JABR: Contact damage tolerance of alumina-based layered ceramics with tailored microstructures
Channel: Chair of Structural and Functional Ceramics
Date: 2022-03-14

[Title]
Contact damage tolerance of alumina-based layered ceramics with tailored microstructures

[Authors]
Abdullah JABR
Josef SCHLACHER
Anna Katharina HOFER
Raul BERMEJO

[Event]
97th DKG Annual Meeting - Ceramics 2022
Monday, 7th March 2022

[Abstract]
Surface contact damage is a major cause for rejection of ceramic components. This work demonstrates strategies to enhance contact damage tolerance on the example of alumina-based ceramics. A bioinspired strategy involves texturing the microstructure to deflect cracks along the elongated grains, resembling the fracture of nacre. Further improvement is achieved by embedding such textured layers in a multilayer architecture to induce compressive residual stresses, acting as a “protective shield against crack propagation. Contact damage resistance of such layered alumina system was investigated under Hertzian contact loading and compared to monolithic equiaxed and textured materials. Acoustic emission detection was used for “in-situ monitoring of the materials response. It was found that a textured microstructure can accommodate the damage below the surface by shear-driven, quasi-plastic deformation instead of the classical Hertzian cone cracking observed in equiaxed alumina. In the multilayer system, a combination of both mechanisms, namely cone cracking on the equiaxed surface layer and quasi-plastic deformation within the embedded textured layer, was identified. Owing to the combined action of textured microstructure and compressive residual stresses, the propagation of cone cracks was hindered even at higher applied loads. These findings demonstrate the potential of embedding textured layers as a strategy to enhance contact damage tolerance in alumina ceramics.