High-Temperature Interaction of Liquid Gd with Y2O3

Abstract

The sessile drop method combined with contact heating procedure was applied for the investigation of hightemperature interaction between liquid Gd and Y 2 O 3 substrate. Real-time behavior of Gd sample in flowing inert gas (Ar) atmosphere upon heating to and at temperature of 1362°C was recorded using high-speed high-resolution CCD camera. The results evidenced that molten Gd wets Y 2 O 3 substrate (the contact angle h < 90°) immediately after melting of metal sample observed at T = 1324°C (T m = 1312°C). During the first 3 min of the sessile drop test, the contact angle dropped from h = 52°to h = 24°and then stabilized at the final value of h f * = 33°. The solidified Gd/Y 2 O 3 couple was subjected to structural characterization using optical microscopy, scanning electron microscopy coupled with x-ray energy-dispersive spectroscopy. The results evidenced that the wettability in the Gd/Y 2 O 3 system has a reactive nature and the leading mechanism of the interaction between liquid Gd and Y 2 O 3 is the dissolution of the ceramic in the liquid metal responsible for the formation of a deep crater in the substrate under the drop. Therefore, the final contact angle h f *, estimated from the side-view drop image, should be considered as an apparent value, compared to the more reliable value of h f = 70°measured on the cross section of the solidified couple.