Advances in nanomanufacturing scale-up and cost control
Sean Davis, Engineering Technician, Nanomaterials Research Group Nanomanufacturing is the production of nanoscaled materials such as carbon nanotubes, nanosheets like graphene, and carbon cage materials like fullerenes and Luna’s proprietary Trimetaspheres®. As these become more prevalent in everyday applications the biggest challenges will be how to produce them on large scales at low costs. Traditional production involves a batch process arc reactor where a carbon rod is fed into the plasma reactor and burned to soot. When the rod is expended the reactor is shut down, the soot is collected and the species of interest (single walled or multi walled nanotubes, buckyballs, etc.) are recovered. For more complex nanomaterials like Trimetaspheres®, carbon rods are drilled out and packed with other elements of interest, but the rest of the process is the same. This batch process is slow, labor intensive, and uses expensive raw materials like helium gas. At our nanomanufacturing facility in Danville VA, we have successfully designed, fabricated, and automated reactors for more continuous production of carbon nanomaterials. Through a series of iterative prototyping we have moved from a small reactor that only produced grams of material to one that now produces kilograms. Instead of manufacturing with a single 16 inch rod that must be used and then exchanged, the new reactor design can accommodate three 32 inch rods. In addition, supplemental elements can be added separately. Rods do not need to be drilled out which keeps the material costs down. Finally, the system needs only nitrogen to run – helium is not required. This further suppressed raw material costs. A prototype version of the vertical three-phase AC arc discharge reactor was recently published in the journal – Fullerenes, Nanotubes and Carbon Nanostructures, 23:7, 612-617, DOI: 10.1080/1536383X.2014.941104, http://dx.doi.org/10.1080/1536383X.2014.941104, and a patent application was filed, Publication Number: WO2014152062. It was experimentally proven that the new three-phase AC arc discharge process is truly scalable for the production of our Trimetasphere® fullerenes for commercial applications including MRI contrast agents. The internal high velocity plasma jet is preferable for Trimetasphere® fullerene formation but not for other fullerene nanomaterials of low commercial values. The most interesting finding is a 5 fold increase in yield due to usage of the three-phase setup.
Using our cost model (labor, overhead, materials, energy, equipment utilization), the cost reduction is estimated at 70–80% compared to the current state of the art. Additional cost savings would be realized from the purification step where the suppressed yields of non-desired fullerenes simplifies the process and saves expensive chemicals. In summary, Luna has created a new nanomaterial production reactor that improves yield, volume, and cost effectiveness over existing processes. As nanomaterials play bigger roles, Luna is ready to assist in development, applications, and production.