Special Ceramic Sensors Used to Monitor Structural Health

Ceramics with networked nanosheets of graphene and white graphene would have the unique ability to alter their electrical properties when strained. Illustration courtesy of Rouzbeh Shahsavari/Rice University.

A nano-infused ceramic that displays different electrical properties under two types of strain was developed by researchers at Rice University (Houston, Texas, USA). This unique ability could make the ceramic particularly useful as a sensor embedded into buildings, bridges, aircraft, and other such structures to monitor their own health. 

Led by Rouzbeh Shahsavari, an assistant professor of civil and environmental engineering and of materials science and nanoengineering, the Rice research team found that the ceramic exhibited increased electrical conductivity under elastic strain, which causes a solid form to distort before returning to its original size and shape when the deforming agent is removed. By contrast, the ceramic showed decreased conductivity under plastic strain, which causes permanent deformation once the elastic limit of the solid has been exceeded.

Shahsavari and his fellow researchers modeled their nanoengineered ceramic after graphene-boron-nitride (GBN), a unique two-dimensional compound that also demonstrated different electrical properties under the two different kinds of strain. They found that under electric strain, the internal structure GBN did not change even when stretched. When it was put under plastic strain, however, the crystalline lattice became distorted. These qualities were enough to convince the Rice researchers that GBN could serve as a structural sensor.

Building on previous research from Shahsavari, Rice researchers discovered that hexagonal-boron nitride, or white graphene, not only made ceramics stronger and more versatile, but imbued them with surprising electrical properties as well. They also observed that combined nanosheets of graphene and white graphene bond in unique ways, particularly during the ceramic manufacturing process when they dispersed into a slurry. This development caused them to theorize that the resulting ceramics would become tunable semiconductors with improved strength, elasticity, and ductility.

Due to its composition, white graphene is a conductive material that, when mixed into the ceramic in a high enough concentration, helps boost the insulation properties of GBN. As a result, the overall composite could potentially be used a variety of electrical applications. “Fusing 2D materials like graphene and boron nitride in ceramics and cements enables new compositions and properties we can’t achieve with either graphene or boron nitride by themselves,” Shahsavari said.

For more information about GBN and the Rice research into ceramic sensors, see Shahsavari’s co-authored paper in the current issue of Applied Materials and Interfaces.

Source: Rice University News & Media, www.news.rice.edu