Values of the equilibrium constants for the system: (1) Fe3C+CO2 ⇔ 3Fe+2CO have been determined at temperatures of 650°C and 700°C. The value of K for this reaction at 6S0°C is 1.66 and at 700°C is 2.21. Values of the equilibria constants for the system: (2) C + CO ⇔ 2CO as calculated by Juptner and determined experimentally by Boudouard; Thead and Wheeler; and checked in part in this laboratory, are smaller than the values of K for reaction (1) at the same temperature. This indicates that iron carbide is metastable with respect to carbon and alpha iron at these temperatures. From the values of the equilibrium constants for reaction (1) its heat effect was calculated and corrected to 20°C. This gave the heat of formation of iron carbide as -18,331 and -16,131, assuming graphite in the first case and amorphous carbon in the second. This is in fair agreement with a calorimetric determination made by Ruff.
Proceedings of the Iowa Academy of Science
©1924 Iowa Academy of Science, Inc.
Maxwell, Harold L. and Hayes, Anson
"The Stability of Iron Carbide and Calculations of Its Heat of Formation from Equilibrium Studies,"
Proceedings of the Iowa Academy of Science, 31(1), 283-284.
Available at: https://scholarworks.uni.edu/pias/vol31/iss1/71