Heterostructured NiCr matrix composites with high strength and wear resistance

摘要

Self-lubricating composites are required to have excellent tribological performances and good mechanical properties when they are applied as mechanic parts.However,the brittle nature of most lubricants will weaken the mechanical properties of the composites where in order to get the lubricating ability proper amount of lubricants are usually incorporated,bringing challenges for them to get well-balanced mechanical and tribological properties.In this study,Ni Cr matrix self-lubricating composites with the addition of WS_(2)and nano-Ti were prepared via spark plasma sintering.The hard phase of Ni_(3)Ti and the lubricant Ti S were formed via in-situ reaction at the interface,which surrounded the soft alloy matrix and developed a heterostructure.Compared with the conventional Ni Cr-WS_(2)composite,the heterostructured composite exhibited a high yield strength of 1645 MPa,a low friction coefficient of 0.37 and a wear rate of as low as 2.25×10^(-5)mm^(3)N^(-1)m^(-1)when sliding.Finite element analysis demonstrated that the heterostructure plays a key role to balance well the mechanical and tribological properties of the Ni Cr matrix composites.