Engineering topics

Loui, Albert

Publications and source records attributed to Loui, Albert.

3 records

DOE OSTI2021

Uranium hydride corrosion. II Modeling spatially random growth using reaction and nucleation kinetics

A uranium hydride (UH 3 ) corrosion kinetics model has been developed, based on dimensionally restricted nucleation kinetics, which combines heretofore separate reaction and nucleation kinetics models into a single predictive construct. This theoretical framework accounts for the superficial and random pitting behaviour of UH 3 corrosion. The model can be used to generate the net corrosion surface area and volume fractions for a uranium specimen, generally accounting for its geometric form factor through the surface-to-volume ratio. Furthermore, the combined corrosion kinetics model enables the generation of quantities which may be directly compared to those obtained by non-destructive, non-contact evaluation methods.

36 MATERIALS SCIENCE↗

DOE OSTI2021

Uranium hydride corrosion. I New insights into the Condon-Kirkpatrick model of uranium hydride formation rate

An analytic solution to the uranium hydride formation rate equation of Condon and Kirkpatrick (CK) has been developed, which is directly solved via algebraic operations and requires only gaseous hydrogen (H 2 ) pressure and temperature as inputs. The solution does not depend on the specific functional forms of the hydriding and dehydriding rate constants, nor of key physical parameters. Furthermore, a modified form of the CK model has also been developed, where replacement of the hydrogen solubility function results in an improved fit to published experimental data as H 2 pressure decreases toward the corrosion threshold value.

36 MATERIALS SCIENCE↗

DOE OSTI2019

Moisture outgassing from siloxane elastomers containing surface-treated-silica fillers

Abstract The outgassing kinetics from siloxane elastomers is dominated by moisture desorption from the reinforcing silica filler and can be detrimental in moisture-sensitive applications. In this study, a custom 3D printable siloxane rubber (LL50) was analyzed in three different states: after a high temperature vacuum heat treatment, limited re-exposure to moisture after vacuum heat treatment, and in the as-received condition. The outgassing kinetics were extracted using isoconversional and iterative regression analyses. Moisture release by physisorbed and chemisorbed water from the samples have activation energies in the range of 50 kJ/mol (physisorbed type) to 220 kJ/mol (chemisorbed type). Overall, moisture outgassing from LL50 was 10 times lower than that from traditionally prepared siloxane rubbers. The vastly diminished moisture content in LL50 is attributed to the existence of a finite low level of silanol groups that remain on the fumed silica surface even after hydrophobic treatment.

36 MATERIALS SCIENCE↗