Method for manufacturing carbon nanotubes

Abstract

The present invention provides a method for manufacturing carbon nanotubes. The method includes the following steps: (a) providing a substrate ( 3 ); (b) depositing a catalyst material ( 1 ) onto the substrate; (c) exposing the catalyst material to a carbon containing gas for a predetermined period of time in a predetermined temperature such that an array of carbon nanotube having a predetermined length grows from the substrate in a direction substantially perpendicular to the substrate; (d) removing the carbon nanotubes from the substrate; and (e) dispersing the carbon nanotubes via ultrasonication in a dispersant, the dispersant being ethanol or 1-2 dichloroethane. The carbon nanotubes of the present invention have a predetermined same length and are aligned parallel to each other.

What is claimed is:  
     
         1 . A method for manufacturing carbon nanotubes comprising steps as follows: 
 (1) providing a substrate;    (2) depositing a catalyst material onto the substrate;    (3) exposing the catalyst material to a carbon containing gas for a predetermined period of time at a predetermined temperature such that an array of carbon nanotubes having a predetermined length grows from the substrate in a direction substantially perpendicular to the substrate; and    (4) removing the carbon nanotubes from the substrate.    
     
     
         2 . The method in accordance with  claim 1 , further comprising dispersing the carbon nanotubes via ultrasonication in a dispersant after step (4).  
     
     
         3 . The method in accordance with  claim 1 , wherein in step (1) the catalyst material is selected from the group consisting of iron, cobalt and nickel.  
     
     
         4 . The method in accordance with  claim 3 , wherein step (2) comprises depositing a catalyst material film between 4 and 10 nm thickness on the substrate and annealing the catalyst material film at between 300-500 degrees Centigrade for between 8-12 hours such that the catalyst material is changed into separate nanoparticles.  
     
     
         5 . The method in accordance with  claim 1 , wherein in step (3) the predetermined temperature is between 600-1000 degrees Centigrade.  
     
     
         6 . The method in accordance with  claim 5 , wherein in step (3) the carbon containing gas is selected from the group consisting of ethylene, methane and acetylene.  
     
     
         7 . The method in accordance with  claim 5 , wherein step (3) further comprises flowing protecting gas before exposing the catalyst material to the carbon containing gas.  
     
     
         8 . The method in accordance with  claim 1 , wherein step (3) comprises exposing the catalyst material iron to ethylene at 690 degrees Centigrade for 15 seconds such that a carbon nanotubes array of 10 micron height grows from the substrate in a direction substantially perpendicular to the substrate.  
     
     
         9 . The method in accordance with  claim 1 , wherein step (3) comprises exposing the catalyst material iron to ethylene at 690 degrees Centigrade for 5 minutes such that a carbon nanotubes array of 100 micron height grows from the substrate in a direction substantially perpendicular to the substrate.  
     
     
         10 . The method in accordance with  claim 1 , wherein step (3) comprises exposing the catalyst material iron to ethylene at 710 degrees Centigrade for 10 minutes such that a carbon nanotubes array of 500 micron height grows from the substrate in a direction substantially perpendicular to the substrate.  
     
     
         11 . The method in accordance with  claim 1 , wherein in step (4) the carbon nanotubes are removed from the substrate by using a blade.  
     
     
         12 . The method in accordance with  claim 2 , wherein the dispersant is select from ethanol or  1 - 2  dichloroethane.  
     
     
         13 . A method for manufacturing carbon nanotubes comprising steps as follows: 
 (1) providing a plurality of substrates in a furnace;    (2) depositing a catalyst material onto each of the substrates;    (3) exposing the catalyst material to a carbon containing gas for a predetermined period of time at a predetermined temperature such that an array of carbon nanotubes having a predetermined length grows from the substrate in a direction substantially perpendicular to the substrate; and    (4) removing the carbon nanotubes from the substrate.    
     
     
         14 . The method in accordance with  claim 13 , wherein said substrates are upwardly obliquely arranged along a lengthwise direction of the furnace and in a parallel relation with one another, and commonly facing toward an entrance of the furnace where the gas comes in.