Heat and Mass Transfer in Ceramic Lattices During High‐Temperature Oxidation

Abstract

This work reports on the heat and mass transfer evolution of ceramic lattices during their oxidation at 1400°C and 1600°C in air. Si–SiC and Si–SiC–ZrB2 systems were employed as skeleton material because they, previously produced as monolithic bars, showed promising oxidation behavior at high temperatures. Regular arrays of tetrakaidecahedra were first designed by CAD, then 3D printed and finally converted into ceramic by replica technique followed by reactive silicon infiltration. The surface area of each sample was calculated and specific weight variations were evaluated as a function of time. During oxidation, effective thermal conductivity and pressure drop of each sample were measured. Finally, results were correlated with the phenomena occurring during high‐temperature oxidation.

Early-stage oxidation behavior at high temperatures of SiSiC cellular architectures in a porous burner

“…A general mass gain was observed in all specimens in agreement with our previous work [25], suggesting passivation as the dominant oxidation mode. Passivation produces a dense oxide layer of SiO 2 according to reactions (3) and (4).…”

“…As pure silicon shrinks upon melting, it further favors the oxidation process by opening up new pores in the microstructure. On the other hand, silica while forming expands and squeezes out the molten silicon alloy from the microstructure [25]. The low wettability of the silicon alloy on SiO 2 [33] favors beads formation on the strut's outer surface.…”

“…Another phenomenon, highlighted by Aronovici et al [25], is the exudation of alloyed silicon beads at temperatures above 1400°C. Oxide scale foaming during long lasting operational conditions slows down the gasses flow in the pores with a subsequent local overheating and degradation of the material [6].…”

“…There are several works in the literature concerning oxidation of SiC (sintered and CVD) and silicon; few of them consider the case of SiSiC by reactive silicon infiltration [6,12,[25][26][27]. There is a lack in studies on the effect of oxidation on macro porous materials in a flowing gas caused by combustion.…”

Tuning the spectral emittance of α-SiC open-cell foams up to 1300 K with their macro porosity

“…2 Hexagonal or α-SiC open-cell foams combine light weight, high surface area per unit volume, high thermal conductivity and good thermomechanical properties. Their tri-dimensional texture, 3 imposed by the interconnected network of struts and cells, manages simultaneously fluid flow and heat transfer.…”