Measure porosity profiles

To calculate the void fraction (Equation 2.6) and the (total) porosity (Equation 2.8) pulses of a nonpenetrating tracer (Tl) and of a nonadsorbable tracer (T2), which penetrates into the pore system (to marker), respectively, are injected. When the resulting measured elution profiles are evaluated by means of moment analysis (Section 6.5.3.1 Figure 6.11), the retention time (it has to be corrected by the dead... 

With this equation, the temporal profile of porosity during the SPS of A1 powder can be derived numerically, with the available experimentally measured temporal profile of temperature, together with the applied voltage gradient and constant pressure. It is found that the model satisfactorily predicts the shrinkage kinetics of the powder compacts. 

Figure4.10.65 Calculated radial porosity profile (dashed line) for dg 25 mm and dp 5 mm (adapted from Delmas and Froment, 1988) and measured data (solid line) (Benenati and Brosilow, 1962).

As a final application of the profiling technique, the sensor for large depth measurements described in Section 2.4.2.5 was used to resolve multi-layer polymer coatings on concrete samples. Such coatings are used to protect concrete from degradation and corrosion. They are applied to the concrete surface to reduce the porosity in the upper first millimeters to prevent the penetration of water and... 

Determination of a pore size distribution profile requires a defined relationship between and the PS diameter ((])). For that purpose, PS standards have been measured in SEC mode, on different silica materials with known porosity, employing CH2CI2 and THF as mobile phase, resulting following correlation between and ( ) (A) for CH2CI2 [119] ... 

A survey of literature exhibits the fact that up to now not much attention has been paid to the impact of porosity and velocity distribution on the analysis of fixed bed chemical reactors. Under non-uniform flow conditions Chaudhary et al. [8] compared measured and calculated concentration profiles for an isomerization reaction in an isothermal fixed bed chemical reactor... 

In this chapter it will be shown with numerous examples how information on open versus closed porosity, the total porosity, the pore sizes and a measure of the average length of connected pores can be measured with varying degrees of ease. Some of these parameters can be obtained from alternate methods. However, none can provide depth dependent profiles of the parameter without microtoming the sample. No special sample preparation is required. A sample investigated by positrons could easily be reinserted in a device production line to correlate results from positron measurements with device performance. 

In this figure, it can be observed that, for both samples, the maximum scattering corresponds to the measurement carried out in the external zone of the fibers, indicating a higher concentration of pores in the outer zone of the fiber. In addition, it can be observed that the PI profiles, as a function of the position of the fibers, are different for CO2 and steam activated materials. In the case of steam, the scattering fi om all the internal zones is very similar and much lower than from the external part of the fiber. On the other hand, in the case of CO2, the porosity is more developed in the inner regions of the fibers compared to the steam activated carbon fibers. 

Note that the value of the Me" ion in the cone is about three times larger than in the exchanger bead. This is attributed to the fact that the resin fiUing the cone has additional porosity, i.e., the space between the resin beads. More information with respect to the various approaches to the study of concentration profiles a, and c as well as to measurements of the exchange rate in a thin layer are disclosed elsewhere [46-48, 50,68,69]. 

From the scattering results, the Porod invariant (PI), which is a parameter related with the porosity development, was estimated for each scattering measurement [77]. From these calculations, the pore distribution across the fiber diameter could be deduced. The results showed that the scattering profiles, as a... 

In Figure 3.14 a sulfate reduction zone is documented by measured profiles of sulfate and methane in pore water. Estimate the diffusive methane flux [mol m a ] and use for the calculation the more reliable profile of sulfate concentrations. Use a temperature of 5°C and a sediment porosity of ([) = 0.7. 

Surface pore diameters were measured by visual inspection of the line profiles of 50 pores of each membrane. All membranes have a wide pore size distribution. The deviation between 20 % and 40% from the average value is noticeable in most cases and is higher for membranes with larger pores (or higher MWCOs). The pore density was obtained by observing several AFM images from different sample areas of the same membrane and counting the number of pores in a unit area. Smface porosity is defined as the ratio of the pore area to the total area of the membrane. The porosity is low and varies between 0.6% and 7%. No relationship between MWCO and porosity was found. 

---