US Patent 8178006 - Nanofiber aggregate

http://www.freepatentsonline.com/8178006.html

This patent from Denso Corporation teaches a heat treatment of electrically conductive carbon nanofibers to create an outer insulating layer of boron nitride nanofibers. Claim 1 reads:

1. An electrically conductive carbon wire comprising a fiber aggregate, wherein:

fine carbon fibers form a core portion of the fiber aggregate; and

fine boron nitride fibers, which are formed by substituting carbon atoms of the fine carbon fibers by boron atoms and nitrogen atoms, form an outer layer portion of the fiber aggregate.