Tribological properties of NiCr-Al2O3 cermet-based composites with addition of multiple-lubricants at elevated temperatures

The tribological properties of NiCr-40 wt% Al2O3 (NC40A) cermet-based composites containing SrSO4 and other lubricant (graphite, MoS2 and Ag) against alumina ball were evaluated to identify their self-lubrication mechanisms from room temperature to 800 °C. The composites demonstrated distinct improvements in effectively reducing friction and wear, as compared to NC40A cermet. The best results were observed for NC40A-10SrSO4-10Ag composite, which exhibited satisfactory reproducibility of friction coefficient over a wide temperature range (200-800 °C) through high temperature cyclic friction tests due to the formation of synergistic lubricating films SrAl4O7, NiCr2O4 and Ag on the contact surface.