Purdue University researchers have developed a new featherweight, flame-resistant and super-elastic metamaterial that could benefit a range of applications from buildings to aerospace.
According to the researchers, the metamaterial combines high strength with electrical conductivity and thermal insulation.
The composite features nanolayers of a ceramic called aluminum oxide with graphene. Although both the ceramic and graphene are brittle, the new metamaterial has a honeycomb microstructure that provides super-elasticity and structural robustness.
Graphene is known to degrade when exposed to high temperature, but the ceramic imparts high heat tolerance and flame-resistance, properties that might be useful as a heat shield for aircraft. On the other hand, the light weight, high-strength and shock-absorbing properties could make the composite a good substrate material for flexible electronic devices and large strain sensors.
The material can also be used as a flame-retardant, thermally insulating coating, as well as sensors and devices that convert heat into electricity, said associate professor Gary Cheng. “This material is lighter than a feather, the density is really low. It has a very high strength-to-weight ratio.”
“The outstanding properties of today’s ceramic-based components have been used to enable many multifunctional applications, including thermal protective skins, intelligent sensors, electromagnetic wave absorption and anticorrosion coatings,” Cheng said.
The composite material is made of interconnected cells of graphene sandwiched between ceramic layers. The graphene scaffold, referred to as an aerogel, is chemically bonded with ceramic layers using a process called atomic layer deposition.
“We carefully control the geometry of this graphene aerogel,” Cheng said. “And then we deposit very thin layers of the ceramic. The mechanical property of this aerogel is multifunctional, which is very important. This work has the potential of making graphene a more functional material.”
Image, video and content source: Purdue University