Carbon-fiber reinforced plastics (CFRPs) are responsible for more than 50 percent of materials by weight in new aircraft such as the Boeing 787 Dreamliner and the Airbus A350. Yet polymer composites on average constitute less than 2 percent of an automobile's total weight. Kozarsky said:
It will take awhile before the average plane has as much carbon fiber as the 787 and the A350. The motivation now for using CFRP is more for long-distance flights. In larger volume, smaller planes for regional use, such as the B787, one trend to watch will be whether aircraft makers choose Alcoa's next-generation aluminum-lithium alloys, or go with CFRP for the skin.
Historically, carbon fiber has been well suited for an aircraft's flat skin, due to the nature of carbon's long fibers. But 3D components involve a more complicated, expensive molding technology. Kozarsky said:
Primary structures like fuselage and wings, and the landing gear and pylons, also have different structural requirements from each other. Secondary structures also have different requirements, further motivating why it's important to look at these structures on a component level while evaluating their ideal materials.
CFRPs are not only more expensive, but using them is also a step change difference, which is much greater than transitioning from using one metal to another metal. "When we talk to builders of wind turbines, automobiles, and aircraft, they're equally interested in advanced metals like aluminum, titanium, magnesium, and AHSS," said Kozarsky.
The lightest structural metal, magnesium, is not widely available, and has drawbacks in its material properties, including brittleness, susceptibility to corrosion, and sourcing difficulty. Despite these difficulties, automotive manufacturers are as interested in magnesium as they are in CFRP. Aircraft manufacturers are looking at titanium more because of its high strength-to-weight properties, but its high cost has limited its adoption outside of a few high-end applications. Some new processing technologies are emerging that may help to reduce costs.