Reactions Between Aluminum Oxide and Carbon The Al2O3—Al4C3 Phase Diagram


  • Presented at the Fall Meeting of the Basic Science Division, The American Ceramic Society, The Pennsylvania State University, University Park, Pennsylvania, October 17, 1955.

  • The authors are, respectively, chief, Physical Chemistry Division; research engineer, Physical Chemistry Division; and assistant chief. Metallography Division, Aluminum Research Laboratories, Aluminum Company of America.


A phase diagram of the system A12O3-A14C3 is proposed. Two intermediate oxycarbides, A14O4C and A12OC, were established. Eutectic melting between alumina and A14O4C occurred at 1840° C. No other low melting was observed. The alumina phase was not corundum but was similar to delta-alumina. Because of the high reactivity of aluminum carbide and all the intermediate compounds with moisture and oxygen, use of refractories based on the system A12O3-A14C3 must be limited to applications where these agents are excluded. The behavior of high-alumina refractories in the presence of carbon is explained.