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Alumina (Al2O3) ceramics are widely used in electronics, machinery, healthcare, and other fields due to their excellent hardness and high temperature stability. However, their high brittleness limits further applications, such as artificial ceramic implants and highly flexible protective gear. To address the limitations of single-phase toughening in Al2O3 ceramics, some researchers have introduced a second phase to enhance these ceramics. However, introducing a single phase still limits the range of performance improvement. Therefore, this study explores the printing of Al2O3 ceramics by adding two different phases. Additionally, a new gradient printing technique is proposed to overcome the limitations of single material homogeneity, such as uniform performance and the presence of large residual stresses. Unlike traditional vat photopolymerization printing technology, this study stands out by generating green bodies with varying second-phase particle ratios across different layers. This study investigated the effects of different contents of sepiolite fiber (SF) and 316L stainless steel (SS) on various aspects of microstructure, phase composition, physical properties, and mechanical properties of gradient-printed Al2O3. The experimental results demonstrate that compared to Al2O3 parts without added SF and 316L SS, the inclusion of these materials can significantly reduce porosity and water absorption, resulting in a denser structure. In addition, the substantial improvements, with an increase of 394.4% in flexural strength and an increase of 316.7% in toughness, of the Al2O3 components enhanced by incorporating SF and 316L SS have been obtained. [ABSTRACT FROM AUTHOR]

Vat photopolymerization is an effective and economical method for preparing ceramic specimens with complex structures. However, the improper selection of process parameters during the preparation process limits the scope of its application. In this study, the most suitable shear rate was determined based on the solid content and rheological properties of the ceramic slurry. In addition, the specific printing‐process parameters were objectively selected, and the gray correlation method was used to determine the improved weight resolution coefficient through orthogonal experiments combined with the entropy weight method to select the most suitable printing parameters. Finally, the main debinding and sintering parameters that affect the heat treatment performance were considered, and multiple characterization methods were used to detect the specimens and study the impact of parameter changes on specimen performance. The experimental results show that when the laser power is 210 mW, the slice layer thickness is.04 mm, the scanning spacing is.05 mm, and the filling mode is XY, the green bodies have the best forming quality. When the sintering temperature is 1600°C, and the holding time is 4 h, the specimens have the best mechanical properties (the flexural strength reaches 114 MPa). [ABSTRACT FROM AUTHOR]

Ceramic materials are highly regarded for their exceptional chemical and mechanical stability; however, their inherent brittleness limits their resistance to impact fractures. Researchers have investigated the design of biomimetic ceramic structures to overcome this problem, demonstrating the ability to toughen ceramics and expand their applications. However, the complexity of these structures makes the implementation of traditional processing methods challenging. To address this problem, a new preparation method for high-strength and high-toughness biomimetic ceramic structures is proposed. First, the primitive structure with the best mechanical performance was selected as the experimental object. Second, the vat photopolymerization printing process was optimized; further, primitive structures were designed with different wall thicknesses to investigate the effects of graded and variable-graded structures on the performance of triply periodic minimal surface structures. Finally, a polymer was used to impregnate the ceramic parts to prepare biomimetic structures. In the experiments, the biomimetic structures outperformed their pure ceramic counterparts in terms of toughness and avoided catastrophic failure. In particular, when the ceramic had graded structures, the energy absorption capability of the part increased by 202%. Finite-element modeling was used to analyze the stress concentration and distribution. Peridynamic simulations provided insights into the strengthening and toughening mechanisms at the micro level and guidance for developing damage-resistant, high-energy-absorbing materials. [Display omitted] • A method for preparing high-strength, toughness biomimetic ceramic was developed. • The vat photopolymerization printing process optimization plan has been determined. • Finite element modeling method was carried out to study fracture mechanisms. • Peridynamics were used to study strengthening and toughening mechanisms. [ABSTRACT FROM AUTHOR]

The unique structure of nacre is composed of 'bricks' and 'mortar,' which gives it excellent damage resistance. In this study, nacre-like bionic ceramic scaffolds were 3D-printed using vat photopolymerization (VPP) technology, filled with polymer, and reinforced with carbon fiber to create high-strength and high-toughness carbon fiber-reinforced bionic composites. This approach leverages additive manufacturing technology to easily overcome the challenges of fabricating complex bionic structures with a simple and flexible production process. It offers a practical method for developing other lightweight, high-strength, and tough bionic materials. The microstructure of the composites was observed using scanning electron microscopy and energy dispersive spectroscopy. Additionally, finite element method and molecular dynamics simulations were performed on the composites. The results indicate that the composite material increased the flexural strength by 293.52 % and the fracture toughness by 109.36 % compared to solid ceramic parts. The primary toughening mechanisms of carbon fiber include crack deflection, fiber "pull-out," and "debonding" within the composite. [Display omitted] • Nacre-like biomimetic composites were fabricated via vat photopolymerization. • Effects of various fillers on flexural properties were investigated. • Atomic-level insights on biomimetic structures were offered by molecular dynamics. • Finite element method reveals filler interaction with the nacre scaffold. [ABSTRACT FROM AUTHOR]

As an additive manufacturing technology, vat photopolymerization (VPP) can print ceramic parts with high resolution and good surface quality at a low cost. Therefore, VPP has been widely used to process a variety of ceramic materials. Despite these benefits, it is still a challenge to fabricate defect-free ceramic parts owing to ceramic materials' inherent brittleness and low toughness. To overcome these issues, two types of coating agents (i.e., E44 and E51 coating agents) are selected to coat alumina (Al 2 O 3) parts by the authors. Experimental results show that the parts coated with the coating agents demonstrate fewer defects, better physical properties, and enhanced mechanical properties (including flexural and compressive properties), compared with the uncoated Al 2 O 3 parts. Particularly, the average surface roughness of coated Al 2 O 3 parts can be reduced from 2 μm to 35–180 nm. In addition, the absorbed energy can be increased by around 17% when E51 coating agent is adopted. To study stress distribution changes and strengthening and toughening mechanisms induced by the coating agents, finite element modeling analysis and molecular dynamic simulations have been performed. [ABSTRACT FROM AUTHOR]