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 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 - CONF A1 - Hübert, Thomas A1 - Boon-Brett, L. A1 - Palmisano, V. A1 - Frigo, G. A1 - Hellstrand, A. A1 - Kiesewetter, O. A1 - May, M. ED - Carcassi, M.N. T1 - Trends in gas sensor development for hydrogen safety N2 - Gas sensors are applied for facilitating the safe use of hydrogen in, for example, fuel cell and hydrogen fuelled vehicles. New sensor developments, aimed at meeting the increasingly stringent performance requirements in emerging applications are presented based on in-house technical developments and a literature study. The strategy of combining different detection principles, i.e. sensors based on electrochemical cells, semiconductors or field effects in combination with thermal conductivity sensor or catalytic combustion elements, in one new measuring system is reported. This extends the dynamic measuring range of the sensor while improving sensor reliability to achieve higher safety integrity through diverse redundancy. The application of new nanoscaled materials, nano wires, carbon tubes and graphene as well as the improvements in electronic components of fieldeffect, resistive-type and optical systems are evaluated in view of key operating parameters such as sensor response time, low energy consumption and low working temperature. T2 - ICHS2013 - 5th International conference on hydrogen safety CY - Brussels, Belgium DA - 09.09.2013 KW - Hydrogen KW - Safety KW - Sensors PY - 2013 SN - 978-2-9601366-0-9 SP - Paper 123, 1 EP - 14 AN - OPUS4-31079 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hübert, Thomas A1 - Banach, Ulrich ED - Carcassi, M.N. T1 - Response time of hydrogen sensors N2 - The efficiency of gas sensor application for facilitating the safe use of hydrogen depends to a considerable extent on the response time of the sensor to change in hydrogen concentration. The response and recovery times have been measured for five different hydrogen sensors, three commercially available and two promising prototypes which operate at room temperature. Experiments according to ISO 26142 show that most of the sensors surpass much for a concentration change from clean to hydrogen containing air the demands of the Standard for the response times t(90) and values of 2 to lös were estimated. For an opposite shift to clean air, the recovery times t(10) are from 7 to 70 s. Results of transient behaviour can be fitted with an exponential approach. It can be demonstrated that results on transient behaviour depend not only from investigation method, and the experimental conditions, like gas changing rate and concentration jump, as well as from operating Parameters of sensors. In comparison to commercial MOS and MIS-FET hydrogen sensors new sensor prototypes operating at room temperature possesses in particular longer recovery times. T2 - ICHS2013 - 5th International conference on hydrogen safety CY - Brussels, Belgium DA - 09.09.2013 KW - Hydrogen sensors KW - Time response PY - 2013 SN - 978-2-9601366-0-9 SP - Paper 124, 1 EP - 8 AN - OPUS4-31082 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Erwamati, F. U. A1 - Pratapa, S. A1 - Suasmoro, S. A1 - Hübert, Thomas A1 - Banach, Ulrich T1 - Preparation and structural study of Mg1−xZnxTiO3 ceramics and their dielectric properties from 1 Hz to 7.7 GHz N2 - A series of Mg₁₋ₓZnₓTiO₃, x = 0–0.5 (MZT0–MZT0.5) ceramics was synthesised and characterised. The dielectric properties of the samples in the frequency range of 1 Hz – 7.7 GHz were explored using three different methods: a contacting electrode method, a parallel-plate method and a perturbed resonator method. The electrical properties in the space charge and dipolar polarisation frequency ranges are discussed in relation to the phase composition and microstructure data. Differences in the zinc Substitution divided the dielectrics into two groups, namely MZT0-MZT0.2 and MZT0.3–MZT0.5, each with different amount of a main Mg₁₋ₓZnₓTiO₃ solid solution phase and a secondary solid solution phase. Zinc substitution promoted the density of the ceramics, improved the purity of the main phase and increased the permittivity for frequencies up to 10⁸ Hz, but reduced the permittivity in the microwave range. In the MZT0.3–MZT0.5 samples, for frequencies less than 1 MHz the quality (Q x ƒ) factors were lower and log σ ₐ.c, the AC conductivity, was higher than for the MZT0–MZT0.2 samples. Above 10 MHz, the (Q x ƒ) factors and log σ ₐ.c of the two groups were similar. KW - Mg1-xZnxTiO3 KW - Space charge polarisation KW - Dipole polarisation KW - Microwave frequency KW - Dielectric properties PY - 2016 DO - https://doi.org/10.1007/s10854-016-4610-6 SN - 0957-4522 VL - 27 IS - 7 SP - 6637 EP - 6645 PB - Springer CY - Dordrecht, Netherlands AN - OPUS4-36466 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ermawati, F. U. A1 - Supardi, Z. A. I. A1 - Suasmoro, S. A1 - Hübert, Thomas T1 - Contribution of Relaxation Effect to the Permittivity of Mg1-xZnxTiO3 Ceramics N2 - This work reported the investigation on the effect of relaxation to the permittivity (epsilon' r ) characteristic of Mg1-x Zn x TiO3 ceramics for x = 0 – 0.5 (MZT0 – MZT0.5) measured from 1 Hz to 330 MHz. Within that frequency range, the relaxation effect that consists of the space charge (SC) and the dipolar (D) polarization mechanisms were identified. The contribution of the D relaxation in MZT0 – MZT0.2 systems extents overall from about 100 Hz to 330 MHz, while that in MZT0.3 – MZT0.5 systems is from 50 kHz to 330 MHz. The remaining frequencies, i.e. from 1 to 90 Hz for MZT0 – MZT0.2 and from 1 Hz to 50 kHz for MZT0.3 – MZT0.5, are attributed to the SC relaxation. The D polarization mechanism provides constant epsilon' r values which vary from (15.4 – 17.0) ± 0.3 throughout the samples. Contribution of the SC polarization mechanism to the characteristic is supported by the simultaneous presence of different content and level of resistivity of the secondary phase of (Mg1-αZnα)2TiO4 in MZT0 – MZT0.2 systems and of (Zn1-αMgα)2TiO4 in MZT0.3 – MZT0.5, along with the presence of the main Mg1-x Zn x TiO3 phase, as a result of the variation of zinc content in the systems. T2 - The 5th International Conference on Advanced Materials Sciences and Technology (ICAMST 2017) CY - Makassar, Indonesia DA - 19.09.2017 KW - Dielectric ceramic KW - dipolar polarization KW - Mg1-xZnxTiO3 KW - permittivity KW - space charge polarization PY - 2018 DO - https://doi.org/10.1088/1757-899X/367/1/012003 SN - 1757-8981 VL - 367 SP - 1 EP - 6 PB - IOP Publishing Ltd AN - OPUS4-45618 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübert, Thomas A1 - Boon-Brett, L. A1 - Palmisano, V. A1 - Bader, Mark Andreas T1 - Developments in gas sensor technology for hydrogen safety N2 - Gas sensors are applied for facilitating the safe use of hydrogen in, for example, fuel cell and hydrogen fuelled vehicles. New sensor developments, aimed at meeting the increasingly stringent performance requirements in emerging applications, are reviewed. The strategy of combining different detection principles, i.e. sensors based on electrochemical cells, semiconductors or field effects in combination with thermal conductivity sensing or catalytic combustion elements, in one new measuring system is reported. This extends the dynamic measuring range of the sensor while improving sensor reliability to achieve higher safety integrity through diverse redundancy. The application of new nanoscaled materials, nanowires, carbon tubes and graphene as well as the improvements in electronic components and optical elements are evaluated in view of key operating parameters such as measuring range, sensor response time and low working temperature. KW - Hydrogen sensor KW - Hydrogen safety PY - 2014 DO - https://doi.org/10.1016/j.ijhydene.2014.05.042 SN - 0360-3199 VL - 39 IS - 35 SP - 20474 EP - 20483 PB - Elsevier CY - Oxford AN - OPUS4-32379 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mosel, Günter A1 - Hübert, Thomas A1 - Nofz, Marianne A1 - Brenneis, Rudolf A1 - Köcher, Peter A1 - Kley, Gerd T1 - Zn-K EXAFS investigations on ZnS/ZnO containing vitrified ashes from municipal incinerator facilities N2 - Zn-K transmission EXAFS measurements were performed on vitrified ashes from municipal waste incinerator facilities, which contain low amounts of Zn (up to 3 wt%) and sulphur (up to 0.5 wt%) in a ZnS phase. From the Fourier transform it can be concluded that the zinc ions are fourfold co-ordinated by oxygen or sulphur ions. The amount of zinc ions of sulphur environment, e.g. the concentration of ZnS, was determined by Fourier filtering and subsequent parameter fitting. A quantitative analysis of low ZnS concentrations up to 1 wt% has been performed for samples with a molar ratio Zn/S < 5. PY - 2001 DO - https://doi.org/10.1023/A:1011802202743 SN - 0022-2461 SN - 1573-4803 VL - 36 SP - 5017 EP - 5025 PB - Springer Science + Business Media B.V. CY - Norwell, Mass. AN - OPUS4-18579 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübert, Thomas A1 - Svoboda, S. A1 - Oertel, B. T1 - Wear resistant alumina coatings produced by a sol-gel process N2 - Aluminium oxide films were prepared by a dip-coating procedure from solutions of hydrolysed aluminium-tri-sec-butoxide in methoxyethanol on austenitic steel as well as hard metal tools. The heat treatment was performed in an argon atmosphere or vacuum at temperatures up to 1100 °C. Characterisation of the coatings by SEM, showed nearly crack free coatings with a dense morphology which completely cover the substrate. The chemical composition of the coatings was investigated by ESCA, GD-OES and XRD measurements. This analysis detected a multi-layered arrangement of spinel phases, ?- and ?-alumina in the coatings. The scratch test showed sufficient adhesion of the coatings comparable to CVD layers. Pin-on-disc and oscillating sliding tests were carried out on sol–gel coated samples and also on uncovered reference samples. The determined wear rates and friction coefficients showed significant improvement in wear resistance of sol–gel coatings containing a corundum phase. The strong adhesion to the substrates is due to a layered assembly formation and gradient composition of the coating caused by an interdiffusion of metal cations and oxygen in the metal/oxide interface during heat treatment. KW - Oxide film formation KW - Film analysis KW - Wear resistance PY - 2006 DO - https://doi.org/10.1016/j.surfcoat.2005.11.014 SN - 0257-8972 VL - 201 IS - 1-2 SP - 487 EP - 491 PB - Elsevier Science CY - Lausanne AN - OPUS4-18583 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübert, Thomas A1 - Hattermann, Hilke A1 - Griepentrog, Michael T1 - Sol-gel-derived nanocomposite coatings filled with inorganic fullerene-like WS2 N2 - Silica coatings filled with nanoscaled inorganic fullerene-like tungsten disulphide (IF-WS2) have been prepared through a sol–gel process on stainless steel substrates, and the structure and mechanical properties have been investigated. The precursor was prepared from a mixture of colloidal silica, 3-glycidoxypropyltrimethoxysilane (GLYMO), water and ethanol, adjusted to pH 4 with HNO3. In this solution WS2 is dispersed and in some cases immediately before coating ethylenediamine (ED) is added. The stainless steel substrates are dip-coated, dried in air and heat-treated in the temperature range of either 150–360 °C in air or up to 900 °C in vacuum. The solidification process is followed by differential thermal analysis (DTA). The resulting brown coloured coatings have a thickness of 1.5–4 µm. Scanning electron microscopy investigations (SEM) show that the WS2 nanoparticles are embedded as small aggregates in a hybrid silica matrix. X-ray diffraction (XRD) measurements prove that most of the tungsten disulphide embedded in the matrix can be protected against oxidation even after curing the samples at temperatures up to 900 °C. Hardness and modulus of the hybrid silica films were measured through an instrumented indentation test. Increasing the temperature of the heat treatment yields an increase of hardness from 0.3 to 1 GPa and of modulus from 3 to 17 GPa. The amount of up to 10 wt.% WS2 in the coatings has no remarkable influence on hardness and modulus of the samples. KW - Nanocomposites KW - Tungsten disulphide KW - Sol-gel KW - Mechanical properties PY - 2009 DO - https://doi.org/10.1007/s10971-009-1896-3 SN - 0928-0707 SN - 1573-4846 VL - 51 IS - 3 SP - 295 EP - 300 PB - Kluwer Academic Publ. CY - Dordrecht AN - OPUS4-19713 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Boon-Brett, L. A1 - Bousek, J. A1 - Black, G. A1 - Moretto, P. A1 - Castello, P. A1 - Hübert, Thomas A1 - Banach, Ulrich T1 - Identifiying performance gaps in hydrogen safety sensor technology for automotive and stationary applications N2 - A market survey has been performed of commercially available hydrogen safety sensors, resulting in a total sample size of 53 sensors from 21 manufacturers. The technical specifications, as provided by the manufacturer, have been collated and are displayed herein as a function of sensor working principle. These specifications comprise measuring range, response and recovery times, ambient temperature, pressure and relative humidity, power consumption and lifetime. These are then compared against known performance targets for both automotive and stationary applications in order to establish in how far current technology satisfies current requirements of sensor end users. Gaps in the performance of hydrogen sensing technologies are thus identified and areas recommended for future research and development. KW - Hydrogen sensor KW - Hydrogen detection KW - Safety KW - Sensor performance testing KW - Performance specifications KW - Performance targets PY - 2010 DO - https://doi.org/10.1016/j.ijhydene.2009.10.064 SN - 0360-3199 VL - 35 IS - 1 SP - 373 EP - 384 PB - Elsevier CY - Oxford AN - OPUS4-22893 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -