Preparation And Properties Of NbSe₂/Cu Composites

NbSe₂is a compound with a lamellar molecular structure, which has both lowerresistivity and lower friction coefficient, so it is a lubricative phase with novel conductiveproperty. In this paper, NbSe₂/Cu composites were prepared by spark plasma sinteringand the effect of technique parameters on microstructure were studied. By using ofEDS, XRD, OM, SEM and TEM, chemical composition, phases and microstructure ofcomposites were analyzed; in addition, the density, Rockwell hardness (HRB), tensilestrength and tribological properties were tested.The optimum process parameters for NbSe₂/Cu composites is: pre-pressure350MPa,sintering temperature750℃, sintering pressure25MPa and holding time10min. By theuse of electroless plating of copper method to modify surface property of NbSe₂powder,the bonding strength between NbSe₂and Cu matrix was enhanced.The result indicated that: the density of NbSe₂/Cu composite was about8.39×10³kg/m³which was close to theoretical density. NbSe₂powder were well-distributed inmatrix and no significant segregation. Phases were well combined with each other at theinterface and amount of defect was little. No phase transition of NbSe₂occurred duringthe sintering process. After surface modification of NbSe₂powder, the density, tensilestrength, wear resistance of NbSe₂/Cu composites had been improved.NbSe₂/Cu composites showed a self-lubriction property, which protected from bothwear and plastic deformation on the matrix. With the increase of load, self-lubricatingfilm was formed quickly and the change of friction coefficient was little, while wearrate increased gradually. The wear mechanism showed a slight abrasive phenomenon.With the increase of sliding speed, consumption rate of self-lubricating film alsoincreased. Under the condition of proper sliding speed, it wound reach a dynamicequilibrium between the consumption and formation. When sliding speed exceed propervalue, friction coefficent changed little, while wear rate increased. With the increase ofconsumption of lubricating film, the main wear mechnism changed from abrasive toadhesive.