Nanomanufacturing is a research area that is growing rapidly in the recent years. The current demands of industry require the precise modification of surfaces to make holes, lines, arrays, structures and so on, that can be used for a diverse number of applications. Thus, the desire to pattern in the nano-scale is the main driver behind the development of new manufacturing tools. As a potential tool for nanomanufacturing, electron field-emission from carbon nanotubes was proposed for nanomachining applications [1]. This process utilizes the energy of the emitted electrons to heat, melt and vaporize holes or any given pattern on a metallic surface. In our recent work, we have investigated the different aspects of carbon nanotubes during field-emission in order to characterize their robustness and reliability [2-5]. This was done combining a finite element methodology to simulate electro-statics and heat transfer on the carbon nanotube, with Newton’s equations of motion to determine the trajectories of the emitted electrons. We also studied what would happen to metallic workpieces when they are heated continuously using the field-emission from multiple carbon nanotubes [6, 7]. The numerical method used combines the two-temperature model and molecular dynamics in a unique way, and offers the best of both the continuum and discrete worlds. Electrons transfer their energy to lattice vibrations, which are represented as atomic motions in the molecular dynamics simulation. In this way, we can accurately study phase change processes that have never been done before. The results indicate that given that a number of carbon nanotubes are available in a controllable array, enough electron energy is available through field-emission to produce considerable damage to the workpiece. The animations shown here correspond to the process of nanomachining of a Ni workpiece assuming that a highly focalized electron beam is available. We extended the methods outlined in our previous work to the three-dimensional case as radial effects are important with such a highly focused electron beam. The atomic trajectories of the system indicate that a well defined crater is produced. The order parameter shows the stages of the melting process by assuming that when the order parameter is unity, the material is in the solid state; when it is zero, the material is in the liquid phase. It can be seen that when the heated region is ejected due to a large concentration of tensile stress, the remainder workpiece cools down rapidly. The x and y axes in both animations are in nanometers.

Dr. M. Pinar Menguc
Professor, Department of Mechanical Engineering,
University of Kentucky

2. Sanchez, J. A., B. T. Wong, M. P. Mengüç and P. Albella (2007). "Field emission and electron deposition profiles as a function of carbon nanotube tip geometries." Journal of Applied Physics 101(11): 114313.

3. Sanchez, J. A. and M. P. Mengüç (2008). "Geometry dependence on the electro-static and thermal response of a carbon nanotube during field emission." Nanotechnology 19(7): 075702, pp. 11.

4. Sanchez, J. A., M. P. Mengüç, K.-F. Hii and R. R. Vallance (2008). "Heat transfer within carbon nanotubes during electron field-emission." Journal of Thermophysics and Heat Transfer 22(2): 281-289.

5. Sanchez, J. A. and M. P. Mengüç (2008). "Effect of Multiple Carbon Nanotube Field Emitters on Electron Deposition Profiles." Journal of Physics D: Applied Physics (under review).

6. Sanchez, J. A. and M. P. Mengüç (2007). "Phase Change Phenomena during Electron-beam Heating: Molecular Dynamics Simulations." Physical Review B 76(22): 224104.

7. Sanchez, J. A. and M. P. Mengüç (2008). "Melting and vaporization of Cu and Ni films during electron-beam heating." Journal of Applied Physics 103(5): 054316.

2. Sanchez, J. A., B. T. Wong, M. P. Mengüç and P. Albella (2007). "Field emission and electron deposition profiles as a function of carbon nanotube tip geometries." Journal of Applied Physics 101(11): 114313.

3. Sanchez, J. A. and M. P. Mengüç (2008). "Geometry dependence on the electro-static and thermal response of a carbon nanotube during field emission." Nanotechnology 19(7): 075702, pp. 11.

4. Sanchez, J. A., M. P. Mengüç, K.-F. Hii and R. R. Vallance (2008). "Heat transfer within carbon nanotubes during electron field-emission." Journal of Thermophysics and Heat Transfer 22(2): 281-289.

5. Sanchez, J. A. and M. P. Mengüç (2008). "Effect of Multiple Carbon Nanotube Field Emitters on Electron Deposition Profiles." Journal of Physics D: Applied Physics (under review).

6. Sanchez, J. A. and M. P. Mengüç (2007). "Phase Change Phenomena during Electron-beam Heating: Molecular Dynamics Simulations." Physical Review B 76(22): 224104.

7. Sanchez, J. A. and M. P. Mengüç (2008). "Melting and vaporization of Cu and Ni films during electron-beam heating." Journal of Applied Physics 103(5): 054316.

1. electron field-emission from carbon nanotubes
2. molecular dynamics
3. nanomachining
4. phase change
5. two-temperature model