Effect of Zr addition on the interfacial reaction of the SiC joint brazed by Inconel 625 powder filler

•Inconel 625 filling powders with different amounts of pure Zr addition are used to braze SiC ceramic. Sound SiC joints are obtained at 1400 °C.•Zr is beneficial in suppressing the formation of graphite, which is a mechanically detrimental product of the reaction between Ni and SiC. When Zr addition reaches 40 wt%, the interface shows no sign of graphite.•Thermodynamic calculations prove that Zr’s activity surpasses that of Ni as the Zr content increases. Zr replaces Ni as the dominating element that reacts with SiC. A dense and consecutive ZrC layer is thus formed along the interface.•The room-temperature shear strength of the SiC joint with no graphite reaches 81.97 MPa, which is almost three times higher than that of the joint with graphite.