Decreasing limiting angle of graphite wetting with copper in graphite-copper current-collecting materials
Carbon-Copper materials are widely used for current collecting purposes on the electrified transport. Electrical conductivity and mechanical properties of such a current collecting material are improved with copper impregnation of carbon matrix. However its main drawback is the lack of any physical and chemical interaction between copper and carbon matrix. Main task of the presented work consists in securing reliable carbon wetting with copper when melted copper is self-spreading over the carbon. It’s well-known that wetting is practically lacking within the copper-graphite system. In the present paper this problem has been solved through graphite surface modification with thin layer of niobium carbide, chromium carbide or molybdenum carbide. Copper alloys with carbide-forming elements were employed as metallic components. For all the specimens there were determined ultimate compression strength, density and specific electrical resistance as depending on the copper content. Also the angle of modified graphite wetting with copper or bronze was measured under various temperature values. It was indicated in the course of conducted research that graphite ought to be covered with niobium carbides to increase the degree of its wetting with copper. Chromium and molybdenum carbides were less encouraging. At 1450 °С melted copper is perfectly wetting graphite modified with niobium. Alloying copper with hafnium or zirconium leads to wetting quality deterioration of modified graphite.