Conversion of basic dicarboxylate Al(III) complexes to aluminum carbide under a flow of argon

The process of conversion of basic dicarboxylate Al(III) complexes Al(OH)(Cn+2H2nO4)·xH2O (n = 2, 3, 6) to aluminum carbide (Al4C3) under a flow of argon was investigated by powder XRD. The thermal decomposition of the glutarate complex (n = 3, AG) at 1100 °C gave a mixture of δ-alumina and carbon. As the calcination temperature was increased, the δ-alumina was first converted into α-alumina, then into aluminum monoxycarbide (Al2OC), and finally into the single phase of aluminum carbide (Al4C3) at 1600 °C. In contrast, the calcination of the succinate (n = 2, AS) complex at 1600 °C gave a mixture of δ-alumina, aluminum tetraoxycarbide (Al4O4C), Al2OC, and Al4C3, while the calcination of the suberate (n = 6, ASu) complex at 1600 °C gave a mixture of α-alumina, Al4O4C, and Al2OC. The difference in the products at 1600 °C was well explained by the relative amount of carbon produced by the thermal decomposition of the complexes. The reaction mechanism for the carburization of alumina to Al4C3 was suggested.