US Patent 7202586 - Carbon nanofiber electrical contact brush material

http://www.freepatentsonline.com/7202586.html

Metal-graphite brushes are common contact elements in motors. However, due to the constant friction with which the contacts undergo they gradually wear out. This patent from Shinano uses carbon nanofibers (or nanotubes) that protrude from a contact surface to reduce such wear. Claim 1 reads:

1. An electrical contact member, comprising: at least one from conductive metal particles and conductive metal fibers; and carbon nanofibers or carbon nanotubes embedded at least partially into the at least one from the conductive metal particles and the conductive metal fibers such that at least a portion of the carbon nanofibers or the carbon nanotubes protrudes from outer circumferential surfaces of the at least one from the conductive metal particles and the conductive metal fibers, wherein the at least one from the conductive metal particles and the conductive metal fibers having the embedded carbon nanofibers or the carbon nanotubes form a contact layer of the electrical contact member through which current flows.