In-line manufacture of carbon nanotubes

Abstract

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.