Enhanced Thermal Shock Resistance of Ceramics through Biomimetically Inspired Nanofins

We propose here a new method to make ceramics insensitive to thermal shock up to their melting temperature. In this method the surface of ceramics was biomimetically roughened into nanofinned surface that creates a thin air layer enveloping the surface of the ceramics during quenching. This air layer increases the heat transfer resistance of the surface of the ceramics by about 10 000 times so that the strong thermal gradient and stresses produced by the steep temperature difference in thermal shock did not occur both on the actual surface and in the interior of the ceramics. This method effectively extends the applications of existing ceramics in the extreme thermal environments.

Figure 1

(a) Experimental results showing the changes of the flexural strength of the ZSAs without and with nanofins along with the different temperatures of thermal shock. (b) Microscope images showing the surface cracks of the ZSAs without nanofins quenched in room temperature water; the initial temperature of the ZSAs are 400, 500, 600, 800, and $1000°\mathrm{C}$, respectively.

Figure 2

SEM images showing different surface structures. (a) The surface structure of the ZSA without nanofins, which displays the water contact angles of $70.6\pm 1.8°$ showing in the inset; (b) the surface structure of the ZSA with nanofins, which displays the water contact angles of $121.6\pm 2.2°$ showing in inset; and (c) the surface structure of the dragonfly (Libellula basilinea McLachlan) wing, whose nanofins are mimicked in roughening by the surface of ZSA and displays water contact angles of $174.21\pm 2.19°$ showing in the inset (16).

Figure 3

Schematic illustrations showing the temperature distribution at the interface between the solid with nanofins and water during quenching. $T_0$ and $T_{\infty }$ are the initial temperature of the solid and the temperature of water, respectively. Inset (A) the interfacial structure composed of the solid, the nanofins, the entrapped air, and water, where $L_M$, $L$, and $L_W$ stand for the lengths of the regions of internal conduction, the interface, and the surface convection resistance, respectively. Inset (B) the evolution of the temperature profile at the contact interface between the top of a nanofin and water, which is the same as the interface between the surface of the solid without the nanofins and water.