A. Brendel

Influence of Different Deposition Parameters on the Performance of a Ti-Ta-C Interface Layer in SiC-Fiber Reinforced Copper Matrix Composites

The mechanical properties of a SiC-fiber/copper matrix composite, reinforced with SCS-0 SiC-fibers ( 140µm, Specialty Materials), can significantly be increased by applying a Ti-Ta-C multilayer between fiber and matrix. This interlayer is deposited with a magnetron sputter device directly on the single fibers. By changing the deposition parameters of this sputter process the Ti-Ta-C interlayer can be optimized regarding fiber strength and fiber/matrix adhesion. Experiments with different deposition pressures, bias voltages and layer thickness’ were performed to increase the bond strength and the ultimate tensile strength when compared to the Ti-Ta-C reference sample.

Synthesis and analysis of the thermal behavior of SiC-fibre reinforced copper matrix composites as heat sink material

Copper matrix composites reinforced with silicon carbide fibres (SiCf/Cu) are considered as heat sink materials for the divertor of DEMO as they combine high thermal conductivity and good mechanical strength at high temperature. A new method was developed to synthesise a metal matrix composite (MMC) consisting of about 3-6 unidirectional reinforced layers (UD-layers). The UD-layers were prepared by two subsequent electroplating processes which allow to adjust various fibre volume fractions. These single UD layers were stacked with different relative fibre orientations (0°/0° and 0°/90°) and consolidated by vacuum hot pressing to form the MMC specimen. The thermal conductivity perpendicular to fibre direction was obtained by laser flash apparatus (LFA) measurements. It is about 310 Wm-1K-1 for electroplated copper (Cu) and above 200 Wm-1K-1 for MMC specimens with a fibre volume fraction of 8-13%. Due to the manufacturing process, boundaries within the matrix were found resulting in a reduction of the values. In addition, DSC (differential scanning calorimetry) measurements were performed which gave similar results.

3D Characterization of Thermal Fatigue Damage in Monofilament Reinforced Copper for Heat Sink Applications in Fusion Reactor Systems

Abstract Monofilament reinforced metals (MFRM) are developed as high temperature heat sink materials for fusion reactor applications. These composites combine the high thermal conductivity (TC) of a Cu matrix with low thermal expansion (CTE) of SiC or W filaments. The CTE mismatch between matrix and reinforcement lead to high micro stresses under operation conditions. Stress induced thermal fatigue damage such as interface delamination and fiber/matrix damage degrades the thermal properties of these composites. Different interface designs are developed for SiC as well as W filaments to improve bonding strength and increase the long term stability. Conventional as well as synchrotron tomography was applied on different MFRMs to characterize thermal fatigue damage and its propagation before, during and after thermal cycling.