Researchers from Rice University and the University of Oulu in Oulu, Finland, have found that carbon nanotubes could significantly improve the performance of electrical commutators that are common in electric motors and generators.
The research, which appeared online this month in the journal Advanced Materials, finds that brush contact pads made of carbon nanotubes had 10 times less resistance than did the carbon-copper composite brushes commonly used today. Brush contacts are an integral part of commutators, or spinning electrical switches, used in many battery-powered electrical devices, such as cordless drills.
The combination of mechanical and electrical properties of nanotubes makes this possible. The carbon nanotubes used in the study are hollow tubes of pure carbon that are about 30 nanometers in diameter. (By comparison, a human hair is about 100,000 nanometers in diameter.) Nanotubes are extremely lightweight and durable, and they are excellent conductors of heat and electricity.
Because of these properties, the researchers decided to test nanotubes as brush contacts. Brush contacts are conducting pads held against a spinning metal disc or rod by spring-loaded arms. Current is passed from the spinning disc through the brush contacts to other parts of the device.
The team believes that the improved contact between the surface of the spinning disc and the brush accounts for the 90% reduction in lost energy.
– from greencarcongress