Once the BMW i3 city car rolls from the company’s Leipzig plant later this year, it would represent the initial carbon-fiber car which will be made in any quantity-about 40,000 vehicles each year 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 growth of carbon-fiber-reinforced plastic (CFRP) materials, that contain traditionally been very costly to use in automotive mass production.
CFRPs are engineered materials which are 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 the skeleton of steel rebar strengthens a poured-concrete structure.
Even though i3 electric vehicle (EV) won’t exactly come cheap-estimates run from $40,000 to $50,000-BMW reportedly claims that forthcoming improvements from the production process during the next three to five years should cut carbon composite costs enough to match those of aluminum chassis, which still command a premium over standard steel car frames.
CFRP structures weigh half that relating to steel counterparts plus a third below aluminum ones. Add the inherent corrosion resistance of composites and the ability of purpose-designed, molded components to reduce parts counts by way of a factor of 10, and also the entice automakers is apparent. But despite the advantages of using CFRPs, composites cost considerably more than metals, even allowing for their lighter weight. The high prices have so far limited their use to high-performance vehicles including jet fighters, spacecraft, racecars, racing yachts, exotic sports cars, and notably, the most up-to-date Airbus and Boeing airliners.
Whereas steel is true of between $.80 and $1/kg, and aluminum costs between $2.40 and $2.60/kg, polyester and epoxy resins cover anything from $5 to $15/kg as well as the reinforcing fiber costs an extra $2 to $30/kg, based on quality. To permit cars to get rid of the U.S. government’s fast-approaching 54.5-mpg average fuel-economy bar, automakers along with their suppliers are striving to generate approaches to produce affordable carbon-fiber cars about the mass-scale.
But adapting structural composites to low-cost mass production happens to be a technical and manufacturing challenge, said Ross Kozarsky, Senior Analyst at Lux Research, an unbiased research and consulting firm that concentrates on emerging technologies.
Kozarsky follows composite materials and led a report team that this past year assessed CFRP manufacturing costs and identified potential innovations in each step in the complex process.
“Our methodology is to follow, through visits and interviews, the full value chain from the tow, yarn, and grade level onwards, examining the supplier structure along with the general market costs,” he explained. The Lux team then designed a cost model that mixes material, capital expenditure, infrastructure, labor, and utility consideration as well as the chances for cost reductions.
Although the sporting goods, military, and aerospace industries have traditionally developed and first applied composite materials, the pre-eminence of those segments with regards to sales is ending, Kozarsky said. The wind-turbine business will contend with aerospace for that top market as larger, more-efficient offshore wind-power installations are made.
“It’s more economical to utilize bigger turbine blades, that may just be made using carbon-fiber materials,” he noted.
The Lux report predicted how the global industry for CFRPs will over double from $14.6 billion in 2012 to $36 billion in 2020, as innovative new production technologies lower carbon-fiber costs-the major cost-driver. During the same period, interest in carbon fiber is predicted to go up fourfold from your 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 twelve smaller Chinese companies.
“A lot of individuals are talking about automotive uses now, which is totally in the other end of the spectrum from aerospace applications, since it features a better volume and much more cost-sensitivity,” Kozarsky said. Following a slow start, the auto industry will delight in the next-largest average industry segment improvement through the decade, growing in a 17% clip, based on the Lux forecast.
The Lux analysis indicates that CFRP technology remains expensive mainly because of high material costs-especially the carbon-fiber reinforcements-as well as slow manufacturing throughput, he reported.
“The industry has reached an intriguing precipice,” he stated, wherein industrial ingenuity will vie with the traditional technical challenges in order to satisfy the new demand while lowering costs and speeding production cycle times.
The most effective-performing carbon fibers-the bigger grades found in defense and aerospace applications-get started as what is called PAN (polyacrylonitrile) precursors. Due to difficulty of the manufacturing process, PAN fibers cost about $21.5/kg, according to Kozarsky, who explained that makers subject the PAN to some thermal treatments wherein the material is polymerized and carbonized because it is stretched. The resulting “conversion” leaves the filaments oriented along the length of the fiber allow it the perfect strength and toughness. Various post-processing stages as well as the surface-acting additives help ensure durability and “handleability.
Kozarsky singled out an industrial/government R&D collaboration in the new Carbon Fiber Technology Facility at Oak Ridge National Laboratory (ORNL), which has been funded with $35 million in United states Department of Energy money as the more promising efforts to decrease fiber costs. Part of the project is to identify cheaper precursor materials that could be processed into good-quality fibers (see “Oak Ridge collaborates for cheaper carbon fiber,”. The blueprint is to test various kinds of potential low-cost fiber precursors like the cheaper polymers, inexpensive textiles, some produced from low-quality plant fibers or renewable natural fibers like wood lignin, and melt-span PAN.
Near term the Lux team expects the task that ORNL is performing with Portuguese acrylic-fiber maker FISIP (majority owned by SGL) on textile-grade PAN to accomplish costs with the pilot-line scale of $19.3/kg in 2013. Although significant, it will be only a modest reduction when compared to the 50% necessary for penetration in high-volume auto applications.
One of the major limitations of PAN, he stated, is that “at best 2 kg of PAN yields 1 kg of carbon fiber, which gives you with a conversion efficiency of just 50%.” Dow Chemical is investigating dexnpky63 polyolefins-polyethylene, polypropylene-since the feedstock mainly because they could offer potential conversion efficiencies of 70% to 75%. If mechanical performance targets can be met, pilot-line costs of $13.8/kg could possibly be achieved by 2017, stated the report.
The Oak Ridge group, Kozarsky said, can also be taking care of novel microwave-assisted plasma carbonization techniques that will produce useful, uniform fiber properties. And ORNL’s nonthermal plasma oxidation process is shown to have the potential to stabilize and cross-link the precursor materials rapidly and efficiently.
Polyolefin-precursor carbon fiber, combined with these kinds of alternative thermal-treatment mechanisms, should reduce costs to sub $11/kg at pilot-line scale in 2017, he noted. Kozarsky added that “there’s plenty of curiosity about boosting the resin matrix also,” with research concentrating on using thermoplastics rather than the existing thermosets and producing higher-toughness, faster-processing polymers.