In order to understand the nature of carbon bonds in an AG refractory, the interface between alumina and amorphous carbon was characterized by TEM and EDX. In addition, the interaction energy of alumina and carbon was simulated using a molecular orbital method to estimate the Al－C and O－C bond lengths. The results indicated that amorphous carbon from the phenol resin played an important role as the binder connecting alumina and graphite. TEM and EDX results showed no reaction layer existed between alumina and graphite, and hence negligible interdiffusion across the interface appeared reasonable. However, intermolecular and covalent bonds were assumed to be partially present. These carbon bonds formed at the interface between alumina and amorphous carbon and gave the refractory thermal shock resistance and strength at high temperature.

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