Artefact porosity

In a recent study conducted by Jonsson et al. [99], a focus ion beam milling method was used to generate a smooth cross-section of the oxide scale for analyses. The study produced some very high quality images, although some artefact porosities were still visible in several of the images shown. 

The porosities discussed above are those normally observable under a microscope or SEM. They probably belong to a different regime from those of very fine pores (<50nm) discussed by Anghel etaJ. [103]. Unfortunately, even in a study dedicated to the discussion of various fine pores , the only optical image shown in Anghel et al. s study revealed numerous artefact porosities generated by poor sample preparation. 

The case of mN2 is once again interesting. It would seem that an overlap is obtained for the smaller pore size whereas adsorption manometry is not able to probe the larger pores. However, the smaller pores are at the limit at which the BJH method is valid. That is to say that from the adsorption data alone, one would discard the peak obtained at around 4 nm as an artefact. From the mercury intrusion data though, a peak is observed which would seem to confirm the presence of a meaningful porosity. 

To measure the porosity of cement pastes, stronger degassing conditions have to be applied to remove the water from the smallest pores and avoid artefacts during the measurement. In this case, degassing under vacuum at... 

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