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The application of lightweight materials for tanks for transportation appears promising. Besides saving weight and therefore transportation costs, new complex geometries that depart from common cylindrical shapes of steel tanks can be manufactured. For transportation of dangerous goods, fire and explosion safety must be maintained to prevent accidents with serious consequences. In this work the fire behavior of lightweight tanks made from glass fiber reinforced plastics (GFRP) with complex geometries is investigated. Pretests on intermediate scale GFRP plates are conducted to identify suitable fire protection systems and surface treatments for composite tanks. The fire resistance is shown to be improved by addition of fire protective coatings and integrated layers. Finally, a complex rectangular GFRP tank with a holding capacity of 1100 liters is fire protected with an intumescent fire coating. The tank is filled up to 80 % with water and burned under an engulfing fully developed fire. It was shown that the intumescent layer could expand before the decomposition of the resin occurred. Furthermore, the adhesion between tank surface and coating was maintained. The structure could withstand a fire for more than 20 min.
Titanium nitride (TiN) was coated on different substrate materials, namely pure titanium (Ti), titanium alloy (Ti6Al4V) and steel (100Cr6), generating 2.5 μm thick TiN layers. Using femtosecond laser pulses (30 fs, 790 nm, 1 kHz pulse repetition rate), large surface areas (5 mm × 5 mm) of laser-induced periodic surface structures (LIPSS) with sub-wavelength periods ranging between 470 nm and 600 nm were generated and characterized by optical microscopy (OM), white light interference microscopy (WLIM) and scanning electron microscopy (SEM). In tribological tests, coefficients of friction (COF) of the nanostructured surfaces were determined under reciprocating sliding conditions (1 Hz, 1.0 N normal load) against a 10-mm diameter ball of hardened 100Cr6 steel during 1000 cycles using two different lubricants, namely paraffin oil and engine oil. It turned out that the substrate material, the laser fluence and the lubricant are crucial for the tribological performance. However, friction and wear could not be significantly reduced by LIPSS on TiN layers in comparison to unstructured TiN surfaces. Finally, the resulting wear tracks on the nanostructured surfaces were investigated with respect to their morphology (OM, SEM), depth (WLIM) and chemical composition by energy dispersive X-ray spectroscopy (EDX) and, on one hand, compared with each other, on the other hand, with non-structured TiN surfaces.
Various methods have been used for introducing fire retardant additives into polymers. Deposition of thick fire retardant coatings directly onto polymer substrates is an alternative technique. An important advantage of the coating technique is the preservation of the physical and chemical integrity of the polymer material. Moreover, the fire retardancy of the polymer materials can be achieved following their production. Suitable coating materials are inorganics, intumescent, char-forming, oxygendiluting, and cooling or radical quenching layers. The most important problem is to achieve sufficient coating thickness to withstand the direct attack of flame and to protect the polymer bulk from pyrolysis, otherwise blistering of coating, caused by emitted pyrolysis gases, is often observed. To avoid blistering of coating, the adhesion between polyolefin substrate and fire retardant coating has to be extraordinarily high.
In order to achieve such a high level of adhesion, the polymer surface has to be modified with adhesion-promoting functional groups. The deposition of thin plasma polymers as adhesion-promoting layers with NH2, OH or COOH groups has been the most suited method. These functional groups are able to form covalent bonds and other interactions between the fire-resistant coating and the plasma-modified polyolefin substrate. Additionally, the plasma polymer counteracts the strong mechanical stresses in the laminate on exposure to high temperatures by its flexibility.
Until the end of the 1980s many wooden artworks underwent surface treatment by liquid preservatives, e.g. Hylotox-59. DDT (dichlorodiphenyltrichloroethane) crystal structures are formed on the wooden surfaces by the "blooming" of chlorine compounds by time. In addition to an aesthetic disturbance, it is assumed that DDT represents a health risk. Therefore, the removal of DDT crystals from the surfaces is requested. Contaminated wood with natural biocide ageing, gilded and wood carved elements and wooden samples with paint layers were provided by the Schlossmuseum Sondershausen, Germany. Laser cleaning on selected surface areas on the objects was done by means of femtosecond and nanosecond laser pulses. For the same object, cleaning results using 30-fs laser pulses at 800 nm wavelength are compared to findings utilizing 10-ns laser pulses at 1064 nm wavelength. Before and after laser treatment, chlorine measurements at the same surface position were done by X-ray fluorescence analysis (XRF) as an indicator for the presence of DDT. In this way, pointwise chlorine depletion rates can be obtained for the different pulse duration regimes and wavelengths. Additionally, the object surfaces were examined using optical microscopy and multi spectral imaging analysis.
We analysed the hydrogen generation during the smouldering of polymeric materials, which are typically used in the household, in the Smoke Density Chamber coupled to a new developed hydrogen sensor to detect early stages of fires. The results of hydrogen generation were compared with the emission of carbon monoxide and smoke during the fire scenarios. Additionally, the results were compared with parameters used in traditional commercial detection systems. In this scenario, the hydrogen sensor showed encouraging results for the detection of fires in earlier phase compared to traditional detectors. Furthermore, we tested the new developed hydrogen sensor in a real room with different fire scenarios. We have also investigated interferences, e.g. steam and cigarette smoke. The hydrogen sensor could detect hydrogen generation in the earliest stage of fire, even before CO and smoke were developed in detectable amounts. Therefore, the hydrogen sensor can be applied for early fire detection in case of pyrolysis. The sensors are quite good for detecting pyrolysis gases. But when it comes to a fast ignition other techniques are more suitable for it. The sensors are best for combination with other techniques, such as smoke detectors.
The passive fire protection of steel structures and other load-bearing components will continue to gain importance in future years. In the present contribution, novel intumescent aluminosilicate (geopolymer-bound) composites are proposed as fire-protective coatings on steel. Steel plates coated with these materials were exposed to the standard temperature-time curve as defined in ISO 834 – 1:1999. The coatings partially foamed during curing and expanded further during thermal exposure, demonstrating their intumescent characteristic.Thermogravimetryandoscillatory rheometry determined that the intumescent behavior is attributed to a transition to a viscous state (loss factor > 1) in the temperature range of major water release, differing from conventional geopolymers. XRD and SEM images showed that the coatings had characteristics of ceramic or glass-ceramic foams after fire resistance testing, suggesting superior performance under challenging conditions. The thickness of the coatings influenced their foaming and intumescent behavior and thus the time for the coated steel plates to reach 500 °C. A number of additives were also studied with the best performance obtained from samples containing sodium tetraborate.Acoating of just 6mmwas able to delay the time it takes for a steel substrate to reach 500 °C to more than 30 minutes.