Special Features Regarding the Certification of Highly Particulated and/or Porous Reference Materials
Katherine Meyer, B Rohl-Kuhn, Dennis B. Minor, P Klobes
Porous and / or finely particulated materials are of growing importance in many fields of technological application. Despite some traditionally used or newly developed experimental methods ofr porosity studies, such as ultrasonic methods, stereology and image analysis, small angle scattering of X-rays or neutrons, maximum bubble pressure, immersion or adsorption calorimetry, thermoporometry, size exclusion chromatography, Xenon NMR, high-resolution transmission electron microscopy, and others, gas adsorption porosimetry and mercury intrusion porosimetry have remained two of the most important methods that are widely practice to characterize porous solids. In contrast to other kinds of reference materials (RMs), the developmnet and certification of porous reference materials for both of these methods is characterized by some special features. Among other things, these are related to (i) the fractal character of some porosity properties of solids, (ii) the dependence of the results of porosity measurements on the method used (including the selected pore model). Further difficulties result from the general fact that the pore system of a solid may be greatly influenced by different kinds of sample pretreatment. Therefore, the question of traceability of certified values and the estimation of their uncertainty are to be solved in a somewhat different manner than, for instance, in the case of the certification of the elemental content of solutions. The contribution will give an overview of the present situation in the field of porous CRMs. After the description of the availability of these materials in the international market, some examples of the approaches used by BAM and NIST for the development and certification of new porous CRMs for the gas adsorption method as well as for mercury intrusion are discussed. The includes some questions of stability and homogeneity testing as well various aspects of the statistical treatment of interlaboratory tests and the estimation of uncertainty budgets for porous CRMs. Another point of importance is the necessity of standardization not only of the experimental procedures used for porosity studies but also of the computational algorithms for calculating the results.
, Rohl-Kuhn, B.
, Minor, D.
and Klobes, P.
Special Features Regarding the Certification of Highly Particulated and/or Porous Reference Materials, Eurolab-Deutschland
(Accessed March 3, 2024)