High temperature thermodynamic properties of the chromium carbides Cr7C3 and Cr3C2 determined using a galvanic cell technique

Thermodynamic investigations of Cr3C2 and reassessment of the Cr-C system

“…The values for the enthalpy of formation of Cr 3 C 2 at 298 K are also included in Table II. As can be seen from Table II and Figure 4, Kelley et al, [4] Coltters and Belton, [11] and Gleiser [6] report significantly lower values than the present study. The results reported by Kleykamp, [9] Tanaka et al, [10] Anthonysamy et al, [14] and Mabuchi et al [12] are much higher than the present values.…”

“…The present obtained result for is not only comparable to the values reported by Kulkarni and Worrell, [8] but also those by Du et al [13] and Kleykamp. [15] As can be seen from Kelley et al [4] Ϫ86,860 Ϫ 18.8T 1200 to 1400 Ϫ95.6 CO equilibrium pressure (1944) Gleiser [6] Ϫ108,262 Ϫ 16.3T 1300 to 1400 Ϫ114.4 CO equilibrium pressure (1965) Kulkarni and Worrell [8] Ϫ68,552 Ϫ 18.4T 1300 to 1500 Ϫ76.7 CO equilibrium pressure (1972) Anthonysamy et al [14] Ϫ54,344 Ϫ 19.6T 973 to 1173 Ϫ63.8 CH 4 /H 2 gas equilibrium (1996) Vintaikin [25] Ϫ34,276 Ϫ 29.2T 1370 to 1570 Ϫ56.8 [11] Ϫ92,860 Ϫ 19.4T 973 to 1173 Ϫ102.1 EMF, BaF 2 -BaC 2 (1984) Mabuchi et al [12] Ϫ43,472 Ϫ 30.7T 1073 to 1303 Ϫ64.4 EMF, ThO 2 -Y 2 O 3 (1971) Kleykamp [9] Ϫ30,096 Ϫ 33.4T 880 to 1100 Ϫ56.4 EMF, CaF 2 (1969) Kleykamp [15] Ϫ83,189 Ϫ 0.97T 930 to 1120 Ϫ72.3 EMF, CaF 2 (2001) Tanaka et al [10] Ϫ55,594 Ϫ 17.3T 885 to 1095 Ϫ65.5 EMF, CaF 2 (1971) Du et al [13] Ϫ42 [7] --Ϫ77.7* combustion calorimetry (1969) Storms [21] Ϫ61,864 Ϫ 14.3T 800 to 1500 Ϫ68.97 estimation (1961) Wicks and Block [23] Ϫ78,166 Ϫ 16.51T 800 to 1500 Ϫ87.8 estimation (1963) Andersson [22,27] Ϫ54,939 Ϫ 14.1T 800 to 1500 Ϫ71.4 estimation (1987) Barin [24] Ϫ77,092 Ϫ 18.5T 800 to 1500 Ϫ85.3 estimation (1993) *This value has been recalculated by Kulkarni and Worrell. [8] ⌬ f H°2 98 (kJ/mol) ⌬ f G°C r 3 C 2 (J/mol) By combining the uncertainties in the EMF values obtained (Ϯ2.7 mV as the maximum error) with the uncertainties in the measurement of temperature (Ϯ2 K for each individual data point), the total uncertainty in Eq.…”

“…The temperature dependences of the Gibbs energies are presented by the following type of expression: [11] where V 1 through V 4 had to be evaluated.…”

“…[1,2] The carbides are all nonstoichiometric compounds with very narrow homogeneity ranges below 1200 K. [3] Numerous experimental investigations have over the years been published on the high-temperature thermodynamic properties of the chromium carbides. [4][5][6][7][8][9][10][11][12][13][14][15] The available experimental data for the Gibbs energy of formation of the chromium carbides, however, are quite scattered. [15] Among the many previous measurements, there have been six determinations of the Gibbs energy of formation of Cr 3 C 2 by the use of the galvanic cell technique (four of them using CaF 2 as the electrolyte).…”

“…The possible reasons for the large scattering of the electromotive force (EMF) results have already been discussed in the respective investigations. [11][12][13][14][15] As a preliminary study on the thermodynamic properties of the Fe-Cr-C transition metal carbides, the Gibbs energies of formation of Cr 3 C 2 were determined in the present study by use of the EMF technique. A CaF 2 single crystal was used as an electrolyte, and extreme precautions were taken to avoid experimental errors.…”