Pressureless brazing of zirconia to stainless steel with Ag–Cu filler metal and TiH2 powder

Partially stabilized zirconia was joined to stainless steel by pressureless active brazing with Ag–Cu filler metal and TiH2 powder. Microstructures, microchemistry and reaction products of the brazing seam were analyzed. The effects of brazing temperature and holding time on the joint shear strength were also investigated. The results showed that there existed three zones in the brazing seam and a double-layer structure at the ZrO2/filler interface. Due to the difference in brazing condition, the microstructures including the thicknesses and compositions of the three zones and two layers were different. It is further found that Ti originated from TiH2 coating diffused into the whole interlayer, resulting in the reaction products such as CuTi3, Ti3Cu3O, Cu4Ti3, NiTi2, Ni3Ti and Ti. The maximum joint shear strength of over 90 MPa was obtained due to the improved interface bonding.