Effects of water vapor on protectiveness of Cr2O3 scale at 1073 k
Fe-Cr alloy is commonly being used as boiler tube’s material. It is subjected to prolonged exposure to water vapor oxidation. The ability to withstand high temperature corrosion can normally be attributed to the formation of a dense and slow growing Cr-richoxide scale known as chromia, Cr2O3 scal...
| Main Authors: | , , , |
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| Format: | Conference or Workshop Item |
| Language: | English English English |
| Published: |
American Scientific Publishers
2017
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| Subjects: | |
| Online Access: | http://irep.iium.edu.my/62459/ http://irep.iium.edu.my/62459/ http://irep.iium.edu.my/62459/ http://irep.iium.edu.my/62459/1/62459_Effects%20of%20water%20vapor%20on%20protectiveness%20of%20Cr2O3%20scale.pdf http://irep.iium.edu.my/62459/6/62459_Effects%20of%20water%20vapor%20on%20protectiveness%20of%20Cr2O3%20scale_SCOPUS.pdf http://irep.iium.edu.my/62459/13/62459_Effects%20of%20water%20vapor%20on%20protectiveness%20of%20Cr2O3%20scale_WoS.pdf |
| Summary: | Fe-Cr alloy is commonly being used as boiler tube’s material. It is subjected to
prolonged exposure to water vapor oxidation. The ability to withstand high temperature
corrosion can normally be attributed to the formation of a dense and slow growing Cr-richoxide
scale known as chromia, Cr2O3 scale. However, oxidation may limit the alloy’s service
lifetime due to decreasing of its protectiveness capability. This paper is to presents an
experimental study of thermo gravimetric and Fourier transform infrared analysis of Cr2O3 at
1073 K in dry and humid environment. Samples were used from commercially available Cr2O3
powder. It was cold-pressed into pellet shape of 12 mm diameter and 3 mm thick with
hydraulic press for 40 min at 48 MPa. It then sintered at 1173 K in inert gas environment for 8
h. The samples are cooled and placed in 5 mm diameter platinum pan. It is subjected to
reaction in dry and wet environment at 1073 K by applying 100%-Ar and Ar-5%H2 gas. Each
reaction period is 48 h utilizing Thermo Gravimetric Analyzer, TGA to quantify the mass
changes. After the reaction, the samples then characterized with Fourier Transform Infrared
Spectroscopy, FT-IR and Field Emission Electron Scanning Microscopy, FE-SEM. The TGA
result shows mass decreasing ratio of Cr2O3 in wet (PH2O =9.5x105Pa) and dry environment is
at a factor of 1.2 while parabolic rate at 1.4. FT-IR results confirmed that water vapor
significantly broaden the peaks, thus promotes the volatilization of Cr2O3 in wet sample.
FESEM shows mostly packed and intact in dry while in wet sample, slightly porous particle
arrangement compare to dry. It is concluded that water vapor species decreased Cr2O3
protectiveness capability. |
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