New materials with mysterious properties could transform aerospace industry

5 Sep 2018

A Ukrainian Sukhoi Su-27 jet taking off. Image: Fasttailwind/Shutterstock

The discovery of a new group of smart materials could transform the aerospace industry with more efficient and quieter engines.

A team of researchers from Texas A&M University has announced the discovery of a group of smart materials with the potential to transform the aerospace industry.

Based on early promise, it is believed they could not only one day significantly improve the efficiency of fuel burn in jet engines, but could also reduce engine noise over residential areas.

In fact, researcher Dr Ibrahim Karaman believes the materials could open up a whole new field of scientific research.

No need for gold

Publishing its findings in Scripta Materialia, the team’s discovery was based on a relatively new area of materials science involving metal alloys.

This involves shape-memory alloys that can switch from one shape to another when a specific trigger is activated, typically being used in extremely hot environments such as a jet engine.

However, until now, economical high-temperature shape memory alloys (HTSMAs) have only worked above 400 degrees Celsius.

While adding elements such as gold or platinum can help increase the temperature in the alloys, they understandably drive up costs.

A glowing hot sphere of a new material in a steel vacuum arc melter.

A vacuum arc melter fabricating a new smart material that could be used by the aerospace industry. Image: Texas A&M University

Yet, by incorporating principles from another new class of materials called high-entropy alloys – composed of four or more elements mixed – the team created HTSMAs without gold or platinum.

“When we mixed these elements in equal proportions, we found that the resulting materials could work at temperatures well over 500 degrees Celsius – one worked at 700 degrees Celsius – without gold or platinum. That’s a discovery,” said Karaman. “It was also unexpected because the literature suggested otherwise.”

‘We can push the boundaries of science’

Applying this knowledge, the team wanted to find a way of controlling the clearance – or space – between turbine blades and the turbine case in a jet engine. In order to be most efficient, the clearance between the turbine bales and case has to be as small as possible. By incorporating HTSMAs into the turbine case, aerospace engineers could help achieve maximum efficiency.

When it comes to making planes quieter at landing, HTSMAs could alter the exhaust nozzle size to make it quieter. Typically, a large exhaust will make the engine quieter, but much less efficient. HTSMAs, however, could automatically change the size of the exhaust depending on whether the aircraft is flying or landing.

How the new smart materials work at an atomic level remains a mystery, however, with only basic theories suggested so far. “That’s why I believe this could open a completely new area of research,” Karaman said.

“While we will continue our own efforts, we are excited that others will now join us so that together we can push the boundaries of science.”

A Ukrainian Sukhoi Su-27 jet taking off. Image: Fasttailwind/Shutterstock

Colm Gorey was a senior journalist with Silicon Republic