A new three-dimensional (3D) printing gel is developed to construct hierarchically porous ceramics with adjustable millimeter-, micrometer-, and nanometer-scale size for application in thermal management. Not only does the gel based on supramolecular micelles exhibit excellent DIW 3D printability but also the supramolecular micelles act as templates that can precisely control the structure of micrometer-scale pores. The effect of millimeter-and μmicrometer-scale size on properties of porous ceramics is investigated in detail. The 3D-printed ceramic foam with millimeter-scale pores and smaller micrometer-scale pores shows better thermal insulation and lower compressive strength. For the thermal insulation, the local temperature of a chip exposed to contact heat is only 34.2 °C in the presence of a printed foam cap with a pore size of 41.5 μm, while the local temperature is 54.8 °C in the absence of the printed foam cap. The study provides a new method to construct hierarchically porous alumina ceramics with precisely tunable size, avoiding the issues of subtractive manufacturing and opening up new applications in portable devices or consumer electronics.
A new graphene (G)/Al2O3 composite ceramic with tunable mechanics is prepared by direct ink writing (DIW) 3D‐printing technology. It is found that the bending strength, fracture toughness, and hardness all increase with increasing in content of G. The bending strength, fracture toughness, and hardness of G/Al2O3 composite ceramic (4.0 wt‰) are improved to be 45.0%, 40.6%, and 21.9% comparing to Al2O3 ceramic, respectively. The result is attributed to good reinforcement of G and inhibition of Al2O3 phase growth by G. Furthermore, the gear wheel with gradient mechanics is also designed and fabricated by the DIW 3D‐printing technology from various G/Al2O3 composite gels. It exhibits excellent wear resistance and low generation of heat during rotational friction. Herein, a new method is provided to fabricate G‐based ceramics with gradient structure and mechanics for various applications.
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