Jia-Jun Zhao

Two-dimensional (2D) materials offer opportunities for constructing functional devices; however, integrating them into macroscopic structures requires precise control over nanosheet dispersion, processing parameters, and structural design. This review summarizes research on the fabrication of 3D structures using nanosheet-based inks and composite feedstocks—including graphene and its derivatives, MXenes, transition metal dichalcogenides, hexagonal boron nitride, and black phosphorus. Studies indicate that material performance is determined by the combined effects of feedstock composition, printing conditions, structural design, and post-processing techniques. Direct Ink Writing (DIW) is a particularly suitable fabrication technique for various porous lattices and self-supporting structures where nanosheets form the primary functional network. High-concentration aqueous MXene inks and rheologically tuned graphene oxide-based inks serve as typical feedstocks, provided they exhibit favorable shear-thinning behavior, shape retention, and structural recovery capabilities. Regarding polymer-based composite components, Fused Deposition Modeling (FDM) is applicable to thermoplastic feedstocks loaded with 2D materials, whereas Stereolithography (SLA) and Digital Light Processing (DLP) utilize nanosheet-loaded photocurable resins to fabricate composites with intricate features, albeit with applications constrained by light attenuation and curing characteristics. Applications in sensing, energy storage devices, and biomedical scaffolds demonstrate the immense potential of these methods, while printed optoelectronic devices are discussed as a complementary case of device integration. Nevertheless, challenges such as material instability, trade-offs between resolution and scale, post-processing shrinkage, and incomplete biosafety assessments remain significant barriers to practical application, highlighting the need to develop reproducible processing techniques and conduct validation studies focused on real-world use.

Additive manufacturing enables ceramic–metal interpenetrating phase composites (IPCs) with designed load paths, but their tribological performance is constrained by coupled infiltration, interfacial damage, and lubrication processes. This review critically evaluates these constraints through an architecture–infiltration–interface–performance framework. Unlike conventional particle-reinforced metal matrix composites, IPCs require both phases to form three-dimensionally continuous networks; successful infiltration additionally requires preservation of the ceramic skeleton, adequate filling of the intended metal channels, and interfaces capable of transferring load. The central mechanical trade-off is between ceramic load support and accommodation of incompatible phase deformation. Thermal-expansion mismatch (Δα) generates residual stresses during post-infiltration cooling, while cyclic frictional heating superimposes spatially nonuniform thermal stresses that can promote interfacial microcracking and delamination. Increasing ceramic content or refining load paths must therefore be assessed against the remaining metal-ligament capacity for plastic accommodation and crack bridging, rather than hardness alone. Lubrication introduces a second trade-off: sufficient lubricant delivery can shift sliding from direct asperity contact toward tribofilm-mediated shear, whereas excessive lubricant content or reservoir porosity can weaken structural continuity and increase wear despite low friction. Sustained protection requires lubricant supply and film formation to offset depletion and removal. Current evidence does not establish universal optimal phase fractions or topology rankings, because direct, matched tribological studies of printed and subsequently infiltrated IPCs remain scarce. Quantitative design therefore requires joint characterization of phase connectivity, infiltration defects, residual and cyclic thermal stresses, interfacial fracture resistance, and tribofilm persistence under specified contact conditions.

The surface quality of metal materials is closely related to their service life and performance. Appropriate polishing techniques can significantly reduce surface roughness and the coefficient of friction, thereby enhancing properties such as wear resistance and corrosion resistance. However, traditional polishing methods have certain limitations. For instance, mechanical polishing has low processing efficiency and fails to ensure consistent product quality; chemical polishing can cause environmental pollution; and electrolytic polishing may result in severe corrosion. In contrast, plasma electrolytic polishing (PEP) has attracted considerable attention for its ability to achieve high-quality surface finishes, its use of environmentally friendly aqueous electrolytes, and its rapid processing speed. It has been successfully applied to the finishing of various metal materials. Hence, this review firstly introduces the basic principles of PEP from two perspectives of macroscopic structure and microscopic mechanism, and summarizes the typical features appearing in the polishing process. Secondly, the key parameters affecting the quality of the polished surface are discussed, including voltage, electrolyte composition and electrolyte temperature, and polishing time. Subsequently, the application of PEP on various metals was discussed, along with considerations regarding the polishing efficiency and removal characteristics of coatings and non-metallic substances. Finally, the challenges and potential future development prospects of PEP are summarized.

Zirconia (ZrO₂) ceramics and composites have attracted much attention in aerospace, biomedical and energy fields due to their high hardness, high wear resistance, excellent chemical stability and biocompatibility. However, the brittleness of ceramics and the high cost of molds have made it difficult for traditional processing techniques to manufacture complex structural and functional components efficiently. Additive manufacturing technology has successfully overcome these challenges by optimizing the preparation process and improving production efficiency. Among them, vat photopolymeriztion (VPP) has been demonstrated to offer distinct advantages, including high precision, high efficiency and low cost. It provides a novel approach to the preparation of zirconia ceramics. VPP preparation of zirconia ceramics and composites needs to consider various steps such as slurry preparation, structural design and printing, debinding and sintering. This review introduces common VPP technologies related to zirconia ceramics and summarizes the factors affecting the rheological and curing properties of zirconia slurry, in order to provide researchers with a reference for studying VPP preparation of zirconia. The current optimization methods for light-curing zirconia slurry formulations are focused on, and common methods for surface modification and optimization of slurry composition and solid loading are introduced. The influencing factors of the printing process are summarized, and the current research on surface texturing of VPP preparation and the influence of printing parameters on the performance and accuracy of the components are introduced. The effects of debinding/sintering processes on cured zirconia ceramics are also summarized. The applications of VPP zirconia ceramics and composites are proposed, especially for their use in biomedical and energy applications.

Alumina is a polycrystalline oxide ceramic with different structures. Currently, α-alumina with a hexagonal close-packed stacking structure is mainly used for a variety of industrial applications. Alumina-based ceramics and composites have been widely used in various fields due to their excellent hardness, strength, creep resistance and good biocompatibility. However, it is difficult for Al₂O₃ ceramic components based on traditional preparation methods to meet the increasing industrial requirements, especially for applications such as precise multi-walled complex structures. Al₂O₃ ceramic additive manufacturing by vat photopolymerization 3D printing stands out owing to its ability to produce complex structures and tailored shaping accuracy/properties. The vat photopolymerization 3D printing of Al₂O₃ ceramics requires multiple steps including slurry preparation, photopolymerization shaping, debinding and sintering. Therefore, many efforts mainly focus on the strategies of optimizing the ceramic slurry formulation and the debinding/sintering process. This paper provides a scoping review to present optimization strategies for the above aspects of vat photopolymerization 3D printing, which creates a strong reference for researchers to improve the accuracy and properties of alumina parts. Finally, this review also states the main applications of Al₂O₃ ceramic components based on vat photopolymerization, and highlights the opportunities and challenges associated with this technology in the future. It is beneficial to understanding the future trends and policy directions of advanced manufacturing industry.