University of Queensland (Australia) researchers are testing new materials that can withstand the extreme heat experienced by hypersonic aircraft to enable longer flight times. The tests use scramjet engines composed of composite materials that may be able to withstand the heat produced at Mach 8.

The $1.5 million project is run by Australia’s Defence Materials Technology Centre.

“A scramjet-powered vehicle could fly between London and Australia in two hours, so we’re looking at materials that can survive hypersonic speeds for longer periods,” said project leader Michael Smart, mechanical engineering professor at UQ.

Smart said the research was particularly looking at new materials for leading edges, the parts of the wings that first contact the air.

At hypersonic speeds, air friction causes extreme heating of the leading edges on wings, fins and engine parts. Temperatures on the surface of an object traveling at Mach 5 can reach 1000 °C. These high temperatures cannot be sustained by standard aircraft and turbine materials. At higher speeds the temperatures can be even more extreme. At Mach 8 the temperatures can reach 2700 °C at the leading edge and 3000 °C in the engine combustion chamber.

Another challenging problem area is inside the scramjet engine. The interior must handle a corrosive mix of hot oxygen and combustion products, as well as high thermal, mechanical and acoustic loadings.

Smart is working with ceramic composite materials engineer John Drennan, director of UQ’s Centre for Microscopy and Microanalysis.

“The technologies we are developing will have application anywhere where performance is needed from materials in high temperature environments for long periods,” Drennan says. “Some potential uses for the new materials might include [use] in power plants and for exhaust nozzles of jet engines.”