TY - CONF A1 - Röhl-Kuhn, Barbara T1 - New Porous Certified Reference Materials (CRMs) - Method: Mercury Intrusion T2 - COPS VI - 6. International Symposium on the Charakterization of Porous Solids CY - Alicante, Spain DA - 2002-05-08 PY - 2002 AN - OPUS4-4526 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Röhl-Kuhn, Barbara T1 - New Porous Certified Reference Materials (CRMs) for the Mercury Intrusion Method in the Pressure Range from 0.2 to 2 MPa T2 - XI. Workshop über die Charakterisierung von feinteiligen und porösen Festkörpern CY - Bad Soden, Germany DA - 2002-11-14 PY - 2002 AN - OPUS4-4531 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Röhl-Kuhn, Barbara T1 - New Porous Certified Reference Materials (CRMs); Method: Mercury Intrusion - Pressure range between 0.2 and 2 MPa; BAM-124 - BAM-P126 N2 - The main problem in the certification of pressure-volume curves for the high-pressure range of the mercury intrusion is the fact that the uncertainty of the pressure (x-axis) should not be neglected. Additionally, the use of pressure-volume curves from different laboratories using different apparatus leads to incomparability of these curves and requires a correction. This is known in the statistical literature as warping. The use of point wise intervals causes difficulties in the interpretation of the results. Such problems have been eliminated in the certification of pressure-volume curves of the new standards ERM®-FD123 and BAM-P124 to BAM-P126. These standards are reference materials for the comparatively low-pressure range of the mercury intrusion method. The materials BAM-P124 and BAM-P126 are made up as flat membranes. The production of these membranes (a-alumina ceramics) was carried out in the HITK, Hermsdorf, Germany. The long ceramic tape was divided into 50 rectangular tapes. These tapes were sintered. Each of the tapes has been cut in 30 dies, numbered by a laser beam. Samples were assigned systematically covering all 50 tapes to allow for an optimal modelling of material inhomogeneities. T2 - XII. Workshop über die Charakterisierung von feinteiligen und porösen Festkörpern CY - Bad Soden, Germany DA - 2004-11-16 PY - 2004 AN - OPUS4-4631 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rabe, Torsten A1 - Mücke, Udo A1 - Röhl-Kuhn, Barbara A1 - Harbich, Karl-Wolfram T1 - Characterization of pores during the densification of SiC T2 - 4th European Ceramic Conference CY - Riccione, Italy DA - 1995-10-02 PY - 1995 SP - 185 EP - 190 CY - Riccione AN - OPUS4-3658 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Röhl-Kuhn, Barbara T1 - New Porous Certified Reference Materials (CRMs) for the Mercury Intrusion Method in the Pressure Range from 0.1 to 1 Mpa T2 - BERM 9 - 9th International Symposium on Biological and Environmental Reference Materials CY - Berlin, Germany DA - 2003-06-15 PY - 2003 AN - OPUS4-4770 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Röhl-Kuhn, Barbara A1 - Klobes, Peter A1 - Meyer, Klaus A1 - Lorenz, Peter A1 - Lamberty, A. A1 - Gawlik, B. A1 - Muntau, H. T1 - Certification of the specific micropore volume and the median width of two microporous reference materials according to Draft-DIN 66135-4 KW - Poröse Materialien KW - ZRM-Entwicklung KW - Gasadsorption KW - Mikroporenbestimmung PY - 2004 UR - https://ec.europa.eu/jrc/sites/default/files/rm/BCR-704_report.pdf SN - 1018-5593 IS - 21065 SP - I-III, 5-38 PB - Office for Official Publications of the European Communities CY - Luxembourg AN - OPUS4-5195 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hellmuth, K.-H. A1 - Klobes, Peter A1 - Meyer, Klaus A1 - Röhl-Kuhn, Barbara A1 - Siitari-Kauppi, M. A1 - Hartikainen, K. A1 - Hartikainen, J. A1 - Timonen, J. T1 - Matrix retardation studies: size and structure of the accessable pore space in fresh and altered crystalline rock N2 - For the assessment of the barrier function of the geosphere around a nuclear waste repository information about the nature of the accessible rock pore space and internal surfaces is needed. Intact samples of various types of fresh and altered crystalline rocks have been studied by means of mercury intrusion porosimetry and gas adsorption methods using various adsorbates. Furthermore, fluorescence microscopy and scanning electron microscopy was applied and the results were compared with those of impregnation with carbon-l4-polymethylmethacrylate (PMMA). Additional structural information was derived from hydraulic conductivity determinations using helium gas. The investigations were focussed on the reliability of these measurements of intact core samples, the influence of rock composition, structure and geological evolution on the microstructure of the matrices and the consequences regarding the retardation properties of the bedrock. PY - 1995 SN - 0303-4534 VL - 23 IS - 5/6 SP - 691 EP - 706 PB - Verl. für Geowissenschaften Wutzke CY - Berlin AN - OPUS4-11979 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meyer, Klaus A1 - Klobes, Peter A1 - Röhl-Kuhn, Barbara T1 - Certification of reference material with special emphasis on porous solids N2 - Certified reference materials (CMRs) are very important for the reliability of the results of chemical analyses and, at the same time, constitute the basis of comparability of analytical data. The development of a new CRM is demonstrated using the example of porous and finely dispersed solids having specific surface area, specific pore volume, pore volume distribution, and mean pore radius as their characteristic values. Many of the properties of reference materials to be certified, such as their elemental content, are established by means of measurement procedures relying on different and independent principles of measurement. With porous or finely dispersed solids, however, the characteristic values referring to pores strongly depend on the size of the probe molecules used, a fact which is due to the fractal character of these substrates. This is particularly true for the specific surface area or the pore volume. As a result, when applying the method of gas adsorption, the certified values refer to a specified probe gas, e.g. to nitrogen. The use of other gases yields different numerical values for the characteristic values to be certified. Generally, the pore system of a solid contains pores of irregular shape. Therefore, depending on the presence of e.g. cylinder or slit pores, different evaluation models must be applied. For the verification of model calculation of microporous solids, zeolites with their crystallographically defined voids are particularly well suited. They can serve as a reference point for the correctness of the model used. PY - 1997 SN - 0023-4753 SN - 1521-4079 SN - 0232-1300 VL - 32 IS - 1 SP - 175 EP - 185 PB - Wiley-VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-11981 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Klobes, Peter A1 - Röhl-Kuhn, Barbara A1 - Meyer, Klaus T1 - Zertifizierung von Referenzmaterialien am Beispiel poröser hochdisperser Feststoffe für die Methode der Gasadsorption N2 - Entsprechend den BCR Guidelines für die Herstellung von zertifizierten Referenzmaterialien (CRMs) und den ISO Guides 30-35 wurden CRMs mit den Kenngrößen spezifische Oberfläche, spezifisches Porenvolumen und Porenradius hergestellt. Als Methode wurde die Gasadsorption verwendet. Die Zertifizierungsanalyse und die Referenzmaterialien selbst werden beschrieben. KW - Zertifizierte Referenzmaterialien KW - Gasadsorption KW - Spezifische Oberfläche KW - Spezifisches Porenvolumen KW - Porenradius KW - Poröse Materialien KW - Disperse Feststoffe KW - Certified reference materials KW - Gas adsorption KW - Specific surface area KW - Specific pore volume KW - Pore radius KW - Porous materials KW - Dispersed solids PY - 1998 SN - 0016-3538 VL - 42 SP - 214 EP - 217 PB - GIT-Verlag CY - Darmstadt AN - OPUS4-11982 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Röhl-Kuhn, Barbara A1 - Meyer, Klaus A1 - Klobes, Peter A1 - Fritz, Thomas T1 - Development of porous and dispersed CRM N2 - Abstract Porous and finely dispersed certified reference materials (CRM) were certified using the gas adsorption method. The special certification procedure for IUPAC isotherm classification types I, II, and IV is presented for meso- and macroporous materials with special emphasis on specific surface area, specific pore volume and pore width according to standards DIN 66 131, 66 134, and 66 135. Four CRMs (SiO2, f-Al2O3, two transition aluminas) with a macro- and mesopore range are presented. Certification was made on the basis of BCR guidelines in connection with interlaboratory tests (altogether 38 participating laboratories, 44 various gas adsorption apparatus). PY - 1998 SN - 0937-0633 VL - 360 IS - 3-4 SP - 393 EP - 397 PB - Springer CY - Berlin AN - OPUS4-11973 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meyer, Klaus A1 - Lorenz, Peter A1 - Röhl-Kuhn, Barbara A1 - Klobes, Peter T1 - Porous Solids and their Characterization N2 - Porous and finely divided solids are distinguished by a large surface to volume ratio. As a result, they have specific properties, such as enhanced reactivity, a high adsorption capacity, and a lowered sinter temperature. This contribution gives a survey over selected aspects of porous solids, with tlfe main emphasis on methods of characterization and their applications. We treat porous solids with a regular pore network (zeolites) and irregular pore structure (sintered compacts,rocks). After a short review of the possibilities orf characterization, we wilI describe the methods of gas adsorption and Hg intrusion in detail. Furthermore, we will give a critical assessment of the measurement of typical characterization parameters, such as the spedfic surface area, the pore volume and the pore volume distribution. The fractal character of large-surface and porous solids and the related uncertainty of the outcomes of measurements result in the necessity of standardization of experimental procedures and in the need for reference materials. The section on applications treats examples of porous solids from different areas: densification of ceramic materials, porous ceramic carriers for flue gas desulfurization, technical catalysts (zeolite/binder), zeolites for the separation of substances, sedimentary and crystalline rocks. PY - 1994 SN - 0023-4753 SN - 1521-4079 SN - 0232-1300 VL - 29 IS - 7 SP - 903 EP - 930 PB - Wiley-VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-11954 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mach, Reinhard A1 - Maneck, Heinz-Eberhard A1 - Röhl-Kuhn, Barbara A1 - Peplinski, Burkhard A1 - Benemann, Sigrid A1 - Strauß, Birgid A1 - Schütz, W. A1 - Kühn, Gerhard A1 - Friedrich, Jörg Florian ED - Pershin, L. T1 - Modification of graphite powders in a thermal RF induction plasma T2 - 17th International Symposium on Plasma Chemistry (ISPC-17) CY - Toronto, Canada DA - 2005-08-07 PY - 2005 SP - 1(?) EP - 6(?) CY - Toronto AN - OPUS4-11942 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Röhl-Kuhn, Barbara A1 - Polzehl, J. A1 - Klobes, Peter T1 - Simultaneous confidence and prediction bands in the certification of pressure-volume curves for the pore size analysis of solids by means of mercury porosimetry N2 - The pore size analysis of solids is widely applied in chemical industries, materials engineering, ceramic production, environmental engineering, catalysis, chromatography, nanotechnology, and many other fields. In spite of several new methods used for determining the pore size distribution of meso- and macropores [see IUPAC Recommendations of 1994], mercury porosimetry has remained one of the most popular methods employed for the characterisation of porous materials. In this paper, a new way is described for the estimation of certified pressure-volume curves from experimental curves measured by different laboratories in connection with the certification of new reference materials for a comparatively low-pressure range of mercury intrusion (<2 MPa). Simultaneous confidence and prediction bands for the certified pressure-volume curves are constructed by bootstrapping. KW - Mercury intrusion KW - Certified reference material KW - Certified pressure KW - Volume curve KW - Bootstrap confidence bands KW - Bootstrap prediction bands PY - 2006 DO - https://doi.org/10.1007/s00769-006-0103-2 SN - 0949-1775 SN - 1432-0517 VL - 11 IS - 3 SP - 107 EP - 115 PB - Springer CY - Berlin AN - OPUS4-12520 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hoinkis, E. A1 - Röhl-Kuhn, Barbara T1 - In situ small-angle neutron scattering study of nitrogen adsorption and condensation in mesoporous silica glass CPG-10-75 N2 - Film formation and capillary condensation of nitrogen at 78 K on the mesoporous controlled pore glass CPG-10-75 have been studied at certain relative pressures by in situ small-angle neutron scattering. On desorption ramified clusters of vapor filled voids have been observed, but not on adsorption. The kinetics of adsorption and desorption have been followed. The experimental results are discussed with respect to recent theoretical studies of fluids in complex pore systems. KW - In situ SANS KW - Controlled pore glass KW - Vitreous silica KW - Adsorption KW - Capillary condensation KW - Percolation KW - Cavitation KW - Self-similar growth PY - 2006 DO - https://doi.org/10.1016/j.jcis.2005.08.044 SN - 0021-9797 SN - 1095-7103 VL - 296 IS - 1 SP - 256 EP - 262 PB - Elsevier CY - Orlando, Fla. AN - OPUS4-12521 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Eschricht, N. A1 - Hoinkis, E. A1 - Mädler, F. A1 - Schubert-Bischoff, P. A1 - Röhl-Kuhn, Barbara T1 - Knowledge-based reconstruction of random porous media N2 - An evolutionary optimization technique is used to reconstruct digitized material models of 3003 nm3 size for mesoporous two-phase systems. The models are adapted to the two-point probability (TPP) and to a volume-based pore-size distribution (PSD) which were derived from SANS and adsorption experiments and which carry statistical information about morphology and topology of the pore system. To avoid extreme update-costs, the bulk of mutations are assessed by means of a suitable approximation of the PSD; it is demonstrated that a sporadic insertion of the PSD suffices to drive the algorithm towards satisfactory models in acceptable time. Our approach is knowledge-based in the sense that (i) the mutations are restricted to expedient exchanges of phase-voxels by a heuristic rule, and (ii) the sporadic calculation of the PSD from the current state of the model, in essence, provides an efficient self-control for the evolutionary process. We applied the method to reconstruct periodic models of the xerogel Gelsil 200. Such reconstructs of real mesoporous solids could be utilized, for instance, to verify theories of adsorption and capillary condensation. KW - Knowledge-based reconstruction KW - Evolutionary optimization KW - SANS KW - Pore size distribution KW - Two-point correlation KW - Porous media KW - Xerogel PY - 2005 DO - https://doi.org/10.1016/j.jcis.2005.05.004 SN - 0021-9797 SN - 1095-7103 VL - 291 IS - 1 SP - 201 EP - 213 PB - Elsevier CY - Orlando, Fla. AN - OPUS4-12522 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hoinkis, E. A1 - Röhl-Kuhn, Barbara T1 - Application of percolation theory to the drainage of liquid nitrogen from mesoporous silica xerogel gelsil 50 N2 - Previous in situ small-angle neutron scattering studies of nitrogen adsorption and desorption at 78 K on the mesoporous silica xerogels Gelsil 50 and Gelsil 75 revealed the formation of ramified clusters of vapor-filled pores on desorption, which is characteristic for a percolation process. In the present work, we check whether the adsorption/desorption isotherm data for a monolithic sample of Gelsil 50 can be analyzed in terms of a bond-percolation model. Three powder samples were studied too. Percolation probability data are presented and the effects of heterogeneous nucleation, finite size, and surface clusters on drainage from Gelsil 50 are addressed. The mean coordination number was derived. The results of the analysis are discussed with respect to recent theoretical work for interactions of fluids with complex pore systems. The monolithic sample and a powder sample were characterized by small-angle neutron scattering data. KW - Percolation Theory KW - Adsorption KW - Desorption KW - Silica Xerogel Gelsil 50 PY - 2005 SN - 0743-7463 SN - 1520-5827 VL - 21 IS - 16 SP - 7366 EP - 7372 PB - American Chemical Society CY - Washington, DC AN - OPUS4-12523 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Harbich, Karl-Wolfram A1 - Fensch-Kleemann, Elisabeth A1 - Röhl-Kuhn, Barbara A1 - Klobes, Peter T1 - Nondestructive Characterization of Porous Ceramics by X-Ray Refraction N2 - X-ray refraction reveals the inner surface concentrations of porous materials within the range of (µm- to nm-dimensions. This technique is compared to mercury pressure porosimetry which is a standard method for pore size determination in porous solids. The mean pore size of several ceramics are investigated over a range of porosity between 30% to 60%. Complementary to high pressure mercury intrusion the refraction technique detects the spatially resolved inner surfaces of both, open and closed pores. Furthermore, X-ray refraction scanning topography visualizes integral interface properties up to 50 m spatial resolution by two-dimensional topographic images. Characteristic microstructure parameters, i. e. inner surface density, porosity and mean pore sizes of some Al2O3 and SiC ceramics are presented. The specific surface data of Al2O3 ceramics obtained from X-ray refraction agree well with the results given by mercury porosimetry. In contrast, the related mean pore sizes differs systematically by about 30%. T2 - 6th International Symposium on the Characterization of Porous Solids (COPS) CY - Alicante, Spain DA - 2002-05-08 PY - 2002 DO - https://doi.org/10.1016/S0167-2991(02)80198-7 SN - 0167-2991 VL - 144 SP - 693 EP - 699 PB - Elsevier CY - Amsterdam AN - OPUS4-1917 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Klobes, Peter A1 - Röhl-Kuhn, Barbara ED - Kriegesmann, J. T1 - Einsatz der Quecksilberporosimetrie zur Grünkörpercharakterisierung - Aussagemöglichkeiten, Grenzen und Perspektiven PY - 2002 SN - 3-87156-091-X IS - Kap. 3.4.1.3 SP - 1 EP - 20 PB - Deutscher Wirtschaftsdienst CY - Köln AN - OPUS4-2003 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -