The miniaturization and thinning of high-temperature co-fired ceramics (HTCC) present challenges for maintaining mechanical properties, which is critical for packaging reliability. This study employed direct ink writing (DIW) technology to fabricate alumina HTCC structures with varying interlayer deflection angles, resulting in improved mechanical performance. By incorporating only 3 wt% of organic additives, we developed a water-based alumina slurry with 86 wt% solid content that exhibits shear-thinning behavior. Our results demonstrate that the mechanical properties peak when the interlayer deflection angle is 15°, though this configuration exhibits a higher degree of anisotropy. Conversely, a 90° deflection angle minimizes anisotropy. This work elucidates how different printing filling methods influence the mechanical properties of alumina HTCC and offers valuable insights and experimental evidence for enhancing the mechanical performance of 3D-printed HTCC materials.

Advanced thermal management for extreme environments urgently demands materials that combine robust environmental stability with adaptive thermal conductivity (κ), specifically the highly desirable but rare positive temperature (T) dependence of κ. Ceramics typically exhibit phonon-dominated heat transfer with decreasing thermal conductivity at elevated temperatures, and achieving an alloy-like positive κ–T relationship in ceramics is a significant scientific and technological challenge with immense application value. To address this, we fabricated fully dense (> 98%) multicomponent nitride bulks via hot-press sintering using aluminum nitride (AlN) as the matrix. Notably, the TiAlN system achieved a high room-temperature (κ) of 48.38 W·m⁻¹·K⁻¹. Counterintuitively, increased diversity of metallic elements induces severe lattice distortion that suppresses phonon thermal conduction while simultaneously forming metallic nitride conductive networks that significantly increase electronic thermal conductivity. This synergistic electron‒phonon regulation successfully transforms the κ–T dependence from negative to positive. Remarkably, TiZrVCrAlN demonstrates a linear 112% κ increase from 8.65 W·m⁻¹·K⁻¹ at −60 °C to 18.34 W·m⁻¹·K⁻¹ at 900 °C, outperforming all known positive-κ ceramics in both the operating temperature range and conductivity values. Moreover, it maintains robust mechanical integrity (24.5 GPa hardness, 273 MPa bending strength). This work elucidates the fundamental mechanism for achieving anomalous positive κ‒T dependence in ceramics through electron‒phonon synergistic regulation. These multicomponent nitrides, combining unprecedented positive κ‒T behavior with excellent mechanical properties, present a breakthrough solution for intelligent thermal management, specifically enabling the development of structural‒functional integrated components operating under extreme and varying thermal conditions.

As advanced ceramic materials, Si₃N₄ ceramics are widely used in strong thermal shock environment in aerospace field because of the excellent properties such as high temperature resistance and corrosion resistance. The Si₃N₄ composites prepared by hot pressing sintering had high flexural strength, but the thermal shock resistance decreased rapidly with the increase of temperature. The hot pressing sintering process was still insufficient to enhance the thermal shock resistance. In this paper, a secondary heat treatment method of hot pressing sintering-gas pressure sintering was proposed to improve the thermal shock resistance of Si₃N₄ ceramics, and obtain a denser Si₃N₄ ceramic material with better thermal shock resistance. The results showed that with the increase of thermal shock temperature and times, the probability of micro-cracks in the Si₃N₄ ceramics prepared by conventional hot pressing increased, and the bending strength of the samples decreased gradually after thermal shock, with the average strength reduction rate reaching 23.48% at 1200℃. After the second heat treatment, the flexural strength of Si₃N₄ ceramics samples decreased slightly, but the thermal shock resistance was obviously improved. With the increase of heat treatment time, the microstructure of Si₃N₄ ceramics after the second heat treatment became denser, and the thermal shock resistance was obviously improved. The strength reduction rate of the sample decreased significantly after 10 times of thermal shock at 1200℃, which was about 12.31%. Method of improving the thermal shock resistance of Si₃N₄ ceramics was proposed to study the thermal shock resistance and the attenuation law of Si₃N₄ ceramics at 1200℃, which provided a reference for improving the high temperature performance of silicon nitride ceramic devices.

This article reports the first example of 3D printed continuous SiO₂ fiber reinforced wave-transparent ceramic composites via an adaptation of direct ink writing technology to improve the mechanical and dielectric properties of ceramics. The ceramic inks showed good printability by adding nano-SiO₂ powder. The effective continuous fiber-reinforced printing progress was achieved through the design and optimization of the coaxial needle structures by finite element simulation. After printing, the continuous fibers were evenly and continuously distributed in the matrix ceramics and the high molding precision for fiber reinforced composite was kept. It is demonstrated that 10 vol% continuous SiO₂ fiber improved the bending strength of ceramics by about 27% better than that of the ceramics without fiber and the dielectric performance has also been greatly improved. The novel method unravels the potential of direct ink writing of continuous fiber reinforced wave-transparent ceramics with complex structures and improved properties.