How do you replace all that copper wiring?

Researchers at Yazaki's California r&d subsidiary, YTC America, are developing automotive wiring that offers the advantages of copper and aluminum while cutting the weight of traditional systems.

Vehicles can contain 30 to 60 pounds of copper, and automakers would like to replace the copper in wires with aluminum because of the potential for cost and weight savings — so long as it doesn't reduce electrical conductivity and tensile strength.

The raw material cost of an aluminum wire is only about 15 percent of that of copper wire, but aluminum offers only 60 percent of copper wire's conductivity. And the tensile strength of aluminum is just 25 to 30 percent of that of copper.

Yazaki, a leading supplier of vehicle wire harnesses, proposes a new approach that adds small amounts of carbon nanotubes — microscopically fine strands of carbon — to aluminum to give it greater strength and enhanced conductivity. Yazaki said that through an extrusion process developed by YTC America, it can create aluminum wire rods that are stronger than extruded aluminum rods.

"By drawing the rods down to fine wire, the strength increases further, hardening to a strength similar to copper wire," said Stefan Maat, YTC America director of materials r&d. "In fact, it exhibits a strength surpassing that of steel."

Maat said the carbon nanotube material also has more heat resistance than aluminum. Unlike aluminum wires, which can only be operated at slightly elevated temperature, Maat said aluminum carbon nanotube material shows the high heat resistance needed for electric vehicle battery cables that operate at high currents.