A new high-strength aluminium-silicon alloy developed at NASA’s Marshall Space Flight Centre, Huntsville, Alabama, 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.
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 aluminium 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 is said to exhibit dramatic strength at temperatures as high as 500 to 700 degrees Fahrenheit. When tested at 600 degrees Fahrenheit, it is said to be three to four times stronger than conventional cast aluminium alloys. The new metal can also 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 moulds or die-casting moulds 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 callipers and rotors,’ said Lee.
‘Increasingly stringent exhaust-emission regulations for internal combustion engines have forced piston designers into a redesign to lower emissions,’ added 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 US patents have been awarded with other domestic patents pending. An international patent is pending for the technology as well, said Sammy Nabors, the commercialisation lead in the Marshall Technology Transfer Department.
NASA is continuing to seek US industries as partners to further transfer this technology to the public and private sector.