Laser Synthesis and Characterization of Copper-Single Walled Carbon Nanotubes Nanocomposites

Copper (Cu) is a highly valuable material with numerous applications such as copper molds, circuit breakers and electronic packaging. However, low fatigue strength, hardness, and the erosion resistance of copper limits its applicability in situations where excellent surface strength is essential. Carbon nanotubes (CNT), due to their superior mechanical and thermal properties are ideal candidates as reinforcements for enhancing the strength and thermal conductivity of copper. Current fabrication techniques for Cu-CNT composites are focused on powder metallurgy. Avoiding agglomeration of CNTs and achieving their uniform distribution are the major challenges for these techniques.;This research work proposes a novel Laser Surface Implanting (LSI) process for synthesizing Cu-Single Walled Carbon Nanotubes (SWNT) nano-composites through non-equilibrium solidification. In LSI process, a single mode Nd:YVO4 laser beam is used to generate micro holes on a copper substrate. These micro-holes are then filled with SWNTs suspended in water-based gel which restricts agglomeration of SWNTs. Finally, the same laser beam is controlled to generate a micro well of molten copper to mix with the pre-deposited SWNTs. SWNTs are trapped inside the copper matrix due to rapid and non-equilibrium solidification of the molten copper to form Cu-SWNT nanocomposite. Dispersion of SWNTs is achieved through flow of molten copper without thermal damage since they are stable beyond the melting temperature of copper.;Detailed nanostructure characterization studies were performed on the implants revealed that small clusters of SWNTs can be dispersed well with LSI process. These studies characterized the nanostructure with the help of transmission electron microscopy, energy-dispersive x-ray spectroscopy, diffraction patterns of TEM images and existence of high density Moire fringes. Characterization of the mechanical properties such as hardness, toughness and compressive strength of implants were performed in this research. Results from these studies show that the LSI process can enhance the surface strength of copper more than twice that of pure copper, with low volume fraction of SWNTs. Potential applications for these composites in electrical contacts and electronics packaging were identified and preliminary studies were done for these applications.