Method of using copper alloy substrate for growing carbon nanotubes

Abstract

A method of using copper alloy substrate for growing carbon nanotubes, wherein copper is used as the base for copper matrix, and catalysts (ferrum, cobalt, and nickel) are dissolved in the copper matrix to form an alloy substrate. During the course of production for the carbon nanotube, the alloy substrate is positioned on the sample holder of the chamber, and the mechanical pump is used to extract the air pressure of the chamber under 10-3 torrs, and then the reaction gas is introduced into the chamber, and the total pressure is maintained at about 3 torrs. The reaction temperature of the alloy substrate at 850˜950° C. is provided by a heat-resistant tungsten fuse, and then preliminary dissociation of the reaction gas before introduced into the chamber is provided by a microwave generator. Furthermore, a radio frequency generator functions at a rate of 100˜600 W to completely dissociate the reaction gas and produces a self bias at −150V˜−450V to direct the straight growth and maintain the steady growth for 20 minutes for the carbon nanotube.

1 . A method of using copper alloy substrate for growing carbon nanotubes, which comprises the following steps: 
 (a) dissolving the catalyst metals to form an alloy substrate in a copper metal matrix;    (b) grinding the alloy substrate with a sand paper to from a reaction region on the surface of the alloy substrate;    (c) setting the alloy substrate on the top of the sample holder in the radio frequency assisted hot filament chemical vapor deposition reaction chamber;    (d) maintaining the reaction temperature of the alloy substrate with a tungsten hot filament;    (e) proceeding with a preliminary dissociation action on the reaction gas entering into the reaction chamber with a microwave generator;    (f) producing a self bias at a rate of −150V˜− 450 V with a radio frequency generator;    (g) forming the nanoscale catalyst particles in the reaction region with hydrogen etching;    (h) a method of growing carbon nanotubes in the reaction region with carbon atoms;    wherein the reaction gas comprises diluted gas (hydrogen) and carbon source gas (methane); first of all, 80 sccm of hydrogen gas is introduced into the reaction chamber and raise the reaction temperature for the alloy substrate inside the reaction chamber to a temperature of 850˜950° C. using heat generated from a tungsten hot filament; proceeding with the hydrogen etching after maintaining time for a while, carbon source of gas is then introduced, and the procedure of introducing the carbon source gas is as follows: 30 sccm of carbon source gas (methane) is introduced first, and then additional amount is added consecutively at a rate of 10 sccm/2 min until reaching an amount of 60 sccm and sustaining the growth time for 20 minutes.    
     
     
         2 . The method of using copper alloy substrate for growing carbon nanotubes according to  claim 1 , wherein the components of the alloy substrate is 80 wt % copper—20 wt % ferrum.  
     
     
         3 . The method of using copper alloy substrate for growing carbon nanotubes according to  claim 1 , wherein the components of the alloy substrate is 80 wt % copper—20 wt % cobalt.  
     
     
         4 . The method of using copper alloy substrate for growing carbon nanotubes according to  claim 1 , wherein the components of the alloy substrate is 80 wt % copper—20 wt % nickel.  
     
     
         5 . The method of using copper alloy substrate for growing carbon nanotubes according to  claim 1 , wherein the components of the alloy substrate is 70 wt % copper—10 wt % ferrum—10 wt % cobalt—10 wt % nickel.  
     
     
         6 . The method of using copper alloy substrate for growing carbon nanotubes according to  claim 1 , wherein the frequency of the radio frequency generator is at 13.56 MHz and the work rate is  100˜600 W.    
     
     
         7 . The method of using copper alloy substrate for growing carbon nanotubes according to  claim 6 , wherein the radio frequency generator can completely dissociate the reaction gas and produce plasma to generate a self bias at −50˜−550V contrasting to the ground from the holder in the reaction region.  
     
     
         8 . The method of using copper alloy substrate for growing carbon nanotubes according to  claim 1 , wherein after addition of 80 sccm hydrogen gas alone into the reaction chamber and raise the reaction temperature to 850˜950° C., hydrion will etch the surface of the alloy substrate.  
     
     
         9 . The method of using copper alloy substrate for growing carbon nanotubes according to  claim 8 , wherein when addition of hydrogen gas alone into the reaction chamber the atoms on the surface of the alloy substrate are rearranged due to the increase of the surface tension and because of the activation affected by the bombardment of the hydrion on the atoms on the surface and the strong reduction effect; hence, the catalysts on the surface of the alloy substrate will exist in nanoscale particles.  
     
     
         10 . The method of using copper alloy substrate for growing carbon nanotubes according to  claim 1 , wherein adjust the size of catalysts being nano-refined by controlling the length of the hydrogen etching time of the alloy substrate, to further control the size of diameters of the carbon nanotubes grown from the carbon atoms dissolved and precipitated thereafter.