Filters

2019 - 20202

More filters

20232
Reset filters

Settings

Author: Pötschke, Petra × Author: Rzeczkowski, P. × DDC: 530 × WGL Institute: IPF ×

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Development of joining methods for highly filled Graphite/PP composite based bipolar plates for fuel cells: Adhesive joining and welding
    (Melville, NY : AIP, 2019) Rzeczkowski, P.; Lucia, M.; Müller, A.; Facklam, M.; Cohnen, A.; Schäfer, P.; Hopmann, C.; Hickmann, T.; Pötschke, Petra; Krause, Beate
    Novel material solutions for bipolar plates in fuel cells require adapted ways of joining and sealing technologies. Safe and life time enduring leak-tight contacts must be achieved by automatic processes using reasonable joint forces. A proper sealing should manage such challenges as good ageing properties, excellent leaktightness, high thermal conductivity and low gas permeability. Hence in this work, adhesive bonding and welding are considered as suitable methods, which can fulfill the requirements mentioned above. Adhesive systems seem to be more easy to apply than conventional sealing (hand layed-up rubber gaskets), e.g. with automatic dispensers. Additionally, the properties of an adhesive joint can be enhanced by a process-specific surface pre-treatment. This work focuses on the characterization of adhesive systems and their joints with highly filled graphite composites. Mechanical properties of the joints were characterized through lap-shear tests. The influence of ageing caused by humidity or acidic solvent at increased temperature on the bond line properties as well as neat adhesive was examined. The thermal conductivities of neat adhesives and through the entire joint were examined. In order to improve above conductivities, roughening, substrate pre-heating, post-curing and various contact pressure weights were applied. Plasma treatment was chosen as surface pre-treatment method for improving substrate's surface energy. An alternative to bonding is plastic welding, which does not require the use of sealants and adhesives. Based on former study of influences of filler content on the welding process using ultrasonic, hot plate or infrared welding, a welding method for joining the graphite compounds was derived.
  • Thumbnail Image
    Item
    Graphite modified epoxy-based adhesive for joining of aluminium and PP/graphite composites
    (New York, NY [u.a.] : Taylor & Francis, 2020) Rzeczkowski, P.; Pötschke, Petra; Fischer, M.; Kühnert, I.; Krause, Beate
    A graphite-modified adhesive was developed in order to simultaneously enhance the thermal conductivity and the strength of an adhesive joint. The thermal conductivity through the joint was investigated by using highly filled PP/graphite composite substrates, which were joined with an epoxy adhesive of different layer thicknesses. Similar measurements were carried out with a constant adhesive layer thickness, whilst applying an epoxy adhesive modified with expanded graphite (EG) (6, 10, and 20 wt%). By reducing the adhesive layer thickness or modifying the adhesive with conductive fillers, a significant increase of the thermal conductivity through the joint was achieved. The examination of the mechanical properties of the modified adhesives was carried out by tensile tests (adhesive only), lap-shear tests, and fracture energy tests (mode 1) with aluminium substrates. Modification of the adhesive with EG led to an increase of the tensile lap-shear strength and the adhesive fracture energy (mode 1) of the joint. In addition, burst pressure tests were performed to determine the strength of the joint in a complex component. The strength of the joint increased with the graphite content in the PP substrate and in the epoxy adhesive.