Heterostructured NiCr matrix composites with high strength and wear resistance

Abstract

• NiCr-WS 2 composites with nano-Ti addition were prepared by spark plasma sintering. • The in situ reaction between NiCr, WS 2 and Ti leads to the formation of a heterostructure. • The heterostructured composite exhibits balanced mechanical and tribological properties. 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, NiCr 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 TiS were formed via in-situ reaction at the interface, which surrounded the soft alloy matrix and developed a heterostructure. Compared with the conventional NiCr-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 NiCr matrix composites.