In-line manufacture of carbon nanotubes
Mass production of carbon nanotubes (CNT) are facilitated by methods and apparatus disclosed herein. Advantageously, the methods and apparatus make use of a single production unit, and therefore provide for uninterrupted progress in a fabrication process. Embodiments of control systems for a variety of CNT production apparatus are included.
1. A method of producing an aggregate of vertically aligned carbon nanotubes, the method comprising:
(a) loading a base material into a controlled environment;
(b) disposing a catalyst onto the base material to provide a substrate in an environment having an oxygen concentration low enough to substantially prevent oxidation of the substrate;
(c) subjecting the substrate to a carbonaceous raw material gas and heating at least one of the raw material gas and the substrate for growing the aggregate onto the substrate without the use of a reducing gas for reducing the catalyst during the growing of the aggregate; and
(d) cooling the aggregate in an environment having an oxygen concentration low enough to substantially prevent oxidation of the aggregate during the cooling;
wherein steps (a) to (d) are performed in the controlled environment comprising chambers sequentially connected in a manner that limits the exposure of the base material and any catalyst, substrate, and aggregate disposed thereon to contamination between each step.
2. The method of claim 1 , further comprising disposing a carburizing prevention layer on at least one of the base material and the catalyst.
3. The method of claim 1 , wherein disposing the catalyst comprises using at least one of sputtering evaporation, cathodic arc deposition, sputter deposition, ion beam assisted deposition, ion beam induced deposition and electrospray ionization.
4. The method of claim 1 , further comprising treating the substrate with a plasma.
5. The method of claim 1 , further comprising subjecting the substrate to a catalyst activation material during the growing of the aggregate.
6. The method of claim 5 , further comprising adding the catalyst activation material to the raw material gas.
7. The method of claim 1 , further comprising selecting a production apparatus comprising components treated to limit buildup of contaminants.
8. The method of claim 7 , wherein treatment of the components comprises passivating the components with at least one passivation material.
9. The method of claim 8 , wherein the passivation material comprises a silicon containing material.
10. The method of claim 1 , wherein, during step (c), a surface of the substrate on which the aggregate is grown is exposed to an environment consisting essentially of the raw material gas and one or more inert gases.
11. The method of claim 5 , wherein, during step (c), a surface of the substrate on which the aggregate is grown is exposed to an environment consisting essentially of the raw material gas, the catalyst activation material, and one or more inert gases.
12. The method of claim 1 , wherein step (a) comprises loading the base material into a load chamber substantially filled with one or more inert gases that substantially displace oxygen from the load chamber.
13. The method of claim 12 , further comprising, prior to step (b), transferring the base material to a catalyst application chamber from the load chamber while substantially preventing intrusion of oxygen into the load chamber and the catalyst application chamber.
14. The method of claim 13 , further comprising, prior to step (c), transferring the base material to a growth chamber from the catalyst application chamber or a buffer chamber while substantially preventing intrusion of oxygen into any of the load chamber, the catalyst application chamber, and the a buffer chamber.
15. The method of claim 1 , wherein, at the commencement of step (c) prior to the growing of the aggregate, the catalyst is substantially oxide free.
16. The method of claim 1 wherein the growing of the aggregate takes place entirely within a single growth chamber, and wherein, prior to the growing of the aggregate, the substrate is free of carbon nanotubes.
17. The method of claim 1 , wherein, during the performance of steps (a) to (d), the chambers are sequentially connected in a manner that substantially prevents the exposure of the base material and any catalyst, substrate, and aggregate disposed thereon to room air between each step.