Brazing of zirconia to titanium using pure gold: Physicochemical aspects

The main objective of this study is to investigate the influence of several experimental parameters on the evolution of the joint microstructure and interfaces during brazing of zirconia with titanium using pure gold foils 25–150 µm thick. The brazing experiments were carried out under high vacuum at 1080–1100°C with 3–60 minutes of holding time. Cross sections of the joints were characterized by SEM with EDX analysis, TEM and X-ray diffraction. Four intermetallics and a Ti-Au solid solution were formed at Au / Ti interface and a submicron Ti₂O₃ layer at Au / ZrO₂ interface. The interdiffusion in Au-Ti intermetallics is so fast that brazing with thin gold foils (25–50 µm) can lead to a total consumption of the liquid Au. To avoid isothermal solidification of the joint and obtain a thin and continuous Ti₂O₃ layer, low temperature, thick gold foil and short holding time are recommended for the brazing process.