Despite pronounced research on hard carbon (HC) anode materials for sodium‐ion batteries (SIB), particularly the impact of particle morphology on electrode microstructure poses open questions regarding ionic as well as electrical transport or sodium metal plating. This study systematically compares two hard carbons, one representing a nonspherical particle morphology (HC‐Ref) and the other representing a spherical particle morphology (HC‐Sph‐10:90). Industrially relevant loadings were investigated across powder, electrode, half‐cell, and full‐cell configurations. The analysis of powder and electrode microstructure revealed that spherical particles exhibited superior packing efficiency, leading to higher electrode densities, whereas nonspherical particles retained electrode porosity upon calendaring, thereby enhancing ionic transport. The formation of multipoint contacts was identified to enhance conductive pathways. The electrochemical characterization revealed a clear trade‐off between the dense packing and transport capability of the anode. This trade‐off translated into three‐electrode full cells, where morphology‐related polarization affected the potential‐defined onset of sodium metal plating. Sodium metal plating is therefore governed by operating conditions like current density and voltage window, while the electrode structure determines the underlying transport limitations and thus the plating susceptibility. Consequently, electrode microstructure is presented as a critical design parameter, together with design guidelines for the optimization of hard carbon anodes for high‐energy and plating‐resistant SIBs.
Fe3Al powders reinforced with TiC were synthesized and deposited as coatings using Cold Gas Spraying (CGS) and High-Velocity Oxy-Fuel (HVOF) techniques. Fe3Al intermetallic compounds are known for their excellent resistance to sulfidizing and carburizing environments. However, their mechanical properties can be enhanced through reinforcement with TiC particles. The Fe3Al/TiC feedstock powder was produced via agglomeration and sintering, resulting in a homogeneous distribution of TiC particles around the Fe3Al matrix. Coatings were deposited onto AISI 316L stainless steel substrates and characterized using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDX), as well as adhesion and erosion tests. The results indicate that CGS coatings exhibit lower oxidation levels, whereas HVOF coatings demonstrate superior adhesion and hardness due to their denser microstructure and greater particle deformation. Hardness increased with the incorporation of TiC. Erosion testing revealed that CGS coatings performed better, attributed to their reduced brittleness compared to HVOF coatings. These findings highlight the potential of Fe3Al/TiC coatings for high-temperature and wear-resistant applications. Moreover, the study demonstrates that comparable performance can be achieved using CGS as with HVOF for depositing Fe3Al/TiC intermetallic coatings.
Structural components of aircraft fuselages, such as frames and stringers, are predominantly manufactured from milled high-strength aluminum profiles. In the milling process of frame structures, particularly at in the area around emergency exit doors, approximately 98% of the raw material is removed. This results in high material and production costs, along with significant energy consumption and a poor CO₂ footprint. Despite these drawbacks, milling remains the standard manufacturing method, as the high-strength aluminum alloys commonly used (e.g. EN AW-7075 T651) are prone to hot cracking and therefore not suitable for conventional welding.This study presents and evaluates weldable fuselage stiffening structures designed to reduce material usage and component mass (with weight savings of up to 4%), while enhancing mechanical performance (achieving stiffness increases of up to 11%) compared to conventionally milled components. Weldability is achieved through structurally optimized joint geometries, tailored friction stir welding (FSW) processes and specialized clamping devices. Additionally, innovative laser welding techniques employing dynamic beam shaping (DBS) are introduced. The proposed solutions for frames and stringers are based on single-sheet designs with load-adapted thickness distributions and weld configurations. Friction Stir Additive Manufacturing (FSAM) is employed to integrate fuselage doublers into highly stressed areas.This work opens new perspectives for resource-efficient structural concepts and represents a key step toward weldable fuselage architectures. Initial prototype simulation and testing have demonstrated promising structural integrity. The proposed solutions offer strong potential for scalable and sustainable production in aerospace as well as the automotive and energy sectors.
In machining deformation-sensitive components, clamping force-related impairments can affect component quality. The reduction of clamping forces to prevent deformation often limits parameters, productivity, and may lead to workpiece detachment. This study addresses these challenges by enhancing friction forces through tailored surface modifications, incorporating specifically designed structures and diamond-like carbon (DLC) coatings on clamping elements. The modified surface topographies were analyzed, and a sensor-integrated clamping device was employed to assess the clamping potential. Retention forces were investigated by varying clamping forces and subjecting workpieces to impulse-like excitation. The results demonstrate the potential for increasing clamping performance, validated for difficult-to-clamp components.
Laser welding of transmission components is well established in automotive engineering, but in aviation, shaft-gear connections are mainly manufactured using monolithic methods. The aim of the development work was to establish new material concepts and manufacturing technologies for highly stressed components for flight control gearboxes. The new approach bases on a material combination of tempered steel for the gear wheels and corrosion-resistant, high-strength steel for shafts in the outer area. The solution was developed using a customized laser welding technology. In the first step, the design and test concept for welded shaft-gear connections were developed, the weldability of relevant steels and dissimilar joints was verified, and fatigue behavior were determined. The second step focused on sintered gears for specific functional integration, verified their laser weldability, and characterized the joint properties as a function of sintering quality. The article presents the work on laser-based joining of relevant material combinations, the process- and load-oriented design of test specimens, and a simulation-based test concept for evaluating joint quality and fatigue behavior. Specific welding parameters were established for martensitic corrosion-resistant steel, tempered and cold-worked steels. In addition, fatigue load limits for tension and multiaxial loads were identified.
