Microstructure and tribological properties of Fe-Cr matrix self-lubricating composites against Si3N4 at high temperature

A series of Fe-Cr matrix high temperature self-lubricating composites were prepared by powder metallurgy technique (PM). The tribological properties of composites sliding against ceramic Si3N4 ball were studied by using a ball-on-disc high-temperature tribometer at 10 N and 0.19 m/s for 20 min from room temperature to 800 °C. Mo element showed an obvious solid solution strengthening effect on the matrix, and formed the high temperature solid lubricant BaMoO4. The obtained results showed that the tribological properties of specimens greatly depended on the additives. Generally speaking, the specimen containing 8.0 wt.% BaF2, 10.0 wt.% Ag and 8.5 wt.% Mo kept the lowest friction coefficient (0.4) and specific wear rate (1.8-3.7 × 10−4 mm3 N−1 m−1) from room temperature to 800 °C. The high-temperature tribological properties of Fe-Cr based alloy were improved due to the addition of additives. The excellent tribological behavior of specimen was attributed to the synergetic action of solid lubricants and high hardness. The wear mechanism of specimen FM is ploughing and slightly delamination at room temperature and 400 °C. At 800 °C, the specimen FM shows the micro-ploughing characteristics.