Improving effect of carbonized quantum dots (CQDs) in pure copper matrix composites

Carbon quantum dots (CQDs), which contain a core structure composed of sp(2) carbon, can be used as the reinforcing phase like graphene and carbon nanotubes in metal matrix. In this paper, the CQD/Cu composite material was prepared by powder metallurgy method. The composite powder was prepared by molecular blending method and ball milling method at first, and then densified into bulk material by spark plasma sintering (SPS). X-ray diffraction, Raman spectroscopy, infrared spectroscopy, and nuclear magnetic resonance were employed to characterize the CQD synthesized under different temperature conditions, and then CQDs with a higher degree of sp(2) were utilized as the reinforcement to prepare composite materials with different contents. Mechanical properties and electrical conductivity results show that the tensile strength of the 0.2 CQD/Cu composite material is similar to 31% higher than that of the pure copper sample, and the conductivity of 0.4 CQD/Cu is ~96% IACS, which is as high as pure copper. TEM and HRTEM results show that good interface bonding of CQD and copper grain is the key to maintaining high mechanical and electrical conductivity. This research provides an important foundation and direction for new carbon materials reinforced metal matrix composites.