Additive manufacturing of thermal management-relevant hybrid structures

Research output: ThesisDoctoral ThesisResearch

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Abstract

The potential of metal additive manufacturing for producing high conductive materials and hybrid systems for thermal management in opto-, power and microelectronics has been investigated. Using the laser-based powder-bed fusion technology (L-PBF), joining and bonding of metals and metal-ceramics have been studied with a focus on the fusion zone and the interlayer, respectively. In the course of this thesis the bonding characteristics of steel/copper and AlN/Al-alloy have been assessed. Owing to residual stress evolution during L-PBF, process-induced material damage such as cracking at the binding zone was investigated and compared to residual stress simulations by which a correlation between process parameters, part geometry and the material failure could be established. A further focus in this work was placed on additive manufacturing of the thermally high conductive Cu-alloy CuCrZr. The influence of process parameters on part properties and surface quality was determined. The heat dissipation properties of conventional and additively manufactured parts were assessed and compared. For this a use case study part with microchannels was produced, whose properties were assessed by thermographic inspection, following a computational fluid dynamics simulation. Furthermore it was demonstrated that L-PBF parts feature a unique thermal history during the layer-by-layer manufacturing process, which is why CuCrZr samples in as-built state are characterized by a microstructure in non-equilibrium. In this state subsequent aging heat treatments were performed to improve material properties. In contrast to conventional manufactured Cu-alloys, a single aging process on laser-fused CuCrZr with adjusted heat treatment parameters is capable of reaching enhanced mechanical as well as thermal properties. The influence of different heat treatments on microstructure and material properties has been investigated and assessed, using SEM- and XRD-analysis.

Details

Translated title of the contributionAdditive Fertigung von Wärmemanagement-relevanten Hybridstrukturen
Original languageEnglish
QualificationDr.mont.
Awarding Institution
Supervisors/Advisors
Publication statusPublished - 2019