Copper - Preparation And Properties Of Graphite Composites

Copper-graphite composite is an ideal self-lubricating and conducting material for electric locomotive pantograph slide plate. Based on the conventional sintering process, the method of pressure to promote sintering process of copper-graphite composite material was explained in this article. Process parameters of sintering experiment were changed to improve the comprehensive performance of copper graphite composite material, their different effects on the material physical properties and change rules were summed up.The major results were concluded as followings:1) The optimal sample that had relative density of0.895, hardness64.7HB, electrical conductivity of6.2Ms/m was made with those parameters:materials’ proportions in powder ratio for copper89wt%, iron5wt%, tin4wt%, graphite2wt%; mixing powder time of3h; suppressing pressure at525MPa and dwelling for3min; sintering temperature at945℃; and sintering pressure at200MPa, the holding time for120minutes.2) The value of samples relative density was affected by sintering temperature, pressing pressure, sintering pressure and holding time. It showed a trend of decrease after the first increase with the increasing of the sintering temperature, and reached the maximum at945℃.It increased with the increasing pressing pressure, sintering pressure and holding time, but this trend was reduced gradually after the compacting pressure raised to525MPa and sintering pressure raised to200MPa.3) The value of samples’hardness increased with the increasing of pressing pressure, sintering pressure and holding time. It showed a trend of decrease after the first increase with the increasing of sintering temperature, and reached maximum at the temperature of945℃.4) The conductivity of the sintered compact increased with the increasing of compacting pressure and sintering pressure. With the increased sintering temperature and the prolonged of holding time the conductivity first increased and then decreased, it reached the maximum when holding120min at920℃.5) The wearing capacity of the sintered compact increased with the increasing of compacting pressure and sintering pressure. It showed a trend of wearing capacity increase after the first decreasing with the increasing of sintering temperature, and reached minimum at the temperature of945℃. With the prolonged of holding time the wearing capacity first increased and then decreased, it reached the maximum when60min.6) The sintering pressure could change the surface state of powder. what’s more, it could improve the surface activities of powder and the diffusion ability of atom. Particle characteristics of contact area were changed for accelerating diffusion and migration abilities of the sintering metal atoms, in this way, the sintering process was promoted.