposite intend. The increase of the friction coefficient is related to the hard crystal phase's generating (such as TiC ) on the surface of the wear, while the increase of the wear rate is attributed dominantly to the ablation of micro-arc, interaction of mechanical friction and couplings of thermal-dynamical.2) The composite material of 50Cu/Ti₃AlC₂ shows excellent current-carrying tribological characteristics against silver-copper alloy in the case of current-carrying. This is mainly related to Cu(Al) alloy layer which has network structure and serves as conducting channel in the composite material. The friction coefficient of 50Cu/Ti₃AlC₂ has little fluctuation as current intensity and sliding speed change, but the wear rate increase obviously as current intensity and sliding speed increase. This is related primarily to strong ablation of micro-arc caused by large current intensity and sliding speed.3) The friction coefficient of Ti₃SiC₂-class material displays fluctuate character randomly in the whole experimental process and the fluctuating behavior of relative stabilization period obeys normal distribute. The friction of material is more stable as the normal pressure increases and be more unstable as the sliding speed increases. The strong stability can restrain the producing of micro-arc effectively in the process of current-carrying friction and reduce the wear rate of material in general. The weak stability results in more effect of the ablation of micro-arc on the wear surface which produces in the friction, and in the meantime, it also increases the wear rate of material in general. 4) The friction coefficient of Ti₃AlC₂ ceramic bulk in the case of low speed and oil lubricated has one less magnitude than it in the dry sliding state and the wear rate has almost four less magnitudes. It results from the formation of lubricant film under lubricated state which changes the friction and wear state between friction couple, and the direct contact between minor particles in the process of friction has become the contact between lubricating oil molecules, therefore, it's difficulty to break the minor particles and the abrasive wear which emerging under low speed and dry sliding conditions has disappeared, so the friction coefficient and the wear rate reduce greatly.