Hydrogen Permeability through n-type Cr2O3 Scale at 1273 K under the Oxygen Activities of 1.6 × 10–18 – 1.0 × 10–16

The effect of dissolution of hydrogen on the defect structure of Cr2O3 was studied. The hydrogen flux and permeability through Cr2O3 scale were measured at 1273 K in the oxygen activities of 1.6 × 10–18 – 1.0 × 10–16. The oxygen activities on the both sides of the sample were controlled by fixing the H2/CO2 and CO/CO2 ratios to measure the hydrogen permeability without oxygen activity gradient through the sample. The measured hydrogen flux and permeability was proportional to aH21/2 and aO2–1/8 respectively. The activity dependences indicate that dissolved hydrogen is the neutral hydrogen at oxygen site as a minor defect and does not affect the oxidation behavior of chromia-forming alloys.