Improving the foaming performance of foamed ceramics using Fe2O3 as an oxygen donor

Abstract

A solution is proposed to reduce the cost of preparing foamed ceramics (FCs) by adding Fe₂O₃ to the material system. As the Si₃N₄ in the Fe₂O₃–free material system increases, the molten ceramic matrix allows a slight increase in gas generation at elevated temperatures, resulting in a slight increase in the foaming volume of FCs. The addition of Fe₂O₃ increases the oxygen supply capacity of the molten ceramic matrix at elevated temperatures, thereby accelerating the oxidation of Si₃N₄ and consequently increasing the foaming volume of the FCs. The FCs sintered from the 5 wt% Fe₂O₃ and 2 wt% Si₃N₄ material system at 1160–1180 °C have satisfactory overall performance with total/closed porosity of (73.6–79.5)%/(71.4–75.7)% and compressive strength of 10.2–15.4 MPa. The addition of Fe₂O₃ to the material system can reduce the dosage of Si₃N₄ for FCs preparation, thereby decreasing the cost of FCs preparation.