Rapid joining of heterogeneous ceramics with a composite interlayer under the action of an electric field

Joining heterogeneous ceramic oxides (e.g., zirconia (ZrO₂), alumina (Al₂O₃)) is important to widen their application horizon. Unfortunately, the joining of heterogeneous ceramics is hindered by dissimilar microstructures. Herein, a composite of 3 mol.% Y₂O₃-stabilized ZrO₂ (3YSZ) and Al₂O₃ was used as interlayer (ZrO₂-Al₂O₃, ZA) to form 3YSZ-ZA-Al₂O₃ joint under the influence of an electric field, which reduced the joining temperature and joining time. The joint strength attained steady state with current and joining time being beyond the threshold. The strength of the 3YSZ-ZA interface decreased and that of ZA-Al₂O₃ interface increased with increasing Al₂O₃ content in ZA. The strength of the 3YSZ-ZA interface is higher than that of the ZA-Al₂O₃ interface under the same joining parameters, and this was ascribed to the higher oxygen vacancies diffusion rate in 3YSZ than in Al₂O₃. The joint was formed by the connection of 3YSZ and Al₂O₃ ceramics to the respective grains in ZA.