Effect of plasma conditions on fabrication of multi-walled carbon nanotubes grown perpendicularly on Hastelloy C276®

We prepared multi-walled carbon nanotubes (MWCNTs) on Hastelloy C276® by a direct current (dc) plasma-assisted hot filament chemical vapor deposition in CH4/N2 atmosphere. Two-step deposition method, consisting of nucleation step and the subsequent CNT growth step, was employed and MWCNTs were grown by the catalytic growth with metal particles, which were precipitated from Hastelloy C276® and mainly consisted of Ni. The plasma generated at the current density of 30 mA/cm2 was necessary to form nuclei for CNT growth, while the reducing of the plasma current density to the range between 10 and 20 mA/cm2 was needed to grow MWCNTs. Based on these results, we proposed the possible mechanisms of the nucleus formation and MWCNT growth.