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材料研究学报 2005
Morphology and microstructure of CO2 corrosion scales
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Abstract:
The morphology and microstructure of the CO2 corrosion scales formed under different conditions were investigated by means of SEM, EDS, XRD in this paper. A typical FeCO3 crystalline was observed in the scales of N80 (carbon steel) and lCr-L80 while chromium compounds were formed on the surface of 3Cr-L80 and 5G-L80. These chromium compounds were confirmed as Cr(OH)3 and Cr2O03. They were loose and formed chaps after dehydration. Under the static condition, the scales of carbon steel and chromium-containing steels all had delamination structure. There were similar compositions between outer and inner scales of carbon steel in the form of (Fe, Ca)CO3. Chromium enrichment in the inner scales of chromium-containing steels was observed with the surface scale presented as (Fe, Ca)CO3. XRD patterns of the scales formed under dynamic condition indicated that the scales of chromium-containing steels gradually translated into amorphous structure with the increase of chromium content. The weight-loss testing results showed that the corrosion rate of chromium-containing steels approached to carbon steel under static condition, while under dynamic condition (1.5 m/s), the corrosion rates of chromium-containing steels were much less than that of carbon steel. And the corrosion rates decreased with the increase of chromium content.
