Anisotropic, biomorphic cellular Si3N4 ceramics with directional well-aligned nanowhisker arrays based on wood-mimetic architectures

Inspired by the transport behavior of water and ions through the aligned channels in trees, we demonstrate a facile, scalable approach for constructing biomorphic cellular Si3N4 ceramic frameworks with well-aligned nanowhisker arrays on the surface of directionally aligned microchannel alignments. Through a facile Y(NO3)(3) solution infiltration into wood-derived carbon preforms and subsequent heat treatment, we can faultlessly duplicate the anisotropic wood architectures into free-standing bulk porous Si3N4 ceramics. Firstly, alpha-Si3N4 microchannels were synthesized on the surface of C-B-templates via carbothermal reduction nitridation (CRN). And then, homogeneous distributed Y-Si-O-N liquid phase on the walls of microchannel facilitated the anisotropic beta-Si3N4 grain growth to form nanowhisker arrays. The dense aligned microchannels with low-tortuosity enable excellent load carrying capacity and thermal conduction through the entire materials. As a result, the porous Si3N4 ceramics exhibited an outstanding thermal conductivity (TC, k(R) approximate to 6.26 W center dot m(-1)center dot K-1), a superior flexural strength (sigma(L) approximate to 29.4 MPa), and a relative high anisotropic ratio of TC (k(R)/k(L) = 4.1). The orientation dependence of the microstructure-property relations may offer a promising perspective for the fabrication of multifunctional ceramics.

Automated summary

Inspired by the transport behavior of water and ions through the aligned channels in trees, the researchers demonstrate a facile, scalable approach for constructing biomorphic cellular Si3N4 ceramic frameworks with well-aligned nanowhisker arrays. The porous Si3N4 ceramics exhibit outstanding thermal conductivity, flexural strength, and anisotropy, making them promising for multifunctional ceramics.