Highly heat conductive open-porous aluminium fibre based parts for advanced heat transfer applications

Due to their oxygen affinity, aluminium alloys are difficult-to-sinter materials. Either mechanical destruction or the action of a liquid phase can be used to break oxide layers and thus achieve the desired diffusion bonds between the individual particles. In the present work, a liquid phase sintering approach is used in conjunction with high-purity particulates and controlled processing conditions in order to obtain high-purity, high-porosity (up to 90 %) parts with an exclusively open porosity. Appropriate sinter conditions were determined with the help of thermodynamic calculations using the PANDAT software package. Bonding of the sintered fibre structures to tubes, sheets and other massive structures may be achieved by co-sintering or brazing. The resulting metallic contacts allow for excellent heat transfer between the fibre structure and heat-carrying fluids. These advantageous properties may be exploited in applications such as adsorption cooling devices or very fast phase-change material (PCM) heat-storage devices. The present study reports on the manufacturing of such PCM-aluminium fibre compounds and their performance measured on a PCM storage demonstrator run in a laboratory environment.