银石墨复合材料是一种具有理想综合性能的电接触材料。为了解决复合材料中石墨分布不均匀,界面结合较弱的问题,通过在石墨表面预先镀铜,再镀银的两步化学镀法,制备镀层致密均匀的预镀铜-镀银石墨粉,并采用热压烧结方式制备高性能银石墨复合材料。结果表明：预镀铜工艺的引入能改善复合材料中石墨的分布均匀性,减少界面处的孔隙和裂纹等缺陷,提高材料的致密度,并且使银基体在石墨颗粒周围形成连续的三维网状结构,有效提升复合材料的力学性能和导电性能。与活化-镀银石墨复合材料相比,预镀铜-镀银石墨复合材料的硬度(HV)由22.9提高至33.0,提升了44.1%;抗弯强度由70.4 MPa提高至97.2 MPa,提升了38.1%;电阻率则由0.11 μΩ∙m降低至0.08 μΩ∙m。
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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