| Carbon nanomaterials exhibit many remarkable electrical and physical properties. An ongoing challenge associated with specific novel carbon nanomaterials, such as graphene, is the development of large-scale production methods at low cost. The broad objective of this work is to investigate flame synthesis of carbon nanomaterials, specifically graphene and carbon nanotubes (CNTs), using open-atmosphere processing, with an eye towards scalability. An experimental study using a novel setup, based on multiple inverse-diffusion flames is undertaken to investigate the direct flame-synthesis of CNTs and graphene on metal substrates.;Few-layer graphene (FLG) is grown on copper and nickel substrates at high rates using the novel flame-synthesis burner. Substrate material (i.e. copper, nickel, cobalt, iron, and copper-nickel alloy), along with its temperature and hydrogen pretreatment, strongly impacts the quality and uniformity of the graphene films. The growth of FLG occurs in the temperature range 750-950°C for copper and 600-850°C for nickel and cobalt. For iron, the growth of graphene is not exclusively observed.;CNT growth is observed on a number of substrates. Transitional growth between CNTs and graphene films occurs on nickel and nickel alloys, depending on composition and temperature. For nickel, copper-nickel, nitinol, and Inconel substrates, CNTs grow at 500°C. The transitional growth to few-layer graphene is observed on nickel, copper-nickel and Inconel by changing the substrate temperature to 850°C. The growth of graphene is not observed on nitinol for the examined experimental conditions.;The growth of few-layer graphene films and CNTs are also investigated using various metal-oxide spinels as catalysts. The growth of CNTs is examined on NiAl2O4, CoAl2O4 and ZnFe 2O4 using counterflow diffusion flame and multiple inverse-diffusion flames, while the growth of graphene is examined on CuFe2O 4 using multiple inverse-diffusion flames.;Finally, the growth of CNTs and iron oxide is studied on stainless steel. At low temperatures (500°C) the growth of alpha-Fe2O 3 is observed, while at higher temperatures (850°C) the growth of CNTs is observed. Additionally, by following a two-step growth process, where the temperature is changed from 500°C to 850°C, the growth of CNTs and gamma-Fe2O3 occurs. |
