Carbon fiber slowly gaining in cars

imagesCAR3B8T9With the administration’s goal to increase automobile fleet mileage standards appreciatively over the next decade, it will be necessary to substantially reduce the weight of cars, which are still largely made of steel. Weight reduction will be essential, since engine efficiency will only be improved in small steps. Carbon fiber-based structural composites, where the fibers are embedded in a matrix of resins,  are lighter and ten times stronger than steel and this material is the obvious answer.

Carbon fiber is now broadly used for advanced airplane bodies and other components (e.g. in the Boeing Dreamliner) and in expensive automobiles like Ferraris and Lamborghinis. As a reference point, carbon fiber is priced around $15 per pound versus steel at less than a dollar per pound.  Thus, cost has so far kept carbon fiber composites out of the mass automobile market. If carbon fiber can be made at a price around $ 5 per pound, the economics become feasible.

All high strength carbon fiber is made from polyacrylonitrile, which accounts for their current high cost. Efforts by both the public and private sector have so far not succeeded in using a much less expensive raw material, such as lignin from wood.

Nevertheless, carbon fiber is starting to make inroads in automobile design.  The 2014 Chevroet Corvette and the 2013 SRT Viper have carbon steel hoods and other parts. BMW is developing a carbon fiber passenger cell for its i3electric vehicle and the Alfa Romeo 4C sports car will have a carbon fiber chassis. None of these cars have or will have the “stratospheric” sticker price of supercars like the Ferrari or Lamborghini. Chrysler, which owns Alfa Romeo, says that substituting carbon fiber for steel for the hood reduces car weight by forty pounds.

Advances in manufacturing are also contributing. Using chopped instead of very long carbon fiber or mixing with fiberglass reduces the cost substantially while accepting loss of strength in car parts that do not require maximum performance. Using a pressure press instead of an autoclave has shortened the production time for the molded Corvette hood, making the process more suitable for mass production.

Watch firms like Cytec and Hexcel, who supply carbon fiber composites to the aerospace industry, to take the lead in this area. The car manufacturers are also teaming up, including GM, BMW, and others.

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2 Responses to Carbon fiber slowly gaining in cars

  1. Michael bennett says:

    Hi Peter!

    Your latest post rang a faint bell – a study we did in London for Burmah Oil around 1972 to identify opportunities for plastics in the car industry. We were very pessimistic as I recall, in the face of much ill placed optimism amongst the plastics and the carbon fibre suppliers.

    Got that one right!

    Best wishes,

    Mike

    P.S. And now I recall visiting VW on that project and suggesting they could use PU foam for seats to which the reply was “Zu teuer”. So I asked them what they preferred and they told me horse hair!!

  2. Peter says:

    Mike: It’s a new world for car materials now, with a need to substantially lighten body weight. Carbon fiber composites are the best answer. I feel sure that the Teijins of the world will find a way to reduce the cost, which obviously relates more to the processing of acrylonitrile (costs less than $ 1/lb) to PAN and spinning the fiber to obtain the high strength. Breakthroughs needed.

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