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

Abstract

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 on the surface of CB-templates via carbothermal reduction nitridation (CRN). And then, homogeneous distributed Y−Si−O−N liquid phase on the walls of microchannel facilitated the anisotropic β-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, 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.

High wave transmittance and low thermal conductivity Y– α-SiAlON porous ceramics for high-temperature radome applications

“…Therefore, it can be considered to some extent that the existence of most submicron grains in prepared porous ceramics improves the number of grain boundaries, which is conducive to better J u s t A c c e p t e d stress relief, and hinder the deformation and brittle failure of Y-α-SiAlON porous ceramics to a certain extent [35]. Meanwhile, the mechanical properties can also be improved through the mechanism of crack deflection, crack bridging and grain pullingout effect by successfully introducing Y-α-SiAlON rod-like grains [5,6,36,37]. Table 1 shows the properties of prepared Y-α-SiAlON porous ceramics compared to those of typical high-temperature wave-transmitting materials [16][17][18][38][39][40][41][42].…”

Enhanced In-Plane Thermal Conductivity and Mechanical Strength of Flexible Films by Aligning and Interconnecting Si3N4 Nanowires

“…Silicon nitride (Si 3 N 4 ) has high thermal conductivity and excellent mechanical properties, making it one of the ideal fillers for thermal management materials. 21 Ramdani et al reported a thermally conductive composite fabricated via Si 3 N 4 nanoparticles compounded with polybenzoxazine, and the composite thermal conductivity was increased to 5.78 W•m −1 • K −1 by adding 70 wt % of Si 3 N 4 nanoparticles. 22 Considering that one-dimensional (1D) materials have an inherent advantage in building thermally conductive networks, if Si 3 N 4 NWs can be synthesized and further used to prepare thermally conductive composite films by structural design, it will be highly potential to achieve significant enhancement of thermal conductivity at a low filling fraction.…”

“…Silicon nitride (Si 3 N 4 ) has high thermal conductivity and excellent mechanical properties, making it one of the ideal fillers for thermal management materials . Ramdani et al reported a thermally conductive composite fabricated via Si 3 N 4 nanoparticles compounded with polybenzoxazine, and the composite thermal conductivity was increased to 5.78 W·m –1 ·K –1 by adding 70 wt % of Si 3 N 4 nanoparticles .…”

Cutting performance improvement of Si3N4 ceramic cutting tools by adding boride

“…Silicon nitride (Si 3 N 4 ) ceramics are widely used as structure ceramics for cutting applications due to their good toughness, high strength, low density, high hardness, and good thermal shock resistance. [1][2][3][4][5][6] It has been widely reported that Si 3 N 4 -based ceramic cutting tools can be used for cutting cast iron [7][8][9] and superalloy 10,11 materials.…”