Wetting of ceramic-metal and ceramic-ceramic interfaces

Contact angles of the metal-ceramic interface in a heating process were measured until the metal melted. Ag on BaTiO₃ disks melted with an almost hemispherical shape at an obtuse angle and did not wet to BaTiO₃. Metal Ag on superconducting Ba₂Y ₁Cu₃O_7-δ showed better wetting than in the case of BaTiO₃, even at an obtuse angle. The same experiments were carried out for ceramic-ceramic interfaces such as Bi ₂(TiO₃)₃ on BaTiO₃ and Pb(Mg _1/3Nb_2/3)O₃ (PMN) on BaTiO₃. Bi₂(TiO₃)₃ showed very good wetting, and it spread very quickly into BaTiO₃, whereas the relaxor PMN never spread. The results seem to be closely related with two phase mixing patterns of both materials. The microstructures of the interfaces were also investigated, and the mechanisms of bonding are discussed