Abstract
The sessile drop method combined with contact heating procedure was applied for the investigation of high-temperature interaction between liquid Gd and Y2O3 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 Y2O3 substrate (the contact angle θ < 90°) immediately after melting of metal sample observed at T = 1324 °C (Tm = 1312 °C). During the first 3 min of the sessile drop test, the contact angle dropped from θ = 52° to θ = 24° and then stabilized at the final value of θf* = 33°. The solidified Gd/Y2O3 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/Y2O3 system has a reactive nature and the leading mechanism of the interaction between liquid Gd and Y2O3 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 θf*, estimated from the side-view drop image, should be considered as an apparent value, compared to the more reliable value of θf = 70° measured on the cross section of the solidified couple.
Highlights
The development of metallic materials technology, especially alloys with highly reactive components, is inextricably linked to the search for new, refractory ceramic materials for crucible-assisted melting and casting processes
The sessile drop method was applied for investigation of high-temperature wetting behavior and reactivity between liquid Gd and Y2O3 substrate using an experimental set up described in details in Ref 11
Since the needle-like precipitates in the 2PL area are rich in Y and they contain Gd and O we suggest that they present Y2O3-based phase, designated as (Y,Gd)2O3 and formed after wetting tests during cooling of the Gd(Y,O) melt saturated with Y and O at high temperature
Summary
The development of metallic materials technology, especially alloys with highly reactive components, is inextricably linked to the search for new, refractory ceramic materials for crucible-assisted melting and casting processes. Such ceramics must be characterized by a set of features, e.g., good mechanical strength, high erosion and corrosion resistance to molten metals, and low levels of impurities, which could significantly affect the metal properties upon entering into the melt. This article is an invited submission to JMEP selected from presentations at the 73rd World Foundry Congress and has been expanded from the original presentation. The characteristic feature of containerassisted methods is a relatively long time of contact of the melt with the container material
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