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.