Carbon nanotubes, sometimes abbreviated to CNTs, are at the forefront of advanced nanomaterials research and development (R&D). A nanomaterial is defined as having constituent parts with nanoscale dimensions usually as small as a few hundred, down to the tens of nanometres (nm). At this remarkably small scale, materials are usually synthesized using specialist furnaces and vacuum processes such as chemical vapor deposition. Carbon nanotube ovens encompass the gradually expanding range of thermal processing products that are suitable for CNT synthesis.
In this blog post, we will explore some of the principles of carbon nanotube ovens in more detail. First, however, it is worth understanding what CNTs are to gain an appreciation for the precision involved in their development.
Carbon Nanotube Ovens: Understanding Single- and Multi-Walled CNTs
Since the successful exfoliation of monomolecular graphene from graphite in 2004, interest in the generation of two-dimensional materials has grown exponentially. Carbon nanotubes are a direct progression from single-layer graphene. They are referred to as allotropes of carbon, which means they are chemically-identical but physically different. A carbon nanotube uses the typical hexagonal carbon lattice to form a single-walled cylinder, multiple of which can be arranged concentrically to form multi-walled CNTs (MWCNTs).
Though it is possible to generate single- and few-layer graphene flakes through methods like exfoliation, CNTs must be epitaxially grown using a technique like chemical vapor deposition (CVD). This is not the only method of generating CNTs, however. Others include:
- Arc discharge synthesis
- Pulsed laser ablation
- Thermal plasma torch method
Arc Discharge Carbon Nanotube Oven
The arc discharge was the first technique used to produce SWCNTs, and it remains popular for bulk synthesis today. Carbon nanotube ovens based on arc discharge generation utilize a pair of graphite electrodes under inert gas (argon, helium, etc.) at low pressures, typically around 500 Torr. Mixed metallic catalysts are used to produce highly structured SWCNTs, typically a combination of cobalt, iron, and nickel.
Pulsed Laser Ablation Carbon Nanotube Ovens
Carbon nanotube ovens based on pulsed laser ablation are highly specialized units comprising high-power pulsed lasers of ultraviolet or infrared wavelengths. The laser is used to ablate a carbon-based target within a low-pressure, high-temperature chamber under inert gas – again, typically argon or helium. SWCNTs are produced by condensation of vaporized carbon within the chamber.
Thermal Plasma Torch Carbon Nanotube Ovens
Plasma torch production of SWCNTs is uncommon but possible. Carbon nanotube ovens of this ilk attempt to emulate the conditions of the two previous techniques without using carbon vapors, instead, using an extremely high-temperature plasma torch to convert a carbon-containing gas into SWCNTs. This method is growing in popularity due to its reduced cost.
We explored the more common CVD method of generating CNTs in a previous blog post. Read Carbon Nanotube Furnaces and Services from Thermcraft if you would like to learn more about CVD generated S/MWCNTs.
Carbon Nanotube Ovens from Thermcraft
Thermcraft is one of the industry-leading suppliers of specialist thermal processing equipment for advanced materials research and industrial-scale production applications. We can offer tailor-made thermal processing solutions specifically designed to meet your stringent materials processing needs. If you would like to discuss purchasing a carbon nanotube oven from Thermcraft or simply have questions about our capabilities, please do not hesitate to contact us.