Synergistic lubrication of Ag and Ag2MoO4 nanoparticles anchored in plasma-sprayed YSZ coatings: Remarkably-durable lubricating performance at 800 °C

Abstract

The high-temperature tribological properties of plasma-sprayed YSZ coatings are enormously weakened by intrinsic cracks and pores, brittleness and lubrication deficiency. Therefore, we are attempting to employ Ag and Ag2MoO4 nanoparticles together, as high-temperature lubricant additives, to chemically modify YSZ coatings. With aid of vacuum impregnation and hydrothermal reaction, Ag and Ag2MoO4 nanoparticles were first anchored in the defects of YSZ coatings. The two nanoparticles dramatically reduced the coefficients of friction and wear rates of YSZ coatings under ultrahigh peak Hertzian contact stress at 800 °C, endowing YSZ coatings with an extremely long lifetime and bringing negligible wear damage to the friction pair. It is liquid lubrication and the formation of stable tribofilm that jointly contribute to the remarkably-durable lubricating performance.