Preparation of Si3N4 ceramic aerogel by foam-gelcasting combined concerted catalysis nitridation method.

High-performance Si 3 N 4 ceramic aerogel (CA) prepared by employing commercial Si powders containing impurity Fe as raw materials and Fe powders as catalyst through a simply Fe-concerted catalyzed nitridation technology, CS Si 3 N 4 CAs, were synthesized at 1473 K for 5 h, and thoroughly characterized. It exhibited a porosity of 87.7 %, a compressive strength of 3.3 MPa and a specific strength of 8.7 MPa cm3 g−1, along with its outstanding low thermal conductivity (as low as 0.108 W m−1 K−1 at 373 K). Compared with the Si 3 N 4 CA catalysis nitridation of concerted reactions by Fe(NO 3) 3 ·9H 2 O and in-situ catalytic nitridation by impurity Fe in commercial Si, and the specific strength of CS Si 3 N 4 CA was about 14 % and 22 % higher than that of the former, respectively. This demonstrated that it may be more conducive to the preparation of Si 3 N 4 CAs with high performance via catalysis nitridation of concerted reactions by Fe than Fe(NO 3) 3 ·9H 2 O. This work also provides an ideal method for the cost-effectiveness synthesis of high-performance Si 3 N 4 and/or Si 3 N 4 composites. [ABSTRACT FROM AUTHOR]