Moisture Corrosion of LiH: A Kinetic Investigation by DRIFT Spectroscopy

Journal Article · Fri Dec 20 00:00:00 EST 2019 · Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory

DOI:https://doi.org/10.1021/acs.jpca.9b09951· OSTI ID:1597620

Matt, Sarah M. ^[1]; Haschke, John M. ^[1]; McLean, William ^[1]; Dinh, Long N.  ^[1]

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1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Lithium hydride (LiH) is a unique, ionic compound with applications in a variety of industries. Unfortunately, LiH is very reactive toward H₂O even at ppm levels, forming oxide (Li₂O) and hydroxide (LiOH) corrosion layers while outgassing H₂. An effective means to eliminate unwanted outgassing is vacuum-heating to convert LiOH into Li₂O, although subsequent re-exposure to moisture during transport/handling reconverts some Li₂O back to LiOH. A corrosion growth model for previously vacuum-baked LiH is necessary for long-term prediction of the hydrolysis of LiH. In this work, a para-linear hydroxide corrosion growth model is proposed for the reaction of previously vacuum-baked LiH samples with moisture. This model, composed of two competing diffusion reaction fronts at the LiOH/Li₂O and Li₂O/LiH interfaces, is validated experimentally by subjecting a previously vacuum-baked polycrystalline LiH sample to 35 ppm of H₂O at room temperature while monitoring the corrosion growth as a function of time with diffuse-reflectance infrared Fourier transform (DRIFT) spectroscopy. The para-linear growth model for the hydrolysis of previously vacuum-baked LiH proposed in this report can also serve as a template for the hydrolysis of other hygroscopic oxides grown on metal or metal hydride substrates.

• Research Organization: Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC52-07NA27344
• OSTI ID: 1597620
• Report Number(s): LLNL-JRNL-778562; 971570
• Journal Information: Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory, Vol. 124, Issue 2; ISSN 1089-5639
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Electrochemistry
Moisture
Interfaces
Diffusion
Oxidation