Tribological properties of self-lubricating NiAl/Mo-based composites containing AgVO3 nanowires

Abstract

Silver vanadate (AgVO3) nanowires were synthesized by hydrothermal method and self-lubricating NiAl/Mo-AgVO3 composites were fabricated by powder metallurgy technique. The composition and microstructure of NiAl/Mo-based composites were characterized and the tribological properties were investigated from room temperature to 900°C. The results showed that NiAl/Mo-based composites were consisted of nanocrystalline B2 ordered NiAl matrix, Al2O3, Mo2C, metallic Ag and vanadium oxide phase. The appearance of metallic Ag and vanadium oxide phase can be attributed to the decomposition of AgVO3 during sintering. Wear testing results confirmed that NiAl/Mo-based composites have excellent tribological properties over a wide temperature range. For example, the friction coefficient and wear rate of NiAl/Mo-based composites containing AgVO3 were significantly lower than the composites containing only metallic Mo or AgVO3 lubricant when the temperature is above 300°C, which can be attributed to the synergistic lubricating action of metallic Mo and AgVO3 lubricants. Furthermore, Raman results indicated that the composition on the worn surface of NiAl-based composites was self-adjusted after wear testing at different temperatures. For example, Ag3VO4 and Fe3O4 lubricants were responsible for the improvement of tribological properties at 500°C, AgVO3, Ag3VO4 and molybdate for 700°C, and AgVO3 and molybdate for 900°C of NiAl-based composites with the addition of metallic Mo and AgVO3.