Tribological behaviour of Cu‒Zn based self-lubricating materials reinforced with rare earth oxide Y₂O₃

Cu‒Zn-based self-lubricating composites contained Y₂O₃ rare-earth oxide and graphite lubricating phase were prepared by spark plasma sintering discharge plasma flash burning method, and the effects of Y₂O₃ and graphite on the mechanical properties and friction and wear properties of the Cu-based self-lubricating composites were studied. The results show that the friction coefficient of the Cu‒Zn composites with 3% graphite (mass fraction) is decreased by 63.6% than that of the ordinary Cu‒Zn alloys. The comprehensive performance of the Cu‒Zn composites with 1% Y₂O₃ (mass fraction) shows the peak effect as the hardness is increased by 41.5% and the friction coefficient is reduced by 25%. The rare-earth oxide Y₂O₃ produces the dispersion strengthening effect in the matrix, refines the grain and the matrix pores, improves the relative density of the composites. During the friction process, the lubrication phases are enriched on the surface of the composite friction pairs, forming the good lubricating layers, which improves the tribological behavior of the Cu‒Zn sliding parts.