When it comes to hybrid cars and trucks, new technologies don't always mean a drastic change in the metals used to make them, according to auto industry insiders. While some analysts and metal industry partisans see a revolution in the making, the auto industry's response might be not so fast.
Ford Motor Co., Dearborn, Mich., builds both its Escape and Escape Hybrid sport utility vehicles (SUVs) off the same platform, Matthew Zaluzec, manager of Ford's Materials and Nanotechnology Department, said. "As built, there are no differences in these two vehicles except for the fact that we've added the electric powertrain (to the hybrid)."
In the future, the company's hybrid electric vehicles will use the latest lightweight technologies—with engineers working with both ultra- and advanced high-strength steels, as well as aluminum and magnesium, he said. "Our product development design staff is looking at lightweight steel, aluminum and magnesium for closures .?.?. as lightweight enablers."
"Closures" refer to vehicle parts such as doors and hoods. Because of the heavy batteries required for hybrids, automakers often look to offset weight elsewhere in the vehicle—and big parts like trunks and hoods are an obvious place to start.
Ford also is looking to lightweight vehicles with cast aluminum alloys for engine blocks and cylinder heads, and is working with "next-generation" cast iron materials such as compacted graphite iron. "This class of cast iron takes advantage of the material's higher strength, excellent mechanical and fatigue properties and higher operating temperature capability," Zaluzec said.
Cast iron was the metal of choice for engine blocks and cylinder heads through the early 1980s. Aluminum cylinder heads, introduced in the early '80s, are now used in 98 percent of Ford vehicles, while aluminum blocks, which started to replace cast iron in the early 1990s, are used in about 65 percent of Ford's engines.
The automaker also is working with lithium-ion and nickel-metal hydride batteries, as well as fuel cells. Fuel cells, which are made from bipolar metallic plates and plastic separator films, will mean a "whole new range of materials development," Zaluzec said. "These propulsion systems will rely upon development of metallic plates made from coated steels, stainless steels and other specialty metals."
"If you talk to someone in the aluminum business, they would probably say steel is antiquated and on it's way out," said Jeff Luke, chief engineer of full-size pickups and SUVs at General Motors Corp., Detroit. "But if you were a steel person, you would say aluminum prices are escalating and pretty soon they'll be uncompetitive." The steel industry also would point out the cost of retooling to switch metals, he said, but GM likes having the option to use different metals for different applications.
But it isn't just through changing metals that vehicles can save fuel in the powertrain, Luke said. GM's FlexFuel vehicles can run on gasoline or E85 ethanol, and some engines sport an active fuel-management system that allows cylinders to deactivate in order to boost efficiency. A truck cruising at a steady speed, for example, can run on fewer cylinders and save fuel.
Even GM's much-touted Chevrolet Volt hybrid electric plug-in car won't necessarily have a dramatically different engine, a company spokesman said. "You're not going to see that drastic of a difference. It's just a typical engine, except there might be fewer components."
The main difference might be not so much in the metals used in the engine but instead in the reduced role it will play in moving the vehicle down the road. "It's going to run at optimal rpm to recharge the battery to run the electrical system," he said. "It'll come on by itself only as necessary."
The lithium-ion battery, however, does bring something new to the table—and much is riding on whether GM and others can perfect the technology. "The ultimate production of (the Volt) still rests on advances in that battery system," the spokesman said. "We have thrown lots of resources at developing it, and we're confident we'll get there."
And what is Japan's Toyota Motor Corp. up to with its hybrids, especially the iconic Prius? It won't say. "We are working to reduce the size and weight of the hybrid system so that we can expand the hybrid application for various types of cars," a company spokesman said. "However, we can't provide specific answers about metal mix, weight, materials, etc."
But Toyota's Japanese rival, Honda Motor Co. Ltd., thinks it has a better hybrid system than Toyota does. Toyota's hybrids rely primarily on battery storage, and that makes its cars a lot heavier, a Honda spokesman said. And while breakthroughs have been made on battery voltage and output, advances have been slower in battery storage systems, he said.
A vehicle like the Honda Civic hybrid instead features applications such as regenerative braking that assists the engine, the spokesman said. Regenerative braking allows a car to capture energy generated during braking. "When you brake the car, you can produce electricity that is stored in batteries, and that electricity is used to turn a wheel (between the engine and transmission) that assists the engine," he explained.
The chief difference between the traditional Civic and the Civic hybrid instead of a 1.6-liter engine, the hybrid comes equipped with a 1.3-liter engine, the spokesman said. "That allows you to get the same performance but with a smaller engine, so you automatically save gasoline," he said. "But it doesn't change the basic architecture of the car." One exception behind the back seat, the Civic hybrid holds a series of nickel-metal hydride batteries.
The story, however, is somewhat different for the Civic GX, which runs on compressed natural gas. "That car does have the standard Civic engine," the spokesman said. "But it has pistons that are beefed up with special alloys and certain other parts are made with different aluminum alloys" because the engine runs 400 degrees hotter than a gasoline engine.
Another different feature of the Civic GX unlike the plastic gasoline tanks Honda uses in its other vehicles, the GX sports a tank made from layers of carbon fibers and other exotic materials that prevent it from leaking or bursting. And the GX fuel tanks are bigger than plastic tanks designed to hold gasoline, because the thermal efficiency of natural gas is about half that of gasoline so you need more of it to power a vehicle, the spokesman said.
The Honda FCX Clarity, which is powered by fuel cells, is where the truly revolutionary changes come. Honda is already producing the vehicles in limited volumes in Japan and leasing them in California.
Because the Clarity relies on fuel cells for power, it doesn't even have an engine block, which in effect eliminates an entire front in the battle for market share. Honda makes the fuel cell stack using a variety of exotic metals, but some of the information about the technology is proprietary, the spokesman said. And while slightly different from a traditional transmission, the Clarity transmission is still made with metals.
Many people assume that electric or hydrogen cars will make heavy use of plastic because limited production models made in the 1980s and '90s did, the Honda spokesman said. But that likely won't be the case, especially when vehicles enter mass production. "It's easier to do a plastic car in small volumes. But for long production runs, it's easier to stamp steel," he said. "There are safety standards, and there is a whole body of knowledge around steel and steel stampings."
And heavy isn't necessarily a bad thing for some hybrids, especially vehicles that employ regenerative braking. A heavier car means more energy is generated by the brakes, and therefore is available for the battery to assist the engine. "So steel isn't necessarily out of the ballgame on a hybrid car," he said.
And it's not as if one technology will suddenly win out and drastically remake the landscape of the auto industry, the Honda spokesman said. "The pace of change will be steady in the auto industry. It won't be radical and there won't be overnight triumphs. There is just a lot of experimenting going on."
But that also means automakers have to keep their engineers busy working on a wide range of technologies. "Right now our view is that there is no emerging technology that is going to trump all of the others as far as fuels of the future," the spokesman said. "You have to have good engineering in a variety of areas to remain competitive right now."