Alloys used as bearings in aircraft landing gear are required to reduce friction and wear as well as improve the load-carrying capability due to the increased aircraft weights. Cu-15Ni-8Sn-0.8Nb alloy is well known for possessing good mechanical and wear properties that satisfy such requirements. In this study, the microstructure, mechanical properties, and grease-lubricated sliding wear behavior of Cu-15Ni-8Sn-0.8Nb alloy with 0.8 wt% Nb are investigated. The nanoscale NbNi₃and NbNi₂Sn compounds can strengthen the alloy through the Orowan strengthening mechanism. A Stribeck-like curve is plotted to illustrate the relationship among friction coefficient, normal load, and sliding velocity and to analyze the grease-lubricated mechanism. The wear rate increases with normal load and decreases with sliding velocity, except at 2.58 m/s. A wear mechanism map has been developed to exhibit the dominant wear mechanisms under various friction conditions. When the normal load is 700 N and the sliding velocity is 2.58 m/s, a chemical reaction between the lubricating grease and friction pairs occurs, resulting in the failure of lubricating grease and an increase in wear.

Inhomogeneous structures with carbon nanotubes (CNTs), reinforced with Cu composite foams as the reinforcing skeletons (CNTs/Cu_f^®Cu), have been designed to overcome the paradox between strength and ductility or conductivity in copper matrix composites. The interface between CNTs and the copper matrix is usually weak, due to poor wettability and interaction. In this study, nickel nanoparticles are decorated onto CNTs to improve interfacial bonding. The broader interface transition area between CNTs and copper with Ni₃C interfacial products formed, and a combination of improved electrical conductivity (95.6% IACS), tensile strength (364.9 MPa), and elongation (40.6%) was achieved for the Ni-decorated CNTs/Cu_f^®Cu (Ni-CNTs/Cu_f^®Cu). In addition, the strengthening mechanisms are discussed in this study.

In this paper, graphite/copper composites with high performance were fabricated by a novel two-steps electroless plating and spark plasma sintering. The interfacial characterization and modification mechanism of nickel coating in the composites were analyzed. Effects of sintering temperature and Ni volume fraction on the mechanical properties and microstructure of composites were also systematically investigated. The results showed that the introduction of Ni coating could significantly improve the interfacial bonding between Cu matrix and graphite and led to the uniform distribution of graphite particles in Cu matrix. Moreover, the mechanical properties of composites increased obviously with the increase of Ni coating content from 0 vol.% to 10 vol.%. When the Ni content was 10 vol. %, the relative density, hardness, and compressive strength of the composites reached to 99.8%, 67.8 HB and 314 MPa, respectively. Graphical abstract Graphical abstract