• Jan 2, 2011
Carbon fiber often occupies the limelight as a light weight material that could take some of the heft out of our cars, and thus improve fuel efficiency -- if only it cost less. But alloys of magnesium, the lightest structural metal, have a history in automotive components tracing back to the 1930s. Now the U.S. government is hoping to jump-start innovative production of the material for use in cars. The Department of Energy opened up a $184 million program this month for advanced vehicle research and development. Among the eight areas where the agency is accepting proposals for improving fuel efficiency in passenger cars is "light weighting materials." As much as $6 million has been designated under this category for projects working toward low-cost, highly efficient production techniques for magnesium components, and another $3 million is available for a demonstration project to develop and construct a front end vehicle sub-structure that's magnesium intensive. The program has a particular interest in techniques using raw materials that are readily available in the U.S.

Difficult To Obtain

"If you have an ocean, you've got raw materials available, but it's very energy intensive to recover them," explained Deborah Kramer, a magnesium specialist and Assistant Chief of Mineral Commodities for the U.S. Geological Survey. In fact, the silvery-white metal is the eighth most abundant element on the planet and the third most plentiful element dissolved in seawater. It can also be recovered from dolomite, a very common raw material used for most of China's magnesium production, said Kramer.

A company in Rowley, Utah about 40 miles west of Salt Lake City, called U.S. Magnesium, is the last remaining producer of magnesium in the United States. Most imports of the metal (87 percent in the third quarter of 2010) come from Israel, said Kramer.

Up until a few years ago, another magnesium producer located in Quebec also supplied magnesium into the U.S. market, but it closed amid rising competition from Chinese and Russian magnesium producer. Anti-dumping duties placed on Chinese imports (following a petition filed by U.S. Magnesium, then called MagCorp) essentially slammed the door on that competition.

Diecastings used for components in automobiles, as well as power tools and lawn mowers, are just one use of magneseium. It's also an ingredient in aluminum alloys (it makes aluminum harder), and it helps with iron and steel desulfurization. As Kramer put it, a magnesium coated salt "pulls sulfur out and gives you better steel." Nonetheless, in the wake of the auto industry's 2008 crisis, as many as 5-6 U.S. magnesium diecasting companies have closed plants due to slumping demand.

U.S. Magnesium's Utah facility has been using brine from the Great Salt Lake as the raw material for magnesium production since 1972. The process leaves behind a slew of wastes, including many hazardous and some cancerous contaminants such as heavy metals, PCBs and dioxins. In November 2009 the government added U.S. Magnesium to the National Priorities List of Superfund sites, declaring it one of the country's most contaminated places. With its new funds for mid-term magnesium projects, the Department of Energy aims to support development of a less polluting process.

How Magnesium Would Benefit Cars

A number of benefits could result from a larger role for magnesium in vehicle design. Used in place of materials such as steel or aluminum for vehicle components and systems, magnesium and its alloys could enable lighter-weight, more fuel-efficient cars. It could also boost performance, as the industry groups USCAR (the United States Council for Automotive Research, made up of Chrysler, General Motors and Ford) and USAMP (United States Automotive Materials Partnership) explained in a 2006 strategic "roadmap." Reducing weight in the front of a car shifts the center of gravity toward the back, which can improve response in steering and cornering. And strategically incorporating magnesium into the roof and doors can lower the center of gravity, reducing rollover risks.

In addition, magnesium parts could potentially reduce noise, vibration and harshness. One large magnesium casting can serve in place of a steel component requiring dozens of pieces, lowering odds that the parts will squeak and rattle due to poor fit. And according to USCAR and USAMP, the thickness and rigidity of a magnesium casting can be varied and controlled in a way that improves crash performance.

That's the hope, anyway. In practice, magnesium alloys can be difficult to work with. According to the Department of Energy, use of magnesium in place of other, higher density materials is often limited by characteristics such as low strength and problems with joining in the manufacturing process. Other issues include variable quality and risk of corrosion on the road. Plus, the overall costs of working with the material are also relatively high, when alloy, tooling, corrosion protection, repair, assembly, and other factors are taken into account.

Seeking to overcome some of these challenges, the DOE's Vehicle Technologies Program spent approximately $6 million this year supporting research at universities, national labs, and in the auto industry. The Pacific Northwest and Oak Ridge National Laboratory, for example, are working to develop new welding methods (ultrasonic and friction stir welding) for joining magnesium in a vehicle structure. Other DOE-funded research is focused on developing computer models for magnesium and advanced magnesium joints that can reliably predict crash properties.

Magnesium Used In Vehicles Before

With all of this research under way, magnesium vehicles might sound futuristic. But the metal has cropped up in vehicle designs for decades. Volkswagen used about 40 pounds of magnesium in its Beetle between the late 1930s and 1960s, for example -- mainly in the transmission and air-cooled engine. A 1967 Fiat and a 1978 Alpha Romeo featured cast magnesium wheels.

Audi introduced a magnesium instrument panel cross-car beam in 1989, and the first magnesium automatic transmission a decade later. Maybe you've heard of "mag wheels." Often mistakenly applied to aluminum rims, the term arose from the use of magnesium alloy wheels on race cars.

By the 1990s, magnesium alloy parts included steering wheels, gear boxes, instrument panels, seat components, rims, rear flaps, reflectors, air bag housings, and other components. In 2006, magnesium made up an average of 10-12 pounds of every 3,360-pound vehicle from Detroit automakers, up from less than two pounds per vehicle in the early 1980s, according to Kramer, and about 8.5 pounds in 2001. For comparison, plastics on average made up as much as 260 pounds, aluminum accounted for about 280 pounds, and steel or cast iron made up more than a ton of each vehicle in 2006.

Yet if all of the magnesium components approved for use in vehicles were used in one car, they would weigh more than 380 pounds. In the 2006 magnesium roadmap, USCAR and USAMP set a goal to substitute 340 pounds of magnesium components for 630 pounds of ferrous and aluminum parts by 2020.

At this point, said Kramer, the industry faces something of a chicken-and-egg problem. "If there's one thing automakers like," she said, "it's having multiple suppliers so they can wheel and deal." With a scant few magnesium diecasting suppliers remaining, automakers will "tend to be more hesitant" to specify magnesium parts. So fewer suppliers results means less demand, which supports fewer suppliers. Still, said Kramer, "The auto industry is where magnesium producers put their eggs, and it's still their best bet." With millions of cars hitting the road each year, even "a pound of magnesium per car adds up to a lot."


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