Ch. Jagadeeswara Rao

Corrosion Behavior of Structural Materials in LiCl-KCl Molten Salt by Thermogravimetric Study

Spent metallic fuel from future fast-breeder reactors would be processed by non-aqueous pyrochemical reprocessing. Different unit operations of pyrochemical reprocessing demands various structural materials that are compatible with molten salt medium at high temperatures. In the present study, the corrosion behavior of the candidate materials stainless steel (SS) 410, alloy 600 and 9Cr-1Mo (9% chromium and 1% molybdenum) steel was investigated in molten lithium chloride–potassium chloride (LiCl-KCl) salt by thermogravimetric studies under inert and reactive atmospheres. The test specimens, along with molten salt, were isothermally heated at 500 and 600°C for 24 h in both atmospheres. Alloy 600 showed marginally higher weight gain than 9Cr-1Mo and SS410 under both atmospheres at 600°C. Higher weight gain was observed under reactive atmosphere than in inert atmosphere at 600°C. All of the samples investigated under both atmospheres at 500°C showed insignificant weight loss. The surface morphology and energy...

Corrosion resistance of pyrolytic graphite in LiCl-KCl-UCl3 molten salt for pyrochemical reprocessing application

ABSTRACT Pyrolytic graphite (PyG) is a highly oriented, dense and crystalline form of graphite, which exhibits superior air oxidation resistance, corrosion resistance, and favourable mechanical, thermal, and electrical properties compared to conventional graphite materials. It is proposed as the material of construction for high-temperature molten LiCl-KCl for pyrochemical reprocessing of metallic fuel. In the present study, long-term corrosion behaviour of PyG in LiCl-KCl molten salt with 5 wt-% UCl3 was evaluated by immersion studies at 873 K for 2000 h, under inert argon atmosphere. Characterisation of PyG before and after molten salt exposure was carried out using X-ray diffraction technique, scanning electron microscope with energy dispersive spectroscopy, laser Raman spectroscopy and X-ray photo-electron spectroscopy. The results revealed the superior corrosion resistance and excellent phase stability of PyG with negligible weight change and no appreciable change in the surface chemistry and morphology up to the exposure time of 2000 h.

Electrochemical behaviour of Cu(II)/Cu(I) redox couple in 1-hexyl-3-methylimidazolium chloride ionic liquid

AbstractThe electrochemical behaviour of Cu(II)/Cu(I) redox couple in 1-hexyl-3-methylimidazolium chloride (C6mimCl) ionic liquid was studied using glassy carbon electrode at 375 K by cyclic voltammetry, chronopotentiometry and electrochemical impedance spectroscopy. In this electrochemical study, we have made an attempt to avoid the problem of water contamination in hygroscopic C6mimCl ionic liquid by setting the temperature at 375 K without glove box. This high temperature cyclic voltammetric study revealed two-step one electron reductions of Cu(II) to Cu(I) followed by Cu(I) to Cu metal. The reduction of Cu(II) to Cu(I) was found to be quasi-reversible at 375 K. The diffusion coefficients of Cu(II) and Cu(I), and the charge transfer rate constant of Cu(II) in C6mimCl were estimated by Randles-Ševčik equation and Nicholson’s method, respectively, and found to be consistent with the quasi-reversible process. Further, constant potential electrodeposition of metallic copper was carried out on a stainless steel electrode at 375 K and the deposit was characterised by X-ray diffraction and electron microscopy. Graphical AbstractQuasi-reversible behavior of Cu(II)/Cu(I) redox couple in C6mimCl is studied at 375 K. Diffusion and mass transport coefficients as well as charge transfer rate constant of copper species are estimated. Copper on stainless-steel electrodes by constant potential electrolysis shows island growth of Cu particles under the influence of C6mimCl.