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; 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 . An apparatus for fabricating an aggregate of vertically aligned carbon nanotubes, the apparatus comprising:
a first section adapted for receiving a substrate and disposing a catalyst thereon; a second section adapted for growing the aggregate onto the substrate;
at least one of the first section and the second section comprising at least component that has been passivated to substantially limit deposition of carbon thereon.
11 . The apparatus of claim 10 , wherein the at least one component has been passivated with at least one form of silicon.
12 . The apparatus of claim 10 , wherein passivation has been completed by at least one cycle of deposition of a silicon containing compound onto the at least one component and heating the at least one component.
13 . The apparatus of claim 10 , wherein at least one of the first section and the second section are fabricated from components substantially capable of resisting high temperatures.
14 . The apparatus of claim 10 , further comprising a control system for controlling the fabricating.
15 . The apparatus of claim 10 , further comprising components for disposing the catalyst by at least one of sputtering, chemical vapor deposition (CVD), thermal deposition and ion-beam deposition.
16 . An apparatus for fabricating an aggregate of vertically aligned carbon nanotubes, the apparatus comprising:
a first section adapted for receiving a substrate and disposing a catalyst thereon; a second section adapted for growing the aggregate onto the substrate; and
a control system for controlling the fabricating.
17 . The apparatus of claim 16 , further comprising at least one sensor adapted for monitoring the fabricating and providing monitoring information.
18 . The apparatus of claim 16 , wherein the control system comprises a set of computer executable instructions stored on machine readable media, the instructions comprising instructions for controlling at least one aspect of the fabricating.
19 . The apparatus of claim 18 , wherein the aspect comprises at least one of: disposing of the catalyst; a temperature; a pressure; a feed rate; a setting for at least one of a valve, a heater, a gas supply, a motor and a servo; an order of steps in the fabricating; an optical system and rejection of defective materials.
20 . 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.