Tribological behavior of Ti3SiC2 and Ti3SiC2/Pb composites sliding against Ni-based alloys at elevated temperatures

The Ti3SiC2 and Ti3SiC2/Pb composites were tested under dry sliding conditions against Ni-based alloys (Inconel 718) at elevated temperatures up to 800 °C using a pin-on-disk tribometer. Detailed tribo-chemical changes of Pb on sliding surface were discussed. It was found that the tribological behavior were insensitive to the temperature from 25 °C (RT) to 600 °C (friction coefficient ≈0.61-0.72, wear rate ≈10−3 mm3 N m−1). An amount of Pb in the composites played a key role in lubricating with the temperature below 800 °C. The friction coefficient (≈0.22) and wear rate (≈10−7 mm3 N m−1) at elevated temperatures were both decreased by the added PbO. The wear mechanisms of Ti3SiC2/Pb-Inconel 718 tribo-pair at elevated temperatures were believed to be the combined effect of abrasive wear and tribo-oxidation wear. During the sliding, two oxidization reactions proceed, 2Pb+O2=2PbO (below 600 °C) and 6PbO+O2=2Pb3O4 (800 °C). The friction coefficient and wear rate of the composites were reduced due to the self-lubricating effect of the tribo-oxidation products.