Wettability, reactivity and interfaces in the Gd/TiO2 system

High-temperature interaction of liquid Gd in contact with dense, polycrystalline TiO₂ substrate, was investigated. Wettability and reactivity tests were carried out at two different temperatures (1362°C and 1412°C) in flowing gas (Ar, 850-900 hPa) using the sessile drop method and classical contact heating of the examined couple of materials. The procedure was combined with a drop pushing procedure. During high temperature studies, images of the Gd/TiO₂ couple were continuously recorded by a high-resolution CCD camera. The results of wettability tests of liquid gadolinium on titanium dioxide substrate show that the Gd/TiO₂ system is non-wettable at both test temperatures (in either case the final contact angle was 100°). The results of structure examinations on the cross-sectioned samples show the dissolution of the TiO₂ substrate in liquid Gd and the presence of two sublayers at the drop/substrate interface: Gd₂TiO₅ (from the drop side) and Gd₂Ti₂O₇ (from the substrate side).

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