Friction and wear behavior of the superconducting compound oxide of PbO/YBa₂Cu₃O_7-δ

The superconducting material YBa₂Cu₃O_7-δ samples were prepared by the sol-gel method. The tribological properties were measured on a friction and wear tester from ambient temperature to liquid nitrogen temperature. The results indicate that the friction coefficient of YBa₂Cu₃O_7-δ against steeliness is about 0.5 at ambient temperature and decreases abruptly to half of the normal state value when the temperature is below the superconducting transition temperature of the YBa₂Cu₃O_7-δ. The measurements prove directly the effect of electronic excitation on friction. Moreover，PbO/YBa₂Cu₃O_7-δ composite samples were prepared by sintering YBa₂Cu₃O_7-δ with PbO at different mass fractions to improve the tribological properties of YBa₂Cu₃O_7-δ at room temperature. The experimental results show that the friction coefficient of 15%PbO/YBa₂Cu₃O_7-δ is about 0.2~0.3 and the wear rate is 4.35×10^-4 mm3·（N·m）^-1，and the superconductivity of 15% PbO/YBa₂Cu₃O_7-δ is not degenerated. Finally，the anti-friction and anti-wear mechanism of PbO/YBa₂Cu₃O_7-δ is discussed.