Microstructures and interfacial behavior of zirconia/stainless steel joint prepared by pressureless active brazing

ZrO₂ ceramic/stainless steel joints were fabricated by pressureless brazing with Ag-Cu filler metals and TiH₂ powders. The microstructures and elemental distributions of the joint cross-section as well as the reaction products at the ceramic/filler interface were analyzed using SEM, EDS, XRD and XPS. The results showed that there existed three zones with a distinguished difference in microstructure crossing the brazing interlayer. A double-layer structure including a reaction layer and a sublayer was formed at the ZrO₂/filler interface, where Ti⁴⁺, Ti²⁺ and Zr²⁺ were located based on the XPS spectra. It is further found that Ti originated from TiH₂ coating diffused into the whole interlayer. The high activity of neonatal Ti caused the reactions of Ti/ZrO₂ and Ti/Cu, resulting in the interfacial phases such as Ti₃Cu₃O, CuTi₃ and Zr.