TRIBOLOGICAL BEHAVIOR OF SUPER CONDUCTING MATERIAL YBa₂Cu₃O₇

The micro and macro tribology characters of sintered YBa₂Cu₃O₇ ( YBCO)in the air were investigated by using ball on disc tester and atomic force microscope(AFM), and a comparison with Cu based solid lubricant composite was prepared. The results indicate that excessive amount of solid lubricant will lead to decrease friction coefficient and increase wear rate for solid lubricant composite. The specimen 4060Cu containing 40%WS₂ exhibits the lowest friction and relatively lower wear rate under the condition of different loads ( P), speeds ( v) and pv values. The friction coefficient of the YBCO specimen is similar to that of 4060Cu, but the wear rate is greatly lower than that. The results of XRD and TEM show that CuO distributes in the YBCO’s out layer and the binder with the body is not strong enough, so they can slip easily under shear stress with a low friction coefficient. In YBCO sample, Y₂O₃ nano particles distribute in the substance dispersedly, which strengthens the matrix and decreases the wear rate greatly. Due to the finer and more disperse Y₂O₃ particles of the specimen prepared by powder melting process, YBCO2 displays better wear-resistance.