The formation of a ceramic layer on the carbon steel surface is proposed as a method to protect carbon steel against corrosion by molten salt at high temperature > 500°C. Has anyone the expertise to explain the protection mechanisms and the effectiveness of the protection method?
Hi Bashar Abdulrahman Mahmoud
Basically the idea of the protection layer is to form an oxide (or any non-metallic system) layer (or film or coating) over the steel. In your case for high-temperature applications, the refractory ceramic oxide layers are preferable over others. For example, refractory ceramic oxides like Al2O3, Cr2O3, CaCO3, etc could be used for many years in certain applications. These oxides exhibit much higher corrosion-resistance against molten salts, slags, and glass, and thus used for high-temperature process industries & pyrometallurgical operations due to high thermal & chemical stability, as well as low cost. Please find a paper attached for the more detailed mechanism (note: CaCO3 could decompose beyond 700 degrees centigrade).
I hope it would be helpful.
Thanks & regards
MN
Corrosion is an important issue in high-temperature applications such as Concentrated Solar Power (CSP) technology, playing a crucial role in the long-term use of storage tanks, heat exchanger and piping materials which account for a considerable component of the investment costs. While there are many studies regarding the corrosion rates of container materials under the conditions of CSP, there is little progress in the field of their degradation prevention by anticorrosion methods. This work presents an analysis of the corrosion mechanisms between the most economical construction material—carbon steel—and molten nitrate salt. A method to protect the carbon steel against corrosion by molten salt at high temperature was proposed, involving the formation of a calcium carbonate layer on the carbon steel surface. The stability of the layer was tested under isothermal and temperature cycling conditions up to 500 °C, in both inert and air atmospheres in the presence or absence of humidity. The protection method proposed has potential to reduce investment costs for CSP technology.
http://helioscsp.com/a-simple-method-for-the-inhibition-of-the-corrosion-of-carbon-steel-by-molten-nitrate-salt-for-thermal-storage-in-concentrated-solar-power-applications/
Dear Mithun and Ayman,
I greatly appreciate all your answers.
Best regards,
BM
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