Abstract
The goal of the research work was the pyrolytic synthesis of straight and spiral carbon nanotubes of approximately the same diameter, as well as their comprehensive analysis. To solve the given problem, a new installation for the pyrolytic synthesis of carbon nanostructures (CNS) with a fusion reactor, which for each fusion process can have its own angle relative to the classical horizontal position of the reactor axis. This reactor made it possible to develop a method for obtaining conglomerates of spiral-shaped multi-walled carbon nanotubes with a diameter of 15–60 nm and to synthesize straight multi-walled carbon nanotubes with a diameter of 5 to 60 nm. The research of pyrolytic synthesis of carbon nanostructures in a vertical reactor allows to work out the technology of purposeful synthesis of nanotubes that have a spiral shape with a certain diameter and pitch of the turn. As part of the work, a new mechanism for the formation of spiral multi-walled carbon nanotubes is also considered and proposed, which is important for their further industrial synthesis and their use in related composites. A scheme is proposed of conditions for the synthesis of carbon nanostructures by the pyrolytic method. Thermal analysis was carried out in the work, which recorded the presence of two different structures with low thermal stability (probably amorphous carbon and higher hydrocarbons). When using scanning and transmission electron microscopy, the formation of spiral nanofibers with a diameter of 15–60 nm in the vertical position of the reactor was recorded, and in the horizontal position of the reactor, the formation of straight and slightly curved MWCTs with a diameter of nanofibers from 5 to 60 nm was found. Raman spectroscopy confirms the presence of multi-layered carbon tubular formation, i.e. MWCT, in both synthesis products.