Corrosion Behaviour of Uncoated and Ceramic Coated 9Cr–1Mo Steel in Molten LiCl–KCl–UCl3 Salt

Abstract

Hot corrosion is usually a significant issue in power plant's boilers. The alloys and metals get corroded, once exposed to high temperature corrosion in air, or in actual boiler environment in power plants. In order to protect materials; thermal spraying is a newly developed technology that enhances high temperature corrosion resistance of boiler steels. In the present study, WC-17Co coating were deposited by HVOF technique on substrate ASTM-SA213-T91. Subsequently; high temperature corrosion behavior of uncoated and WC-17Co coated substrate T91 was investigated in molten salt environment at an elevated temperature of 900⁰C for 50 cycles. The experimental cyclic study consisted a cycle of 1 hour heating of samples in SiC tube furnace, followed by 20 minutes of cooling in room temperature. Surface morphologies of corroded samples were carried out by SEM/EDS and XRD analysis. In the results, bare material is corroded with intense peeling and spalling. But on the other side, WC-17Co coating performed better than the uncoated steel substrate.

High temperature molten salt corrosion of structural materials in UCl3–LiCl–KCl

“…The U on the surface of the sample could be in the form of oxides resulting from the oxidation of the UCl 3 salt in the presence of moisture and/ or oxygen. A similar type of observation was also evidenced in the long duration immersion studies on 9Cr-1Mo steel in UCl 3 -LiCl-KCl molten salt [26]. In the reactive atmosphere (Figure 8(C and D)), the attack by molten salt was more significant and the formation of oxides and fluxing of the oxides than inert atmosphere.…”

“…Depletion of Cr from hot regions of the surface and migration to the colder regions will result in variation of Cr as evidenced in the present study and in all our previous studies. Since Cr has a high affinity towards oxygen, it is deposited on the surface of the alloy as oxides of Cr [26].…”