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- ItemWettability and reactivity of ZrB2 substrates with liquid Al(Heidelberg : Springer, 2016) Nowak, R.; Sobczak, N.; Bruzda, G.; Wojewoda-Budka, J.; Litynska-Dobrzynska, L.; Homa, M.; Kaban, I.; Xi, L.; Jaworska, L.Wetting characteristics of the Al/ZrB2 system were experimentally determined by the sessile drop method with application of separate heating of the ZrB2 and Al samples and combined with in situ cleaning of Al drop from native oxide film directly in vacuum chamber. The tests were performed in ultrahigh vacuum of 10−6 mbar at temperatures 710, 800, and 900 °C as well as in flowing inert gas (Ar) atmosphere at 1400 °C. The results evidenced that liquid Al does not wet ZrB2 substrate at 710 and 800 °C, forming high contact angles (θ) of 128° and 120°, respectively. At 900 °C, wetting phenomenon (θ < 90°) occurs in 29th minute and the contact angle decreases monotonically to the final value of 80°. At 1400 °C, wetting takes place immediately after drop deposition with a fast decrease in the contact angle to 76°. The solidified Al/ZrB2 couples were studied by scanning and transmission electron microscopy coupled with x-ray energy diffraction spectroscopy. Structural characterization revealed that only in the Al/ZrB2 couple produced at the highest temperature of 1400 °C new phases (Al3Zr, AlB2 and α-Al2O3) were formed.
- ItemHigh-Temperature Interaction of Liquid Gd with Y2O3(New York, NY : Springer, 2019) Turalska, P.; Sobczak, N.; Bruzda, G.; Kaban, I.; Mattern, N.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. © 2019, The Author(s).