Production of high purity ultrafine metal carbide particles

• US 7,438,880 B2
• Filed: 12/20/2006
• Issued: 10/21/2008
• Est. Priority Date: 12/20/2006
• Status: Active Grant

• Current Assignee: PPG Industries Ohio Incorporated (Nouryon BV)
• Original Assignee: PPG Industries Ohio Incorporated (Nouryon BV)
• Inventors: Hung, Cheng-Hung, Vanier, Noel R.
• Primary Examiner(s): LANGEL, WAYNE A
• Application Number:
  US11/613,551
• Publication Number:
  US 20080148905A1
• Time in Patent Office: 671 Days
• Field of Search: 423/291, 423/440, 423/441, 423/345, 423/439, 422/186
• US Class Current: 423/291
• CPC Class Codes: B01J 19/088 giving rise to electric discharges for heating purposes H05B7/00; for the production of ozone C01B13/11, H01T19/00
• CPC Class Codes: B01J 2219/0871 Heating or cooling of the reactor
• CPC Class Codes: B01J 2219/0875 Gas
• CPC Class Codes: B01J 2219/0877 Liquid
• CPC Class Codes: B01J 2219/0894 Processes carried out in the presence of a plasma
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01B 32/90 Carbides
• CPC Class Codes: C01B 32/956 Silicon carbide
• CPC Class Codes: C01B 32/984 Preparation from elemental silicon
• CPC Class Codes: C01B 32/991 Boron carbide
• CPC Class Codes: C04B 2235/3821 Boron carbides
• CPC Class Codes: C04B 2235/5454 nanometer sized, i.e. below 100 nm
• CPC Class Codes: C04B 35/56 based on carbides or oxycarbides containing free metal binder C22C29/00
• CPC Class Codes: C04B 35/563 based on boron carbide
• CPC Class Codes: C04B 35/62665 Flame, plasma or melting treatment

Abstract

The production of ultrafine metal carbide powders from solid metal carbide and nitrogen-containing material is disclosed. The starting materials are fed together or separately to a plasma system where the solid metal carbide is melted and/or vaporized in the presence of nitrogen to form ultrafine metal carbide particles of high purity.

Claims

1. A method for making ultrafine metal carbide particles comprising:

introducing a solid metal carbide and a nitrogen-containing material into a plasma;

heating the solid metal carbide and nitrogen-containing material by the plasma to form ultrafine particles of the metal carbide; and

collecting the ultrafine metal carbide particles.

2. The method of claim 1, wherein the nitrogen-containing material is provided in the form of a nitrogen compound.

3. The method of claim 2, wherein the nitrogen-containing material comprises urea, ureaform, urazole, ammonium acetate, N-N-dimethylformamide, methylformamide, methylhydrazine, formamide, ethylenediamine, methylamine and/or ammonia.

4. The method of claim 1, wherein the nitrogen-containing material is solid.

5. The method of claim 4, wherein the solid nitrogen-containing material comprise urea.

6. The method of claim 4, wherein the solid nitrogen-containing material has an average particle size of from 10 micron to 1,000 microns.

7. The method of claim 1, wherein the solid metal carbide comprises boron carbide.

8. The method of claim 1, further comprising mixing the solid metal carbide and nitrogen-containing material before the introduction into the plasma.

9. The method of claim 1, further comprising contacting the solid metal carbide and nitrogen-containing material with a carrier gas before the introduction into the plasma.

10. The method of claim 1, further comprising introducing an additional reactant into the plasma.

11. The method of claim 10, wherein the additional reactant comprises a metal of the metal carbide.

12. The method of claim 11, wherein the metal is boron.

13. The method of claim 10, wherein the additional reactant comprises silicon.

14. The method of claim 13, wherein the silicon is introduced into the plasma in the form of SiC.

15. The method of claim 1, wherein the ultrafine metal carbide particles have an average particle size of less than 100 nm.

16. The method of claim 1, wherein the ultrafine metal carbide particles comprise B₄C, B₁₃C₂, B₈C, B₁₀C and/or B₂₅C.

17. The method of claim 1, wherein the ultrafine boron carbide particles comprise B₄C.

18. The method of claim 17, wherein the ultrafine B₄C particles include less than 5 weight percent oxide impurities.

19. An apparatus for making ultrafine metal carbide particles comprising:

a source of solid metal carbide;

a source of nitrogen-containing material;

a plasma chamber; and

at least one feed line for delivering the solid metal carbide and nitrogen-containing material to the plasma chamber.

20. The apparatus of claim 19, wherein the nitrogen-containing material is solid.

21. The apparatus of claim 19, further comprising at least one carrier gas feed line for delivering a carrier gas to the plasma chamber.

22. The apparatus of claim 19, further comprising means for collecting the ultrafine metal carbide particles.