The wetting behaviour and interfacial interactions between liquid Al and TiB 2 ceramic have been studied by the sessile drop technique in the temperature range from 700 to 1400°C. At about 800°C, liquid Al starts to wet TiB 2 and at about 1000°C it completely spreads over the ceramic. Al 3 Ti and Al 2 O 3 are found to be the main phases precipitating at the interface. Starting from 1000°C, liquid Al either fill pores or penetrates along the grain boundaries of the TiB 2 ceramic. Scanning electron microscopy analysis of the interfaces evidences that the TiB 2 grains remain intact after the aluminium melt/ceramic interaction even at 1400°C.

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During the test, no spallation of the external oxide scale was observed. The kinetic data showed that only the 263 alloy oxidized according to parabolic behaviour, whereas the other alloys deviated from the parabolic rate law, with time exponents of 0.4-0.6 or 0.3. Finally, cross-sectioned investigations of the exposed samples revealed that Ni-based alloys underwent extended internal oxidation, with the highest extent in HAYNES Ò 282 Ò reaching 25 lm and the lowest in HAYNES

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For a successful implementation of newly proposed silicon-based latent heat thermal energy storage systems, proper ceramic materials that could withstand a contact heating with molten silicon at temperatures much higher than its melting point need to be developed. In this regard, a non-wetting behavior and low reactivity are the main criteria determining the applicability of ceramic as a potential crucible material for long-term ultrahigh temperature contact with molten silicon. In this work, the wetting of hexagonal boron nitride (h-BN) by molten silicon was examined for the first time at temperatures up to 1750°C. For this purpose, the sessile drop technique combined with contact heating procedure under static argon was used. The reactivity in Si/h-BN system under proposed conditions was evaluated by SEM/EDS examinations of the solidified couple. It was demonstrated that increase in temperature improves wetting, and consequently, non-wetting-to-wetting transition takes place at around 1650°C. The contact angle of 90°± 5°is maintained at temperatures up to 1750°C. The results of structural characterization supported by a thermodynamic modeling indicate that the wetting behavior of the Si/h-BN couple during heating to and cooling from ultrahigh temperature of 1750°C is mainly controlled by the substrate dissolution/reprecipitation mechanism.