TY - BOOK

T1 - Additive manufacturing of thermal management-relevant hybrid structures

AU - Wallis, Christopher

N1 - no embargo

PY - 2019

Y1 - 2019

N2 - 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.

AB - 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.

KW - Additive manufacturing

KW - Laser-powder bed fusion

KW - Hybridstrukturen

KW - Wärmemanagement

KW - Maraging Stahl

KW - Kupfer-Legierung

KW - Aluminium-Legierung

KW - Metal-Keramiken

KW - Wärmebehandlungen

KW - Mikrostruktur

KW - thermische Eigenschaften

KW - mechanische Eigenschaften

KW - Additive manufacturing

KW - Laser-powder bed fusion

KW - hybrid structures

KW - thermal managment

KW - maraging steel

KW - copper alloy

KW - aluminium alloy

KW - metal-ceramic

KW - heat treatments

KW - microstructure

KW - thermal properties

KW - mechanical properties

M3 - Doctoral Thesis

ER -