The sessile drop technique was used to measure the temperature dependence of the contact angle of liquid Ag and Cu in contact with polycrystalline yttrium oxide at 1333 to 1773K in an Ar-4%H2 atmosphere. A combination of the experimental results with literature data on non-wetted and non-reactive oxide/liquid metal systems permitted the calculation of the surface energy of Y2O3 giving,

γsv(J/m2) = 2.278 - 0.000391T

Under the same atmospheric conditions, thermal etching experiments performed on grain boundaries which intersected the surface of the polycrystalline ceramic permitted the determination of the groove angles with respect to temperature and time, and indicated that the grain-boundary energy of Y2O3 was given by:

γss(J/m2) = 1.785 - 0.000306T

Surface and Grain-Boundary Energies as Well as Surface Mass Transport in Polycrystalline Yttrium Oxide. G.Triantafyllou, G.N.Angelopoulos, P.Nikolopoulos: Journal of Materials Science, 2010, 45[8], 2015-22