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Digital light processing (DLP) provides a promising avenue for constructing ceramic parts with high precision and complex shapes, yet the inherent brittleness and strength‐toughness trade‐off hinder their wide applications. Here, according to DLP 3D printing, the textured alumina ceramic components with horizontally aligned textured microstructure were successfully created by adding anisotropically shaped platelets. As a critical process in the preparation of textured ceramics, the alumina platelets were aligned horizontally during printing by using the special shear fields and forming capabilities of DLP technology. The shrinkage, density, microstructure, mechanical performance, and damage‐tolerance behavior of alumina parts with different platelet concentrations were examined, and the toughening mechanisms were investigated. The strength and toughness of ceramics with 5 vol.% platelet addition are increased by 22% and 43%, respectively, as compared with those without platelets. The improved damage tolerance capabilities were primarily ascribed to the collaborative toughening mechanisms stimulated by the platelet addition, including crack branching, crack deflection, uncracked‐ligament bridging, and platelet pull‐out, which increased the crack tortuosity and consumed more fracture energy. The strategy opens up new opportunities to design complex 3D ceramic geometries with bio‐inspired layered or textured architectures, providing optimized damage tolerance. [ABSTRACT FROM AUTHOR]

ZrO 2 –Al 2 O 3 (ATZ) ceramics are attracting high interest in biomedical applications because of their desirable mechanical performance and biocompatibility. However, strength and toughness are mutually exclusive in structural ceramics. In this paper, based on digital light processing, novel textured ATZ ceramics with obvious crystallographic orientations were fabricated by incorporating Al 2 O 3 platelets with a high aspect ratio and equiaxed particles into the ZrO 2 matrix. The optimized fracture toughness of 16.9 ± 0.8 MPa m1/2 was achieved in the textured ATZ ceramic, which was about 67.3 % higher than non-textured ZrO 2 ceramics, without sacrificing strength. The coupling toughening effects of macrolayer structure, equiaxed and platelet-shaped Al 2 O 3 particles, and ZrO 2 particles were responsible for the enhanced mechanical performance. The macroscale toughening of 3D-printed lamellar architecture led to effective energy dissipation. Additionally, the crack deflection and crack branching induced by dual-morphology Al 2 O 3 particles, accompanied by the phase transformation of the ZrO 2 matrix, were significant microscopic toughening mechanisms. [ABSTRACT FROM AUTHOR]

Lanthanum silicate oxyapatite (LSO) is a promising alternative electrolyte for solid oxide fuel cell (SOFC) applications. They exhibit anisotropic oxide-ionic conduction; therefore, a preferential crystal orientation along the c-axis is necessary to achieve optimal conductivity. This study is performed to understand the reaction mechanisms involved in the formation of an LSO layer at the interface of the La 2 SiO 5 /SiO 2 diffusion pair during reactive sintering at high temperatures. Different La 2 SiO 5 /SiO 2 bilayers were fabricated in sandwich-type structures using silica-type quartz or La 2 SiO 5 supports obtained via electrophoresis and uniaxial pressing, respectively. These supports were pre-sintered and then coated with a suspension of the opposite component. The diffusion pairs were isothermally heated at 1500 °C at different holding times (10, 20, and 40 h) and at 1600 °C for 10 h. Their surfaces and cross-sections were investigated via X-ray diffraction, scanning electron microscopy (SEM) observations, energy-dispersive X-ray spectroscopy (EDS), and Raman spectroscopy. Experimental results show that two different driving forces were involved in the nucleation and growth of apatite crystals. The first is the chemical potential gradient in lanthanum between the components of the layers, and the second is the electric field created to preserve the electroneutrality of the system. The predominant diffusing species in this bilayer system were La+III and O-II, and their diffusion is enhanced by the formation of a glassy phase on the silica grains through the transformation of silica-type quartz into cristobalite. The formation of a La 2 Si 2 O 7 intermediate phase was detected, which is vital to the interdiffusion of species and the nucleation and growth of oriented apatite crystals. The porosity gradient observed in the cross-section after reactive diffusion suggests the possibility of achieving an SOFC half-cell device via this process. [ABSTRACT FROM AUTHOR]

Mimicking the damage tolerance of biological materials such as nacre has been realised in textured layered alumina ceramics, showing improved reliability as well as fracture resistance at room temperature. In this work, the fracture behaviour of alumina ceramics with textured microstructure and laminates with embedded textured layers are investigated under uniaxial bending tests at elevated temperatures (up to 1200 °C). At temperatures higher than 800 °C monolithic textured alumina favours crack deflection along the basal grain boundaries, corresponding to the transition from brittle to more ductile behaviour. In the case of laminates, the loss of compressive residual stresses is counterbalanced by the textured microstructure, effective up to 1200 °C. This study demonstrates the potential of tailoring microstructure and architecture in ceramics to enhance damage tolerance within a wide range of temperatures. [ABSTRACT FROM AUTHOR]

Highly textured TiN ceramic was successfully prepared by edge-free spark plasma sintering (EFSPS) method at 1600°C using anisotropic Ti2AlN cylinder as preform. The phase and crystalline evolutions from anisotropic Ti2AlN to textured bulk TiN were revealed via changing the EFSPS temperature. The orientation degree of the as-fabricated TiN ceramic was evaluated by X-ray diffraction and electron backscattered diffraction. It was found that the lll planes of TiN grains were perpendicular to the SPS-loading direction and the Lotgering orientation factor on the top surface of bulk TiN was as high as f(lll) = 0.88. Because of the highly textured microstructure, the obtained TiN ceramic exhibited anisotropic mechanical and physical properties. [ABSTRACT FROM AUTHOR]

Hertzian contact damage upon spherical indentation is investigated in alumina-based ceramics designed with embedded textured compressive layers. The effect of the location of the embedded layer and the testing configuration (parallel or normal to the layer orientation) on the sub-surface damage evolution is explored. An acoustic emission system for crack detection and post-mortem cross sectioning are employed to evaluate the onset and extension of damage in the different samples. Distinct acoustic signals detected at different contact loads are correlated with the onset of the ring crack, cone crack propagation and quasi-plastic deformation within the textured layer. The distinct damage mechanisms are influenced by the location of the embedded textured compressive layer and the loading orientation with respect to the layers. The design of layered ceramics for contact applications should consider the loading orientation as well as the contact stress field with respect to the "protective" layer to enhance damage tolerance. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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.

Highly textured Ti 2 AlN ceramic was successfully fabricated by edge-free spark plasma sintering (EFSPS) of Ti 2 AlN discs synthesized by thermal explosion (TE). The orientation degree of as-sintered Ti 2 AlN ceramic was evaluated by X-ray diffraction and electron backscattered diffraction. It was found that the preferred orientation of Ti 2 AlN grains paralleled to the SPS-loading direction was along the c -axis and the Lotgering orientation factor on the textured top surface was as high as f (00 l ) = 0.80. Due to the highly textured microstructure, the obtained Ti 2 AlN ceramic showed anisotropic mechanical and physical properties. The results highlight the advantages of EFSPS combined with TE technique. [ABSTRACT FROM AUTHOR]

In this study, ZrB 2 –ZrC–Zr cermets containing c -axis-oriented ZrB 2 grains were prepared by the reactive hot pressing of a Zr+B 4 C powder mixture, followed by hot forging at 1600 °C and 30 MPa. The textured microstructure formed during hot forging was characterized by X-ray diffraction and electron backscatter diffraction. In addition, the flexural strengths of the hot forged cermets were measured using four-point bend tests. The results show that the anisotropic strengths of the hot forged cermets depend on the textured microstructure. Furthermore, the textured microstructures and the anisotropic strengths of the hot forged cermets were related to the microstructures of the pristine cermets. [ABSTRACT FROM AUTHOR]

Abstract: Two-dimensional phase-field simulations were performed of grain growth in highly textured materials with equal fractions of two texture components, denoted as and grains, and assuming two values of the grain boundary energies, namely for the boundaries between grains of a different texture component and for boundaries between grains of a similar orientation, resulting in microstructures with alternating and grains and stable quadruple junctions. For different magnitudes of the anisotropy in grain boundary energy , the occurrence of the different types of triple and quadruple junctions and the distributions of the normalized grain size, the number of faces per grain, the normalized grain boundary length per grain and the dihedral angles at grain boundary junctions were investigated. [Copyright &y& Elsevier]

Abstract: This paper considers the synthesis of Ti3SiC2/TiC composites by pulse discharge sintering (PDS) using initial TiH2/SiC/TiC powder mixtures of different molar ratios without preliminary dehydrogenation. X-ray diffraction and scanning electron microscopy (SEM) with elemental energy dispersion analysis were utilized for the evaluation of the phase content and features of the microstructure. The sintered materials were found to have a dense structure and possess (001) texture. Scanning electron microscopy study showed that the specimens synthesized from the TiC-depleted mixtures have a double-phase composition of 60–80 vol.% of Ti3SiC2 and TiC. The specimens demonstrated good mechanical performance—the hardness being in the range of 4–6 GPa and the flexural strength in the range of 400–550 MPa. [Copyright &y& Elsevier]