Preparation For Copper-graphite By Semi-solid Forming Method And The Frictional Behavior Study

Copper-graphite composite is a very ideal self-lubricating and conducting material for electric locomotive pantograph slide plate. In this paper, copper-graphite slurry is prepared using electromagnetic-mechanical stirring technology, its microstructure and friction performance is studied as follows.1. The -mechanical stirring technology is developed and the uniform cooper-graphite slurry is prepared by this technology. The relationship between the solid fraction and the size of aggregate graphite is determined and the condition for eliminating macro-segregation of graphite in copper-graphite composite is obtained as follows: when the solid fraction of the composite slurry is above 40%, the macro-segregation of graphite can be eliminated.2. Friction behavior of semi-solid casting copper-graphite composite against 45 steel under dry sliding is evaluated in the pin-on-disc tribological tester. The relationship between friction coefficient and load is investigated, linear formula is concluded as follows:μ = 0.22641 + (4.64952E - 4)NThe relationship between friction coefficient and friction time is got. The microstructure character of friction surface under different friction time is analysed and the mechanism of friction is confirmed. The results show that when friction time is controlled between 0～40minutes, friction coefficient toboggan as time extends; on the other hand, while time is controlled between 40-120 minutes , descend of friction coefficient goes to be slower, and only a little declining is done After the 120 minutes, friction coefficient has a steady value of about 0.3009, without change by time.