Joining of Si 3 N 4 to Si 3 N 4 was performed using newly developed rapidly-solidified CuNiTiB brazing foils of different thickness, three-point bending tests then being employed at room temperature to measure the strength of the joints. The microstructures of the joints were observed and the element area distribution of Cu, Ni and Ti was examined by scanning electron microscope with an X-ray wave-dispersion spectrometer. The results of the strength test show that when using rapidly-solidified brazing filler foils of suitable thickness (for example, 40 μm and 80 μm) the joint strength was increased greatly (up to 402 MPa and 380 MPa respectively) compared with the use of paste brazing filler of the same alloy. Moreover, the fracture form of the Si 3 N 4 /Si 3 N 4 joints also varied with the change of strength. The thickness of the brazing foils used has an important effect on the corresponding joint strength, reasons for which are discussed.