Influence of carbon nanotube and graphen on the properties of copper matrix composite produced by powder metallurgy

Copper matrix composites have been used in spot welding electrodes for the automotive assembly and sliding electrical contact applications. In this study, two types of copper matrix composites powder reinforced with carbon nanotube (CNT) and graphene (Gr) were prepared using high energy ball milling. The subsequent consolidation process of resulting powder was done by cold and hot press sintering at different conditions. For this purpose, the copper powder with different percentages of CNT and Gr (0.5 and 1 wt.%) was mechanically ball milled for 5 hours. Then, discs with 10 mm diameter and 10 mm thickness were prepared by the cold press under pressure of 20 MPa. Also, compacts were processed by hot-pressing at 500 °C under the pressure of 20 MPa. Under the same conditions as compacts processed from milled composite powders, compacts from 5 hours milled pure electrolytic copper powders were also synthesized for comparison. Subsequently, these samples were sintered at 800 °C for 1 hour under argon atmosphere. The samples characterized by X-ray diffraction, optical and scanning electron microscopy. The microstructure, density and mechanical properties of samples have been studied. Microstructure analysis results have proved that homogeneous microstructure was formed after the consolidation process. The results showed that increases in Gr and CNT percentage caused to increase in hardness of samples. Also, the hardness of hot pressed sample was more than that of cold pressed one. Also, the Cu-Gr composites have higher density and hardness.