Contact damage tolerance of alumina‐based layered ceramics with tailored microstructures

Abstract

This work demonstrates how to enhance contact damage resistance of aluminabased ceramics combining tailored microstructures in a multilayer architecture. The multilayer system designed with textured alumina layers under compressive residual stresses embedded between alumina-zirconia layers was investigated under Hertzian contact loading and compared to the corresponding monolithic reference materials. Critical forces for crack initiation under spherical contact were detected through an acoustic emission system. Damage was assessed by combining cross-section polishing and ion-slicing techniques. 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 Hertzian cone cracking on the top (equiaxed) surface layer and quasi-plastic deformation within the embedded textured layer, was identified. Further propagation of cone cracks at higher loads was hindered and/or deflected owed to the combined action of the textured microstructure and compressive residual stresses. These findings demonstrate the potential of embedding textured layers as a strategy to enhance the contact damage tolerance in alumina ceramics.

Prediction of ring crack initiation in ceramics and glasses using a stress–energy fracture criterion

“…5,6,8,9 F I G U R E 3 Crack initiation forces 𝐹 𝑐 normalized by ball radii 𝑅 𝑏 for indentation of ceramics by various balls. 11,12,13,2 indented by diamond balls, 11 and 10%-26% for soda-limesilica glass indented by tungsten carbide balls, 15 among others. Recent work from Schlacher et al 2 showed that for Al 2 O 3 and Si 3 N 4 indented by WC balls cracks may be 20%-40% larger than the contact radius (Figure 4), which seems inconsistent with other reported values.…”

“…11,12,13,2 indented by diamond balls, 11 and 10%-26% for soda-limesilica glass indented by tungsten carbide balls, 15 among others. Recent work from Schlacher et al 2 showed that for Al 2 O 3 and Si 3 N 4 indented by WC balls cracks may be 20%-40% larger than the contact radius (Figure 4), which seems inconsistent with other reported values. In the case of Si 3 N 4 indented by WC balls, additional experiments were done to analyze the effect of friction due to contact.…”

“…Wereszczak et al 11 investigated the fracture of SiC indented by diamond balls using an acoustic emission method. More recently, the method has been extended and applied by Schlacher et al 2 to Al 2 O 3 with equiaxial and textured microstructures indented by WC balls.…”

Stereolithographic 3D Printing of Ceramics: Challenges and Opportunities for Structural Integrity

“…[37,51,53] This concept has been recently demonstrated, both under bending and contact loading, in tape-casted alumina-based layered ceramics designed with "textured" layers embedded between "equiaxed" layers. [54,55] In this regard, there is a great potential for employing additive manufacturing techniques, based on layer-by-layer deposition methods, to fabricate 3D-printed multilayer architectures (of different complexity) with improved fracture resistance and guaranteed minimum strength. The "multimaterial" approach aiming to tailor the microstructure of the parts by combining materials during the printing work has already been successfully employed in recent years; some examples will be presented in the next section.…”

“…[ 37,51,53 ] This concept has been recently demonstrated, both under bending and contact loading, in tape‐casted alumina‐based layered ceramics designed with “textured” layers embedded between “equiaxed” layers. [ 54,55 ]…”