Computer tomography applied to complex monolith sample surface area estimation
EMSL Project ID
61037
Abstract
Chemical durability of simulated waste forms is one of the most important benchmarking parameters for the waste management strategy assessment. In almost all cases to assess the chemical durability of these materials, the surface-to-area ratio (S/V) is the governing parameter given by the standard testing procedures. That means, the surface area of the tested material must be reliably calculated, to add a correct volume of corrosive liquid. Depending on a procedure, S/V parameter can be obtained through variety of ways, i.e. assuming spherical shape of carefully sieved, narrow fractions of powders, or through straightforward analysis of perfect monoliths. However, in the case of some materials, i.e. iron-phosphates we propose this study for, the path forward may not be so straightforward. Testing of iron phosphates is suggested to be done through monoliths, however these waste forms occur in multi-crystalline forms. That means, that due to natural crystal formations potential voids and cracks may be a part of natural monolith structure. In that case, the assessment of sample’s surface area needs to consider not the assumed perfect flat surface of the sample, but the area including pores, pits, voids and cracks, which will significantly impact S/V ratio, therefore the traditional image-based surface calculation is going to underestimate the S parameter. Another option is Brunauer–Emmett–Teller (BET) technique traditionally used for the assessment of specific surface area for samples with complicated surface topography. However, due to current geopolitical situation, BET becomes unjustifiably expensive, as Krypton, gas needed for the analysis is scarce on the current market. Our proposal hopes to obtain support for assistance in X-ray computed tomography (CT-Xray) to demonstrate its suitability as a viable alternative to above-mentioned analyses. The proposes suggests application of CT-Xray to 1) assessment of the specific surface area for tested iron-phosphate glasses, and 2) generate a digital map of crystalline clusters comprising individual specimens. The tested specimens are smaller-than 10x10x1.5mm, and due to this small size, measurement time should be reasonably short enough for this technique to be a suitable alternative to BET. Moreover, the additional data on the crystal density distribution and its 3D projection, can be an attractive supplemental information to X-ray diffraction of corresponding powders and Scanning Electron Microscopy.
Project Details
Project type
Contracted Time
Start Date
2023-12-04
End Date
N/A
Status
Active
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Principal Investigator
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