TY - JOUR A1 - Usmani, Shirin M. A1 - Plarre, Rüdiger A1 - Hübert, Thomas A1 - Kemnitz, E. T1 - Termite resistance of pine wood treated with nano metal fluorides JF - European Journal of Wood and Wood Products N2 - Fluorides are well-known as wood preservatives. One of the limitations of fluoride-based wood preservatives is their high leachability. Alternative to current fluoride salts such as NaF used in wood protection are low water-soluble fluorides. However, impregnation of low water-soluble fluorides into wood poses a challenge. To address this challenge, low water-soluble fluorides like calcium fluoride (CaF2) and magnesium fluoride (MgF2) were synthesized as nanoparticles via the fluorolytic sol−gel synthesis and then impregnated into wood specimens. In this study, the toxicity of nano metal fluorides was assessed by termite mortality, mass loss and visual analysis of treated specimens after eight weeks of exposure to termites, Coptotermes formosanus. Nano metal fluorides with sol concentrations of 0.5 M and higher were found to be effective against termites resulting in 100% termite mortality and significantly inhibited termite feeding. Among the formulations tested, the least damage was found for specimens treated with combinations of CaF2 and MgF2 with an average mass loss less than 1% and visual rating of “1”. These results demonstrate the efficacy of low water-soluble nano metal fluorides to protect Wood from termite attack. KW - Wood Protection KW - Nano Particles KW - Termites PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-508377 DO - https://doi.org/10.1007/s00107-020-01522-z VL - 78 SP - 493 EP - 499 PB - Springer AN - OPUS4-50837 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Usmani, S. A1 - Voss, L. A1 - Stephan, Ina A1 - Hübert, Thomas A1 - Kemnitz, E. T1 - Improved Durability of Wood Treated with Nano Metal Fluorides against Brown-Rot and White-Rot Fungi JF - Applied Sciences N2 - Low-water soluble metal fluorides such as magnesium fluoride (MgF2) and calcium Fluoride (CaF2) were evaluated for decay protection of wood. Initially, the biocidal efficacy of nano metal fluorides (NMFs) against wood destroying fungi was assessed with an in-vitro agar test. The results from the test showed that agar medium containing MgF2 and CaF2 was more efficient in preventing fungal decay than stand-alone MgF2 or CaF2. These metal fluorides, in their nanoscopic form synthesized using fluorolytic sol-gel synthesis, were introduced into the sapwood of Scots pine and beech wood and then subjected to accelerated ageing by leaching (EN 84). MAS 19F NMR and X-ray micro CT images showed that metal fluorides were present in treated wood, unleached and leached. Decay resistance of Scots pine and beech wood treated with NMFs was tested against Wood destroying fungi Rhodonia placenta and Trametes versicolor in accordance with EN 113. Results revealed that mass losses were reduced to below 3% in wood treated with the combination of MgF2 and CaF2. It is concluded that NMFs provide full protection to wood even after it has been leached and can be used as wood preservatives in outdoor environments. KW - Nanoparticles KW - Fluoride KW - Wood protection KW - Fluorolytic sol-gel synthesis KW - Brown-rot fungi KW - White-rot fungi KW - Basidiomycetes PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-543877 DO - https://doi.org/10.3390/app12031727 VL - 12 IS - 3 SP - 1 EP - 11 PB - MDPI AN - OPUS4-54387 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Unger, Brita A1 - Bücker, Michael A1 - Reinsch, Stefan A1 - Hübert, Thomas T1 - Chemical aspects of wood modification by sol-gel-derived silica JF - Wood science and technology N2 - It has been shown that tetraethoxysilane-derived precursors are suitable solutions for impregnating pine sapwood to improve its dimensional stability. Tailored sol–gel syntheses result in precursors with nano-scaled silica species which are able to penetrate into the cell walls of wood. The physical fixation of those species inside the cell walls was verified by ESEM/EDX investigations. There is evidence that the silica species are chemically bonded to wood components. Nonreacted alkoxy groups can exist in the wood composites after impregnation. The amount of these organic residues depends on the composition of the precursors, especially their condensation degree and reactivity. Treatments for finishing the composites after the impregnation step to get clean products and stable properties are discussed in this context. An explanation of the complex relationship between solids content in the impregnation solutions and percentage weight gain and bulking of the composites is given. It can be demonstrated that high WPG values (>20 %) are pre-conditions for an effective protection of the resulting composites but they only guarantee efficient improvements if connected with the incorporation of the inorganic component inside the cell walls. Therefore, the sol–gel syntheses have to be carried out in such a manner that very small (<2 nm) as well as reactive species are sufficiently available. This demands syntheses using sub-stoichiometric water contents (H2O/TEOS <4, better <2). KW - Silica-wood composites KW - Sol-gel derived precursors KW - Curing KW - Fixation of silica KW - Dimensional stability PY - 2013 DO - https://doi.org/10.1007/s00226-012-0486-7 SN - 0043-7719 SN - 1432-5225 VL - 47 IS - 1 SP - 83 EP - 104 PB - Springer CY - Berlin AN - OPUS4-26258 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tiebe, Carlo A1 - Miessner, H. A1 - Koch, B. A1 - Hübert, Thomas T1 - Detection of microbial volatile organic compounds (MVOCs) by ion-mobility spectrometry JF - Analytical and bioanalytical chemistry N2 - Traces of microbial volatile organic compounds (MVOCs) in air can indicate the presence of growth of moulds in the indoor environment. Ion-mobility spectrometry is a very promising method for detection of these MVOCs, because of its high sensitivity. For development of an in-situ method for detection of MVOCs, a portable ion-mobility spectrometer (IMS) was used and test gases of 14 MVOCs and their respective mixtures were investigated. IMS spectra were recorded as a function of concentration of MVOCs in air. Drift time and mobility of reactant ions formed in positive polarity mode were determined and correlated with the mass-to-charge ratio (m/z) of the MVOCs investigated. The estimated detection limit has a specific value for each MVOC and is in the range 3 to 96 µg m-3 (1 to 52 ppbV). Indoor trials show that IMS can indicate hidden mould growth. KW - Trace gas analysis KW - MVOCs KW - Ion-mobility spectrometry KW - Mould detection PY - 2009 DO - https://doi.org/10.1007/s00216-009-3147-4 SN - 1618-2642 SN - 1618-2650 VL - 395 IS - 7 SP - 2313 EP - 2323 PB - Springer CY - Berlin AN - OPUS4-20082 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tiebe, Carlo A1 - Hübert, Thomas A1 - Lorek, A. A1 - Wernecke, R. T1 - New planar trace humidity sensor T2 - IMCS 2012 - 14th International meeting on chemical sensors N2 - A new planar sensor element for continuous coulometric trace humidity measurements in industrial gases has been developed. In order to ensure precise measurements a calibration facility including a precision dew point hygrometer as a reference device was developed. The sensor can measure the humidity in the frost point temperature range of -20 °C to -80 °C and has an expanded uncertainty of 2 K, a fast reaction time and a settling time of the entire system from 15 to 30 min. T2 - IMCS 2012 - 14th International meeting on chemical sensors CY - Nuremberg, Germany DA - 2012-05-20 KW - Trace humidity KW - Coulometric principle KW - HUMITRACE sensor KW - Humidity measurement PY - 2012 SN - 978-3-9813484-2-2 DO - https://doi.org/10.5162/IMCS2012/3.4.2 SP - 294 EP - 297 PB - AMA Service GmbH CY - Wunstorf AN - OPUS4-27570 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tiebe, Carlo A1 - Detjens, Marc A1 - Banach, Ulrich A1 - Hübert, Thomas T1 - Measurement uncertainty of coulometric trace humidity sensors JF - tm - Technisches Messen N2 - Especially trace amounts of water vapour in gases can be reliably determined by coulometric trace humidity sensors. The principle of these sensors is based on water vapour absorption in a hygroscopic layer and its subsequent electrolytic decomposition. The calibration of sensors was performed in the humidity range, expressed as frost point temperature, from −30°C to −80°C . This range is equivalent to volume fractions smaller than 376 µL·L−1. Generated humidity was measured with coulometric sensors and a chilled dew point hygrometer that was used as reference. An empirical non-linear function was found between sensor signal and measured reference humidity. This function consists of two parameters with a measurement uncertainty. Both calibration parameters were checked by means of one-way analysis of variance. It showed that gas specific function can be used for humidity measurement in nitrogen, hydrogen, dinitrogen monoxide, compressed and synthetic air. It is possible to determine trace humidity in all tested gases with an expanded uncertainty less than 2.1 K (coverage factor k=2 ) regarding frost point temperature. KW - Trace humidity KW - Coulometric sensor KW - Measurement uncertainty KW - ANOVA PY - 2018 DO - https://doi.org/10.1515/teme-2018-0031 SN - 0171-8096 VL - 85 IS - 12 SP - 746 EP - 753 PB - De Gruyter CY - Oldenbourg AN - OPUS4-45959 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tahri, K. A1 - Tiebe, Carlo A1 - El Bari, N. A1 - Hübert, Thomas A1 - Bouchikhi, B. T1 - Geographical provenience differentiation and adulteration detection of cumin by means of electronic sensing Systems and SPME-GC-MS in combination with different chemometric approaches JF - Analytical Methods N2 - The detection of the aroma and flavour volatile compounds of spices is key in product quality control. Accordingly, it is necessary to develop new electronic sensing systems for food adulteration control and authenticity assessment for protecting customer's health. In this work, the capability of the E-nose and VE-tongue in combination with SPME-GC-MS to correctly discriminate between several cumin samples of different geographical origins and to detect their adulteration, by using unsupervised and supervised chemometric tools, was evaluated. Regarding the aroma profile, eleven volatile compounds were characterized by SPME-GC-MS; all of them were found in cumin powder while only eight are found in cumin seeds. The main volatile compounds detected were b-pinene, m-cymene, g-terpinene, cuminaldehyde and cuminic alcohol, in different proportions depending on the cumin sample form (seed or powder). In summary, the results obtained are sufficiently encouraging as a starting point for the development of new electronic sensing systems with more improvement in the reliability of the sensor's performance as well as chemometric tools in order to deal with a complex dataset. KW - Voltammetric electronic tongue KW - Electronic nose KW - SPME-GC-MS KW - Chemometric tool KW - Cumin discrimination KW - Geographical origins KW - Adulteration detection PY - 2016 DO - https://doi.org/10.1039/c6ay01906d SN - 1759-9660 VL - 8 IS - 42 SP - 7638 EP - 7649 PB - RCS AN - OPUS4-38558 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tahri, K. A1 - Tiebe, Carlo A1 - El Bari, N. A1 - Hübert, Thomas A1 - Bouchikhi, B. T1 - Geographical classification and adulteration detection of cumin by using electronic sensing coupled to multivariate analysis JF - Procedia Technology - Special Issue Biosensors 2016 N2 - The objective of this work is to report the improvement obtained in the discrimination of complex aroma and taste with subtle differences in odor and flavor, by the use of fast suitable procedures for the cases of measurements in the field demanding decision-making in real time. The proposed electronic sensing systems, formed by an E-nose and VE-tongue, were used to discriminate cumin cultivars from different geographical origins, as well as to quantify the cumin adulteration percentages by using unsupervised and supervised chemometric tools. Thus, the results obtained are sufficiently encouraging as a starting point for the development of new electronic sensing systems with more improvement such the reliability of the sensors’ performance as well as the chemometric tools in order to deal with a complex dataset. KW - VE-tongue KW - E-nose KW - Chemometric tools KW - Cumin discrimination KW - Geographical origins KW - Adulteration detection PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-409735 DO - https://doi.org/10.1016/j.protcy.2017.04.102 SN - 2212-0173 VL - 27 SP - 240 EP - 241 PB - Elsevier B.V. AN - OPUS4-40973 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tahri, K. A1 - Tiebe, Carlo A1 - Bougrini, M. A1 - Saidi, T. A1 - El Alami-El Hassani, N. A1 - El Bari, N. A1 - Hübert, Thomas A1 - Bouchikhi, B. T1 - Determination of safranal concentration in saffron samples by means of VE-tongue, SPME-GC-MS, UV-vis spectrophotometry and multivariate analysis T2 - Proceedings of IEEE Sensors 2015 N2 - An experimental investigation has been carried out to characterize and discriminate seven saffron samples and to verify their declared geographical origin using a voltammetric electronic tongue (VE-tongue). The ability of multivariable analysis methods such as Principal Component Analysis (PCA), Hierarchical Cluster Analysis (HCA) to classify the saffron samples according to their geographical origin have been investigated. A good discrimination has reached using PCA and HCA in the VE-tongue characterization case. Furthermore, cross validation and Partial Least Square (PLS) techniques were applied in order to build suitable management and prediction models for the determination of safranal concentration in saffron samples based on SPME-GC-MS and UV-Vis Spectrophotometry. The obtained results reveals that some relationships were established between the VE-tongue signal, SPMEGC-MS and UV-Vis spectrophotometry methods to predict safranal concentration levels in saffron samples by using the PLS model. In the light of these results, we can say that the proposed electronic system offer a fast, simple and efficient tool to recognize the declared geographical origin of the saffron samples. T2 - IEEE Sensor 2015 CY - Busan, South Korea DA - 01.11.2015 KW - Chemometrics KW - Voltammetric electronic tongue KW - SPME-GC-MS KW - UV-vis Spectrometry KW - Saffron KW - Geographic differentiation PY - 2015 SN - 978-1-4799-8202-8 VL - CFP15SEN-USB SP - 68 EP - 71 PB - IEEE CY - Piscataway AN - OPUS4-36545 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tahri, K. A1 - Tiebe, Carlo A1 - Bougrini, M. A1 - Saidi, T. A1 - El Alami El Hassani, N. A1 - El Bari, N. A1 - Hübert, Thomas A1 - Bouchikhi, B. T1 - Characterization and discrimination of saffron by multisensory systems, SPME-GC-MS and UV-Vis spectrophotometry JF - Analytical methods N2 - Different electronic sensor systems coupled with multivariate data analysis were applied to characterize and classify seven saffron samples and to verify their declared geographical origin. The proposed electronic sensing consists of a low-cost electronic nose (E-nose) based on metal oxide semiconductor sensors and a voltammetric electronic tongue (VE-tongue) based on voltammetric sensors. The ability of multivariable analysis methods such as Principal Component Analysis (PCA), Hierarchical Cluster Analysis (HCA) and Support Vector Machines (SVMs) to classify the saffron samples according to their geographical origin have been investigated. Both PCA and HCA have shown an overlapping of E-nose responses. Moreover, the SVM analysis of the E-nose database reached a 66.07% success rate in the recognition of the saffron sample odour. On the other hand, good discrimination has been reached using PCA and HCA in the VE-tongue characterization case, besides a 100% accuracy in the saffron flavour recognition was attained. To validate the proposed electronic sensing systems, analytical chemical methods such as SPME-GC-MS and UV-Vis spectrophotometry were used. These analytical methods could be helpful tools to identify the composition of volatile compounds of the analysed saffron samples. Moreover, UV-Vis spectrophotometry was also used to determine the non-volatile profile of the samples from different geographic origins. It is demonstrated that the electronic sensing systems' findings are in a satisfactory correlation with the analytical methods. In the light of these results, we might say that the electronic systems offer a fast, simple and efficient tool to recognize the declared geographical origin of the saffron samples. KW - Electronic nose KW - Voltammetric electronic tongue KW - SPME-GC-MS KW - UV-vis spectrophotometry KW - Saffron KW - Geographic differentiation KW - Multivariable analysis PY - 2015 DO - https://doi.org/10.1039/C5AY01986A SN - 1759-9660 SN - 1759-9679 VL - 7 IS - 24 SP - 10328 EP - 10338 PB - RSC Publ. CY - Cambridge AN - OPUS4-35174 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shimamura, Aki A1 - Hübert, Thomas A1 - Thust, H. T1 - Characterization of sol-gel derived glass composite thin films JF - Surface and interface analysis N2 - A comprehensive analysis of composition and structure is essential for the development of new materials with tailored properties. We will demonstrate the application of SEM, XPS and XRD for the development of thin films containing nano-scaled electrical conductive particles for application in hybrid resistors. The films were prepared using the sol-gel process and precursor solutions were synthesized from an acid hydrolysis of a mixture of TEOS, water and ethanol. Alcoholic solutions of ruthenium chloride were then allocated to obtain up to 30 vol% filler in the films. The films were precipitated by dip-coating on silicon, silica or glass sheets and heat treated at up to 600°C in air or nitrogen atmospheres. A nano-structured morphology could be identified consisting of homogeneously dispersed crystalline RuO2 particles of 10 to 180 nm in size, in an amorphous SiO2 matrix. Film morphology can be varied using the synthesis process. The resistivity of the films was measured by an I-V measurement system. It changes drastically from 109·cm to 10-2·cm according to the amount of dispersed conductive particles. The results show that composition-structure-property relations can be described by use of sophisticated analytical methods. T2 - 10th European Conference on Applications of Surface and Interface Analysis (ECASIA '03) CY - Berlin, Germany DA - 2003-10-05 KW - Sol-gel KW - Thin film KW - Nano-structure KW - Electrical resistivity KW - RuO2 PY - 2004 DO - https://doi.org/10.1002/sia.1877 SN - 0142-2421 SN - 1096-9918 VL - 36 IS - 8 SP - 1207 EP - 1209 PB - Wiley CY - Chichester AN - OPUS4-4753 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shabir Mahr, Muhammad A1 - Hübert, Thomas A1 - Stephan, Ina A1 - Militz, H. T1 - Decay protection of wood against brown-rot fungi by titanium alkoxide impregnations JF - International biodeterioration & biodegradation N2 - Decay resistance of pine sapwood treated with titanium alkoxide solutions was tested against the brown-rot fungi Coniophora puteana and Poria placenta for exposure times of 10 and 16 wk. In practice, wood-specimens were vacuum-impregnated by alcoholic solutions of titanium alkoxide with concentrations in the range of 5–16 mass % (solid content in solution) and subsequently cured under different humidity conditions. Results reveal that treated wood degraded up to 5% in comparison to untreated one that deteriorated 38% and 50%, respectively against both wood-decay fungi. Even full protection (mass loss below 3%) was achieved against brown rot with titanium alkoxide solution containing solid content of around 5 mass% with a weight percentage gain (WPG) of 9 mass%. With increased concentration, fungal resistance decreased slightly which was associated with more cracks and imperfections formed in the deposited layers of titanium dioxide in the adjacent wood matrix. Thermal analysis verified that a considerable amount of precursor remained in the wood structure as un-hydrolyzed organic residues. These organics, being bioactive, had the tendency to induce similar fungicidal effects as those of conventional fungicides. The amount of organic residues is correlated with the decay resistance of the tested samples. In a prolonged decay test, mass losses of 16-wk incubated samples do not show behavior different from that of the wood samples incubated for 10 wk. This result implies that the decay protection is permanent and confirms further the fungicidal activity of titanium-alkoxide-treated wood. KW - Precursor solutions KW - Sol-gel process KW - Equivalent solid content KW - Brown rot KW - Coniophora puteana KW - Poria placenta KW - Fungal colonization KW - Biocidal effect PY - 2013 DO - https://doi.org/10.1016/j.ibiod.2012.04.026 SN - 0964-8305 VL - 77 SP - 56 EP - 62 PB - Elsevier Ltd. CY - Barking AN - OPUS4-27622 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shabir Mahr, Muhammad A1 - Hübert, Thomas A1 - Stephan, Ina A1 - Bücker, Michael A1 - Militz, H. T1 - Reducing copper leaching from treated wood by sol-gel derived TiO2 and SiO2 depositions JF - Holzforschung N2 - The antileaching efficacy of sol-gel-derived TiO2- and SiO2-based precursors has been evaluated through laboratory leaching trials with pine sapwood in two different ways. In a one-step process, wood was vacuum impregnated by the precursor solutions containing CuCl2. The copper (Cu) emission rates of the sol-gel-based impregnated woods were up to 70% lower than that of wood treated with pure CuCl2 solution at the same level of concentration. More improvement (80%) could be achieved in a two-step process, in which sol-gel precursors were introduced into an already CuCl2-treated wood. The refinement was attributed to several effects. In the one-step approach, Cu was embedded in the TiO2/SiO2 gels formed in the wood texture. During a two-step impregnation, gel layers that were formed in the wooden interior acted as an effective diffusion barrier. The sol-gel impregnations made wood more hydrophobic; therefore, the low amount of water that penetrated the cell wall was less efficient to leach out Cu. KW - Copper leachability KW - SiO2-based gel KW - Sol-gel treatment of wood KW - TiO2-based gel KW - Wood impregnation KW - Wood protection PY - 2013 DO - https://doi.org/10.1515/hf-2012-0105 SN - 0018-3830 SN - 1437-434X VL - 67 IS - 4 SP - 429 EP - 435 PB - De Gruyter CY - Berlin AN - OPUS4-28892 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shabir Mahr, Muhammad A1 - Hübert, Thomas A1 - Schartel, Bernhard A1 - Bahr, Horst A1 - Sabel, Martin A1 - Militz, H. T1 - Fire retardancy effects in single and double layered sol-gel derived TiO2 and SiO2-wood composites JF - Journal of sol gel science and technology N2 - Sol–gel derived TiO2 and SiO2-wood inorganic composites are prepared by direct vacuum infiltration of silicon and titanium alkoxide based precursors in pine sapwood in one or two cycles followed by a controlled thermal curing process. The resulting flame retardancy effect is investigated under two different fire scenarios using cone calorimetry and oxygen index (LOI). Heat release rates (HRR) especially the values for the second peak, are reduced moderately for all single layered composites. This effect is more pronounced for double layered composites where HRR was reduced up to 40 % showing flame retardancy potential in developing fires. Beside this, smoke release was lowered up to 72 % indicating that these systems had less fire hazards compared to untreated wood, whereas no meaningful improvement is realized in terms of fire load (total heat evolved) and initial HRR increase. However impressively, the LOI of the composites were increased up to 41 vol% in comparison to 23 vol% for untreated wood displaying a remarkable flame retardancy against reaction to a small flame. An approximate linear interdependence among the fire properties and the material loading as well as fire residue was observed. A residual protection layer mechanism is proposed improving the residue properties for the investigated composites. KW - Wood KW - Sol-gel KW - Composite materials KW - Cone calorimeter KW - Fire retardance KW - Flammability PY - 2012 DO - https://doi.org/10.1007/s10971-012-2877-5 SN - 0928-0707 SN - 1573-4846 VL - 64 IS - 2 SP - 452 EP - 464 PB - Kluwer Academic Publ. CY - Dordrecht AN - OPUS4-27618 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shabir Mahr, Muhammad A1 - Hübert, Thomas A1 - Sabel, Martin A1 - Schartel, Bernhard A1 - Bahr, Horst A1 - Militz, H. T1 - Fire retardancy of sol-gel derived titania wood-inorganic composites JF - Journal of materials science N2 - Sol–gel technology was applied in tailoring novel wood-made-inorganic composites with improved thermal and fire properties. In practice, composites materials were prepared by impregnating pine sapwood wood with nano-scaled precursor solutions derived from titanium(IV) isopropoxide followed by a thermal curing process. Thermal and fire properties were evaluated by thermal analysis and cone calorimetry, whereas flammability was specified by oxygen index (LOI) and UL 94 test. Peak heat release rates were moderately reduced indicating fire retardance potential in terms of flame spread attributed to the appropriate protection layer action of the titania-based depositions. LOI (oxygen index) values of these composites were increased up to 38 vol.% in comparison to 23 vol.% for untreated wood. The flame retardancy performance depends on the fire scenario and is strongly influenced by wood loading and crackfree deposition of the titania layers inside the composite. PY - 2012 DO - https://doi.org/10.1007/s10853-012-6628-3 SN - 0022-2461 SN - 1573-4803 VL - 47 IS - 19 SP - 6849 EP - 6861 PB - Springer Science + Business Media B.V. CY - Norwell, Mass. AN - OPUS4-26235 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Reinecke, E.-A. A1 - Hübert, Thomas A1 - Tkatschenko, I. A1 - Kessler, A. A1 - Kuznetsov, M. A1 - Wilkins, M. A1 - Hedley, D. A1 - Azkarate, I. A1 - Proust, C. A1 - Acosta-Iborra, B. A1 - Gavrikov, B. A1 - De Bruijn, P.C.J. A1 - Marangon, A. A1 - Teodorczyk, A. A1 - Grafwallner, A. T1 - Integration of experimental facilities: a joint effort for establishing a common knowledge base in experimental work on hydrogen safety JF - International journal of hydrogen energy N2 - In the area of hydrogen safety, research facilities are essential for the experimental investigation of relevant phenomena, for testing devices and safety concepts, as well as for the generation of validation data for the various numerical codes and models. Within the framework of the European HySafe Network of Excellence (NoE), the 'Integration of Experimental Facilities (IEF)' activity has provided basic support for joint experimental work. Even beyond the funding period of the HySafe NoE in the 6th Framework Program, IEF represents a long-lasting effort for the sustainable integration of experimental research capacities and expertise of the partners from different research fields. In order to achieve a high standard in the quality of experimental data provided by the partners, emphasis was put on the know-how transfer between the partners. On the one hand, documentation on the experimental capacities was prepared and analyzed. On the other hand, a wiki-based communication platform was established, supported by biannual workshops covering topics ranging from measurement technologies to safety issues. Based on the partners' contributions, a working document was created on best practice including the joint experimental knowledge of all partners with regard to experimental set-ups and instrumentation. The paper gives an overview of the IEF partners and the network activities over the last five years. KW - Hydrogen safety KW - Experiments PY - 2011 DO - https://doi.org/10.1016/j.ijhydene.2010.04.162 SN - 0360-3199 VL - 36 IS - 3 SP - 2700 EP - 2710 PB - Elsevier CY - Oxford AN - OPUS4-23257 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Polyakova, Irina A1 - Hübert, Thomas T1 - Thermal stability of TiN thin films investigated by DTG/DTA JF - Surface and coatings technology N2 - The paper demonstrates the scope of the differential thermal analysis coupled with the thermal gravimetry as an express method for estimation of thin film protecting ability and oxidation kinetics. Oxidation of an iron foil protected by the PVD titanium nitride thin film coating was investigated as well as non-isothermal oxidation of PVD thin films of TiN (two types of the preparation procedure), (Ti,Nb)N and (Ti,Al)N isolated from a substrate by dissolving them in an acid. Additions of aluminium and niobium are expected to improve chemical, thermal and biomedical properties of thin films for their technical application. It was established that the addition of niobium decreases, whereas the addition of aluminium not only increases the thermal stability of TiN coatings, but also changes the oxidation mechanism. It was demonstrated that the TiN film oxidation is a many-staged process depending on the heating rate. An opportunity of a quite formal treatment for getting Kissinger's estimation of kinetics parameters of different oxidation stages is also demonstrated. PY - 2001 DO - https://doi.org/10.1016/S0257-8972(01)01042-8 SN - 0257-8972 VL - 141 IS - 1 SP - 55 EP - 61 PB - Elsevier Science CY - Lausanne AN - OPUS4-2050 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nie, Yaru A1 - Hübert, Thomas T1 - Effect of carbon nanofiber (CNF) silanization on the properties of CNF/epoxy nanocomposites JF - Polymer International N2 - Carbon nanofibers (CNFs) were functionalized by a multistage process including oxidation, reduction and silanization. The chemical modifications were examined by Fourier transform infrared spectroscopy, X-ray photoelectron spectrometry, Raman spectroscopy and thermogravimetric analysis. The silanized CNFs were then added into an epoxy resin (EPON 828) to study the effect of the surface modification of CNFs on the properties of nanocomposites. For comparison, nanocomposites containing original unmodified CNFs were also investigated. Scanning electron microscopy indicates better dispersion of modified fibers in the epoxy polymer matrix; the mechanical and thermal properties of composites are also improved; the electrical conductivity of the composites is reduced. KW - Carbon nanofibers KW - Epoxy composites KW - Silanization KW - Electrical conductivity KW - Thermal conductivity KW - Mechanical properties PY - 2011 DO - https://doi.org/10.1002/pi.3124 SN - 0959-8103 SN - 1097-0126 SN - 0007-1641 VL - 60 IS - 11 SP - 1574 EP - 1580 PB - Wiley InterScience CY - Chichester, West Sussex AN - OPUS4-25865 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nie, Yaru A1 - Hübert, Thomas T1 - Surface modification of carbon nanofibers by glycidoxysilane for altering the conductive and mechanical properties of epoxy composites JF - Composites / A N2 - Carbon nanofibers (CNFs) were functionalized with 3-glycidoxypropyltrimethoxysilane and dispersed into epoxy resin. The chemical modification of CNFs was confirmed by FTIR, SEM, EDX and TGA measurements. After silanization, FTIR showed the existance of epoxy ring; EDX detected Si element; while TGA indicated 1.1 wt.% Si on CNFs. Mechanical properties were analyzed by DMA. Silanized CNFs/epoxy composites demonstrated improved dispersion of CNFs in the matrix, and an enhancement of storage modulus for about 20% compared to the neat matrix, which indicated that the modification of CNFs improved the adhesion between fillers and matrices. DC electrical conductivity of CNFs was reduced about 7-fold compared to the original CNFs due to the silane coating. Accordingly, the composites containing silanized CNFs also had lower electrical conductivity than those containing original CNFs. In spite of decreased electrical conductivity, thermal conductivity of silanized CNFs/epoxy composites was increased due to the surface modification of CNFs. KW - A. Polymer-matrix composites (PMCs) KW - B. Mechanical properties KW - B. Electrical properties KW - B. Thermal properties PY - 2012 DO - https://doi.org/10.1016/j.compositesa.2012.03.025 SN - 1359-835X VL - 43 IS - 8 SP - 1357 EP - 1364 PB - Elsevier CY - Oxford AN - OPUS4-26073 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mosel, Günter A1 - Willfahrt, Manfred A1 - Banach, Ulrich A1 - Hübert, Thomas T1 - An extended X-ray absorption fine structure investigation on the local environment of niobium ions in Nb2O5-doped SrTiO3 glass ceramics JF - Journal of materials science PY - 1997 SN - 0022-2461 SN - 1573-4803 VL - 32 SP - 1591 EP - 1597 PB - Springer Science + Business Media B.V. CY - Norwell, Mass. AN - OPUS4-2045 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -