TY - JOUR A1 - D'Accardi, E. A1 - Krankenhagen, Rainer A1 - Ulbricht, Alexander A1 - Pelkner, Matthias A1 - Pohl, Rainer A1 - Palumbo, D. A1 - Galietti, U. T1 - Capability to detect and localize typical defects of laser powder bed fusion (L‑PBF) process: an experimental investigation with different non‑destructive techniques N2 - Additive manufacturing (AM) technologies, generally called 3D printing, are widely used because their use provides a high added value in manufacturing complex-shaped components and objects. Defects may occur within the components at different time of manufacturing, and in this regard, non-destructive techniques (NDT) represent a key tool for the quality control of AM components in many industrial fields, such as aerospace, oil and gas, and power industries. In this work, the capability of active thermography and eddy current techniques to detect real imposed defects that are representative of the laser powder bed fusion process has been investigated. A 3D complex shape of defects was revealed by a μCT investigation used as reference results for the other NDT methods. The study was focused on two different types of defects: porosities generated in keyhole mode as well as in lack of fusion mode. Different thermographic and eddy current measurements were carried out on AM samples, providing the capability to detect volumetric irregularly shaped defects using non-destructive methods. KW - Additive Manufacturing KW - Defect detection KW - Thermography KW - Eddy-current testing KW - Micro-computed tomography PY - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-546680 SN - 2363-9512 VL - 7 IS - 6 SP - 1239 EP - 1256 PB - Springer AN - OPUS4-54668 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kruschwitz, Sabine A1 - Oesch, T. A1 - Mielentz, Frank A1 - Meinel, Dietmar A1 - Spyridis, P. T1 - Non-Destructive Multi-Method Assessment of Steel Fiber Orientation in Concrete N2 - Integration of fiber reinforcement in high-performance cementitious materials has become widely applied in many fields of construction. One of the most investigated advantages of steel Fiber reinforced concrete (SFRC) is the deceleration of crack growth and hence its improved sustainability. Additional benefits are associated with its structural properties, as fibers can significantly increase the ductility and the tensile strength of concrete. In some applications it is even possible to entirely replace the conventional reinforcement, leading to significant logistical and environmental benefits. Fiber reinforcement can, however, have critical disadvantages and even hinder the Performance of concrete, since it can induce an anisotropic material behavior of the mixture if the fibers are not appropriately oriented. For a safe use of SFRC in the future, reliable non-destructive testing (NDT) methods need to be identified to assess the fibers’ orientation in hardened concrete. In this study, ultrasonic material testing, electrical impedance testing, and X-ray computed tomography have been investigated for this purpose using specially produced samples with biased or random Fiber orientations. We demonstrate the capabilities of each of these NDT techniques for fiber orientation measurements and draw conclusions based on these results about the most promising areas for future research and development. KW - Spectral induced polarization KW - Steel fiber reiniforced concrete KW - Fiber orientation KW - Non-destructive testing KW - Micro-computed tomography KW - Ultrasound PY - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-543520 VL - 12 IS - 2 SP - 1 EP - 14 PB - MDPI CY - Basel Switzerland AN - OPUS4-54352 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Peruzzi, N. A1 - Galli, S. A1 - Helmholz, H. A1 - Kardjilov, N. A1 - Krüger, D. A1 - Markötter, Henning A1 - Moosmann, J. A1 - Orlov, D. A1 - Prgomet, Z. A1 - Willumeit-Römer, R. A1 - Wennerberg, A. A1 - Bech, M. T1 - Multimodal ex vivo methods reveal that Gd-rich corrosion byproducts remain at the implant site of biodegradable Mg-Gd screws N2 - Extensive research is being conducted on magnesium (Mg) alloys for bone implant manufacturing, due to their biocompatibility, biodegradability and mechanical properties. Gadolinium (Gd) is among the most promising alloying elements for property control in Mg alloy implants; however, its toxicity is contro- versial. Investigating Gd behavior during implant corrosion is thus of utmost importance. In this study, we analyzed the degradation byproducts at the implant site of biodegradable Mg-5Gd and Mg-10Gd implants after 12 weeks healing time, using a combination of different imaging techniques: histology, energy-dispersive x-ray spectroscopy (EDX), x-ray microcomputed tomography (μCT) and neutron μCT. The main finding has been that, at the healing time in exam, the corrosion appears to have involved only the Mg component, which has been substituted by calcium and phosphorus, while the Gd remains localized at the implant site. This was observed in 2D by means of EDX maps and extended to 3D with a novel application of neutron tomography. X-ray fluorescence analysis of the main excretory organs also did not reveal any measurable accumulation of Gd, further reinforcing the conclusion that very limited or no removal at all of Gd-alloy happened during degradation. KW - Magnesium-gadolinium alloy KW - Biodegradable implant KW - Multimodal analysis KW - Energy-dispersive x-ray spectroscopy KW - Micro-computed tomography PY - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-535910 SN - 1742-7061 SP - 1 EP - 10 PB - Elsevier Ltd. AN - OPUS4-53591 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Müller, Patrick A1 - Morys, Michael A1 - Sut, Aleksandra A1 - Jäger, Christian A1 - Illerhaus, Bernhard A1 - Schartel, Bernhard T1 - Melamine poly(zinc phosphate) as flame retardant in epoxy resin: Decomposition pathways, molecular mechanisms and morphology of fire residues N2 - Synergistic multicomponent systems containing melamine poly(metal phosphate)s have been recently proposed as flame retardants. This work focuses on the decomposition pathways, molecular mechanisms and morphology of the fire residues of epoxy resin (EP) flame retarded with melamine poly(zinc phosphate) (MPZnP) to explain the modes of action and synergistic effects with selected synergists (melamine polyphosphate (MPP) and AlO(OH), respectively). The total load of flame retardants was always 20 wt.%. The decomposition pathways were investigated in detail via thermogravimetric Analysis coupled with Fourier transform infrared spectroscopy. The fire residues were investigated via elemental analysis und solid-state nuclear magnetic resonance spectroscopy. The morphology of intumescent fire residues was investigated via micro-computed tomography and scanning electron microscopy. EP + (MPZnP + MPP) formed a highly voluminous residue that showed structural features of both EP + MPZnP and EP + MPP, resulting in a highly effective protection layer. EP + (MPZnP + AlO(OH)) preserved the entire quantity of phosphorus content during combustion due to the Formation of Zn₂P₂O₇ and AlPO₄. KW - Melamine poly(metal phosphate) KW - Flame retardancy KW - Epoxy resin KW - Solid-state NMR KW - Micro-computed tomography KW - Fire residue PY - 2016 U6 - https://doi.org/10.1016/j.polymdegradstab.2016.06.023 SN - 0141-3910 VL - 130 SP - 307 EP - 319 PB - Elsevier AN - OPUS4-36863 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -