Development of porous corundum layers on cordierite ceramics

The surface of cordierite ceramics is transformed into porous corundum (α-Al2O3) by heating the ceramic at 1350–1450 °C in a controlled reducing atmosphere with a partial CO pressure below 10−8 atm. The least stable oxides in the cordierite (SiO2 and MgO) are selectively reduced and volatilized, leaving the most stable Al2O3 as a surface layer up to 15 μm thick, with a specific surface area of up to 15 m2/g. The characteristics of this layer and the chemical and thermal stability of corundum make ceramics treated in this way well suited for use as catalyst supports for high-temperature catalysis.