Heat capacity of 2Al 4C 3·SiC from 447 to 1447 K and enthalpy of peritectic decomposition of Al 4C 3, 2Al 4C 3·SiC, and Al 4C 3·SiC

Abstract

The molar heat capacity of 2Al 4C 3·SiC and the enthalpy of peritectic decomposition of Al 4C 3, 2Al 4C 3·SiC, and Al 4C 3·SiC were measured by the Bureau of Mines to provide fundamental data to assist in the development of a carbothermic reduction process for aluminum. The molar heat capacity of 2Al 4C 3·SiC was measured by differential scanning calorimetry from 447 to 1447 K. The enthalpy of peritectic decomposition was calculated from time-temperature thermal analyses of samples, synthetic sapphire (NBS Standard Reference Material 720), and an empty crucible. The value at T = 298.15 K for C p,m o of 2Al 4C 3·SiC is 260.24 J K −1 mol −1. The enthalpy of peritectic decomposition for Al 4C 3 at 2429 K is (140 ± 20) kJ mol −1, for 2Al 4C 3·SiC starting at 2358 K it is (210 ± 50) kJ mol −1, and for Al 4C 3·SiC starting at 2345 K it is (160 ± 20) kJ mol −1.