Processing of Copper-Graphite-Alumina Powders by High-Energy Milling

Rodrigues, I.; Guedes, M.; Ferro, A. C.

http://hdl.handle.net/10400.26/7081

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Authors

Rodrigues, I.

Guedes, M.

Ferro, A. C.

Abstract(s)

Copper-matrix composites are versatile materials used in several electromechanical applications, but relatively low strength and thermal stability impair advanced uses. Development of robust solutions combining low wear and low electrical loss are thus paramount. This work proposes high-energy milling of copper-graphite-alumina powders: graphite is conductive and self-lubricating; alumina toils as dispersion-strengthener and grain refiner. Tailored batches with 2wt%-graphite and 2wt%-alumina were milled up to 16h in planetary ball mill and characterized by XRD, FEG-SEM/EDS, microhardness and Raman. Produced powders are nanostructured, containing graphite and alumina nanoparticles homogeneously distributed in copper. Increasing milling time results in some degree of nanographite amorphization and size decrease. Copper crystallite size and achieved hardness are affected mainly above 4 h milling. Attained results suggest that efficient dispersion of graphite and alumina nanoparticles is achieved, envisaging high conductivity, high strength and thermal stability. The copper-graphite-alumina system thus seemingly opens an opportunity window for PM processing of advanced copper composites.