Huge Potential of Fly Ash

 (ECO Composites 3-27-2011) Composite metal foams that can replace solid aluminum and magnesium have the potential to keep millions of tons of toxic waste out of landfills while improving performance and lowering the cost of some automotive and consumer products. 
US researchers have reported the results of experiments designed to utilize fly ash – a by-product of coal combustion – as an additive to create the lightweight composites.
Nikhil Gupta, associate professor of mechanical and aerospace engineering at the Polytechnic Institute of New York University NYU-Poly’s Composites Materials and Mechanics Laboratory and collaborators from the University of Wisconsin-Milwaukee have published their findings in a recent issue of Journal of Metals.
More than 70 million tons of fly ash are produced by coal power plants in the United States every year, and more than half that amount is dumped in landfills. Fly ash contains hollow particles that, when added to a molten metal such as aluminum, create a porous metal foam that is lighter than solid metal, yet absorbs a higher amount of energy under compression. The team tested aluminum and magnesium alloys filled with fly ash at high compression rates – similar to those experienced in high-speed car accidents – and found that the lightweight foams absorb more energy than the solid metals. 
“Composite metal foams made with fly ash could be seamlessly incorporated into vehicle manufacture with no compromise in performance,” said Gupta. “As a starting point, these materials are ideal replacements in automotive parts that aren’t load-bearing – for example, engine and wheel covers and intake manifolds, where the weight and strength of solid metal doesn't provide any benefit – in fact, it just costs more and weighs more."
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