Continuous method for producing inorganic nanotubes

• US 20060165914A1
• Filed: 04/03/2002
• Published: 07/27/2006
• Est. Priority Date: 04/03/2002
• Status: Abandoned Application

• Current Assignee: Canterprise Limited (University of Canterbury)
• Original Assignee: Canterprise Limited (University of Canterbury)
• Inventors: Abrahamson, John
• Application Number:
  US10/509,721
• Publication Number:
  US 20060165914A1
• Time in Patent Office: Days
• US Class Current: 427/580
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: C01B 2202/02 Single-walled nanotubes
• CPC Class Codes: C01B 2202/36 Diameter
• CPC Class Codes: C01B 32/162 characterised by catalysts
• CPC Class Codes: C01B 32/164 involving continuous processes
• CPC Class Codes: D01F 9/12 Carbon filaments; Apparatus specially adapted for the manufacture thereof
• CPC Class Codes: Y10S 977/742 Carbon nanotubes, CNTs
• CPC Class Codes: Y10S 977/844 Growth by vaporization or dissociation of carbon source using a high-energy heat source, e.g. electric arc, laser, plasma, e-beam

Abstract

Production of nanotubes of carbon or of other inorganic material by moving a carbon-containing substrate (8), such as a tape or belt of carbon fibres, within a reaction chamber (1) either through an electric arc in a gap between two electrodes (2, 3) or adjacent an electrode so that an electric arc exists between the electrode and the substrate, to cause the nanotubes to form on the substrate (8). The method enables the continuous or semi-continuous production of nanotubes. Preferably, the process is carried out at atmospheric pressure and nanotubes of high purity are produced.

Claims

1. A method for producing nanoscale hollow inorganic fibrils or nanotubes, including moving a carbon-containing substrate within a reaction chamber either through an electric arc in a gap between two electrodes or adjacent an electrode so that an electric arc exists between the electrode and the substrate, to cause the nanotubes to form on the substrate.

2. A method according to claim 1 including moving the substrate at a substantially steady speed through the arc.

3. A method according to claim 1 including moving the substrate through the arc in steps.

4. A method according to claim 1 wherein at least one electrode is a carbon containing electrode.

5. A method according to claim 4 wherein the substrate is composed of carbon fibres.

6. A method according to claim 5 wherein the substrate is a tape or belt woven from carbon fibres.

7. A method according to claim 5 wherein the substrate is a paper of carbon fibres.

8. A method according to claim 1 including tensioning the substrate against the anode of the electrodes.

9. A method according to claim 1 including moving the substrate at a speed such that the substrate has a residence time in the arc of at least three seconds.

10. A method according to claim 1 including moving the substrate at a speed of less than 5 mm per second.

11. A method according to claim 1 wherein the arc current is sufficiently low to form nanotubes on the substrate but avoid structural damage to the substrate.

12. A method according to claim 1 wherein the arc current is set at a level which causes some vaporisation of the substrate without structurally damaging the substrate.

13. A method according to claim 1 wherein the arc has a current density in the range 0.1 to 1 Amps/mm2.

14. A method according to claim 1 wherein a catalyst is present which will favour the production of single wall nanotubes.

15. A method according to claim 1 including flushing a gas through the reaction chamber which contains sufficient oxygen to react with other species without oxidising the nanotubes on cool down.

16. A method according to claim 1 including directing a flow of gas to cool one or both of the electrodes and/or the substrate.

17. A method according to claim 1 including directing a flow of gas onto the substrate after it has passed through the arc to cool the substrate and/or clear it of carbon vapour.

18. A method according to claim 1 wherein the nanotubes are carbon nanotubes.

19. A method according to claim 1 wherein the electrodes and the substrate have a carbon purity in excess of 99.5%.

20. A method according to claim 1 wherein the nanotubes are composed of BC₂N and/or BC₃.

22. Carbon nanotubes formed by the method of any one of claims 1 to 21.

23. A method according to any one of claims 1 to 21 wherein a power supply which supplies the arc current has a rms voltage ripple of less than 1 volt and current ripple of less than 0.5 Amps.

21. A method of producing nanoscale hollow carbon fibrils or nanotubes, comprising moving a tape or belt composed of carbon filaments having a carbon purity in excess of 99.5% through an electric arc in a gap between two carbon containing electrodes having a carbon purity in excess of 99.5% at a speed sufficient relative to the arc current to form carbon nanotubes on the fibres or filaments of the substrate without damaging the substrate.