Konferenzbeiträge

Friction stir welding is a solid-state joining process with a wide range of industrial applications in the e-mobility, automotive, aerospace and energy industries. However, friction stir welding is subjected to process-specific challenges, including comparatively high process forces and friction stir welding tool wear resulting from tribological interaction between the tool and workpiece. The geometric-related friction stir welding tool wear can cause varying material flow conditions, lateral path deviations and premature tool failure, with detrimental economic and technological consequences. This study systematically analyses the wear behaviour of friction stir welding tools as a function of tool hardness. To compare and differentiate the geometric-related tool wear as a function of tool hardness, experiments were carried out with a hardness of 240 HV, 410 HV and 580 HV. Whereas 240 HV is non-hardened, 410 HV is 50% of the secondary hardness maximum and 580 HV is the secondary hardness maximum of the tools made of H13 tool steel (hot-working steel, X40CrMoV5-1). During the experimental tests, the shoulder and probe exhibited varying wear and geometrical deviations. The investigations were carried out with a force-controlled robotized welding setup in which AA-6060 T66 sheets with a thickness of 8 mm were joined by weld seams up to a total length of 80 m.

The paper presents a single-channel gate driver IC with galvanic isolation that uses embedded coreless transformer technology. The IC is suitable for driving and monitoring Si-IGBTs or SiC-MOSFETs up to 1700 V and gate currents of ±3 Apeak directly. For higher gate currents, external post-amplifiers can be used. A 0.35 µm mixed-signal CMOS technology was extended by using a very thick isolation layer process to form high-voltage coreless transformers or capacitors between different metallization layers to get an impulse withstand voltage capability of > 10 kV.

Quantum technologies have matured in a way that real applications are considered to be viable. The new quality emerges from the use of explicit quantum phenomena in single objects as qubits for computation, or photons for sensing and communication. However, to make these features exploitable, suitable microelectronic components for controlling and readout of the quantum states have to be available. For this, superconductive solid-state electronic circuits are considered to be promising candidates. First demonstrations for suitability are known. In order to provide scaling towards large-scale integrated structures, appropriate design methods and capabilities have to be developed. We provide an assessment of the current state of design automation for such superconducting digital electronic structures and survey existing approaches and tools.

Friction brakes are one of the main sources of PM emissions from cars today. However, due to the electrification of the powertrain, the share of friction brakes in vehicle deceleration is continuously decreasing. Due to the reduced number of braking applications and the lower brake pressure level, the amount of emitted particles also decreases. This is associated with the disadvantage of an increased potential for the formation of rust on the surfaces of the friction materials, which is expected to influence friction and wear. Due to the increasing challenge posed by corroded friction partners, drum brakes are increasingly used to decelerate bat-tery electric (EV) and hybrid electric vehicles (HEV). In this study, basic investigations on the particle emission behaviour of drum brakes are carried out using an inertia dynamometer (LINK 3900-NVH). To en-sure representative sampling, a constant-volume sampling system is used, which is optimised in terms of transport efficiency and particle distribution. Condensa-tion particle counters (CPC) and filter holders (TX40) are used to determine PN/PM emission factors. CPCs with differently calibrated cut-off are used to evaluate the formation of nanoscale particle formations. In this context, special at-tention is paid to the influence of temperature on the particle formation process. From the comparison between rear-axle disc brake and rear-axle drum brake it could be proven that the predominant part of the wear mass remains within the drum, which affects the size distribution of the emitted particles. The ratio be-tween PM10 and PM2.5 mass-related emissions factors decreases from about 2 (disc brake) to about 1.3 (drum brake). In addition, the emission behaviour is dif-ferentiated via the bedding procedure of the drum brake. To achieve a reproduci-ble emission level, a doubling of the number of cycles (WLTP-brake cycle) is necessary. Due to a higher temperature level, nanoparticles could be detected dur-ing testing of the drum brake, whereby the number-related emission factor (PM2.5) was partly higher than for the disc brake.

A LTCC patch antenna array was designed and fabricated in Low Temperature Co-fired Ceramic (LTCC) multilayer technology using picosecond laser structuring for precise manufacturing of embedded air cavities and feeding structures, which are beneficial for the antenna RF performance. Moreover, free-standing feeding vias in the embedded air cavities were successfully implemented in LTCC technology that enable a very simple and low-loss feed at the antenna ports. The 2x2 dual-polarized patch antenna array with embedded air cavities and transitions was first characterized by reflection measurements. The measured center frequency of the antenna is about 29.5 GHz and a bandwidth of nearly 1 GHz was achieved.