Cool heat resistance

Materials research promises resistance to extreme temperatures inflicted on a spacecraft leaving and re-entering the earth’s atmosphere

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A CERAMIC has been crowned the world’s most heat resistant material after withstanding temperatures of nearly 4000 degrees Celsius.

Researchers believe hafnium carbide(HfC) may find uses on spacecraft, protecting them as they enter and leave Earth’s atmosphere.

Hafnium carbide (HfC) is a refractory ceramic which means it is highly resistant to heat so it is suited to extreme environments and, with such a high melting point, could be used as fuel cladding in nuclear reactors.

There was no method available for getting the material hot enough to test its thermal limits in the lab so the team at Imperial College London had to develop a way of using laser-heating technology to reach its melting point which was recorded at 3958 degrees Celsius.

Dr Omar Cedillos-Barraza, now an Associate Professor at the University of Texas – El Paso, carried out the research while doing his PhD at Imperial’s Department of Materials. HfC was tested alongside another refractory ceramic – Tantalum carbide (TaC) – which also has an extremely high melting point.

Dr Cedillos-Barraza said: “The friction involved when travelling above Mach 5 – hypersonic speeds – creates very high temperatures.

“So far, TaC and HfC have not been potential candidates for hypersonic aircraft, but our new findings show that they can withstand even more heat than we previously thought – more than any other compound known to man.

“This means that they could be useful materials for new types of spacecraft that can fly through the atmosphere like a plane, before reaching hypersonic speeds to shoot out into space. These materials may enable spacecraft to withstand the extreme heat generated from leaving and re-entering the atmosphere.

“Our tests demonstrate that these materials show real promise in the engineering of space vehicles of the future. Being able to withstand such extreme temperatures means that missions involving hypersonic spacecraft may one day be manned missions. For example, a flight from London to Sydney may take about 50 minutes at Mach 5, which could open a new world of commercial opportunities for countries around the world.”