Wetting and interfacial phenomena in Ni-Cr-Hf/sapphire systems

Valenza, Fabrizio; Sobczak, N.; Sobczak, J.; Nowak, R.; Muolo, Maria Luigia; Passerone, A.; Sitzia, Saverio; Cacciamani, G.

doi:10.1016/j.jeurceramsoc.2019.10.007

Cited by 5 publications

(2 citation statements)

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“…The contact angle of pure Ni on sapphire substrates was measured to be 113°in accordance with the available literature [4,24,25], while additions of 1 at% of Al into Ni led the contact angle to slightly decrease. This effect was not observed for NiAl10 (h = 112°).…”

Section: Ni-al Alloys On Sapphiresupporting

confidence: 83%

“…This means that the cleaning effect due to the evaporation of Al 2 O and its kinetics are enhanced by the increase in Al concentration in the melt. For the NiAl1 alloy, the amount of Al is too low to have an oxide film covering the drop: this resulted in an improved wetting compared with pure Ni by virtue of the adsorption of Al at the metal/ceramic interface which causes the decrease in the liquid/solid interfacial energy [5,24]. The higher Al concentration in the NiAl10 alloy led to an increased oxidation of the drops while the very low value of P Al2O is insufficient for a complete and fast cleaning of the drop; this resulted in higher contact angles.…”

Section: Ni-al Alloys On Zirconiamentioning

confidence: 99%

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Wetting and interfacial reactivity of Ni–Al alloys with Al2O3 and ZrO2 ceramics

et al. 2021

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The isothermal wetting, spreading behaviour and interfacial reactivity of NiAl1, NiAl10 and NiAl25 alloys (1, 10, 25 at% Al, respectively) on monocrystalline alumina (sapphire) and polycrystalline zirconia oxides stabilized with MgO (stoichiometric and non-stoichiometric ones) were studied by means of the sessile drop method at 1500°C in vacuum. A detailed characterization of solidified couples was performed in order to analyse the final interfacial microstructure and microchemistry. The results were discussed in terms of chemical interactions and by means of ad-hoc calculated phase diagrams. The final contact angles varied with the content of Al leading to a slight wetting situation (contact angle h \ 90°), for the NiAl25 alloy on both sapphire and zirconia. The contact of liquid Ni-Al alloys on sapphire was not accompanied by interfacial chemical reaction. The wetting of pure Ni and NiAl1 alloy was found to be worse for fully stoichiometric ZrO 2 compared with under-stoichiometric ZrO 2-x by virtue of the increased metallicity of the latter. On the other hand, the formation of interfacial a-Al 2 O 3 for the NiAl10 and NiAl25 alloys on ZrO 2 , as foreseen by thermodynamic modelling and experimentally confirmed by transmission electron microscopy characterization, determined the kinetics of wetting and the final contact angle whatever the zirconia stoichiometry.

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Section: Ni-al Alloys On Sapphiresupporting

confidence: 83%

Section: Ni-al Alloys On Zirconiamentioning

confidence: 99%