COPPER-GRAPHITE COMPOSITE MATERIAL WITH LOW ELECTRIC RESISTANCE AND IMPROVED RESISTIVITY TO WEAR AND PROCESS FOR PRODUCING THE SAME

摘要

The invention relates to a composite material having a IACS value of the conductivity of minimum 40% relative to 100% conductivity annealed copper, produced by mixing, tamping and sintering the mixtures of copper powder having a purity of approximately 99.9% and graphite powder, comprising a copper network matrix with a plurality of pores, at least some of them containing graphite. According to the invention, the process for obtaining the copper-graphite composite material comprises the following steps of purifying the copper powder by the annealing thereof in a reducing atmosphere and the purging thereof; mixing the copper and graphite powders; pressurizing the powder mixture in order to obtain a tamped product; sintering the product tamped at high temperatures, in a specific period of time. The copper powder is preferred to have the particle size less then or of maximum 10 mium, and the graphite powder to have a particle diameter of 5 mium at the most. The tamping conditions may be achieved with a pressure between 500 and 1600 Mpa for 5...10 min. The sinterization of the powders may be performed in tamped forms, at temperatures in the range between 960 and 1100 degree C, under a protecting atmosphere of H2 and N2, or by another heating or pressurizing process.