Sintered Al2O3 was joined to Ni–Cr steel by the active metal brazing route with Ag–Cu–Zr brazing alloys containing Sn or Al. A single ZrO2 layer with a monoclinic structure was formed at the Al2O3 /brazement interface by the migration of Zr in the molten brazing alloy to the Al2O3 surface, followed by a redox reaction between the Al2O3 and Zr. The remainder of the brazement formed a Cu–Ag eutectic alloy. Precipitates CuZr2 and Cu–Zr–Al were formed in the brazements of the Ni–Cr steel/ Al2O3 joints brazed with Ag–Cu–Zr alloys and Al containing Ag–Cu–Zr alloys, respectively. On the other hand, no precipitates were formed in the brazement of the Ni–Cr steel/Al2O3 joints brazed with Sn containing Ag–Cu–Zr alloys. The Ni–Cr steel/ Al2O3 joints brazed with Sn containing Ag–Cu–Zr alloys showed much higher fracture shear strengths than those brazed with Ag–Cu–Zr alloys or Al containing Ag–Cu–Zr alloys.