Research On Preparation And Properties Of Copper-graphite Composites

Copper-graphite composites with properties of anti-friction and electrical conductivity play an important role in the mechanical transmission system in relation to conductive performance. They are widely used in many aspects of national economic development and national defense building. Therefore, research on copper-graphite composites has an important application value. Aiming at improving the wetting of graphite in the copper body and state of distribution, This paper studied process and methods of electroless copper plating on the surface of graphite powder and preparation of ultra-fine copper powder by chemical reduction method, prepared copper-graphite composite on this basis, and studied electrical conductivity and wear resistance of the composites.Discussed impact of various factors on plating by comparison tests, after electroless copper plating on the surface of the pre-treated graphite. By scanning the SEM morphology, the optimum value was obtained: the main salt 15~25g/L, reducing agent 25ml/L, loading 1g/L, temperature 40~55℃, pH 11~13. Prepared five kinds of copper powders with methods of formaldehyde dir-reduction, formaldehyde with glucose pre-reduction, hydrazine dir-reduction, hydrazine with glucose pre-reduction, and hydrazine-formaldehyde compound reduction, respectively. Observed SEM morphology, particle size and distribution of copper powder comparatively by electron microscopy and laser particle size analyzer, and found that copper powders prepared by hydrazine- formaldehyde compound reduction method had a good dispersion and a narrow size distribution range.Using graphite with copper plating and ultra-fine nano-copper powder obtained by the best technology to prepare copper-graphite with copper plating composites, observed the microstructure by metallographic microscope, determined the density, studied their electrical conductivity and wear resistance, and compared with copper-graphite without copper plating composites prepared using marketed copper and graphite powder.Experiments show that copper-graphite with copper plating composites have dense structure, and fine graphite dispersed evenly in the composites, copper-coated graphite forms three-dimensional space for a small network, the status of such organizations fully play their respective advantages of copper and graphite, and increase the electrical conductivity and wear resistance of composites; electrical resistivity is inversely proportional to density and preparing pressure, but it is proportional to sintering temperature; wear rate is inversely proportional to preparing pressure, while with the sintering temperature increasing, wear rate firstly decreases and then increases, and wear rate reaches the minimum at 850℃. Conductivity and abrasion resistance copper-graphite with copper plating composites are superior to copper-graphite without copper plating composites.