A joint of 3mol\%$Y_2O_3$-Tetragonal Zirconia Polycrystals was brazed with a 50Ag-50Cu-xTiwt\% (x=0.5, 2.0) alloy at $900\circ \!C$. The microstructures and crystal structures of reaction layers formed between the Zirconia and the brazing alloy were investigated by X-ray, TEM analysis. The composition distribution was examined in cross sectional specimen by AES. Also the method for preparing cross-section TEM specimens from ceramic-metal braze joints relies on masking the brazing alloy so that metallic portion was shield in order to avoid preferential thinning of the metallic alloy during ion-milling.
The reaction layers of the Cramic/Metal joint vary mainly with braze-holding time and Ti concentrations. The reaction layer formed between zirconia and Ag-Cu-0.5wt\%Ti for 10min. at $900\circ \!C$ is only the one continuous layer. This layer was about 0.65um thick and has monoclinic structure of the space group A2/m (with a lattice parameter 4.18 A) was identified as $\alpha$-TiO formed of equiaxed about 0.15um-diameter grains by electron diffraction analysis.
For zirconia / Ag-Cu-2.0wt\%Ti brazed for 10min. at $900\circ \!C$, Two reaction layers were formed. The first layer is a 0.45um-thick $\alpha$-TiO layer formed on the zirconia surface. The second reaction layer is about 3-4um thick and it separated the $\alpha$-TiO layer from the brazing alloy. The structure of this layer is diamond cubic of the space group Fd3m. It has reported that this phase is $Ti_3Cu_3O$ with a lattice parameter of 11.24 A. As braze-holding time is 60min., a elongated grain formed between the $\alpha$-TiO layer and $Ti_3Cu_3O$ is $\delta$-TiO. Its crystal structure is hexagonal of the space group P6/mmm.
