Title of Invention

"A PORTABLE ARC REACTOR USEFUL FOR PRODUCING MATERIALS SUCH AS FULLERENES AND CARBON NANOTUBES"

Abstract

A portable are reactor useful for producing materials such as fullerenes and carbon nanotubes, which comprises an electrode assembly, characterised in that the said electrode assembly essentially consisting of an anode (20) and cathode (18) mounted on an electrode support (17) by means of feeder springs (15), the said feeder springs (15) being provided at the free ends with removably fixed power connectors (14) connected to a DC power source (5) through a switch (6) and means (12,13,10) such as flexible connectors (12) and insulation( 16,11) connecting studs(13,10); the said electrode assembly being fixed by means of said studs (10) on to a rigid base (1), the said base mounted electrode assembly being provided with a removable copper dome(3), the said copper dome enclosed electrode assembly being enclosed in a glass dome (2) having a peripheral leak-proof gasket (4) and placed on to the said rigid base (1), the rigid base (1) being provided with means such as vacuum line (8), vacuum gauge(7) and gas inlet (9).

Full Text

The present invention relates to a portable arc reactor useful for producing materials such as fullerenes and carbon nanotubes. The present invention relates to the development of a portable arc reactor useful for producing exotic materials that require high temperature and controlled atmosphere. The main usage of the invention is in the field of production of materials such as fullerenes and carbon nanotubes that require high temperatures and controlled atmospheres. Hitherto many reactors have been proposed to produce fullerenes. Huffman et al (Nature 347, 354, 1990) proposed a water-cooled chamber to deposit fullerenes by evaporating fine graphite filaments. This process had the drawback that the filaments were fragile and power dissipation was localized leading to non-uniform evaporation of the filament. Haufler et al (J. Phys. Chem. 94, 8634, 1990) have proposed "contact-arc" method inside a water- cooled reactor wherein a graphite anode of 6mm diameter was fed horizontally using a flexible copper braid to maintain required pressure on the anode. The typical drawback of the setup was the melting of the copper braid. To provide a constant feeding pressure on the anode, a vertical gravity feed setup was proposed (A S Koch et al-J. Org. Chem. 56,4543, 1991). This technique had the drawback in that the anode would stick to the cathode base electrode and the entire rod would become a heated filament. As an improvement, continuous arcing was suggested wherein the electrodes were fed from outside the reactor vessel. Continuous arcing at high temperatures requires cooling of the electrodes and the vacuum chamber. Also in case of the spring - loaded anodes the length of the anode consumed is less depending on the length and tension of the feeder spring. In addition the dismantling of the chamber to collect the soot and again assembling it is a cumbersome and time- consuming process. The main object of the present invention is to provide a portable arc reactor useful for producing materials such as fullerenes and carbon nanotubes , which obviates the above noted drawbacks. Another object of the present invention is to provide a portable arc reactor useful for producing exotic materials by incorporating pulse arc technique that avoids the necessity of cooling. Yet another object of the present invention is to feed additional length of anode per single loading by using feeder springs to mount both anode and cathode. Still another object of the present inventidrHs to provide a light-weight copper dome for depositing fullerene soot inside a glass vacuum chamber thus providing a simple and easy method to collect the fullerene soot and to re-assemble the arc vessel without difficulty. The arc reactor of the present invention is a portable equipment useful for producing materials such as fullerenes and carbon nanotubes at high temperatures under controlled atmospheres. It consists of an electrode assembly with feeder springs, an external power source, a vacuum pumping and measuring system, a copper dome on which material deposits, a glass vacuum chamber and a switch to operate the arcing process with periodic interruptions to provide pulse arcing, which avoids cooling of electrodes and vacuum chamber. The reactor has been used to produce fullerenes by arcing graphite electrodes of different diameters in helium atmosphere. The fullerene soot deposits on a copper dome placed surrounding the electrode assembly from which its collection becomes simple. Since the whole system is built inside a glass vacuum chamber its dismantling and assembling becomes very easy. In the drawing accompanying this specification figure 1 represents the arc reactor of the present invention for producing materials such as fullerenes and carbon nanotubes. It consists of a glass dome (2) placed on a metal base (1) with a neoprene gasket (4). A copper dome (3) inside which the soot is deposited is placed inside the glass dome (2). A dc power source (5) is connected to the electrode assembly through a switch (6) and brass studs (10) that are insulated from the chamber with the help of ceramic insulators (11). Provision is also made to connect vacuum gauge (7), pumping line (8) and a gas inlet (9). The anode (20) and cathode (18) are mounted on an electrode support (17) with the help of feeder springs (15). Power is supplied to the eTertrbddis'through flexible power connectors (12,14) and means (13,16) with proper insulation. A hole (21) is provided in the copper dome to observe the arcing process during the production. The present invention relates to the development of a portable arc reactor useful for producing exotic materials such as fullerenes and carbon nanotubes. The arc reactor consists in combination an electrode assembly with feeder springs, a copper dome on which the soot deposits, a glass dome to create vacuum under controlled atmosphere, a vacuum line with pumping and measuring system, a gas inlet for creating inert atmosphere and a switch to interrupt the arcing process periodically thus avoiding the necessity for cooling the electrodes and the chamber. provides a portable arc reactor useful for producing materials such as fullerenes and carbon nanotubes, which comprises an electrode assembly, characterised in that the said electrode assembly essentially consisting of an anode (20) and cathode (18) mounted on an electrode support (17) by means of feeder springs (15), the said feeder springs (15) being provided at the free ends with removably fixed power connectors (14) connected to a DC power source (5) through a switch (6) and means (12,13,10) such as flexible connectors (12) and insulation(16,ll) connecting studs(13,10); the said electrode assembly being fixed by means of said studs (10) on to a rigid base (1), the said base mounted electrode assembly being provided with a removable copper dome(3), the said copper dome enclosed electrode assembly being enclosed in a glass dome (2) having a peripheral leak-proof gasket (4) and placed on to the said rigid base (1), the rigid base (1) being provided with means such as vacuum line (8), vacuum gauge(7) and gas inlet (9). In an embodiment of the present invention the electrodes are such as graphite electrodes. In another embodiment of the present invention the de power source is of voltage in the range of 0 to 20V and capable of providing arcing current in the range of 0 to 100A. In still another embodiment of the present invention the switch is capable of periodic interruptions in the de power supply to provide pulse arcing. In a further embodiment of the present invention the copper dome is provided with an arc observation opening (11). In another embodiment of the present invention the glass dome, with peripheral leak proof gasket, placed on the rigid base, is a vacuum chamber. The following paragraph gives details of process steps to be followed while using the arc reactor of the present invention. Clean graphite rods are mounted on the electrode assembly with the help of the feeder springs. The copper dome is cleaned, degreased and placed around the electrode assembly. The glass dome with the neoprene gasket is placed surrounding the copper dome. Rotary pump is switched on till the pressure falls below 10 ~2 millibar. Evacuation is stopped and the chamber is flooded with helium gas to attain predetermined pressure in the range of 300 to 400 millibar. The process of evacuation and flooding is repeated three times to get a clean helium atmosphere inside the reactor chamber. The chamber is filled ' •"•-•*•' *"-'" ' with helium gas to required pressure in the range 'tif 100 to'300 millibar. The dc power source is switched on and the voltage adjusted to the required level in the range of!6 to 20V to obtain arcing current in the range of 50 to 100A. Operating the switch at specified time intervals (2 seconds on and 10 seconds off) starts the production process. After completing the production process the chamber is allowed to cool. Air is admitted to the chamber to break the vacuum. The copper dome is removed from the chamber and the fullerene soot is collected using a soft brush. The novelty of the arc reactor of the present invention, useful for producing materials such as fullerenes and carbon nanotubes resides in that it is portable, does not need cooling of chamber and electrodes, easy to use and maintain and provides higher yield per production run. These have been made possible by the non-obvious inventive combination of electrode assembly with feeder springs, copper dome, glass dome vacuum chamber and switch to operate the arcing process with periodic interruptions to provide pulse arcing. The following examples are given by way of illustration of the present invention and therefore should not be construed to limit the scope of the present invention. Example 1 The reactor chamber was thoroughly cleaned and all parts were degreased using acetone. Electrode assembly was mounted on the support. A clean graphite rod of 6mm diameter was mounted on cathode holder. Another graphite rod of 3 mm diameter was mounted on anode holder of the electrode assembly. Both anode and cathode were aligned and tensioned using the respective feedef springS.'The cleaned and degreased copper dome was placed around the electrode assembly. The glass dome with the neoprene gasket was placed surrounding the copper dome. Rotary pump was switched on and the chamber was evacuated below a pressure of 10"2 millibar. Then evacuation was stopped and the chamber was flooded with helium gas to attain pressure of 350 millibar. The process of evacuation and flooding was repeated three times to get a clean helium atmosphere inside the reactor chamber. Finally the chamber was filled with helium gas having pressure of 100 millibar. The dc power was switched on and voltage was adjusted to 18 volts. The switch was kept on for two(2) seconds to start the arcing process and kept off for ten(10) seconds, that is the switch was operated on a schedule of 2 seconds on and 10 seconds off to provide periodic interruptions and cause the desired pulse arcing. The arcing current noted was 55 amperes. After the arcing was complete the chamber was allowed to cool. Air was admitted to the chamber to break the vacuum. The copper dome was removed from the chamber and the fullerene soot was collected using a soft brush. The main process parameters and fullerene yield was as follows: Anode diameter: 3 mm Cathode diameter Helium pressure: Set voltage: Arcing current: Fullerene yield: 6 mm lOOmbar 18V 55 Amps. 9.5% Example 2 The reactor chamber was thoroughly cleaned and all parts were degreased using acetone. Electrode assembly was mounted on the support. A clean graphite rod of 6mm diameter was mounted on cathode holder. Another graphite rod of 4 mm diameter was mounted on anode holder of the electrode assembly. Both anode and cathode were aligned and tensioned using the respective feeder springs. The cleaned and degreased copper dome was placed around the electrode assembly. The glass dome with the neoprene gasket was placed surrounding the copper dome. Rotary pump was switched on and the chamber was evacuated below a pressure of 10"2 millibar. Then evacuation was stopped and the chamber was flooded with helium gas to attain pressure of 350 millibar. The process of evacuation and flooding was repeated three times to get a clean helium atmosphere inside the reactor chamber. Finally the chamber was filled with helium gas having pressure of 250 millibar. The dc power was switched on and voltage was adjusted to ' 20 volts. The switch was kept on for two(2) seconds to start the arcing process and kept off for ten(10) seconds, that is the switch was operated on a schedule of 2 seconds on and 10 seconds off to provide periodic interruptions and cause the desired pulse arcing. The arcing current noted was 60 amperes. After the arcing was complete the chamber was allowed to cool. Air was admitted to the chamber to break the vacuum. The copper dome was removed from the chamber and the fullerene soot was collected using a soft brush. The main process parameters and fullerene yield was as follows: Anode diameter: ''**'4 mlrf Cathode diameter 6 mm Helium pressure: 250 mbar Set voltage: 20 V Arcing current: 60 Amps. Fullerene yield: 6.27% Example 3 The reactor chamber was thoroughly cleaned and all parts were degreased using acetone. Electrode assembly was mounted on the support. A clean graphite rod of 6mm diameter was mounted on cathode holder. Another graphite rod of 6 mm diameter was mounted on anode holder of the electrode assembly. Both anode and cathode were aligned and tensioned using the respective feeder springs. The cleaned and degreased copper dome was placed around the electrode assembly. The glass dome with the neoprene gasket was placed surrounding the copper dome. Rotary pump was switched on and the chamber was evacuated below a pressure of 10"2 millibar. Then evacuation was stopped and the chamber was flooded with helium gas to attain pressure of 350 millibar. The process of evacuation and flooding was repeated three times to get a clean helium atmosphere inside the reactor chamber. Fftrafly tile-chamber was filled with helium gas having pressure of 300 millibar. The dc power was switched on and voltage was adjusted to 18 volts. The switch was kept on for two(2) seconds to start the arcing process and kept off for ten(10) seconds, that is the switch was operated on a schedule of 2 seconds on and 10 seconds off to provide periodic interruptions and cause the desired pulse arcing. The arcing current noted was 90 amperes. After the arcing was complete the chamber was allowed to cool. Air was admitted to the chamber to break the vacuum. The copper dome was removed from the chamber and the fullerene soot was collected using a soft brush. The main process parameters and fullerene yield was as follows:Cathode diameter 6 mm Helium pressure: 300 mbar Set voltage: 18V Arcing current: 90 Amps. Fullerene yield: 7.9% Example 4 The reactor chamber was thoroughly cleaned and all parts were degreased using acetone. Electrode assembly was mounted on the support. A clean graphite rod of 6mm diameter was mounted on cathode holder. Another graphite rod of 4 mm diameter was mounted on anode holder of the electrode assembly? Both anode and cathode were aligned and tensioned using the respective feeder springs. The cleaned and degreased copper dome was placed around the electrode assembly. The glass dome with the neoprene gasket was placed surrounding the copper dome. Rotary pump was switched on and the chamber was evacuated below a pressure of 10"2 millibar. Then evacuation was stopped and the chamber was flooded with helium gas to attain pressure of 350 millibar. The process of evacuation and flooding was repeated three times to get a clean helium atmosphere inside the reactor chamber. Finally the chamber was filled with helium gas having pressure of 150 millibar. The dc power was switched on and voltage was adjusted to 16 volts. The switch was kept on for two(2) seconds to start the arcing process and kept off for ten(10) seconds, that is the switch was operated on a schedule of 2 seconds on and 10 seconds off to provide periodic interruptions and cause the desired pulse arcing. The arcing current noted was 60 amperes. After the arcing was complete the chamber was allowed to cool. Air was admitted to the chamber to break the vacuum. The copper dome was removed from the chamber and the fullerene soot was collected using a soft brush. The main process parameters and fullerene yield was as follows: Anode diameter: 4 mm Cathode diameter 6 mm Helium pressure: 150 mbar Set voltage: 16V Arcing current: 60 Amps. Fullerene yield: 8.5% The main advantages of the present invention are: 1. The arc reactor is portable. 2. The interrupted / pulse arcing avoids the necessity to cool the electrodes and the chamber. 3. Use of double feeder springs facilitate to consume greater length of anode producing higher yield per production run. 4. Collection of soot is easy as the deposition takes place on the polished copper surface. 5. Dismantling and setting up of the arc reactor is easy as the whole system is enclosed in a glass vacuum chamber. We claim: 1. A portable arc reactor useful for producing materials such as fullerenes and carbon nanotubes, which comprises an electrode assembly, characterised in that the said electrode assembly essentially consisting of an anode (20) and cathode (18) mounted on an electrode support (17) by means of feeder springs (15), the said feeder springs (15) being provided at the free ends with removably fixed power connectors (14) connected to a DC power source (5) through a switch (6) and means (12,13,10) such as flexible connectors (12) and insulation(16,l 1) connecting studs(13,10); the said electrode assembly being fixed by means of said studs (10) on to a rigid base (1), the said base mounted electrode assembly being provided with a removable copper dome(3), the said copper dome enclosed electrode assembly being enclosed in a glass dome (2) having a peripheral leak-proof gasket (4) and placed on to the said rigid base (1), the rigid base (1) being provided with means such as vacuum line (8), vacuum gauge(7) and gas inlet (9). 2. A portable arc reactor as claimed in claim 1, wherein the electrodes are such as graphite electrodes. 3. A portable arc reactor as claimed in claims 1-2, wherein the DC power source is of voltage in the range of 0 to 20V and capable of providing arcing current in the range of 0 to 100A. 4. A portable arc reactor as claimed in claims 1-3, wherein the switch is providing periodic interruptions in the dc power supply to provide pulse arcing. 5. A portable arc reactor as claimed in claims 1-4, wherein the copper dome is provided with an arc observation opening (21). 6. A portable arc reactor as claimed in claims 1-5, wherein the glass dome, with peripheral leak-proof gasket, placed on the rigid base, is a vacuum chamber. 7. A portable arc reactor useful for producing materials such as fullerenes and carbon nanotubes, substantially as herein described with reference to the examples and drawing accompanying this specification.

Documents:

773-DEL-2002-Abstract-(19-08-2008).pdf

773-DEL-2002-Abstract-(28-08-2008).pdf

773-del-2002-abstract.pdf

773-DEL-2002-Claims-(19-08-2008).pdf

773-DEL-2002-Claims-(28-08-2008).pdf

773-del-2002-claims.pdf

773-DEL-2002-Correspondence-Others-(19-08-2008).pdf

773-del-2002-correspondence-others.pdf

773-del-2002-correspondence-po.pdf

773-DEL-2002-Description (Complete)-(28-08-2008).pdf

773-del-2002-description (complete)-19-08-2008.pdf

773-del-2002-description (complete).pdf

773-del-2002-drawings.pdf

773-DEL-2002-Form-1-(19-08-2008).pdf

773-del-2002-form-1.pdf

773-DEL-2002-Form-18-(28-08-2008).pdf

773-del-2002-form-18.pdf

773-del-2002-form-2.pdf

773-DEL-2002-Form-3-(19-08-2008).pdf

773-del-2002-form-3.pdf