Phillipp Schultheiß
Materialwissenschaften M.Sc.
Nanotechnologie B.Sc.
Publikationen
Paper
Huber, L., Schultheiß, P., Thiele, M., Rößler, C., Höppel, H. W.
Impact of Various Rotary Friction Welding Process Parameters on the Mechanical Properties of a Steel–Aluminum Joint
First published: 10 June 2025 | https://doi.org/10.1002/adem.202500842
Abstract:
Lightweight materials offer a great potential for reducing CO₂ emissions by enhancing energy efficiency. However, not all components can easily be replaced by lighter alternatives, but hybrid materials made from steels and aluminum alloys offer a viable solution to using lightweight materials on the one hand and withstanding high mechanical stresses on the other. Rotary friction welding is a promising method for fabricating such hybrids, as it enables joining without achieving the components’ melting points.
The latter is particularly crucial for steel–aluminum joints due to their very different mechanical and physical properties where brittle intermetallic phases (IMP) are formed. A minimal thickness of IMPs is essential for achieving a high strength of the joints between steel E355 and EN AW-6082, but by exceeding a phase width of 0.4 μm the mechanical properties drop. Alloying elements, such as silicon and manganese, also impact the mechanical behavior of the joint. Silicon diffuses rapidly and has limited solubility in iron-aluminides IMPs, creating the hexagonal α-phase. In contrast, manganese diffuses slower and transforms hexagonal to cubic IMPs. Best result of Rm = 248 MPa with a joint quality of 65 % is achieved at higher rotational speeds with low welding times.
Vorträge
Schultheiß, P., Hücking, J.-O., Dörflinger, P., Riedl, H., Felfer, P.
ZrC und ZrN Wasserstoffpermeationsbarriereschichten hergestellt durch Hochleistungsimpuls-Magnetronsputtern
Vortrag im Rahmen der DGM-Arbeitskreissitzung Materialprüfung unter Wasserstoffeinfluss, November 2024
Abstract:
Wasserstoffpermeationsbarrieren (HPB) in Form von Beschichtungen stellen einen vielversprechenden Ansatz zur Minimierung der Wasserstoffversprödung in Stählen dar. Keramische Beschichtungen sind für diesen Anwendungsfall besonders interessant, da sie eine geringe Wasserstoffpermeabilität aufweisen. Allerdings weisen konventionelle Beschichtungen wie TiC, TiN und Al₂O₃ erhebliche Einschränkungen für ihren Einsatz als HPB-Materialien auf. In dieser Studie wurden dichte ZrN- und ZrC-Beschichtungen mittels Hochleistungsimpuls-Magnetronsputtern (HiPIMS) auf 42CrMo4 (1.7225) Stahlsubstraten abgeschieden. Die Qualität der Schichten sowie ihr Potenzial als effektive HPB-Materialien werden untersucht.
Studienarbeiten an der FAU Erlangen-Nürnberg
Materialwissenschaften und Werkstofftechnik
ZrC and ZrN hydrogen permeation barrier coatings produced via high-power impulse magnetron sputtering
Abstract:
Hydrogen permeation barrier (HPB) coatings provide a promising solution to mitigate hydrogen embrittlement in steels. Ceramic coatings are particularly suited for this application due to their inherently low hydrogen permeability. However, conventional ceramic coatings such as TiC, TiN, and Al₂O₃ often exhibit significant limitations as HPB materials. In this study, uniform and under-stoichiometric ZrN and ZrC coatings were deposited on 42CrMo4 (1.7225) steel substrates using the high-power impulse magnetron sputtering (HiPIMS) technique. To evaluate their HPB potential, a self-developed Zr interlayer method was employed, enabling rapid and cost-effective assessment of hydrogen permeation behavior.
The deposition parameters used in this study were unsuitable for producing low-defect ZrC coatings, limiting their HPB applicability. In contrast, bilayer Zr + ZrN coatings deposited with a bias voltage of –85 V demonstrated the highest potential for HPB applications. Mechanical properties were evaluated using nanoindentation, revealing that bias voltage had no significant effect on the hardness of ZrN films. Furthermore, electrochemical hydrogen charging for 4 hours at room temperature did not induce detectable hydrogen-related hardness changes in the ceramic thin films, suggesting that these conditions are insufficient to trigger hydrogen effects.
Hydrogen Embrittlement in Steels
Abstract:
As global demand for renewable and carbon-free energy increases, questions regarding the reusability of existing infrastructure and widely used materials, such as steel, become more critical. A major technical challenge in the transition from a carbon-based to a hydrogen-based economy is the issue of hydrogen embrittlement, particularly in steels. Conventional hydrogen trapping methods, commonly used in oil and gas pipelines, are unsuitable for long-term application in hydrogen-rich environments, as trapping efficiency decreases over time due to trap saturation. Consequently, there is growing interest in strategies to minimize hydrogen ingress into the base material.
This work provides an overview of this issue, with a specific focus on permeation barriers. Current research primarily investigates conventional barrier systems, including nitrides, oxides, and carbides, which are deposited onto the steel substrate. These systems leverage well-established deposition techniques and known material properties. Further advancements in barrier performance can be achieved through nanostructuring, such as multilayering and the use of nano-sized grains. Recent studies on multilayered graphene and graphene oxide have opened new possibilities for creating highly effective permeation barriers.
Nanotechnologie
Characterisation of ADA-GEL based composite bioinks
Abstract:
Biofabrication is a promising field for tissue (and organ) engineering, because it enables processing materials, cells and biological molecules in one step. Hydrogels are widely used for biofabrication because they provide cell friendly process parameters as well as they are similar to the extracellular matrix. In this research, alginate dialdehyde combined with gelatin and bioactive fillers (ADA-GEL-BIF) are used as hydrogel system. This composite system provides cell adhesion and a gentle and rapid crosslinking in the presence of divalent cations.
In this Bachelor thesis different composite hydrogel compositions will be evaluated. The bioinks will be dissolved either in DPBS or in DMEM and the long-term stability in terms of shape, mechanical properties or release of specific proteins and ions will be evaluated. Furthermore, the ratio of ADA and gelatin will be varied and the obtained hydrogels will be crosslinked ionically and enzymatically, respectively.
This research aims to gain a deeper insight in the influence of the dissolution medium on important parameters for biofabrication, like cell viability and the mechanical properties of composite hydrogel scaffolds over time. In addition, an optimized composition of the composite bioink for soft tissue engineering will be determined.
Link zum Abstract auf der Website des FAU Lehrstuhls für Biomateralien
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