Yu Zhou

Direct ink writing (DIW) is a promising additive manufacturing technique for flexible electronics; however, lateral spreading of conventional silver inks often limits printing resolution and geometric fidelity. To address this limitation, an in situ UV-assisted DIW strategy using photocurable silver inks was developed for the fabrication of high-resolution conductive features. The effects of Ag loading, TPO photoinitiator concentration, and dispersant type on the rheological behavior, photocuring response, and stability of the inks were systematically investigated. Excessive TPO concentrations were found to induce rheological instability, whereas an optimized formulation enabled a stable photocuring response. Among the dispersants investigated, AH100 provided the most favorable balance between ink flowability and controlled substrate wetting, thereby suppressing excessive lateral spreading. During printing, in situ UV irradiation rapidly promoted crosslinking of the resin matrix, increasing the structural rigidity of the deposited filament and restricting capillary-driven spreading. Using the optimized printing conditions and a photocurable silver ink with a Ag powder-to-photosensitive resin mass ratio of 4:1, the post-sintering line width was reduced from 269.8 to 72.57 μm, corresponding to a reduction of approximately 73%. After sintering at 800 °C, the printed tracks exhibited an electrical conductivity on the order of 10⁷ S/m, demonstrating that the substantial improvement in printing resolution was achieved without significantly compromising electrical performance. This in situ UV-assisted DIW strategy therefore provides an effective route for fabricating fine conductive features with improved dimensional fidelity and competitive electrical performance, showing promise for high-resolution flexible electronics and sensor applications.

Inkjet printing technology shows significant potential for producing high-performance conductive circuits in printed electronics. However, conventional silver nanoparticle (Ag NP) inks often face challenges such as nozzle clogging, poor stability, and low conductivity after low-temperature sintering. While most existing studies focus solely on dispersant selection or individual process optimization, few have systematically explored the synergistic effects of particle size distribution, dispersion methods, and dispersant dosage. This study proposes a sequential optimization approach involving centrifugal classification to identify an optimal Ag NPs source and size distribution, followed by comparison and optimization of different dispersion methods. Furthermore, the effects of dispersant (a PEO-PPO-PEO triblock copolymer) concentration and application strategy (individual or combined use) on the rheological properties and conductivity of the ink were systematically investigated. The optimized Ag NP ink demonstrated excellent jetting stability with no nozzle clogging, exhibiting a surface tension of 19.60 mN/m and a viscosity of 6.83 mPa·s. After low-temperature sintering at 260 °C on glass or polyimide (PI) substrates, the printed patterns achieved a high electrical conductivity of 1.506 × 10⁷ S/m. Printing on polyethylene terephthalate (PET) at 150 °C confirmed compatibility with heat-sensitive flexible substrates. This work offers a comprehensive and practical strategy for developing highly reliable and conductive Ag NP inks, facilitating their application in next-generation printed electronics.

With the development of aerospace, energy and power, nuclear energy, and chemical industries, hot-end components of various key equipment are gradually facing more severe high-temperature challenges. The high-temperature oxidation failure of key thermal structural materials in hot-end components has become a critical bottleneck restricting their service life. Consequently, there is an urgent need for oxidation protection of these components. Oxidation-resistant composite coatings are widely recognized as one of the most effective approaches to mitigating high-temperature oxidation. This review initially outlines the characteristics and anti-oxidation mechanisms of various coating materials, followed by an in-depth examination of the impact of structural modifications such as multi-layer/gradient design, diffusion barriers, and self-healing structures on the anti-oxidation efficacy of coatings. Furthermore, it discusses the fundamental principles and key features of advanced coating fabrication techniques, as well as summarizes the methods for characterizing the performance of anti-oxidation composite coatings under real operating conditions. Lastly, the review analyzes the current limitations and challenges facing anti-oxidation coatings in practical applications and provides insights into future development prospects.

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.

To address the biological inertness of pure titanium implants, a composite coating with a strontium-doped hydroxyapatite (Sr-HA) phase and H₂Ti₅O₁₁·H₂O nanorods was engineered via ultrasonic-assisted micro-arc oxidation (UMAO) with hydrothermal treatment (HT). The ultrasonic field was applied to modulate the MAO discharge behavior, enhancing ion transport and coating formation. Structural characterization revealed that UMAO-HT coatings exhibited a lower anatase/rutile ratio and higher Sr-HA crystallinity, as compared to MAO-HT. In vitro simulated body immersion studies showed that UMAO-HT induced rapid apatite formation within 24 h, with a better apatite-inducing ability than the conventional MAO-HT. Density functional theory (DFT) simulations demonstrated that Sr substitution in HA lowered the (001) surface work function, enhancing Ca²⁺ adsorption energy and promoting apatite phase nucleation. This work reported the synergistic effects of ultrasonic-induced microstructure optimization and Sr-HA higher bioactivity, providing a mechanistic framework for designing next-generation bioactive coatings with enhanced osseointegration potential.

In this study, the SiBCN-Ti series ceramics with different Ti contents were fabricated, and the oxidation resistance and microstructural evolution of the ceramics at 1500 °C for different times were explored. The results show that with the increase in oxidation time, pores and bubbles are gradually formed in the oxide layer. When the oxidation time is less than or more than 4 h, the Ti(C, N) in the ceramics will maintain its initial structure or mostly transform to TiN. The introduction of Ti content can promote the formation of rutile silicate glass, thus healing the cracks and improving the oxidation resistance of the ceramics effectively.