Abstract
A study of the ionic and electronic partial conductivity of Cr2O3 scales selectively grown on Ni-20%Cr alloy with and without yttria additions in hydrogen water vapour at 900 degrees C, was carried out by the asymmetry polarisation technique. The results revealed that there were two main regions for the temperature dependence of conductivity in the range 300-900 degrees C. Above 700 degrees C, the Cr2O3 scale was an intrinsic electronic conductor with a corresponding activation energy of 1.7 eV. Below 700 degrees C, the Cr2O3 scale was a mixed ionic and electronic conductor. The activation energy was 0.6eV for electronic conductivity and 0.3 eV for ionic conductivity. The ionic transference number decreased as the temperature or applied voltage increased. The data strongly suggest that the presence of the reactive element in the scale reduces the concentration of mobile species, thus lowering the ionic transport number.
| Original language | English |
|---|---|
| Pages (from-to) | 247-257 |
| Number of pages | 11 |
| Journal | Solid State Ionics |
| Volume | 109 |
| Issue number | 3-4 |
| DOIs | |
| Publication status | Published - Jun 1998 |
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Keywords
- chromia scale
- defects structure
- ionic conductivity
- ionic transport number
- reactive elements effects
- high temperature oxidation
- electrical conductivity
- defect structures
- chromium
Cite this
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Reactive element effects on the ionic transport processes in Cr2O3 scales. / Liu, H.; Stack, M.M.; Lyon, S.B.
In: Solid State Ionics , Vol. 109, No. 3-4, 06.1998, p. 247-257.Research output: Contribution to journal › Article
TY - JOUR
T1 - Reactive element effects on the ionic transport processes in Cr2O3 scales
AU - Liu, H.
AU - Stack, M.M.
AU - Lyon, S.B.
PY - 1998/6
Y1 - 1998/6
N2 - A study of the ionic and electronic partial conductivity of Cr2O3 scales selectively grown on Ni-20%Cr alloy with and without yttria additions in hydrogen water vapour at 900 degrees C, was carried out by the asymmetry polarisation technique. The results revealed that there were two main regions for the temperature dependence of conductivity in the range 300-900 degrees C. Above 700 degrees C, the Cr2O3 scale was an intrinsic electronic conductor with a corresponding activation energy of 1.7 eV. Below 700 degrees C, the Cr2O3 scale was a mixed ionic and electronic conductor. The activation energy was 0.6eV for electronic conductivity and 0.3 eV for ionic conductivity. The ionic transference number decreased as the temperature or applied voltage increased. The data strongly suggest that the presence of the reactive element in the scale reduces the concentration of mobile species, thus lowering the ionic transport number.
AB - A study of the ionic and electronic partial conductivity of Cr2O3 scales selectively grown on Ni-20%Cr alloy with and without yttria additions in hydrogen water vapour at 900 degrees C, was carried out by the asymmetry polarisation technique. The results revealed that there were two main regions for the temperature dependence of conductivity in the range 300-900 degrees C. Above 700 degrees C, the Cr2O3 scale was an intrinsic electronic conductor with a corresponding activation energy of 1.7 eV. Below 700 degrees C, the Cr2O3 scale was a mixed ionic and electronic conductor. The activation energy was 0.6eV for electronic conductivity and 0.3 eV for ionic conductivity. The ionic transference number decreased as the temperature or applied voltage increased. The data strongly suggest that the presence of the reactive element in the scale reduces the concentration of mobile species, thus lowering the ionic transport number.
KW - chromia scale
KW - defects structure
KW - ionic conductivity
KW - ionic transport number
KW - reactive elements effects
KW - high temperature oxidation
KW - electrical conductivity
KW - defect structures
KW - chromium
U2 - 10.1016/S0167-2738(98)00101-5
DO - 10.1016/S0167-2738(98)00101-5
M3 - Article
VL - 109
SP - 247
EP - 257
JO - Solid State Ionics
JF - Solid State Ionics
SN - 0167-2738
IS - 3-4
ER -