The National Institute of Standards and Technology (NIST) has awarded a $10.1 million, five-year grant to an interdisciplinary team of researchers led by University of Wisconsin-Madison mechanical engineering professor Xiaochun Li.
The researchers are working to implement nanotechnology into the traditional casting industry, which could yield high-quality aluminum and magnesium nanocomposites in the next five years.
The grant is from the NIST Technology Innovation Program, which has announced support for 20 innovative projects in new technologies that address critical national needs.
The UW-Madison project, titled "Transformational Casting Technology for Fabrication of Ultra-High Performance Lightweight Aluminum and Magnesium Nanocomposites," will yield a new casting technology for commercial-scale production of aluminum and magnesium matrix nanocomposites.
Writing in support of the project, Wisconsin Gov. Jim Doyle noted the potential benefit of Li's work for manufacturers.
"Wisconsin is one of the most important manufacturing states in the United States and is an historical leader in the metal casting industry for a diverse range of applications," Doyle writes. "Nanotechnology, a field where UW-Madison is a recognized leader, provides opportunities to develop new materials and processes that will help our metal-casting industry remain competitive in existing markets and allow us to develop new global markets where the strength and weight advantages of nanocomposites will be advantageous."
Manufacturers are increasingly turning to lightweight aluminum and magnesium alloys, which have better performance and energy efficiency than iron and steel. The lighter alloys can be reinforced with nanoparticles, usually ceramic, which significantly enhances the material properties. However, because nanoparticles are difficult to disperse evenly in materials, their use in the casting industry is not widespread.
It is especially challenging for researchers to disperse and stabilize nanoparticles in molten metals (or melts) because most melts have a large surface-to-volume ratio and are unable to maintain contact with the solid nanoparticle surfaces (a quality known as poor wettability). The result is the nanoparticles clump together.
In the last six years, Li's lab has developed an experimental technique that uses high-intensity ultrasonic waves to disperse the nanoparticles through the melts. The waves cause the formation, growth and collapse of microbubbles within the material. The collapse of the microbubbles produces microscopic "hot spots" that can reach temperatures above 9,000 degrees Fahrenheit, causing micro-shock waves. Li and his team have shown that the violent micro-shock waves effectively disperse the nanoparticles evenly through the molten metals.
"If successful, the commercial-scale production of these metal nanocomposites will enable transformative changes in multiple industries and directly address the critical national needs of reducing oil dependency, lowering greenhouse gas emissions, and maintaining U.S. leadership in manufacturing," says Li.
The NIST grant will allow Li and his collaborators to continue building a fundamental knowledge base and scale up the process. Li anticipates widespread use of his technique will produce high-quality aluminum and magnesium nanocomposites in the next five years. He also predicts that a new metal-metrix nanocomposites industry will rise along with the use of nanotechnology in casting.
Li's collaborators at UW-Madison include Tim Osswald, Kuo K. and Cindy F. Wang Professor of Mechanical Engineering, and Shiyu Zhou, associate professor of industrial and systems engineering. The team also is partnering with Wisconsin-based Eck Industries Inc., the Oshkosh Corp., and Houston-based Nanostructured & Amorphous Materials Inc., as well as the Wisconsin Alumni Research Foundation. Li and his collaborators plan to establish an industrial consortium to disseminate and implement their research results.