Not all carbon nanotubes (CNTs) are created equally. While single-wall CNTs are widely available, high-purity, low-cost multi-wall carbon nanotubes (MWCNTs) have until now eluded the R&D community. In the interest of making the attractive properties of this material (high modulus, tensile strength, and conductivity) available to a wider audience, Oak Ridge National Laboratory and Babcock & Wilcox Technical Services Y-12 LLC, both of Oak Ridge, Tenn., have developed Cratos V, a process for high-rate, low-cost production of pure MWCNTs and nanotube arrays for weaving them into high-strength, lightweight fibers (also known as nano-wool).

The key to the process is a new catalyst that allows for a 50°C lower production temperature than conventional catalysts and produces MWCNTs that are free of graphite to deliver at least 50°C higher thermal stability temperature. The ability to use low-cost feedstock also helps mitigate production costs substantially, from approximately $500/g to just $10/g. Cratos V can also be grown in situ on metallic and nonmetallic particles, which has allowed the material to be readily integrated in products such as aluminum composite disks for heat sinks, resin-bonded diamond grinding wheels, and flexible heater prototypes.