Structure modification of carbon nanotube powder and film by laser shock peening process

Since their discovered in 1991, carbon nanotubes have demonstrated many remarkable mechanical, electrical and thermal properties, showing promising potentials in many fields. Carbon nano tubes have attracted world-wide attentions during the years, many research work have been performed during the years. At Tsinghua University, we have reported previously two kinds of research work on laser processing of canbon nanotubes: (1) Connection of macro-sized double-walled carbon nanotube strands by laser irradiation; (2) Light emission from multiwalled carbon nanotubes under CW CO2 laser irradiation. This work is a continuous effort in the research area, which focuses on the structure modification of carbon nano tube powder and film by laser shock peening process. A Q-switched nano second Nd:YAG laser pulse induces a shock wave on metal surface with very high pressure (up to Giga or even tens of Giga pascal), which produces normally plastic deformation and a few hundred MPa of the residual compressive stress on the surface of materials, enhancing the anti-fatigue properties of metals and extending the fatigue life of the processed components. We used laser shock peening to process the carbon nanotube powder and carbon nanotube film to explore the possible structure modification. Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Micro Raman Spectrum were used to analyze the morphology and spectrum to identify the structure modification of the carbon nanotube powder and film after laser shock peening process and then to establish the relationship between the process parameters and the structure modification. The research impact and potential applications were discussed based on the research.