Effect of Alumina-Coated Graphite (ACG) on the Microstructure and Mechanical Properties of Al2O3-C Refractories

Alumina-coated graphite(ACG) was prepared by soaking expanded graphite (EG) in an AlCl3 solution withvacuum impregnation. The graphite was then filtered, dried and treated in a coke bed at 400 -1000 degrees C. TheACGwas incorporated into Al2O3-C refractories, partly or completely replacing EG. The results showed that the alumina coating on the graphite was effective and delayed the oxidation behavior of the expanded graphite. It also allowed the structure of the graphite to survive largely intact at high temperatures as it had been incorporated into the Al2O3-C refractories while there were fewer in situ-formed ceramic phases in the matrix, e. g. SiC whiskers. As a result, ACG-containing Al2O3-C refractories exhibited better thermal shock resistance than that of common Al2O3-C refractories.