A new composite material is viewed with a scanning electron microscope, while its flame resistance is put to the test. Image credit: Purdue University.Combining high strength with electrical conductivity and thermal insulation, a new graphene/ceramic metamaterial (GCM) is super-light, flame-resistant and super-elastic, with the potential for a wide range of applications.

The material was profiled recently in a collaborative study by Purdue University; Lanzhou University and the Harbin Institute of Technology, both in China; and the U.S. Air Force Research Laboratory.

Metmaterials are engineered with features, patterns or elements on the scale of nanometers, or billionths of a meter, to provide new properties. In this case, nanolayers of aluminum oxide, a ceramic, were combined with graphene, an extremely thin carbon sheet, to create the new material. Although both source materials are brittle, engineers designed a hierarchical honeycomb microstructure for the GCM to provide super-elasticity and structural robustness.

Multi-nanolayer cellular walls served as the basic elastic units. By carefully controlling the geometry of the graphene scaffold, also known as an aerogel, it could be chemically bonded with very thin layers of the ceramic in a process called atomic layer deposition. According to Gary Cheng, associate professor in the School of Industrial Engineering at Purdue University, that process might be scaled up for industrial manufacturing.

The end result is a material in which ceramic imparts high heat tolerance and flame-resistance to graphene, giving it potential usability as an aircraft heat shield. It could also serve as a high-strength, shock-absorbing and lightweight substrate for flexible electronic devices and large strain sensors. And its high electrical conductivity combined with excellent thermal insulating properties could allow for use as a flame-retardant, thermally-insulating coating, or in sensors and devices that convert heat into electricity.

Future work will include research to enhance the material’s properties -- possibly by changing its crystalline structure and controlling the microstructure to tune material properties.