The Effect of Various Stoichiometric Strontium Aluminates on the High-Temperature Tribological Properties of NiCr-Al2O3 Composites

The effect of multiple stoichiometric strontium aluminates (Sr4Al14O25, SrAl12O19, and Sr4Al2O7) on the tribological properties of NiCr-Al2O3 composites was investigated between room temperature and 800 °C. The results indicated that the synergistic interaction of multiple stoichiometric strontium aluminates played an important role in the improvement in the friction and wear performance at elevated temperatures. Satisfactory tribological properties were observed for the synergistic lubricating film consisting of Sr4Al14O25, SrAl12O19, and oxides (NiO, Cr2O3, and NiCr2O4) on the worn surface above 600 °C, compared to those for the tribofilm containing Sr4Al14O25, SrAl12O19, Sr4Al2O7, SrCrO4, and oxides. Furthermore, the low friction coefficient and wear rate were attributed to the formation of Sr4Al14O25, Sr4Al2O7, SrCrO4, and oxides on the rubbing surface at 800 °C.