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- Monitoring (3)
- Acoustic emission (2)
- Beschleunigungssensoren (2)
- Crystallization (2)
- Faseroptische Sensorik (2)
- Rohrleitung (2)
- Schallemission (2)
- Accelerometer (1)
- Accelerometers (1)
- Bending tests on pipe segments (1)
Organisationseinheit der BAM
- 2 Prozess- und Anlagensicherheit (4)
- 2.1 Sicherheit von Energieträgern (4)
- 3 Gefahrgutumschließungen; Energiespeicher (4)
- 3.2 Gefahrguttanks und Unfallmechanik (4)
- 5 Werkstofftechnik (4)
- 5.4 Multimateriale Fertigungsprozesse (4)
- 8 Zerstörungsfreie Prüfung (4)
- 8.1 Sensorik, mess- und prüftechnische Verfahren (4)
- 8.4 Akustische und elektromagnetische Verfahren (4)
- 8.6 Faseroptische Sensorik (4)
Theophylline has been used as an active pharmaceutical ingredient (API) in the treatment of pulmonary diseases, but due to its low water solubility reveals very poor bioavailability. Based on its different hydrogen-bond donor and acceptor groups, theophylline is an ideal candidate for the formation of cocrystals. The crystal structure of the 1:1 benzamide cocrystal of theophylline, C7H8N4O2·-C7H7NO, was determined from synchrotron X-ray powder diffraction data. The compound crystallizes in the tetragonal space group P41 with four Independent molecules in the asymmetric unit. The molecules form a hunter’s fence packing.
The crystal structure was confirmed by dispersion-corrected DFT calculations.
The possibility of salt formation was excluded by the results of Raman and 1H solid-state NMR spectroscopic analyses.
The monitoring of oil and gas pipelines by means of distributed fibre optic sensors is becoming common. The most recent development in the field of fibre optic sensing is the distributed acoustic sensing (DAS), which allows to detect and to localize third party threats to pipelines. For this purpose, fibre optic telecommunication cables located close to the pipelines are usually used. However, DAS carries a far greater potential for continuous condition monitoring of pipelines.
The interdisciplinary research project AGIFAMOR (Ageing Infrastructures – Fibre Optic Monitoring of Pipes) at BAM investigates a new technical approach to extend the application field of DAS towards the detection and localization of acoustic signals that indicate critical alterations and certain damage scenarios originated from within the pipeline or the pipe wall. Therefore, the optical fibre sensors are applied onto the pipe itself and the application procedure towards an optimal acoustic signal transduction is optimized.
A number of laboratory scale experiments were performed focusing on the signal transmission of acoustic signals as well as the detection of damages in the pipe wall by means of DAS. Furthermore, real-scale tests on a pipeline DN100 of 38m length have been carried out at the BAM test site for technical safety (BAM-TTS) to study the detection and localization of leaks and of changing flow profiles due to corrosion or sedimentation processes.
Schäden an Rohrleitungen können zu hohen Umweltbelastungen und wirtschaftlichen Schäden führen. Um die dauerhafte Verfügbarkeit der Infrastruktur zu gewährleisten, wird im Rahmen des Projekts AGIFAMOR an der Bundesanstalt für Materialforschung und -prüfung (BAM) erprobt, inwiefern das Verfahren der verteilten akustischen faseroptischen Sensorik (Distributed acoustic sensing – DAS) zur kontinuierlichen Überwachung von Rohrleitungen eingesetzt werden kann. Neben der DAS werden erprobte Verfahren der zerstörungsfreien Prüfung wie Schallemissionsanalyse (SEA) und Beschleunigungssensoren eingesetzt. An dieser Stelle soll detailliert auf die Hauptschadensursachen an Rohrleitungen, den Versuchsstand zur mechanischen Belastung von Rohren sowie die Möglichkeiten zu Untersuchungen im Realmaßstab eingegangen werden.
Time-resolved in situ investigation of Portland cement hydration influenced by chemical admixtures
(2016)
Numerous admixtures are used in the building practice to customize the properties of the cement paste during application. The influences of admixtures on the course of cement hydration and formation of hydrate phases have to be considered. Polycarboxylate ether (PCE) based polymeric superplasticizers (SPs) are known to retard the setting of the cement paste. The extent of the retardation differs depending on the molecular structure of the SP. Additionally, the presence of a stabilizing agent (SA) in the cement paste has a retarding side effect on the setting. The initial cement hydration processes and the detailed mechanisms of the retardation influenced by PCEs, as well as their interactions with particular SAs, are insufficiently understood. Up to now, only the results of phenomenological studies were taken into account to describe this retardation process. A detailed structure analysis monitoring the change of the phase composition during the hydration was never applied. Both SP and SA affect the adsorption of the sulphate ions on the clinker particles, causing changes in the formation of ettringite during the initial hydration, and are therefore a crucial part of the setting process itself. Here, the initial hydration of cement influenced by the interaction of SP and SA was monitored in situ by synchrotron X-ray diffraction. The high time resolution of the measurements allowed a continuous detection of the hydrates formed. The hydration was followed from the starting point of water addition and for couple of hours afterwards. The hydration of the levitated cement pellets containing starch as SA was initialized by adding aqueous solutions of different commercial SPs. Changes in the ettringite formation were detected in comparison to the reference hydration of pure cement.
Spherical mesoporous bioactive glasses in the silicon dioxide (SiO2)-phosphorus pentoxide (P2O5)–calcium oxide (CaO) system with a high specific surface area of up to 300m2/g and a medium pore radius of 4 nm were synthesized by using a simple one-pot surfactant-assisted sol–gel synthesis method followed by calcination at 500–700°C. The authors were able to control the particle properties by varying synthesis parameters to achieve microscale powders with spherical morphology and a particle size of around 5–10 mm by employing one structure-directing agent. Due to a high Calcium oxide content of 33·6mol% and a phosphorus pentoxide content of 4·0mol%, the powder showed very good bioactivity up to 7 d of immersion in simulated Body fluid. The resulting microspheres are promising materials for a variety of life science applications, as further processing – for example, granulation – is unnecessary. Microspheres can be applied as materials for powder-based additive manufacturing or in stable suspensions for drug release, in bone cements or fillers.
The freeze casting technique assisted with cryo thiol-ene photopolymerization is successfully employed for the fabrication of macroporous polymer-derived silicon oxycarbide with highly aligned porosity. It is demonstrated that the free radical initiated thiol-ene click reaction effectively cross-linked the vinyl-containing liquid polysiloxanes into infusible thermosets even at low temperatures. Furthermore, mixed solution- and suspension-based freeze casting is employed by adding silica nanopowders. SiOC/SiO2 foams with almost perfect cylindrical shapes are obtained, demonstrating that the presence of nano-SiO2 does not restrict the complete photoinduced cross-linking. The post-pyrolysis HF acid treatments of produced SiOC monoliths yields hierarchical porosities, with SiOC/SiO2 nanocomposites after etching demonstrating the highest specific surface area of 494 m2/g and pore sizes across the macro-, meso- and micropores ranges. The newly developed approach gives a versatile solution for the fabrication of bulk polymer-derived ceramics with controlled porosity.
Dual-phase membranes for high-temperature carbon dioxide Separation have emerged as promising technology to mitigate anthropogenic greenhouse gases emissions, especially as a pre- and post-combustion separation technique in coal burning power plants. To implement These membranes industrially, the carbon dioxide permeability must be improved. In this study, Ce_(0.8) Sm_(0.2) O_(2-d) (SDC) and Ce_(0.8)Sm_(0.19)Fe_(0.01)O_(2-d) (FSDC) ceramic powders were used to form the skeleton in dual-Phase membranes. The use of MgO as an environmentally friendly pore generator allows control over the membrane porosity and microstructure in order to compare the effect of the membrane’s ceramic phase. The ceramic powders and the resulting membranes were characterized using ICP-OES, HSM, gravimetric analysis, SEM/EDX, and XRD, and the carbon dioxide flux density was quantified using a high-temperature membrane permeation setup. The carbon dioxide permeability slightly increases with the addition of iron in the FSDC membranes compared to the SDC membranes mainly due to the reported scavenging effect of iron with the siliceous impurities, with an additional potential contribution of an increased crystallite size due to viscous flow sintering. The increased permeability of the FSDC system and the proper microstructure control by MgO can be further extended to optimize carbon dioxide permeability in this membrane system.
Chemically modified bioactive glasses based on ICIE16 were prepared with the melt-quenching method using water as a quenching medium. The sinterability of these bioactive glasses was investigated and is discussed in this article. The sintering experiments were conducted with different sintering temperatures, sintering times and heating rates. Those parameters are crucial for dense glass with an amorphous structure. The particle size (d50) of the starting glass powder was determined at 88 μm and kept constant. The pre-pressed glass pellets were cold-isostatically pressed at 300 MPa to a green density of around 63 %. Density development, phase identification, shrinkage behavior and the microstructure were investigated to determine the sinterability of the developed glasses. The glass powders were sintered at different temperatures inside the processing window while crystallization was monitored. The results have shown that the sinterability of the developed glasses strongly dependsonthe proposed chemical additions. The highest density reached was 96 %, which belongs to BP1 glass with sintering conditions of 20 K/min heating rate for 60 min at 750 °C.
Rohrleitungssysteme sind aufgrund ihrer Funktion und Ausdehnung für den Betrieb, die Verfügbarkeit und die Sicherheit von Industrieanlagen von besonderer Bedeutung. Die bisher in definierten Intervallen durchgeführten, wiederkehrenden Prüfungen zur Sicherstellung leckagefreier Rohrleitungen sind kostenintensiv und mit einem erhöhten Aufwand verbunden.
Mit dem interdisziplinären Forschungsprojekt AGIFAMOR (Ageing Infrastructures – Akustisches Monitoring von Rohrleitungen) arbeitet die BAM an der Entwicklung und Erprobung einer örtlich und zeitlich kontinuierlichen Zustandsüberwachung von Rohrleitungen basierend auf einem faseroptischen akustischen Messsystem, welches einen vergleichsweise geringen Installationsaufwand der Sensoren erfordert. Mit diesem Verfahren sollen vor allem betriebsbedingte Schädigungen infolge von Korrosion sowie daraus entstehende Pittings oder Risse erkannt und damit Leckagen verhindert werden.
Im Rahmen einer Machbarkeitsstudie zum Teilaspekt „Detektion von Risswachstum“ wurde ein 2,5 m langes, definiert vorgekerbtes Stahlrohr mit der faseroptischen Sensorik (FOS) ausgestattet und quasistatisch unter 4-Punkt-Biegung belastet. Mit fortschreitender Belastung wächst, ausgehend vom vorhandenen Außenumfangskerb, ein Riss im Stahlrohr bis zum Erreichen der Leckage – in der Praxis ein gefährliches Schadensszenario.
Parallel zur FOS erfolgten Messungen mit Schallemissionssensoren, Beschleunigungssensoren und Potentialsonden, deren Ergebnisse die Interpretation der FOS-Messergebnisse unterstützen sollen.
In der Prozessindustrie werden häufig gefährliche Stoffe eingesetzt, so dass auch kleinste Leckagen der medienführenden Anlagenteile zu Gefährdungen der Arbeitnehmer sowie zur Belastung der Umwelt führen können. Für die Gewährleistung einer dauerhaften Verfügbarkeit der Infrastruktur ist die frühzeitige Erkennung und Ortung von potentiell gefährlichen Veränderungen an den Wandungen von Rohrleitungen und Behältern (in Form von Rissen, Pittings und Ablagerungen) erforderlich. Am Beispiel von Rohrleitungen, sollen im Rahmen des Projekts AGIFAMOR an der Bundesanstalt für Materialforschung und -prüfung (BAM), im Sinne einer Machbarkeitsstudie die Verfahren der verteilten akustischen und faseroptischen Sensorik zur kontinuierlichen Überwachung und Detektion potentiell gefährlicher Veränderungen in Industrieanlagen erprobt und qualifiziert werden. Dabei sollen die Applikation der optischen Sensorfasern hinsichtlich der Signalübertragung auf den Sensor optimiert und die Erkennung der für dieses Anwendungsgebiet relevanten Schallsignaturen entwickelt werden. Mithilfe eines solchen Messsystems können mit geringem Aufwand ausgedehnte Strukturen, auch unter erschwerten Bedingungen (z.B. hohe Temperatur, Einfluss von Chemikalien) kontinuierlich überwacht werden.