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, α-Si3N4 microchannels were synthesized via carbothermal reduction nitridation. And then, homogeneous distributed Y-Si-O-N liquid phase on the walls of microchannel facilitated the anisotropic β-Si3N4 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 excellent thermal conductivity (TC, kR≈6.26 W·m− 1·K− 1), a superior flexural strength (σL ≈ 29.4 MPa), and a relative high anisotropic ratio of TC (kR/kL = ~ 4.1). The orientation dependence of the microstructure-property relations may offer a promising perspective for the fabrication of multifunctional ceramics.