TY - JOUR A1 - Krüger, Simone A1 - Wachtendorf, Volker A1 - Rauth, W. A1 - Klimmasch, T. A1 - Krüger, P. T1 - Screening the weathering stability of automotive coatings by chemiluminescence JF - Journal of coatings technology and research N2 - Chemiluminescence (CL) is a sensitive method of investigating the thermo-oxidative stability of polymers in the early stages of degradation. Therefore, CL measurements were applied to different automotive coatings to evaluate their degradation behavior during artificial weathering. In this work, CL measurements were carried out for different automotive coatings to follow their degradation behavior during artificial weathering. The CL emission depends on sample-specific parameters like stabilizer, matrix, or hardener; experimental parameters like the oxygen partial pressure; and exposure parameters like the duration of weathering. The potential of CL could be demonstrated by classifying materials into categories of good, medium, and low degradation performance at a much earlier stage of weathering exposure than in combination with the usual visual detection of weathering effects. KW - Accelerated weathering KW - Coating KW - Chemiluminescence KW - Sensitive detection KW - Weathering PY - 2008 DO - https://doi.org/10.1007/s11998-007-9071-7 SN - 1547-0091 SN - 1935-3804 VL - 5 IS - 1 SP - 17 EP - 24 PB - Springer CY - Blue Bell, Pa. AN - OPUS4-16723 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krüger, Simone A1 - Brademann-Jock, Kerstin A1 - Rauth, W. A1 - Klimmasch, T. A1 - Krüger, P. T1 - Analysis of weathering effects in automotive coatings using thermoluminescence JF - Journal of coatings technology and research N2 - Thermally stimulated luminescence (TL) can be used to detect damage in the early stages of degradation after artificial weathering, and to analyze the efficiency of stabilizers used in automotive coatings. TL is particularly suitable for this task due to its inherent high sensitivity to structural, morphological, and chemical changes in macromolecular chains. In this work, TL measurements were carried out for different automotive coatings to follow their degradation progression during artificial weathering. The TL results demonstrate high sensitivity to parameters like stabilizers, matrices, hardeners, and weathering time, and provide an opportunity to monitor the early stages of damage in polymers, which therefore reduce the time required for further outdoor weathering tests. KW - Accelerated weathering KW - Automotive coating KW - Thermoluminescence KW - Sensitive detection KW - Weathering PY - 2008 DO - https://doi.org/10.1007/s11998-007-9072-6 SN - 1547-0091 SN - 1935-3804 VL - 5 IS - 1 SP - 11 EP - 16 PB - Springer CY - Blue Bell, Pa. AN - OPUS4-16722 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kautek, Wolfgang A1 - Pentzien, Simone A1 - Conradi, Andrea A1 - Krüger, Jörg A1 - Brzezinka, Klaus-Werner T1 - Pulsed-laser deposition and boron-blending of diamond-like carbon (DLC) thin films JF - Applied surface science KW - Pulslaser KW - Bor KW - Dünnfilmtechnologie KW - Dünnfilm, diamantartig PY - 1996 SN - 0169-4332 SN - 1873-5584 VL - 106 SP - 158 EP - 165 PB - North-Holland CY - Amsterdam AN - OPUS4-630 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Brademann-Jock, Kerstin A1 - Krüger, Simone A1 - Wachtendorf, Volker A1 - Goering, Harald T1 - Degradation effects of automotive coatings after weathering as detected by thermoluminescence T2 - 27th FATIPEC Congress (Proceedings) T2 - 27th FATIPEC Congress CY - Aix-en-Provence, France DA - 2004-04-19 KW - Automobillacke KW - Bewitterung KW - Thermolumineszenz KW - Automotive coatings KW - Weathering KW - Thermoluminescence PY - 2004 VL - 3 SP - 1045 EP - 1050 PB - Association Francaise des Techniciens des Peintures, Vernis,Encres CY - Aix en Provence AN - OPUS4-4054 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krüger, Simone A1 - Stark, Wolfgang A1 - Goering, Harald A1 - Michel, Uwe T1 - Thermoanalyse der Phenolharzhärtung - Ein Weg zur Optimierung der Nachtemperung JF - Materialprüfung = Materials testing N2 - Angesichts der spezifischen Bedeutung der Aushärtung von Phenolharzen für ihre Eigenschaften als Ingenieurwerkstoffe besteht großes Interesse an deren quantitativer Charakterisierung. Mittels DSC-Messungen unter hohem Druck (HP-DSC) kann die Vernetzungsreaktion der Phenolharzformmassen durch die Unterdrückung der Verdampfung niedermolekularer Substanzen ohne störende Überlagerungen verfolgt werden. Mittels verschiedener Vernetzungsgrade können die Einflussparameter der Aufheizrate und der Nachtemperung optimiert werden. Die Messergebnisse ermöglichen eine Modellierung der Reaktionskinetik mit dem Ziel einer verbesserten Prozessführung und Qualitätskontrolle in der industriellen Praxis. KW - Phenolharze KW - Thermische Analyse KW - DMA KW - DSC KW - Aushärtung KW - Glasübergang PY - 2006 SN - 0025-5300 VL - 48 IS - 11-12 SP - 556 EP - 561 PB - Carl Hanser Verlag CY - München AN - OPUS4-13802 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kautek, Wolfgang A1 - Pentzien, Simone A1 - Röllig, Mathias A1 - Rudolph, Pascale A1 - Krüger, Jörg A1 - Maywald-Pitellos, C. A1 - Bansa, H. A1 - Grösswang, H. A1 - König, E. T1 - Near-UV laser interaction with contaminants and pigments on parchment: laser cleaning diagnostics by SE-microscopy, VIS-, and IR-spectroscopy JF - Journal of cultural heritage PY - 2000 SN - 1296-2074 SN - 1778-3674 VL - 1 IS - sup.1 PB - Elsevier CY - Paris AN - OPUS4-5981 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pentzien, Simone A1 - Rabin, Ira A1 - Hahn, Oliver A1 - Krüger, Jörg A1 - Kleber, F. A1 - Hollaus, F. A1 - Diem, M. A1 - Sablatnig, R. ED - Park, J.-I. ED - Kim, J. T1 - Can Modern Technologies Defeat Nazi Censorship? T2 - ACCV 2012 Workshops, 11th Asian conference on computer vision N2 - Censorship of parts of written text was and is a common practice in totalitarian regimes. It is used to destroy information not approved by the political power. Recovering the censored text is of interest for historical studies of the text. This paper raises the question, whether a censored postcard from 1942 can be made legible by applying multispectral imaging in combination with laser cleaning. In the fields of art conservation (e.g. color measurements), investigation (e.g. Analysis of underdrawings in paintings), and historical document analysis, multispectral imaging techniques have been applied successfully to give visibility to information hidden to the human eye. The basic principle of laser cleaning is to transfer laser pulse energy to a contamination layer by an absorption process that leads to heating and evaporation of the layer. Partial laser cleaning of postcards is possible; dirt on the surface can be removed and the obscured pictures and writings made visible again. We applied both techniques to the postcard. The text could not be restored since the original ink seems to have suffered severe chemical damage. T2 - ACCV 2012 Workshops, 11th Asian conference on computer vision CY - Daejeon, Korea DA - 05.11.2012 KW - Laser cleaning KW - Multispectral imaging KW - Image restoration KW - Image enhancement PY - 2013 SN - 978-3-642-37483-8 SN - 0302-9743 VL - II IS - LNCS 7729 SP - 13 EP - 24 PB - Springer CY - Berlin Heidelberg AN - OPUS4-28160 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mann, Guido A1 - Pentzien, Simone A1 - Krüger, Jörg T1 - Beam diameter dependence of surface damage threshold of fused silica fibers and preforms for nanosecond laser treatment at 1064 nm wavelength JF - Applied surface science N2 - Optical fibers made of fused silica are a common method of transmitting high laser pulse energies. Failure of those fibers is a significant risk. The determination of laser-induced damage thresholds (LIDT) on fiber end facets according to ISO 21254 standard is needed. In the past, single pulse nanosecond laser experiments showed an improvement of LIDT with increasing fiber core diameter for 1064 nm wavelength and a constant beam diameter of 50 µm. This paper pays particular attention to the influence of the laser beam diameter on damage resistance. All-silica fiber types (LEONI) with different core diameters (100–600 µm) were investigated using beam diameters in a range from 30 µm to 100 µm. For comparison experiments on fused silica preform material (Heraeus F300) were performed. On one hand, surface LIDT of fused silica preform material decreases significantly with increasing beam size. A model considering a random distribution of point defects explains the experimental data qualitatively. On the other hand, LIDT of fiber end facets stays constant. White light microscopy results suggest that the point defect density on fiber end facets is lower compared to the preform surface due to an excellent surface polish quality. KW - Laser-induced damage threshold KW - Nanosecond laser KW - Optical fiber KW - Fused silica KW - Spot size KW - Defect model PY - 2013 DO - https://doi.org/10.1016/j.apsusc.2013.03.088 SN - 0169-4332 SN - 1873-5584 VL - 276 SP - 312 EP - 316 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-28310 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mohamed, Zeinab A1 - Krüger, Simone A1 - Hidde, Gundula A1 - Schimanski, A. A1 - Jäger, Christian A1 - Friedrich, Jörg Florian T1 - Deposition of thick polymer or inorganic layers with flame-retardant properties by combination of plasma and spray processes JF - Surface and coatings technology N2 - Mixtures of hexamethyldisiloxane (HMDSO) and oxygen have been used for deposition of SiO2-like layers by plasma polymerization under low-pressure conditions onto polyethylene and polystyrene used as basecoat. Water glass was cast onto these 0.5 µm plasma thick siloxane-like layers with a thickness of 5 to 40 µm. The adhesion of these bilayer systems and their flame resistance were tested. The effect of different plasma parameters such as monomer/gas ratio, pressure and power input into the discharge on the deposition rate and the composition of the formed layers was studied. Characterization and chemical composition of the formed films were performed using infrared, X-ray photoelectron and solid state nuclear magnetic resonance spectroscopy. Peel strengths of composites were measured and the locus of peel front propagation was detected. Thermal properties of composites were analyzed by thermo-gravimetric analysis. Finally, the fire-retardant properties of thick coated polymers were determined by exposure to flames and the behavior of coatings on the polymers during flaming was observed visually. KW - Plasma polymerization KW - Hexamethyldisiloxane plasma polymer KW - Polystyrene KW - Polyethylene KW - Flame retardancy PY - 2013 DO - https://doi.org/10.1016/j.surfcoat.2013.04.039 SN - 0257-8972 VL - 228 SP - 266 EP - 274 PB - Elsevier B.V. CY - Lausanne AN - OPUS4-28735 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kautek, Wolfgang A1 - Pentzien, Simone A1 - Rudolph, Pascale A1 - Krüger, Jörg A1 - König, E. T1 - Laser interaction with coated collagen und cellulose fibre composites: fundamentals of laser cleaning of ancient parchment manuscripts and paper JF - Applied surface science N2 - Laser cleaning of delicate biological composite materials such as ancient parchment manuscripts from the 15th and 16th century and printed paper from the 19th century is demonstrated with an ultraviolet excimer pulsed laser at 308 nm. Laser fluence levels must stay below the ablation and destruction threshold of the parchment or paper substrate, and have to surpass the threshold of the contaminant matter. Foreign layers to be removed must exhibit a higher optical density than the artifact substrates. Synthetic carbonaceous dirt modelled by water-soluble black crayons showed a characteristically weak featureless laser-induced plasma spectroscopy spectrum near the noise limit. It turned out that laser-induced plasma spectroscopy is of limited use in monitoring halting points (or etch-stops) because it relies on the destruction not only of the laterally inhomogenously distributed contaminant but also of pigment phases on a microscopically rough parchment substrate. Laser-induced fluorescence spectroscopy, however, promises to be a valuable non-destructive testing technique for etch-stop monitoring. KW - Laser KW - Parchment KW - Papery KW - Spectroscopy KW - Laser cleaning PY - 1998 SN - 0169-4332 SN - 1873-5584 VL - 127-129 SP - 746 EP - 754 PB - North-Holland CY - Amsterdam AN - OPUS4-11516 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -