Many automakers believe that the time to use carbon fiber composites in mass-produced cars has come, reports Marc S. Reisch in a cover story for Chemical & Engineering News. However, Reish writes, “if carbon fiber makers hope to gain more than a toehold in the auto market, they’ll have to make efforts on their own or with industry consortia to make composites more affordable.”
Making automobiles out of carbon fiber rather than steel is not a new idea. Car makers have been toying with the idea since the disco era, but only a few automakers now sell high-end, limited-production cars like the $3 million Lamborghini Siesto Elemento. One automaker told Reisch that the three important reasons expanding use of carbon fiber is that it is lightweight, has safety potential, and reduces the number of parts needed to assemble a car.
Reisch also reports that “automakers are increasingly looking to combine emission-limiting propulsion technologies with stiff, lightweight carbon composite frames.” “Their hope,” he writes, “is that the new components will replace steel and aluminum in the assembly of energy-efficient hybrid and all-electric vehicles.”
Carbon fiber is significantly more expensive than steel, but its lower weight becomes important in trying to make a car as fuel-efficient as possible. It is generally made from polymerizing acrylonitrile into polyacrylonitrile (PAN), which is extruded into fibers and carbonized. Those fibers are woven and formed into the shape of a desired part. Finally, that part is bonded together with epoxy or other resins.
Right now, more carbon fiber is used to make aerospace and sporting goods than cars, according to Anthony J. Roberts, an expert in carbon fiber technology who heads AJR Consultant. He told Chemical & Engineering News that talk about using carbon fiber is hype meant to make auto companies look environmentally responsible.
Roberts added that he expects that carbon fiber use will instead grow in markets such as turbine blades for offshore wind-energy projects, compressed natural-gas storage tanks, and components for deep-sea oil-drilling platforms. “How many people will really spend an extra $5,000 to $6,000 beyond the usual cost for a small car to own an electric car with a carbon composite body?” he asks.
Although Roberts is skeptical, several automakers are pushing ahead with plans to make carbon fiber composites an integral part of a new generation of electric cars intended mostly for inner-city use. They will be going beyond fiberglass composite body panels, already found in some cars, to create structural composite components that are now the province of metal.
In fact, Reisch mentions numerous automakers around the world that are teaming up with chemical companies to create the materials with the properties needed for building cars, whether that means tweaking the carbon content of the fibers, adjusting the chemistry of the epoxy resins, or making the production process an energy miser.
Even the U.S. government has been researching ways to improve carbon fiber since the 1990s. Oak Ridge National Laboratory is now involved in several projects related to cars, including developing polyethylene-based precursors. Reisch reports that the resulting fibers are strong enough for auto body panels but not structural components. Oak Ridge has also developed processes “to reduce the time and energy needed to make carbon fiber by a factor of two or three,” which could increase production time and lower cost, Reish writes.
Rachel Petkewich is a freelance science writer and editor. She has worked as a research scientist in the chemical industry and spent eight years as a staff writer and editor at various science journals and magazines, including Chemical & Engineering News.