Abstract
In order to obtain a better fundamental understanding of factors responsible for the high temperature oxidation behavior of Fe–Cr alloys, the electrical conductivity of sintered Cr2O3 doped with various amounts of Fe2O3 was measured in the temperature range from 773 to 1473 K at near-atmospheric oxygen pressures.
The electrical conductivity of Cr2O3 doped with Fe2O3 showed a very complex dependence on the Fe2O3 concentration. It was at its maximum at 3 mass% and at its minimum at 10 mass% Fe2O3. The oxygen pressure dependence of the conductivity and the sign of the thermoelectric power of the samples showed that the semi-conductivity changed from a p-type on the low Fe2O3 side of the minimum in conductivity to an n-type on the high Fe2O3 side of the minimum in the conductivity. However, the oxygen pressure dependence of the conductivity was too small to be explained by a simple model. The electrical conductivity of Cr2O3 doped with Fe2O3 showed a complex temperature dependence. The temperature dependence of the conductivity of undoped Cr2O3 consisted of two straight lines, while that of Cr2O3 doped with Fe2O3 consisted of three straight lines, two of which possessed approximately the same slopes as those of undoped Cr2O3.
