Synthesis of multi-walled carbon nanotubes on a metal substrate using an ethylene inverse diffusion flame

To satisfy the criteria for the formation of carbon nanotubes on a catalytic metal substrate, a C₂H₄ fueled inverse diffusion flame was chosen as the heat source. The substrate and the substrate holding device did not have to pass through the high-temperature flame front. Two bare stainless steel (304) plates, each of which had a width and thickness of 2.5 and 0.2 mm, respectively, were folded and used as a catalytic metal substrate. The two plates were coated with Ni(NO₃)₂ (nickel-nitrate, hex-hydrate) before folding them together. Based on the TEM-EDS, most of the catalytically grown nanomaterials on the substrate were iron (Fe) catalyzed. Using a substrate coated with nickel-nitrate, carbon nanomaterials were formed in the region of 4 to 7 mm from the flame center. The wider formation zone was caused mainly by the activation of the metal particles at lower temperatures. The lower activation temperature of the coated nickel-nitrate particles lowered the onset temperature for synthesis and broadened the formation zone. This is an abstract of a paper presented at the 30th International Symposium on Combustion (Chicago, IL 7/25-30/2004).