A new high-strength aluminum-silicon alloy developed at NASA's Marshall Space Flight Center, Huntsville, Ala., promises to lower engine emissions and could improve gas mileage in cars, boats and recreational vehicles. The new alloy, co-invented by Jonathan Lee, a NASA structural materials engineer, was originally developed for the automotive industry.
Although most Americans associate NASA with space flight, one of the space agency's missions is to share its cutting-edge technologies with U.S. industry. "Partnerships with U.S industries are the main way NASA transfers these technologies to the public," explains Vernotto McMillan, deputy manager of Marshall's Technology Transfer Department.
Lee and co-inventor PoShou Chen, a scientist with Morgan Research Corp., began work on the new alloy seven years ago when a major automobile manufacturer approached NASA about developing a strong and low-cost aluminum alloy for use in a piston redesign that would lower engine emissions.
Lee and Chen came up with MSFC-398, a wear-resistant alloy that exhibits dramatic strength at temperatures as high as 500 to 700 degrees Fahrenheit. In fact, when tested at 600 degrees Fahrenheit, it is three to four times stronger than conventional cast aluminum alloys. The new metal also can be produced at a projected cost of less than $1 per pound.
NASA High-Strength Alloy can be poured as a molten metal into conventional steel molds or die-casting molds to create specially shaped parts -- a cost-saving advantage over machining of parts.
"The new alloy is ideal for high-temperature cast components used in engines such as pistons, connecting rods, actuators, brake calipers and rotors," said Lee. This makes NASA High- Strength Alloy a good choice for high-temperature applications in the automotive, aerospace, marine and recreational vehicle industries.
"Increasingly stringent exhaust-emission regulations for internal combustion engines have forced piston designers into a redesign to lower emissions," said Lee. "The current modification is to reduce the piston's crevice volume -- the air gap between the piston wall and the cylinder bore -- by moving the top piston ring closer to the top of the piston crown."
Such a modification promises to be a key to reaching the goal of making today's high-performance gasoline and diesel engines meet tougher exhaust standards.
To accomplish this, engine makers needed a strong, low-cost alloy that would allow them to make the piston-crown depth thinner -- yet still curb piston failure caused by high work and heat loads.
"NASA High-Strength Alloy offers greater wear resistance and surface hardness which enables manufacturers to use less material, thus reducing the part's weight and cost and improving gas mileage, engine performance and engine durability," said Lee.
Two U.S. patents have been awarded with other domestic patents pending. An international patent is pending for the technology as well, said Sammy Nabors, the commercialization lead in the Marshall Technology Transfer Department. Through NASA's Technology Transfer program, non-exclusive licenses to develop new products from the improved alloy have been awarded to Advanced Materials Technology Inc., Manitowoc, Wis.; Swan Metal Composites Inc., Woodinville, Wash.; and Eck Industries, Manitowoc, Wis.
NASA is continuing to seek U.S. industries as partners to further transfer this technology to the public and private sector.
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