If the BMW i3 city car rolls out of your company’s Leipzig plant later this year, it will represent the initial carbon-fiber car that can be made in any quantity-about 40,000 vehicles annually at full output. The lightweight but sturdy nonmetallic structure of your new commuter car, the result of BMW’s joint venture with SGL Technologies in Wiesbaden, will mark a milestone in the creation of carbon-fiber-reinforced plastic (CFRP) materials, that have traditionally been expensive for usage in automotive mass production.
CFRPs are engineered materials which can be fabricated by embedding webs of carbon fiber inside molded polymer resins. The fibers bolster the physical properties from the plastic matrix component in the same way that a skeleton of steel rebar strengthens a poured-concrete structure.
While the i3 electric vehicle (EV) won’t exactly come cheap-estimates run from $40,000 to $50,000-BMW reportedly claims that forthcoming improvements in the production process through the next 3 to 5 years should cut CC composite costs enough to complement the ones from aluminum chassis, which still command a premium over standard steel car frames.
CFRP structures weigh half those of steel counterparts plus a third below aluminum ones. Add the inherent corrosion resistance of composites and also the ability of purpose-designed, molded components to cut parts counts by a factor of 10, as well as the appeal to automakers is clear. But despite the advantages of using CFRPs, composites cost far more than metals, even allowing for their lighter weight. The high prices have so far limited their use to high-performance vehicles like jet fighters, spacecraft, racecars, racing yachts, exotic sports cars, and notably, the newest Airbus and Boeing airliners.
Whereas steel applies to between $.80 and $1/kg, and aluminum costs between $2.40 and $2.60/kg, polyester and epoxy resins range from $5 to $15/kg and also the reinforcing fiber costs an additional $2 to $30/kg, according to quality. Make it possible for cars to clear the United states government’s fast-approaching 54.5-mpg average fuel-economy bar, automakers and their suppliers are striving to generate methods to produce affordable carbon-fiber cars around the mass-scale.
But adapting structural composites to low-cost mass production has long been a technical and manufacturing challenge, said Ross Kozarsky, Senior Analyst at Lux Research, a completely independent research and consulting firm that is focused on emerging technologies.
Kozarsky follows composite materials and led a report team that last year assessed CFRP manufacturing costs and identified potential innovations in each step in the complex process.
“Our methodology is always to follow, through visits and interviews, the whole value chain in the tow, yarn, and grade level onwards, examining the supplier structure along with the general market costs,” he explained. The Lux team then created a cost model that combines material, capital expenditure, infrastructure, labor, and utility consideration and also the chances for cost reductions.
While the sporting goods, military, and aerospace industries have traditionally developed and first applied composite materials, the pre-eminence of the segments regarding sales is ending, Kozarsky said. The wind-turbine business will deal with aerospace for the top market as larger, more-efficient offshore wind-power installations are designed.
“It’s less expensive to make use of bigger turbine blades, which can just be made using carbon-fiber materials,” he noted.
The Lux report predicted that the global niche for CFRPs will greater than double from $14.6 billion in 2012 to $36 billion in 2020, as innovative new production technologies lower carbon-fiber costs-the key cost-driver. In the same period, need for carbon fiber is expected to rise fourfold in the current 27,000 million ton (24,500 million t) to 110,000 million ton (99,800 million t).
Major suppliers of carbon fiber include Toray, Zoltek, Toho, Mitsubishi, Hexcel, Formosa Plastics, SGL Carbon, Cytec, AKSA, Hyosung, SABIC, and more than a dozen smaller Chinese companies.
“A great deal of folks are discussing automotive uses now, which is totally at the opposite end of your spectrum from aerospace applications, since it possesses a much higher volume and many more cost-sensitivity,” Kozarsky said. Following a slow start, the car industry will love the next-largest average industry segment improvement during the entire decade, growing at a 17% clip, in accordance with the Lux forecast.
The Lux analysis shows that CFRP technology remains expensive mainly because of high material costs-particularly the carbon-fiber reinforcements-in addition to slow manufacturing throughput, he reported.
“The industry has reached an interesting precipice,” he stated, wherein industrial ingenuity will vie with the traditional technical challenges to try to meet the new demand while lowering costs and speeding production cycle times.
The best-performing carbon fibers-the greater grades employed in defense and aerospace applications-start off as precisely what is called PAN (polyacrylonitrile) precursors. Due to the difficulty of the manufacturing process, PAN fibers cost about $21.5/kg, based on Kozarsky, who explained that makers subject the PAN to a number of thermal treatments where the material is polymerized and carbonized as it is stretched. The resulting “conversion” leaves the filaments oriented along the duration of the fiber allow it the perfect strength and toughness. Various post-processing stages and the surface-acting additives help ensure durability and “handleability.
Kozarsky singled out an industrial/government R&D collaboration at the new Carbon Fiber Technology Facility at Oak Ridge National Laboratory (ORNL), which was funded with $35 million in Usa Department of Energy money as one of the more promising efforts to decrease fiber costs. Portion of the project would be to identify cheaper precursor materials that could be processed into good-quality fibers (see “Oak Ridge collaborates for cheaper carbon fiber,”. The program is usually to test various types of potential low-cost fiber precursors like the cheaper polymers, inexpensive textiles, some made out of low-quality plant fibers or renewable natural fibers such as wood lignin, and melt-span PAN.
Near term the Lux team expects the task that ORNL has been doing with Portuguese acrylic-fiber maker FISIP (majority belonging to SGL) on textile-grade PAN to accomplish costs on the pilot-line scale of $19.3/kg in 2013. Although significant, it would be simply a modest reduction as compared to the 50% required for penetration in high-volume auto applications.
One of the major limitations of PAN, he was quoted saying, is “at best 2 kg of PAN yields 1 kg of carbon fiber, that gives that you simply conversion efficiency of only 50%.” Dow Chemical is investigating dexnpky63 polyolefins-polyethylene, polypropylene-as being the feedstock simply because they could offer potential conversion efficiencies of 70% to 75%. If mechanical performance targets could be met, pilot-line costs of $13.8/kg might be achieved by 2017, stated the report.
The Oak Ridge group, Kozarsky said, can also be concentrating on novel microwave-assisted plasma carbonization techniques that could produce useful, uniform fiber properties. And ORNL’s nonthermal plasma oxidation process can have the potential to stabilize and cross-link the precursor materials rapidly and efficiently.
Polyolefin-precursor carbon fiber, along with most of these alternative thermal-treatment mechanisms, should reduce costs to sub $11/kg at pilot-line scale in 2017, he noted. Kozarsky added that “there’s a great deal of fascination with improving the resin matrix at the same time,” with research centering on using thermoplastics as opposed to the existing thermosets and producing higher-toughness, faster-processing polymers.