Microstructure and properties of silver-graphite composites prepared with silver-coated graphite powders
Silver-graphite composites are electrical contact materials with ideal comprehensive properties.In order to solve the problem of uneven distribution of graphite and weak interfacial bonding in the composites,the dense and uniform pre-copper-silver-coated graphite powder was prepared by the two-step electroless plating method of copper plating first and then silver plating on the surface of graphite,and the high performance silver-graphite composites were prepared by hot press sintering.The results show that the introduction of pre-copper plating technology can improve the distribution uniformity of graphite in the composites,reduce the pores and cracks at the interface,improve the density of the composites,furthermore,make the silver matrix form a continuous three-dimensional network structure around the graphite particles,and effectively improve the mechanical properties and electrical conductivity of the composites.Compared with the activation-silver-coated graphite composite,the hardness(HV)of the pre-copper-silver-coated graphite composite increases from 22.9 to 33.0 by 44.1%;the bending strength increases from 70.4 MPa to 97.2 MPa by 38.1%;the resistivity decreases from 0.11 μΩ·m to 0.08 μΩ·m.
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