Corrosion characteristics of Inconel 625 cladding layer and NiCrMoAl cladding layer in molten NaCl-KCl and NaCl-KCl-Na2SO4

The high-temperature corrosion characteristics of Inconel 625 and NiCrMoAl cladding layers were investigated in molten NaCl-KCl and NaCl-KCl-K2SO4. In NaCl-KCl, the corrosion was dominated by electrochemical mechanism, subsequently triggering chlorine-active corrosion mechanism. NiCrMoAl cladding layer provided significantly higher corrosion resistance than Inconel 625 cladding layer, due to the generated greatly Al2O3 enhanced the difficulty of inward diffusion of Cl-. In NaCl-KCl-K2SO4 , protective Al2O3 and Cr2O3 faced basic fluxing mechanism, considerably aggravating the corrosion. Additionally, Al easily reacted with SO42- , which further consumed Al and generated free S, causing NiCrMoAl cladding layer to suffer serious corrosion than Inconel 625 cladding layer.

Automated summary

The high-temperature corrosion characteristics of Inconel 625 and NiCrMoAl cladding layers were studied in molten NaCl-KCl and NaCl-KCl-K2SO4. In NaCl-KCl, the corrosion behavior was primarily controlled by an electrochemical mechanism, followed by a chlorine-active corrosion mechanism. NiCrMoAl cladding layer exhibited significantly higher corrosion resistance than Inconel 625 cladding layer due to the enhanced difficulty of Cl- inward diffusion by the generated Al2O3. In NaCl-KCl-K2SO4, the presence of protective Al2O3 and Cr2O3 worsened the corrosion due to the basic fluxing mechanism. Furthermore, the reaction between Al and SO42- resulted in the consumption of Al and the formation of free S, leading to severe corrosion of the NiCrMoAl cladding layer compared to Inconel 625 cladding layer.