The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 24, 1997
Filed:
Jun. 02, 1994
Applicant:
Inventors:
Assignee:
NEC Corporation, Tokyo, JP;
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
C01B / ; D01F / ;
U.S. Cl.
CPC ...
4234472 ; 4234 / ; 4234471 ; 423461 ;
Abstract
A mixture of carbon nanotubes and impurity carbon materials, which include carbon nanoparticles and may possibly include amorphous carbon, is purified into carbon nanotubes of high purity by utilizing a significant difference in oxidizability between the nanotubes and the nanoparticles. The mixture is pulverized and heated in the presence of an oxidizing agent at a temperature in the range from 600.degree. to 1000.degree. C. until the impurity carbon materials are oxidized and dissipated into gas phase. The nanotubes remain almost unoxidized except for loss of some lengths from the tube tips. It is suitable to perform the heating in air or oxygen.