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This work demonstrates how to enhance contact damage resistance of alumina-based 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.

In this work we demonstrate the feasibility of fabricating textured alumina employing a lithography-based ceramic manufacturing process. The combination of vat rotation and platform immersion contributes to the alignment of alumina templates during printing. Templated Grain Growth during sintering provides a high degree of texture (Lotgering Factor ​~ ​0.80) with relatively low porosity (approx. 7%). A comparable characteristic biaxial strength of 640 ​MPa and 570 ​MPa was measured for textured and equiaxed alumina samples, opening the path for 3D printing textured ceramics of complex architectures for structural and functional applications.

Texture-engineered ceramics enable access to a vast array of novel texture-property relations leading to property values ranging between those of single crystals and isotropic bulk ceramics. Recently developed templated grain growth and magnetic alignment texturing methods yield high quality crystallographic texture, and thus significant advances in achievable texture-engineered properties in magnetic, piezoelectric, electronic, optical, thermoelectric, and structural ceramics. In this paper, we outline the fundamental basis for these texture-engineered properties and review recent contributions to the field of texture-engineered ceramics with an update on the properties of textured lead-free and lead-based piezoelectrics. We propose that further property improvements can be realized through development of processes that improve crystallographic alignment of the grain structure, create biaxial texture, and explore a wider array of crystallographic orientations. There is a critical need to model the physics of texture-engineered ceramics, and more comprehensively characterize texture, thus enabling testing of texture orientation-property relations and materials performance. We believe that in situ measurements of texture evolution can lead to a more fundamental and comprehensive understanding of the mechanisms of texture development.

Fabrication of 3D-printed ceramic parts with high complexity and high spatial resolution often demands low wall thickness as well as high stiffness at the green state, whereas printing simpler geometries may tolerate thicker, more compliant walls with the advantage of a rapid binder-burn-out and sintering process. In this work, the influence of the binder system on the thermophysical properties of 3D-printed stabilized zirconia ceramics was investigated. Samples were fabricated with the lithography-based ceramic manufacturing (LCM) technology using two different photosensitive ceramic suspensions (LithaCon 3Y230 and LithaCon 3Y210), with the same ZrO

doi: https://doi.org/10.1557/jmr.2017.207, Published by Cambridge University Press, 27 June 2017 In Messing et al.1, the compound Pb(Yb1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 was incorrectly abbreviated on page 10. The sentence reading “Similar to PIN–PMN–PT, [001]c textured PIN–PMN–PT ceramics with f(00l) of 0.91 show a high level of strain (0.33%) and a higher Tc of 214 °C” should say, “Similar to PIN–PMN–PT, [001]c textured PYN–PMN–PT ceramics with f(00l) of 0.91 show a high level of strain (0.33%) and a higher Tc of 214 °C.” The authors apologize for this error.

This work demonstrates the use of additive manufacturing to design and fabricate alumina ceramics with strength as high as 1 ​GPa. A multi-material approach is employed by embedding alumina-zirconia layers between outer pure alumina layers with significant compressive residual stresses. Biaxial bending is performed both on the 3D printed multi-material and monolithic alumina parts. Results are analysed in the framework of Weibull statistics. A characteristic biaxial strength higher than 1 ​GPa is measured on the multilayers, compared to 650 ​MPa in monolithic alumina, the difference corresponding to the magnitude of compressive residual stresses due to the thermal mismatch between material regions during cooling from sintering. This is the first report of employing additive manufacturing to tailor the strength of alumina ceramics, taking advantage of the layer-by-layer printing process. Designing complex-shaped ceramic architectures with residual stresses through additive manufacturing opens a new path for fabrication of technical ceramics with tailored mechanical properties.