Advanced nuclear reactors using alkali chloride molten salts are actively being developed for deployment as safer next generation reactors. These reactors operate more efficiently and can enable a more flexible nuclear fuel cycle. These designs require the development of the understanding of corrosion at operational conditions. Static corrosion studies fail to capture the effects of flowing electrolyte on the corrosion in these systems. To simulate the effects of flow, we have designed and commissioned an apparatus for such corrosion studies. This study explored the corrosion of alloys in LiCl-KCl eutectic molten salt. After long-term exposure under simulated flow conditions, corrosions samples were evaluated using gravimetric analysis, scanning electron microscopy and energy dispersive spectroscopy, Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy and the results are compared to corrosion under static conditions. Results and analysis of the effects of fluid flow on the corrosion on structural materials will be presented.
more »
« less
Evaluation of Metal Oxide Coated Stainless Steel As a Potential Anode for Pyroprocessing
Pyroprocessing is a potential route to close the nuclear fuel cycle. Used nuclear fuel (UNF) is electrolytically reduced from UO2 to U0 at a stainless-steel cathode while oxygen evolution occurs at a platinum anode in a molten LiCl-Li2O environment. Platinum is consumed during this process as a result of the formation and spallation of lithium platinate. To increase the economic viability of pyroprocessing, alternative low-cost, electrochemically efficient materials are needed to replace platinum. In this study, metal-oxide coated 316L stainless streel rods were explored as potential replacements. The characteristics of these coatings in molten LiCl-Li2O was evaluated through electrochemical techniques. The surface chemistry of the coatings was explored through X-ray photoelectron spectroscopy, X-ray diffraction, Raman spectroscopy and scanning electron microscopy before and after exposure to molten salts to understand the degradation of the coatings. Results detailing the performance of the coatings will be presented.
more »
« less
- Award ID(s):
- 2117820
- PAR ID:
- 10388327
- Date Published:
- Journal Name:
- The Electrochemical Society Meeting Abstracts
- Volume:
- MA2022-02
- Issue:
- C03
- Page Range / eLocation ID:
- 776-776
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract This study demonstrates the simultaneous achievement of high strength and excellent corrosion resistance in a Ni-free, high N austenitic stainless steel fabricated by laser powder bed fusion (PBF-LB). The formation of a single-phase austenitic structure was confirmed through X-ray diffraction analysis, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Cyclic potentiodynamic polarization tests conducted in 0.6 M NaCl solution at room temperature revealed high breakdown potential (1187 ± 31 mVSCE), indicating excellent corrosion resistance for the additively manufactured Ni-free austenitic stainless steel compared to wrought 316L stainless steel. These findings were further supported by immersion tests in FeCl3solution. The additively fabricated alloy’s yield strength and ultimate tensile strength exceeded 800 MPa and 1 GPa, respectively. The results highlight the potential for developing highly corrosion-resistant, high-strength Ni-free austenitic stainless steel by PBF-LB for possible applications for biomedical implants and structures relating to nuclear energy.more » « less
-
Abstract New acceptor‐type graphite intercalation compounds (GICs) offer candidates of cathode materials for dual‐ion batteries (DIBs), where superhalides represent the emerging anion charge carriers for such batteries. Here, the reversible insertion of [LiCl2]−into graphite from an aqueous deep eutectic solvent electrolyte of 20mLiCl+20mcholine chloride is reported. [LiCl2]−is the primary anion species in this electrolyte as revealed by the femtosecond stimulated Raman spectroscopy results, particularly through the rarely observed H–O–H bending mode. The insertion of Li–Cl anionic species is suggested by7Li magic angle spinning nuclear magnetic resonance results that describe a unique chemical environment of Li+ions with electron donors around.2H nuclear magnetic resonance results suggest that water molecules are co‐inserted into graphite. Density functional theory calculations reveal that the anionic insertion of hydrated [LiCl2]−takes place at a lower potential, being more favorable. X‐ray diffraction and the Raman results show that the insertion of [LiCl2]−creates turbostratic structure in graphite instead of forming long‐range ordered GICs. The storage of [LiCl2]−in graphite as a cathode for DIBs offers a capacity of 114 mAh g−1that is stable over 440 cycles.more » « less
-
null (Ed.)Superhard boron-rich boron carbide coatings were deposited on silicon substrates by microwave plasma chemical vapor deposition (MPCVD) under controlled conditions, which led to either a disordered or crystalline structure, as measured by X-ray diffraction. The control of either disordered or crystalline structures was achieved solely by the choice of the sample being placed either directly on top of the sample holder or within an inset of the sample holder, respectively. The carbon content in the B-C bonded disordered and crystalline coatings was 6.1 at.% and 4.5 at.%, respectively, as measured by X-ray photoelectron spectroscopy. X-ray diffraction analysis of the crystalline coating provided a good match with a B50C2-type structure in which two carbon atoms replaced boron in the α-tetragonal B52 structure, or in which the carbon atoms occupied different interstitial sites. Density functional theory predictions were used to evaluate the dynamical stability of the potential B50C2 structural forms and were consistent with the measurements. The measured nanoindentation hardness of the coatings was as high as 64 GPa, well above the 40 GPa threshold for superhardness.more » « less
-
Many functional materials have relatively low decomposition temperatures ( T ≤ 400 °C), which makes their synthesis challenging using conventional high-temperature solid-state chemistry. Therefore, non-conventional techniques such as metathesis, hydrothermal, and solution chemistry are often employed to access low-temperature phases; the discovery of new chemistries is needed to expand access to these phases. This contribution discusses the use of triphenylphosphine (PPh 3 ) as a molten flux to synthesize superconducting iron selenide (Fe 1+δ Se) at low temperature ( T = 325 °C). Powder X-ray diffraction and magnetism measurements confirm the successful formation of superconducting iron selenide while nuclear magnetic resonance spectroscopy and in situ X-ray diffraction show that the formation of superconducting FeSe at low temperatures is enabled by an adduct between the triphenylphosphine and selenium. Exploration of the Fe–Se–PPh 3 phase space indicates that the PPh 3 –Se adduct effectively reduces the chemical potential of the selenium at high concentrations of triphenylphosphine. This contribution demonstrates that the use of a poorly-solvating yet reactive flux has the potential to enable the synthesis of new low-temperature phases of solid materials.more » « less
An official website of the United States government

