Study Shows Ceramics Can Deform Like Metals if Sintered Under an Electric Field

High temperature deformability of ductile flash-sintered ceramics via in-situ compression

Applying an electric field to ceramics during their formation gives them the metal-like characteristics needed for sustaining heavy loads without sudden collapse. (source: Purdue University)

October 22, 2018 | Source: Purdue University, purdue.edu, 29 May 2018, Kayla Wiles

Purdue researchers have observed a way that the brittle nature of ceramics can be overcome as they sustain heavy loads, leading to more resilient structures such as aircraft engine blade coatings and dental implants.

While inherently strong, most ceramics tend to fracture suddenly when just slightly strained under a load unless exposed to high temperatures. Structural ceramic components also require high temperatures to form in the first place through a lengthy process called sintering, in which a powdered material coalesces into a solid mass.

These issues are particularly problematic for ceramic coatings of metal engine blades intended to protect metal cores from a range of operational temperatures. A study published in Nature Communications demonstrates for the first time that applying an electric field to the formation of yttria-stabilized zirconia (YSZ), a typical thermal barrier ceramic, makes the material almost as plastic, or easily reshaped, as metal at room temperature. Engineers could also see cracks sooner since they start to slowly form at a moderate temperature as opposed to higher temperatures, giving them time to rescue a structure.

Improved plasticity means more stability during operation at relatively low temperatures. The sample could also withstand almost as much compression strain as some metals do before cracks started to appear. Even when the sample did begin to crack, the cracks formed very slowly and did not result in complete collapse as would typically happen with conventional ceramics. The next steps would be using these principles to design even more resilient ceramic materials.

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