Surface, grain-boundary and interfacial energies in Al₂O₃ and Al₂O₃-Sn, Al₂O₃-Co systems

Abstract

Using the multiphase equilibrium method for the measurement of contact angles, the surface and grain-boundary energies of polycrystalline Al₂O₃ in the temperature range of 1473 to 1923 K were determined. Linear temperature functions were obtained by extrapolation for both quantities between absolute zero and the melting point of Al₂O₃. The temperature dependence of the surface and grain boundary energies can be expressed as

$$\gamma _{{\rm A}l_2 O_3 } = 2.559 - 0.784 \times 10^{ - 3} T(J m^{ - 2} )$$

and

$$\gamma _{{\rm A}l_2 O_3 - Al_2 O_3 = } 1.913 - 0.611 \times 10^{ - 3} T(J m^{ - 2} )$$

respectively. The interfacial energies of Al₂O₃ in contact with the molten metals tin and cobalt revealed a linear dependence on temperature.