Common wisdom holds that ceramics, despite their strength and durability, are brittle. Thus, when architects, engineers, and manufacturers look for materials capable of withstanding high tensile forces, they often eschew ceramics in favor of alternatives such as metals and polymers.
Materials scientists at the California Institute of Technology (Caltech), in Pasadena, Calif., have demonstrated that ceramics can actually be made flexible at the nanoscale level and capable of returning to their original shape after being compressed to 50 percent of their original size.
"Ceramics have always been thought to be heavy and brittle,” said Julia Greer, a professor of materials science and mechanics at Caltech, in a press release. "We're showing that, in fact, they don't have to be either. This very clearly demonstrates that if you use the concept of the nanoscale to create structures and then use those nanostructures like Lego[s] to construct larger materials, you can obtain nearly any set of properties you want. You can create materials by design."
Greer and her team achieved the unexpected material design property by coating tiny polymer scaffolds with aluminum oxide, or alumina, to create hollow-tube structures with diameters between 450 nanometers and 1,380 nanometers. These micro-lattices were made by printing 3D patterns in plastic using two-photon lithography, which is the initial step when fabricating biomimetic materials like synthetic bone. Once the researchers stress-tested the alumina-covered scaffold, they learned that ceramics behave differently when created in a highly-controlled process. That is because while a series of internal flaws renders ceramics and glasses prone to breaking, the materials' fragility is reduced as its flaws decrease in size or number.
"One of the benefits of using nanolattices is that you significantly improve the quality of the material because you're using such small dimensions,” Greer said. "It's basically as close to an ideal material as you can get, and you get the added benefit of needing only a very small amount of material in making them.”
Specific applications for the forthcoming flexible ceramic have yet to be determined. However, the team aims to increase the size of the materials it can produce. Flawless ceramics created at sufficient scale—such as the size of a tile or a brick—could radically change the way we approach ceramic materials in products and buildings, transforming them into prime ingredients for resilient architecture.
Blaine Brownell, AIA, is a regularly featured columnist whose stories appear on this website each week. His views and conclusions are not necessarily those of ARCHITECT magazine nor of the American Institute of Architects.
