Flash joining of 3YSZ and 430 SS using Ag–CuO filler

Abstract Conventional reactive air brazing (RAB) of stainless steel (SS) to ceramic components usually encounters Cr oxidation and joint embrittlement problems due to high temperature and long dwelling time. Herein, 3 mol% yttria-stabilized zirconia (3YSZ) and 430 SS were joined using an Ag–CuO filler in seconds at relatively low temperatures (875 °C–1050 °C) with the assistance of a direct current passing through the seam. The applied current promoted the melting of the filler and rapid filling of the gap due to Joule heating effect. Also, it facilitated atomic/ionic transport and interfacial reaction. Key joining parameters including current density, joining time and furnace temperature were investigated, and a maximum joint strength of 158 ± 9 MPa was achieved at a current density of 4 A/cm2 for 30 s at 950 °C, which is approximately 50% higher than that of the RAB joints. The formation of AgCu4Zr and Zr-rich intermetallic phases at the 3YSZ/Ag and Ag/430 SS interfaces, respectively, together with the suppression of the growth of Cr-containing oxide, was responsible for the robust joining.